Eureka!, science and technology, secondary cycle one : student textbook B [1B] 9782765202806, 276520280X, 9782765202875, 2765202877

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Laboratory Instruments and Equipment Stirring rod and magnetic stir bar

Dropping pipette and dropper bottle

Quad-beam balance

Stopwatch

Graduated cylinder Round-bottom flask

Dynamometer Beakers and beaker tongs

Petri dish

Cleaning brushes

Alcohol burner and wire mesh with stand

Funnel and funnel stand

Test tubes, rubber stoppers, test-tube stand and test-tube tongs

Erlenmeyer flasks, rubber stoppers and crucible tongs

Wash bottle

Litmus paper

Set of weights

Hot plate

Slides and cover glasses

Spatula

Safety glasses Retort stand, ring clamp and universal clamp Microscope

Mortar and pestle

Thermometer

Pipettes Overflow can

Eureka! Science and Technology • Secondary Cycle One Student Textbook B Inés Escrivá, Chantal Ouellette, Denis Pinsonnault, Mary Zarif, Trân Khanh-Thanh © 2008 Les Éditions de la Chenelière Inc. Editor: Annie Fortier Coordinators: Claire Campeau, Marielle Champagne Copy Editor: Ginette Gratton Proofreader: Renée Bédard Layout: Infoscan Collette, Québec Graphic Designer: Infoscan Collette, Québec; Dessine-moi un mouton Image Researchers: Marie-Chantal Laforge, Patrick St-Hilaire Book Cover Designer: Arto Dokouzian

Acknowledgments The Editor wishes to thank the following consultants for their pedagogical expertise and invaluable collaboration in bringing this work to fruition: Denis Fyfe and Brigitte Loiselle, Centre de développement pédagogique pour la formation générale en science et technologie; Annie Huberdeau, Vice-Principal, Commission Scolaire (C.S.) de la Rivière-du-Nord; André De Lafontaine, Teacher, C.S. du Chemin-Du-Roy.

English Version Project Manager: Philip Fine Copy Editors: Robb Beattie, Sarah Haggard, Michelle Mulder Pedagogical Consultant: Heather Usher, Laurentian Regional High School, Sir Wilfrid Laurier School Board Proofreaders: Zofia Laubitz, Wendy Scavuzzo Layout: Transcontinental Transmédia Printer: Transcontinental Printing

The Editor wishes to thank the following people for their scientific revision carried out with expertise and great generosity: Philippe Angers, Eng., Service des infrastructures, transport et environnement – Wastewater Treatment Plant; Jocelyne Blouin, Meteorologist; Bertrand Brassard, M.Sc., Coordinator of Educational Services, Musée minéralogique et minier de Thetford Mines; Daniel Borcard, Ph.D.Sc., Université de Montréal; Michel Caillier, Doctorate in Pedology, Université Laval; Pierre Chastenay, M.Sc., Montréal Planetarium; André Chulak, BFI Canada landfill site; Concept Naval Réjean Desgagnés Inc.; Marc Constantin, Ph.D.Sc., Université Laval; Marie Lorraine Côté, Laboratory Technician, C.S. de Montréal; Hélène Crevier, M.Sc.; Daniel Dufort, M.Eng., Division Manager, Atwater Plant, City of Montréal; Serge Gaudard, M.A., Curator, Musée minéralogique et minier de Thetford Mines; Dominic Goulet, Jr. Eng.; Éric Guadagno, M.Sc. Université de Montréal; Renée Gaudette, horticulturist, Montréal Botanical Garden; André Laperrière, Eng., Laboratoire des technologies de l’énergie de Shawinigan – Institut de recherche d’Hydro-Québec; Serge Laurendeau, Agence de l’efficacité énergétique; Richard Martel, Ph.D.Sc., Université de Montréal; Michel Nepveu; Pierre Payment, Ph.D.Sc., INRS – Institut Armand-Frappier; Lucie Saint-Germain, Laboratory Technician, C.S. de la Seigneurie-des-Milles-Îles; Jean-Paul Viaud, Curator, Exporail Canadian Railway Museum; François Wesemaël, Ph.D.Sc., Université de Montréal.

CHENELIÈRE ÉDUCATION

We wish to thank the following people in particular for their careful evaluation and insightful comments during the development of this collection: Diane Beaulieu, Teacher, C.S. des Découvreurs; Nadine Demuy, Teacher, C.S. de la Rivière-du-Nord; Caroline Dubé, Teacher, C.S. de la Seigneurie-des-Mille-Îles; Martin Dubé, Teacher, C.S. de la Seigneurie-des-Milles-Îles; Martin Dugas, Teacher, C.S. de Montréal; Nathalie Flamand, Teacher, C.S. de la Rivière-du-Nord; Mélanie Fortin, Teacher, C.S. de la Capitale; Guillaume Gobeil, Teacher, C.S. au Cœur-des-Vallées; Myriam Larue, Educational Consultant, C.S. de la Seigneurie-des-MillesÎles; André Hardy, Teacher, C.S. des Trois-Lacs; Mélanie Payant, Teacher, C.S. des Affluents; Mélanie Plante, Teacher, C.S. des Premières-Seigneuries.

5800, rue Saint-Denis, bureau 900 Montréal (Québec) H2S 3L5 Canada Téléphone : 514 273-1066 Télécopieur : 450 461-3834 ou 1 888 460-3834 [email protected]

All rights reserved. No part of this book may be reproduced in any form or by any means without written permission from the Publisher. ISBN 978-2-7652-0287-5 Legal deposit: 2nd quarter 2008 Bibliothèque et Archives nationales du Québec Library and Archives Canada Printed in Canada            We acknowledge the financial support of the Government of Canada through the Book Publishing Industry Development Program (BPIDP) for our publishing activities. These programs are funded by Québec’s Ministère de l’Éducation, du Loisir et du Sport, through contributions from the CanadaQuébec Agreement on Minority-Language and Second-Language Instruction. Chenelière Éducation wishes to thank the Gouvernement du Québec for the financial support granted through its tax credit program for book publishing (SODEC).

The Editor wishes to thank the following students for their generous participation in photo shoots: Catherine Boily, Alexandre Chenel, Joanie Corbey, François Côté Paquet, Jean-Philippe d’Aoust, Kevin Del Tejo-Sanchez, Gensom Dos Goncalves, Amélia Gontero, Fajana Haque, Anne Lafortune-Rabbat, Valérie Laniel, Carolane Lortie, Stéphanie Lovato, Maxime Michaud, Juan Sebastian Millán Gómez, Myriam Montreuil, Tanfwiq Rahimuddin, Dimitri Rateau Valcin, Charles Hugo St-Hilaire, Raphaëlle St-Pierre Damini, Sylvia Tran and Vivianne Tran. The English team wishes to thank translator Linda Anderson for her help with specific engineering terms.

Foreword y into the world of science and Eureka! invites you on a voyage of discover the serie s, this one offers a unique technology. Like the previous textbook in al kingdoms, matter and technology. opportu nity to explore the plant and anim A, you probably realized why it is After completing the activities in Textbook When you study scie nce, you are important to study scie nce and technology. c thought and procedu re that has learning about the whole history of scientifi more and find answers to important evolved over time. You will want to know whole new perspective. For example, questions, and you will see the world from a ing, that water is a precious resource, you will discover that the Universe is expand ge and that the planet’s resources that it is possible to slow down climate chan are not unli mited. you will notice the progress you are As you perform the activities in Textbook B, your observation skills will improve. making. You r interest in nature will grow, and ribing scientifi c or technolo gical You will become more comfortable in desc your classmates. You will learn how phenomena and explaining your findings to oning and experimentation process. to solve problems based on a specific reas e proc edu re that scientists have Grad ually, you will learn to follow the sam knowledge. This year, you will learn developed and applied in their search for i-aquatic envi ronments and the water about some fascinating topics, such as sem interesting activities, like preparing cycle. You will also be carr ying out some very launching your own perfume. a game show on human development and in it, inst ead of just talking about it. Eureka! lets you stud y science by taking part er in science. In any case, you will This series might inspire you to pursue a care can apply to other fields too. On have acquired knowledge and skill s that you book series will help deepen your behalf of the entire team, I hope this text share with the other living creatures understanding of the amazing world that you around you.

Trân Khanh-Thanh Editorial Director of the Eureka! series

Foreword

III

Table of Contents Textbook Layout

. . . . . . . . . . . . . . . . . . . . . . . . . . . VIII

Unit 2 The Balance of the Planet . . . . . . . . . . . . . . . . . . 44

Part 1: The Units

Chapter 1 The Water Cycle . . . . . . . . . . . . . . . . . . . . 46 Activity 1 The Movements of Water . . . . . 48 Activity 2 Evaporation and Transpiration . . . . . . . . . . . 49

Unit 1 The Diversity of Ecosystems: A Treasure . . . .

2

Chapter 1 The Terrarium: An Ecosystem in Miniature . . . . . . . . . . .

4

Activity 1 Every Creature Has a Name . . . Insects: Some Surprising Characteristics . . . . . . . . . . . . . .

Activity 3 Disturbing Data . . . . . . . . . . . . 51 Activity 4 Condensation . . . . . . . . . . . . . . 53

6 7

Activity 2 The Hunt . . . . . . . . . . . . . . . . . . 10 Activity 3 Make Yourself at Home! . . . . . . 13

Activity 5 The Movements of the Atmosphere . . . . . . . . . . . . . 55 Activity 6 Why the Difference? . . . . . . . . . 57 A Mountain Range’s Effect on Precipitation . . . . . . . . . . . . 58

Activity 5 Weekly Observations . . . . . . . . . 17

Activity 7 The Movement of Water in the Ground . . . . . . . . . 59 After It Rains, What Happens to the Water? . . . . . . . . . . . . . . . 61

Activity 6 Microscopic and Primitive . . . . . 18

Review Activity A Special Supplement . . . 62

Activity 4 A Bug’s Life . . . . . . . . . . . . . . . . 15 The Life Cycle of Insects . . . . . . . 16

Activity 7 Multiple Interrelations . . . . . . . . 19 Review Activity A Research Report . . . . . . 21 Chapter 2 The Forest: An Ecosystem on a Natural Scale . . . . . . . . . 22 Activity 1 The Forest in My Life . . . . . . . . 24 Activity 2 Forests of the World . . . . . . . . . 25 Distribution of the World’s Forests . . . . . . . . . . . . . 26 Activity 3 Who Lives Here? . . . . . . . . . . . . 28

Chapter 2 Biking for a Greener Planet . . . . . . . . . . . . 63 Activity 1 The World of Levers . . . . . . . . . 65 Activity 2 Pedal Power . . . . . . . . . . . . . . . 68 Activity 3 The Human Body: A High-Performance Machine . . 70 At Your Own Pace . . . . . . . . . . . 71 Activity 4 A Very Fragile Planet . . . . . . . . 72 Greenhouse Gases . . . . . . . . . . . 73

Activity 4 Finding the Way Home . . . . . . . 29 Magnetic North and Geographic North . . . . . . . . . . . 30

Review Activity The Bicycle: A User’s Guide . . . . . . . . . 74

Activity 5 Feeding the Birds . . . . . . . . . . . 31

Chapter 3 Inventing Solutions . . . . . . . . . . . . . . . . . . 75

Activity 6 Identifying Trees . . . . . . . . . . . . 33 The Unknown Tree . . . . . . . . . . . 34

Activity 1 The Paper Clip Challenge . . . . . 77

Activity 7 Discovering Trees . . . . . . . . . . . 35 Activity 8 An Oxygen Factory . . . . . . . . . . 36 Activity 9 A Variety of Colours . . . . . . . . . 38 Paper Chromatography . . . . . . . . 40 Review Activity A Forest Story . . . . . . . . . 41 My Discoveries

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Unit 1 Project My First Job . . . . . . . . . . . . . . . . . . . . . 43

IV Table of Contents

Activity 2 Archimedes’ Principle . . . . . . . . 79 Activity 3 Don’t Rock the Boat! . . . . . . . . 81 Activity 4 Steadying the Course . . . . . . . . 83 Review Activity The Wind in Your Sails . . . . . . . . . . . 85 My Discoveries

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Unit 2 Project Necessity Is the Mother of Invention . 88

Unit 3 The Adventure of Living Organisms . . . . . . . . . 90 Chapter 1 A Fascinating Development . . . . . . . . . . . . 92 Activity 1 Reproducing and Evolving . . . . 94 The Cradle of Life . . . . . . . . . . . 95 Activity 2 Sex Cells . . . . . . . . . . . . . . . . . . 96

Activity 2 What Is Soil Used For? . . . . . . . 130 Different Types of Soil . . . . . . . . 131 Activity 3 Thirsty Soil . . . . . . . . . . . . . . . . 132 Activity 4 Too Much Salt in the Soil? . . . . 134 Mineral Salts and Soil . . . . . . . . 136 Activity 5 The World of Rocks . . . . . . . . . 137

Activity 4 Puberty Already! . . . . . . . . . . . . 99

Activity 6 Minerals . . . . . . . . . . . . . . . . . . 138 What Lies Hidden Underground? . . . . . . . . . . . . . . . 140

Activity 5 The Cycle of Life . . . . . . . . . . . . 100

Review Activity Potted Flowers . . . . . . . . . 141

Activity 3 Extracting DNA . . . . . . . . . . . . . 97

Review Activity Our Story . . . . . . . . . . . . . 101

Chapter 2 Solutions and Mixtures . . . . . . . . . . . . . . . 142

Chapter 2 Healthy Habits for a Healthy Body . . . . . . 102

Activity 1 Preparing Mixtures . . . . . . . . . . 144

Activity 1 A Look at What You Eat . . . . . . 104

Activity 2 Heterogeneous or Homogeneous? . . . . . . . . . . . 146 Heterogeneous Mixtures . . . . . . . 148

Activity 2 Canada’s Food Guide . . . . . . . . . 105 Activity 3 Surprising Saliva . . . . . . . . . . . . 107 Activity 4 Eating Well to Stay Healthy . . . . 109 An Overview of the Digestive System . . . . . . . . . . . . 110 Activity 5 Gateway into the Cell . . . . . . . . 111 Activity 6 The Technology behind Our Food . . . . . . . . . . . . 113 Review Activity Camp Cuisine . . . . . . . . . . 115 Chapter 3 Do Not Enter! . . . . . . . . . . . . . . . . . . . . . . 116 Activity 1 An STD? What STD? . . . . . . . . . 118 Activity 2 At the Speed of Light . . . . . . . . 119 Activity 3 A Baby? Now? . . . . . . . . . . . . . . 120 Review Activity The Information Challenge . . . . . . . . . . . . . 121 My Discoveries

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Unit 3 Project It’s My Life . . . . . . . . . . . . . . . . . . . . . 123

Activity 3 Separating Mixtures . . . . . . . . . 149 Using Distillation to Extract the Essence of Aromatic Plants . . . . . . . . . . . 150 Activity 4 Mixtures in Everyday Life . . . . . 151 Review Activity Hidden in a Mixture . . . . 152 Chapter 3 Perfume Makes Perfect “Scents” . . . . . . . . 154 Activity 1 Do You Have Flair? . . . . . . . . . . 156 Perfumes of the World . . . . . . . . 158 Activity 2 Taking Care of Your Nose . . . . . 159 The Perception of Odours . . . . . . 160 Activity 3 A Field Survey . . . . . . . . . . . . . . 161 Activity 4 Extracting a Delicate Flower . . . 162 Activity 5 The Birth of a Fragrance . . . . . . 164 The Music of Perfume . . . . . . . . 165 Activity 6 A Production Line of Scents . . . 166

Unit 4

Review Activity Perfume: The Work of a “Nose” . . . . . . . . . . . . . 167

Creating Your Own Perfume . . . . . . . . . . . . . . . . 124 My Discoveries

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

Chapter 1 Soil: A Priceless Resource . . . . . . . . . . . . . 126 Activity 1 Is All Soil the Same? . . . . . . . . . 128

Unit Project 4 Launching a New Perfume . . . . . . . . . 169

Table of Contents

V

Part 2: Encyclopedia . . . . . . . . . . . . . . . . 170 The Material World . . . . . . . . . . . . . . . . . . . 172 Section 1

Section 2

The Properties of Matter . . . . . . . . . . . . . . 174 Non-Characteristic Properties of Matter . . . . . . . . . . . . . . . . . . . . . . . . . . 175 Characteristic Properties of Matter . . . . . . . . . . . . . . . . . . . . . . . . . . 188

The Atom . . . . . . . . . . . . . . . . . . . . . . . . . 203 The Elements . . . . . . . . . . . . . . . . . . . . . . 204 The Molecule . . . . . . . . . . . . . . . . . . . . . . . 209

The Living World . . . . . . . . . . . . . . . . . . . . . 212

Section 2

The Diversity of Life Forms . . . . . . . . . . . Species . . . . . . . . . . . . . . . . . . . . . . . . . . . Habitat . . . . . . . . . . . . . . . . . . . . . . . . . . . Evolution . . . . . . . . . . . . . . . . . . . . . . . . . .

214 216 224 235

Reproduction of Living Organisms . . . . . . 238 Asexual and Sexual Reproduction . . . . . . . 240 Reproduction in Plants . . . . . . . . . . . . . . . 240 Reproduction in Animals . . . . . . . . . . . . . 250 Reproduction in Humans . . . . . . . . . . . . . 257

VI Table of Contents

. . . . . . . . . 276 . . . . . . . . . 277 . . . . . . . . . 277 . . . . . . . . . 284

The Earth and Space . . . . . . . . . . . . . . . . . 286 Section 1

General Characteristics of the Earth . . . . . The Earth’s Internal Structure . . . . . . . . . . The Biosphere . . . . . . . . . . . . . . . . . . . . . . The Atmosphere: A Protective Envelope . . The Hydrosphere: The Distribution of Water on the Earth . . . . . . . . . . . . . . . . . . The Lithosphere . . . . . . . . . . . . . . . . . . . .

298 302

Geological Phenomena . . . . . . . . . . . . . . . The Earth in Motion . . . . . . . . . . . . . . . . . Volcanoes: The Wrath of Vulcan . . . . . . . . Earthquakes: When the Earth Trembles . .

312 313 322 325

Orogenesis: Mountain Formation . . . . . . . Erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . The Water Cycle . . . . . . . . . . . . . . . . . . . . Winds: Aeolus’ Choice . . . . . . . . . . . . . . . Natural Energy Sources . . . . . . . . . . . . . . .

328 329 332 334 340

Section 3 Astronomical Phenomena . . . . . . . . . . . . . Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Law of Universal Gravitation . . . . . . . The Birth of the Solar System . . . . . . . . . The Earth . . . . . . . . . . . . . . . . . . . . . . . . . The Moon . . . . . . . . . . . . . . . . . . . . . . . . .

344 345 351 352 359 368

Transformation of Matter . . . . . . . . . . . . . 190 Physical Changes . . . . . . . . . . . . . . . . . . . 191 Chemical Changes . . . . . . . . . . . . . . . . . . 193 Conservation of Matter . . . . . . . . . . . . . . . 194 Pure Substances and Mixtures . . . . . . . . . 195

Section 3 Organization of Matter . . . . . . . . . . . . . . . 202

Section 1

Section 3 Life-Sustaining Processes . . . . Characteristics of Living Organisms . . . . . . . . . . . . . . . . The Cell . . . . . . . . . . . . . . . . . . Two Vital Functions of the Cell

Section 2

288 290 291 292

The Technological World . . . . . . . . . . . . . . 372 Section 1

Section 2

Topic 3 How to Apply the Design Process . . . . . . . . . 433

374 376 378 382 385

Topic 4 How to Conduct a Research Project . . . . . . . 436

Raw Material, Material and Equipment . . . . . . . . . . . . . . . . . . . . . 386

Topic 7 How to Draw Diagrams . . . . . . . . . . . . . . . . . 446

Engineering . . . . . . . . . . . . . . . . . . . . . . . . The Design Process . . . . . . . . . . . . . . . . . . Specifications . . . . . . . . . . . . . . . . . . . . . . Technical Diagrams . . . . . . . . . . . . . . . . . . The Manufacturing Process Sheet . . . . . . .

Technological Systems . . . . . . . . . . . . . . . Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . Basic Mechanical Functions . . . . . . . . . . . Energy Transformation . . . . . . . . . . . . . . .

388 389 392 395

Section 3 Forces and Motion . . . . . . . . . . . . . . . . . . Types of Motion . . . . . . . . . . . . . . . . . . . . Effects of a Force . . . . . . . . . . . . . . . . . . . Simple Machines . . . . . . . . . . . . . . . . . . . . The Transmission of Motion . . . . . . . . . . . The Transformation of Motion . . . . . . . . .

404 406 410 412 419 423

Topic 5 How to Communicate Effectively . . . . . . . . . 438 Topic 6 How to Present Scientific Results . . . . . . . . . 440

Topic 8 How to Build a Model . . . . . . . . . . . . . . . . . . 450 Topic 9 How to Scale Down an Object . . . . . . . . . . . 451 Topic 10 How to Use Observation Instruments . . . . . . 452 Topic 11 How to Use Measuring Instruments . . . . . . . 457 Topic 12 How to Use Technological Instruments . . . . . 461 Glossary and Index . . . . . . . . . . . . . . . . . . . . . . . . . . . 464 Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475 Index of Cycle One Concepts . . . . . . . . . . . . . . . . . . 477

Part 3: Skills Handbook . . . . . . . 426 Topic 1 How to Work Safely . . . . . . . . . . . . . . . . . . . . 428 Topic 2 How to Apply the Experimental Method . . . . . . . . . . . . . . . . . . 430

Table of Contents

VII

Textbook Layout The textbook is divided into three parts: Part 1

Units

Part 2

Encyclopedia

Part 3

Skills Handbook

Units

Part 1

FOUR UNITS | 11 Chapters Preparation Phase The units are independent of each other and need not be completed in the order in which they appear.

Unit 2

The Balance of the Planet Summary Chapter 1 The Water Cycle . . . . . . . . . . . . . . . . . . 46

The Summary lists the chapter titles.

Chapter 2 Biking for a Greener Planet . . . . . . . . . 63 Chapter 3 Inventing Solutions . . . . . . . . . . . . . . . . 75

Being Aware of the Effect of Our Actions Every one of your actions has an effect on the environment. For example, when you ask your parents to take you somewhere by car, you contribute to gas consumption. Like it or not, the combustion of petroleum products is a probable cause of global warming, and the consequences of this warming are far reaching: desertification in certain regions and increased flooding in others. Of course, the simple decision to use a car does not make you alone responsible for such serious consequences. In many cases, though, you can choose to get to where you are going by bike, public transportation or simply by stretching your legs and walking. Each of these choices is an action that reduces your fuel consumption.

The scenario in the unit’s opening pages serves as an introduction to the activities and unit project.

Carefully study the pictures on the following page. 1. How do actions that humans perform every day disrupt the balance of the planet? 2. Discuss your answers with your classmates.

Project In the “Necessity Is the Mother of Invention” project at the end of this unit, you will design and build the small-scale prototype of a machine. To complete this project, you must apply the knowledge that you acquired in the unit’s three chapters about the water cycle and concepts of technology.

44

45

Each chapter begins with a scenario that serves as an introduction to the chapter activities and review activity. C HAPTER 1

E XPLORATION The Water Cycle

Your challenge in Chapter 1 is to describe the water cycle. You will also explain the factors that can disrupt it. • In Activity 1, “The Movements of Water” on page 48, you will learn about water’s movements on the planet. • In Activity 2, “Evaporation and Transpiration” on pages 49 and 50, you will see how water turns into vapour and spreads in the atmosphere. • In Activity 3, “Disturbing Data” on pages 51 and 52, you will analyze weather data gathered over the last 50 years. You will then speculate on forecasts that can be made from these data. • In Activity 4, “Condensation” on pages 53 and 54, you will study the conditions in which precipitation occurs. • In Activity 5, “The Movements of the Atmosphere” on pages 55 and 56, you will establish the cause of movements of the atmosphere and the water it contains.

Figure 1 Water and humans are in constant interaction.

Key Concepts The key concepts discussed in the chapter are listed here.

KEY CONCEPTS IN CHAPTER 1 • atmosphere • conservation of matter • hydrosphere • layers of the atmosphere • light • mass • physical change • states of matter • system (overall function, inputs, processes, outputs, controls) • temperature • volume • water (distribution)

What Happened? The media report natural disasters on a regular basis. Is the planet’s situation deteriorating? Or are we just better informed than in the past? Increasingly, we are recognizing that the planet is fragile. The pictures in Figure 1 show certain problems associated with the water cycle. Study these pictures carefully. Then, in teams, discuss your answers to the following questions: 1. To which situation does each picture in Figure 1 refer? 2. What similar situations have you experienced or observed? 3. Name some everyday occurrences in which you personally noticed disruptions in the water cycle. 4. What part did humans play in these occurrences?

• In Activity 6, “Why the Difference?” on pages 57 and 58, you will discover how neighbouring regions can have very different climates. • In Activity 7, “The Movement of Water in the Ground” on pages 59 to 61, you will describe factors affecting the movement of water on and in the ground. At the end of this chapter, in the review activity “A Special Supplement” on page 62, you will write an article for a special supplement distributed with your local newspaper. This supplement will present the water cycle.

5. Propose solutions to improve the situations you mentioned.

• water cycle • winds

46

UNIT 2

The Balance of the Planet

This page presents the main theme of the chapter (the challenge) and describes the activities, including the review activity.

VIII Textbook Layout

CHAPTER 1 The Water Cycle

47

The boomerang sidebars provide references to the Encyclopedia or to the Skills Handbook. Students need this information to carry out the unit activities.

Performance Phase A CTIVITY 3 Experimentation Don’t Rock the Boat!

The type of activity is shown beside the activity number. The student textbook includes five types of activities: communication, experimentation, analysis, research and technology.

Sometimes all it takes is one false move, one big wave, or a gust of wind to capsize a boat. In order to design a boat that can maintain its balance, you must fully understand the principle of stability.

Basic Mechanical Functions ENCYCLOPEDIA, pp. 392–394 The Transmission of Motion ENCYCLOPEDIA, pp. 419–422

The Experimental Method SKILLS HANDBOOK, pp. 430–432 The Dynamometer SKILLS HANDBOOK, p. 458

HISTORY

OF

Figure 33 The capsizing of a sailboat

I observe

SCIENCE

The shape of the keel alone does not guarantee a sailboat’s stability. Gerry Roufs, a Montréaler, perished in the Antarctic in January 1997. He had been competing with 17 others in the Vendée Globe single-handed round-the-world race. His sailboat likely capsized, as did the sailboats of two other contestants, Tony Bullimore and Thierry Dubois. Their occupants narrowly escaped death. The criteria for sailboat stability in such races are stricter now.

Certain boats capsize easily. Others are very stable. After capsizing, certain boats right themselves on their own. Others are very difficult to right.

History of Science This sidebar presents a historical figure or an event that has had an impact on the development of science and technology.

I develop a research question “What must I do to build a boat that is virtually capsize-proof and that will right itself easily if it does capsize?”

Procedure This pictogram indicates that the procedure for the experiment is provided in a worksheet.

I define the variables Your experiment must enable you to discover

Hull The exterior surface of a boat and its framework. Fixtures, such as the mast, keel and rudder are attached to it.

• how the shape of the hull influences a boat’s stability • how the distribution of a boat’s cargo can modify its stability • what the basic mechanical function of the keel is

‹

Keel The flat, heavy structure attached to the bottom of a sailboat. CHAPTER 3 Inventing Solutions

81

I define the variables Your experiment must enable you to verify how temperature influences the condensation of water vapour in the air.

I experiment

Equipment • safety glasses • three 50-mL beakers • a 200-mL beaker • a hot plate • a retort stand • a ring clamp • mesh or wire gauze

PROCEDURE

1

Using the available equipment and material, determine a procedure for conducting this experiment.

2

Draw a diagram of your set-up.

3

Have your teacher approve your procedure and diagram.

4

Conduct your experiment.

Material • 40 mL ice water • 40 mL lukewarm water • 250 mL boiling water

The sidebar definitions explain words that appear in blue print in the text. These definitions are also found in the glossary, at the end of the student textbook.

These symbols warn of a potential danger or recommend safety precautions. They are explained in the Skills Handbook.

NEWS FLASH . . . There is always evaporation near bridges. Under certain conditions, this water vapour condenses into droplets near the ground. It then forms a fog that greatly reduces visibility and makes crossing bridges dangerous. Sometimes, when the temperature is below 0°C, another difficulty arises: the bridge surface becomes coated with ice. In other words, the water droplets forming the fog freeze.

A Mountain Range’s Effect on Precipitation States of Matter ENCYCLOPEDIA, pp. 176–177

Temperature ENCYCLOPEDIA, pp. 181–183

This page provides additional information required to carry out an activity.

I analyze my results and present them 1

Describe the relationship that you discovered between air temperature and the condensation of water vapour.

2

Illustrate your description with a diagram.

3

Answer the following questions: a) In winter, why does your exhaled water vapour condense? b) Why is dew best observed in the morning?

4

Figure 11 A humid air mass passes over a mountain range Legend

When a mass of warm, moist air arrives at the foot of a mountain range, it has to rise to clear the obstacle. As the air rises, it cools. The water vapour it contains condenses. When the water droplets that form clouds are too heavy, they fall back down in the form of precipitation. That is why the climate is wet on that side of the mountain. When the air goes down the other side of the mountain, it becomes warmer and drier. Therefore, there is little or no precipitation. The climate is quite dry. Southern Alberta, for instance, has a semi-desert climate.

Average annual precipitation Over 4000 mm 2000 to 3999 mm 1600 to 1999 mm

If you were to repeat this experiment, how would you change the procedure? Explain why.

1200 to 1599 mm 800 to 1199 mm 400 to 799 mm 0 to 399 mm

54

UNIT 2

The Balance of the Planet YUKON

YUKON

NORTHWEST TERRITORIES

NORTHWEST TERRITORIES

Prince Rupert

Prince Rupert

Queen Charlotte Islands

BRITISH COLUMBIA

ALBERTA

Prince George

BRITISH COLUMBIA

N

W E

W E

Vancouver Scale 250

S

Kelowna

Vancouver Island Vancouver

Victoria 500 km

0

Scale 250

8

Calculate the buoyancy force exerted by the water on the object. Use the following formula. Record the results in your table.

9

Calculate the weight of the water collected in the beaker. Use the following formula. Record the results in your table.

10

Repeat steps 4 to 8 with the other objects.

11

Repeat the experiment using alcohol instead of water.

NEWS FLASH . . . Luckily for fish, ice floats on water. If this were not the case, ice would sink to the bottom of the water as soon as it was formed. In no time, all of the water in the lake would freeze. Fish would have no free water to swim in during winter, and they would die.

Buoyancy force Object’s Force indicated on the dynamometer of the water  weight  when the object is in the water

Weight of the Weight of the water, beaker  displaced water  and tray

58

Kelowna

Victoria 500 km

UNITED STATES

Figure 12 Average annual precipitation in British Columbia

r Rive

Vancouver Island

S

0

ALBERTA

Prince George

Fraser River

Queen Charlotte Islands

Fort Nelson

N

Further Study This sidebar suggests a supplementary activity that includes an interesting challenge. This Way to the Finish Line or This Way to the Project This sidebar describes elements of the current activity that may be useful in the review activity or project.

PACIFIC OCEAN

Fort Nelson

Dease Lake

ALASKA (U.S.)

bi a lum Co

News Flash This sidebar presents an interesting fact or story that has had an impact on the field of science and technology.

PACIFIC OCEAN

Dease Lake

ALASKA (U.S.)

UNITED STATES

Figure 13 Relief of British Columbia

UNIT 2 The Balance of the Planet

Weight of the empty beaker and tray

FURTHER STUDY How does a life jacket prevent someone from sinking in the water?

Figure 32 This model allows you to measure the buoyancy force of a liquid on

an object and to collect the displaced liquid.

I analyze my results and present them

This Way to the Review Activity Keep the discoveries that you made in this activity. They will help you confirm the buoyancy of your boat in the chapter review activity.

80

1

Explain in your own words the force that different liquids exert on objects that have been dropped into them.

2

Illustrate your explanation with a diagram.

3

Discuss your results with your classmates.

4

If you were to repeat this experiment, how would you change the procedure? Explain why.

UNIT 2

The Balance of the Planet

Textbook Layout

IX

Awareness and Integration Phase Review Activity In the review activity, students put into practice the concepts that they have learned and the competencies that they have developed throughout the chapter. Job Opportunity This sidebar describes a career in the field of science and technology. ICT This sidebar suggests that students use information and communications technologies, such as word processing, spreadsheet programs, the Internet and projectors.

MY

R EVIEW

ACTIVITY

1

Communication

A Special Supplement Communicating Effectively SKILLS HANDBOOK, pp. 438–439

JOB OPPORTUNITY Journalist Are you a newshound? Do you like to communicate? The life of a journalist may be for you. To be a journalist, you should be ready to delve into news that touches on politics, culture, science or other fields. If you want to eventually practise this profession, you will have to graduate from high school. Following that, several options are open to you. For example, you can get a college diploma in the Arts, Media and Theatre program at Vanier College. You can also study for an honours degree incommunications after two years of Cégep studies.

Some people believe that Canada could become the land of liquid gold. In fact, the demand for drinking water is so great that several countries would like to buy it from us. Some people are even talking of diverting a portion of our rivers’ waters to the United States. The local newspaper’s editorial board wishes to inform people in the area about the water cycle. It is therefore asking the students of your class to write a special supplement on the water cycle. 1

From the following questions, choose one or more that your team will answer in its article: a) What are the stages of the water cycle? b) How does an increase in the atmosphere’s temperature modify the quantity of water available? c) How is precipitation formed? d) Why does the atmosphere move? e) Why isn’t precipitation uniform everywhere? f) What happens to rainwater when it falls to the ground? g) What water-related dangers threaten us?

2

Each team must write an article of approximately 450 words, accompanied by a photograph or illustration of the chosen phenomenon.

Figure 17 In the U.S. state

of Colorado, canals have been built to transport drinking water. How can this action disturb the water cycle?

Checklist You can ask a Website to host an online version of your special supplement. You can also send an email to a list of potential readers to announce its publication.

62

1. I appropriately integrated the scientific information found in the chapter activities. 2. I correctly used scientific conventions and vocabulary seen in the chapter. 3. I wrote my text in the form of a news article.

UNIT 2 The Balance of the Planet

Checklist The checklist contains criteria that may be used for evaluation purposes.

My Discoveries This page summarizes the topics discussed in the unit.

DISCOVERIES

Chapter 1 • The water cycle consists of a series of endlessly repeating stages. Water evaporates from the ground, bodies of water and living organisms (through transpiration). It then condenses to form clouds. Finally, it returns to the ground in the form of precipitation (page 48). • Evaporation is quicker when the air is warm, dry and in motion (pages 49 and 50). • The planet’s average temperature has risen approximately 0.45°C over the past 25 years. Annual temperature variations are much greater than average temperature variations, however (pages 51 and 52). • In some places, the hotter the air is, the more water vapour and precipitation it can carry. In other places, hot air is more likely to dry out the ground. Condensation occurs when the air cools and can no longer contain all the water in the form of vapour (pages 53 and 54). • The greater the temperature difference, the more powerful the winds (pages 55 and 56). • Hot air rises and cold air drops. The farther hot air rises, the cooler it becomes. The farther cool air drops, the warmer it becomes (pages 57 and 58).

Chapter 2 • If a lever arm is shortened, then the force applied to the load will be weaker. However, the movement obtained will be greater. If a lever arm is lengthened, then the force applied to the load will be stronger. However, the movement obtained will be smaller (pages 65 to 67). • A bicycle pedal increases the force applied to the chain. When this movement is transmitted to the gears, it increases the motion of the back wheel (pages 68 and 69). • To obtain maximum efficiency on a long bike journey, a cyclist’s heart rate must remain at less than 85% of its maximum rate. The cyclist must also maintain a cadence of 60 to 80 pedal rotations a minute (pages 70 and 71). • The consumption of petroleum products causes the release of large quantities of carbon dioxide into the atmosphere. This contributes to an increase in the greenhouse effect and can have disastrous effects on the environment (pages 72 and 73).

Chapter 3 • In a comparison of two objects with similar masses, the object with the larger volume floats more easily (pages 77 and 78). • An object that floats displaces a quantity of liquid that is equivalent to its weight. The immersed portion corresponds to the volume of the displaced liquid (pages 79 and 80). • The deeper a boat’s keel extends and the heavier a boat is at the stern, the less likely the boat is to capsize, and the easier it is to right after capsizing. The larger a boat’s hull, the harder it is to capsize. However, a large hull makes righting a capsized boat more difficult (pages 81 and 82). • The farther forward a boat’s mast is, the more easily a boat points in the direction of the wind. The presence of a keel under its hull, at the back, helps point the boat in the direction of the wind (pages 83 and 84).

Unit Project The unit project encourages awareness and integration of the concepts that students have learned and the competencies that they have developed throughout the unit.

87

U NIT

PROJECT

2

Technology

Necessity Is the Mother of Invention How to Apply a Technological Procedure SKILLS HANDBOOK, pp. 433–435

Key Concepts in the Unit The key concepts discussed in the unit are listed here.

KEY CONCEPTS IN UNIT 2 • atmosphere • basic mechanical functions • components of a system • conservation of matter • design plan • effects of a force • energy transformation • hydrosphere

How do the people in a region surrounded by sea water get drinking water locally? This is your next challenge. You will design and build the prototype of a machine that can transform salt water into fresh water. An invention of this kind would be useful in Thailand, for instance, which borders the ocean. It would enable the country to produce drinking water locally.

• light

1

Examine the list of specifications and Figure 37 on the next page.

• list of specifications

2

• manufacturing process sheet

When water evaporates from the ocean, it essentially contains no salt. How can you imitate this phenomenon with your machine?

3

Design and build your machine using the technological procedure. You can base it on the diagram in Figure 37 on the next page.

4

You must give your teacher a report containing the following elements: • a design plan of your machine • a technical drawing of your machine • a manufacturing process sheet for your machine • a testing procedure • a record of results obtained during testing • a record of modifications made after testing

• mass • mechanisms that bring about a change in motion • mechanisms that transmit motion • physical and behavioral adaptation • physical change • simple machines • states of matter • system (overall function, inputs, processes, outputs, control) • technical drawing • temperature • types of motion • universal gravitation • volume • water cycle • water (distribution) • winds

88

X Textbook Layout

Checklist 1. 2. 3. 4.

I designed a machine that meets specifications. I proposed a solution that protects the planet’s balance. I tested my prototype and use my test results to improve it. I used effective work methods to develop my technological process.

Checklist The checklist contains criteria that may be used for evaluation purposes.

L’organisation du manuel Encyclopedia

PART 2

THE PROGRAM’S FOUR MAJOR AREAS

THE MATERIAL WORLD Matter: Natural and Synthetic Substances

A short text and flowchart introduce each area.

Take a look around you. Whether you are in class, at home or on your way to school, you see many objects of different shapes and sizes. Everything you see is matter. Some matter is natural, other matter is synthetic. A lot of matter is essential to life. You cannot live without natural matter like water and air. Synthetic matter can be important as well. What would you do if there were no chairs in your class, no buses to take you to school or no telephones?

The Overview summarizes each section.

However, the production and use of matter can have negative effects on the air we breathe and the water we drink. It is important to be aware of these effects and to use matter responsibly.

S ECTION 1

SECTION 1 The Properties of Matter

OVERVIEW

The Properties of Matter States of Matter p. 176

Solids

p. 176

Liquids

p. 176

Gases

p. 177

Particle Theory Mass

p. 178

Volume

p. 180

Temperature

p. 181

Non-Characteristic Properties of Matter

p. 175

Characteristic Properties of Matter

p. 188

Physical Changes

If you look around your class, you will notice that none of the students look exactly alike. Each student has certain characteristics or properties that help to identify them. For example, one student might have brown hair. However, this property alone is not enough to recognize the student because many of your classmates also have brown hair. This is called a non-characteristic property. On the other hand, no two fingerprints are alike, so they can be used to specifically identify someone (see Figure 1). A person’s fingerprints are a characteristic property.

The Material World

SECTION 2 Transformation of Matter

p. 190

Organization of Matter

p. 202

p. 177

p. 191

Chemical Changes

p. 193

Conservation of Matter

p. 194

Pure Substances and Mixtures

SECTION 3

p. 195

The Atom

p. 203

The Elements

p. 204

The Molecule

p. 209

172

The Celsius Scale p. 181

Non-Characteristic Properties of Matter p. 175

p. 174

Temperature and Atmospheric Pressure p. 182

Figure 1 Fingerprints are a charac-

teristic property because they can be used to specifically identify a person.

Temperature and Particle Theory p. 183

Non-Characteristic Properties of Matter Measuring Acidity or Alkalinity p. 185

SECTION 1 The Properties of Matter Acids and Bases

SECTION 2 The Material World

p. 183

Transformation of Matter

Litmus Paper

p. 186

pH

p. 186

Different Degrees of Acidity p. 187

SECTION 3

Universal Indicator Paper p. 188

Organization of Matter The Melting Point Characteristic Properties of Matter

The pH Meter

p. 188

p. 188 p. 188

The Boiling Point p. 188

Adapting through the Way They Reproduce

There are many substances in your class. Although there are numerous differences between them, they can be divided into three categories: solids, liquids and gases. This is what we refer to as states of matter.

Flowering plants have strikingly beautiful physical adaptations. Since these living organisms cannot move about, they sometimes use insects to help them reproduce. Insects carry the pollen (containing spermatozoa) of one flower to the pistil (containing ovules) of another flower (see Figure 29 on page 248). The members of the orchid family have many different ways of attracting insects (see Table 7).

It takes more effort to lift a desk than to lift a pencil. Why? One reason is that a desk contains more matter than a pencil. The quantity of matter of a substance is expressed by its mass. The mass of a desk is greater than the mass of a pencil. Look at the objects in your class. Your chair takes up more space than your pencil case. The space that matter occupies is called volume. The chair has a greater volume than a pencil case. Matter is anything that has mass and volume. Your body is able to feel things that are hot and cold. For example, you can easily distinguish hot water from cold water. The temperature indicates the quantity of heat an object or matter contains.

Table 7 Reproductive adaptations of the flowers of different species of orchids

In the next few pages, you will learn how to measure a few non-characteristic properties of matter. These properties are mass, volume and temperature. We will also discuss another non-characteristic property of substances: acidity and alkalinity.

ENCYCLOPEDIA

SECTION 1 The Properties of Matter

174 The Material World

The lady’s slipper (Cypripedium acaule) is a type of orchid found in Québec. An insect that lands on its flower must slip under the stamen to reach the nectar. Its body then becomes covered in pollen, which it carries over to the next flower.

175

A flowchart outlines the concepts discussed in each section.

The bee orchid (Ophrys apifera) can reproduce only with the help of certain species of wild bees. Its flowers look a lot like the female bee of these species. The male bees are therefore tricked into carrying the pollen from flower to flower.

Some orchids such as the Angraecum sesquipedale (also known as the star of Bethlehem orchid) store their nectar at the bottom of a spur. Only butterflies with very long snouts can reach this nectar and therefore pollinate the flower.

Some orchids have pleasant scents like chocolate, vanilla, coconut, cinnamon, cloves, corn chips, leather, or honey. Others have unpleasant odours like fish, rotting fruit, manure, or rotting meat. Some relase their perfume only at night to attract moths.

Memory Check

Memory Check Students can use this sidebar to review the concepts that they have studied.

1. Give two physical or behavioural adaptations of the Arctic fox to the Arctic climate. 2. Goats of a certain species have soft pads under their hooves that stick to rocks. Is this an adaptation to climate, the way they move, or the way they communicate? 3. You are given the skull of an unknown animal. You notice that it has incisors only in its lower jaw and has no canines. On the other hand, its premolars and molars are very large and flat. What do you think this animal ate?

4. a) How can a male bird communicate its desire to mate with a female? b) How does a pack of wolves indicate to another pack of wolves the limits of its territory? c) How can a bee tell the other bees in its hive where to find food? 5. Describe the physical adaptations orchid species use to attract insects.

SECTION 1 The Diversity of Life Forms

Skills Handbook

PART 3

231

STRATEGIES AND TECHNIQUES TOPIC

10

How to Use Observation Instruments

The Light Microscope

Observation instruments are used to extend your senses. They help distinguish important elements that can help you solve scientific and technological problems. In this topic, you will learn how to use three instruments: a magnifying glass, a light microscope and a binocular microscope.

How to use a magnifying glass

Parts

A magnifying glass can be used to closely examine items, such as a stamp, a rock sample or an insect. Follow these instructions when using a magnifying glass:

The microscope is used to magnify objects that are too small to be seen with the naked eye. To use a microscope, you must be familiar with its parts and their functions (see Figure 26).

The Magnifying Glass Properties •

A magnifying glass is a biconvex lens. In this type of lens, the edges are thinner than the centre. The lens can be glass or plastic (see Figure 25).

•

The more domed the lens, the greater the magnification.

•

A magnifying glass can magnify an image from 2 to 20 times.

1

Place the magnifying glass as close as possible to your eye.

2

Bring the studied object closer to the magnifying glass until you obtain a clear image.

lA Eyepiece

lI

Pointer

lB

Body

lC

Revolving nosepiece

lE

Stage

lF lG

Stage clips

lH

Light source

lJ

Arm

lK

Coarse-focus knob

Revolving nosepiece This revolving disk holds the objective lenses. It rotates so that you can use different lenses.

lD Objective lenses The objective lenses magnify your specimen. Each objective lens has a different power of magnification. A light microscope usually has four lenses that magnify the object 4, 10, 40 and 100. Magnification can be calculated by multiplying the number on the eyepiece (for example, 10) by the number on the lens (for example, 4). In this example, an object will appear 40 times larger under the microscope than to the naked eye.

The Skills Handbook presents strategies and techniques used in science and technology.

Stage The stage holds the slide. An opening in the centre of the stage allows light to pass through the slide.

lF

Stage clips The stage clips hold the slide in place on the stage.

lG

Condenser The condenser directs the light toward the specimen. It includes the diaphragm, which controls the amount of light that reaches the specimen.

lH

Light source The light source illuminates the specimen.

lI

Pointer The pointer is the line that you see when you look through the eyepiece. You can use the pointer to identify a specific area in the field of vision.

lJ

Arm The arm connects the base to the body.

Fine-focus knob

lM Base

lK

Coarse-focus knob This knob brings the image into rough focus.

lL

Fine-focus knob This smaller knob brings the image into sharp focus. It is used after the coarse-focus knob.

lM Base

Figure 25 A biconvex lens has thin

SKILLS HANDBOOK

Body The body is made up of the eyepiece and the objective lenses.

lC

Condenser

lL

452 Topic 10

Eyepiece The eyepiece is the part that you look through. In most microscopes, the eyepiece magnifies the object 10 times (10).

lB

lE

lD Objective lenses

edges and a thick centre.

lA

The base supports the microscope.

Figure 26 The various parts of a microscope

SKILLS HANDBOOK

Topic 10

453

Textbook Layout

XI

Unit 1

The Diversity of Ecosystems: Summary Chapter 1 The Terrarium: An Ecosystem in Miniature . . . . . . . . . . . . . . . . . . . . . . 4 Chapter 2 The Forest: An Ecosystem on a Natural Scale . . . . . . . . . . . . . . . . 22

Treasures to Share In 2006, over 33 million people visited Canada. Each visitor spent an average of $718 during their stay. The number of people who visit Québec from other provinces often surpasses 5 million. In addition, people make an estimated 40 million trips of all kinds within the province. Throughout Canada, tourism generates about 585 000 jobs. Each region in Québec has a wide variety of ecosystems. 1. Do you know some of the ecosystems that exist in your region? 2. What interest might tourists have in these ecosystems?

2

A Treasure

Advertising Designer

Op

po Jo rt b un i

ty

Imagine that your region wants to increase tourism and that the regional tourism bureau has just published this job opportunity in the local paper.

The advertising designer will be responsible for advertising and marketing the region’s tourism industry. This person will work primarily in the environmental sector and will also manage print, radio and television advertising campaigns. Required skills • mastery of information and communication technologies • mastery of the written language

Benefits • base salary and benefits • car provided • expenses covered for visits to the region’s tourist attractions • laptop computer How to apply Interested candidates must present an advertisement for one of the region’s ecosystems. The advertisement must be in an electronic format. It may be in the form of a video clip, a radio or television spot, a website, a script or another media format.

Project At the end of this unit, as part of the project “My First Job,” you must fulfil the application requirements listed in the job offer: publicize an ecosystem through an advertisement designed for your choice of electronic transmission. The two chapters in this unit will help you learn more about semi-aquatic and forest ecosystems.

3

C HAPTER 1 KEY CONCEPTS IN CHAPTER 1 • acidity/alkalinity • cellular components visible under a microscope • characteristics of living organisms • ecological niche • habitat • physical and behavioural adaptation • plant and animal cells

The Terrarium: An Ecosystem in Miniature A Living Environment Under Observation You might have tried, at some point, to raise insects in a jar or terrarium. If so, you know that you cannot just put a bit of soil in the jar and expect the insects to survive. What else do they need? 1. What do you think insects and small animals need to survive? 2. How does their natural environment meet their needs?

• reproduction in animals

3. How could an artificial environment meet these needs?

• species

4. Imagine putting certain living organisms in a terrarium.

• taxonomy • types of soil

UNIT 1

a) Which ones would still be there after several weeks? Why? b) What would you be able to learn by observing living organisms in this re-created environment?

4 The Diversity of Ecosystems: A Treasure

E XPLORATION 1 Your challenge in Chapter 1 is to carry out an experiment, following the steps outlined in the experimental method. You must re-create a semi-aquatic ecosystem in a terrarium. Over several weeks, you will raise a number of small living organisms in the terrarium: plants, worms, insects, amphibians and so on. You will observe this living environment and make some surprising discoveries. • In Activity 1, “Every Creature Has a Name” on pages 6 to 9, you will learn to identify insects and discover some of their characteristics.

Semi-aquatic ecosystem A container space made up of a shoreline, a shallow body of water and all the living organisms that inhabit this environment.

Terrarium A container in which we reproduce an ecosystem in order to raise small living organisms.

• In Activity 2, “The Hunt” on pages 10 to 12, you will capture insects and small animals that are adapted to a semi-aquatic environment. • In Activity 3, “Make Yourself at Home!” on pages 13 and 14, you will reconstruct the ecosystem of your specimens. • In Activity 4, “A Bug’s Life” on pages 15 and 16, you will research one of the insects in your terrarium and present your findings to the class. Observing a Terrarium • In Activities 5 to 7, you will observe the phenomena occurring in the artificial ecosystem that you created, and then you will analyze them. – In Activity 5, “Weekly Observations” on page 17, you will fill in an observation sheet each week. – In Activity 6, “Microscopic and Primitive” on page 18, you will observe microscopic living organisms. – In Activity 7, “Multiple Interrelations” on pages 19 and 20, you will use your observations to figure out what is happening in your terrarium. In the review activity at the end of this chapter, “A Research Report” on page 21, you will present your research results, your analysis and your discoveries in a report.

Tip! If there is not enough space to use one terrarium for each team, you can choose to use a single terrarium for the whole class.

CHAPTER 1

The Terrarium: An Ecosystem in Miniature

5

Insects: Some Surprising Characteristics Insects are invertebrates belonging to the arthropod class. Invertebrates do not have internal skeletons. The surface of the arthropod’s body is rigid, in order to protect and support the internal organs. This is why we say that they have an external skeleton (also called an exoskeleton). Insects are found everywhere, from deserts to frozen lakes. They have adapted to all environments.

The Insect’s Body

HISTORY

Part

tics

Head

It has two eyes, a pair of antennae and the buccal apparatus (mouth parts).

Thorax

It is made up of three segments, each of which has a pair of legs. The second and third segments also have wings, if the insect is winged.

Abdomen

It contains the digestive and respiratory systems, the heart and the reproductive organs.

ABDOMEN

George Brossard is a passionate entomologist and insect collector. In 1990, he and Pierre Bourque, who was then director of the Montréal Botanical Gardens, founded the Montréal Insectarium. It has become the largest insectarium in North America and among the largest in the world. Every year, over 400 000 people come to view the 4000 specimens on display. You can also see about 100 living species and … eat a few insects! In summer, you can wander around gardens designed to attract insects. The Insectarium’s scientific collection includes 140 000 insect specimens.

SCIENCE

Table 1 The characteristics of the main parts of an insect’s body

OF

Insects come in many different shapes, colours and adaptations. However, the adult insect’s body is almost always made up of three parts: a head equipped with antennae, a thorax and an abdomen. The thorax has three pairs of legs and often two pairs of wings. The Latin word insectum actually means “cut” or “sectioned.”

Posterior wing

Anterior wing Posterior leg

THORAX Compound eye HEAD

Antenna Buccal apparatus Median leg

Anterior leg

Figure 2 The main parts of an insect’s body (in this case, a dragonfly)

CHAPTER EXPLORATI1

The Terrarium: An Ecosystem in Miniature

7

A Buccal Apparatus Adapted to Diet Scientists have discovered that the buccal apparatuses of different insects are adapted to their diets (see Table 2). Table 2 Types of buccal apparatuses in insects

Species

Diet

Grasshopper

Grinder

The grasshopper eats blades of grass.

Mosquito

Stinger-sucker

The female mosquito bites to suck up the blood of her prey and to provide nutrients for the development of her eggs.

Sucker

The butterfly drinks nectar.

Fly

Sucker-licker

The fly has a liquid diet: fruit nectar, meat juices and so on.

Bee

Sucker-licker

The bee drinks nectar.

Butterfly

8

Type of buccal apparatus

UNIT 1

The Diversity of Ecosystems: A Treasure

1000 Eyes for Better Vision Insects can have simple eyes or compound eyes. The fly’s head in Figure 3 is only 2 mm long. On the right, enlarged 240 times, we see the hexagons of one of its two compound eyes. The compound eyes of insects can be made up of thousands of these hexagons. Each hexagon corresponds to a small sight organ. Many insects also have, on top of their heads, two or three small simple eyes, or ocelli. These are actually light catchers and not real sight organs.

a) The head of a fly, photographed with an electron microscope.

b) A close-up of a compound eye with its multiple hexagons.

Figure 3 The complex eyes of a fly

Legs Adapted to Various Ways of Moving Around

a) Z-shaped legs allow for a quick escape by hopping. For example, the grasshopper.

b) These legs enable insects that visit flowers to collect the pollen, which sticks to their hairs. For example, the bee.

c) These legs are perfect for walking and climbing on plants. The extremities are equipped with small pads (as well as claws), which serve as suction cups. For example, the fly.

d) These legs enable the insect to swim, due to the long hairs that act as oars. For example, the diving beetle.

Figure 4 Adaptations of insect legs

CHAPTER 1

The Terrarium: An Ecosystem in Miniature

9

ACTIVITY 2 The Hunt Taxonomy ENCYCLOPEDIA, p. 217

Habitat ENCYCLOPEDIA, p. 224

Ecological Niches ENCYCLOPEDIA, pp. 232–234

How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

Experimentation

In this activity, you will have to capture the living organisms that will live in your terrarium. In the following activity, you will reconstruct their habitat.

I observe Even though you may not see them, there are often invertebrates and small vertebrates (like amphibians and reptiles) around you. Table 3 presents animals that would suit a semi-aquatic terrarium. It will be easier to capture these animals if you know something about their habits and where they take shelter. This knowledge will allow you to set effective traps. Table 3 Animals that live in a semi-aquatic ecosystem

Group

Description

Examples

Worms

Their bodies are made up of rings.

Earthworms

The Montréal Biodôme has successfully reconstructed a number of living environments. You can visit four different ecosystems from the Americas: tropical forest, boreal forest, St. Lawrence marine ecosystem and polar ecosystem. You can also follow these ecosystems through the seasons.

Mollusks

They have soft bodies and live in damp environments. They move around on a muscular foot. Some, such as snails, have soft bodies protected by a shell.

Snails, slugs

Arthropods

They have rigid external skeletons and articulated limbs.

Insects, myriapods (such as centipedes), arachnids (such as spiders), crustaceans (such as pill bugs)

Amphibians

They are cold-blooded and breathe partly Frogs, salamanders through their skin. They live on the land and in water. Their larvae are aquatic.

Reptiles

They are cold-blooded and move around by crawling. Their limbs are often very small or absent. They lay eggs, and their skin is covered in scales.

Vertebrates

Invertebrates

NEWS FLASH . . .

Snakes, lizards

I develop research questions 1. “What are the habits of animals that live in a semi-aquatic ecosystem, and where do they take shelter?” 2. “What traps should I use to catch a wide variety of small animals for my terrarium?”

UNIT 1

10 The Diversity of Ecosystems: A Treasure

I define the variables 1. You must: • capture small live animals in different ecological niches in a habitat: under rocks, in the soil, on trees, on flowers and vegetation, in the water and so on • capture both diurnal and nocturnal animals • prepare traps suited to the animals that you want to catch • set up your traps and check them at least twice a day 2. Throughout the hunt, pay special attention to the habits of the animals that you capture: shelter, diet and so on. I experiment

Diurnal Active during the day.

Nocturnal Active at night.

PROCEDURE

1

Create a list of equipment and material that you have available (in class and at home) to build your traps.

2

Develop a procedure. You must describe how you will use different traps to catch the following types of animals: • nocturnal • ones that live in the soil • diurnal • ones that live in water • ones that spend most of their • consumers time in flight • decomposers or scavengers

3

Discuss your ideas with your classmates. Choose the traps that you will use.

FURTHER STUDY Write the specifications for your traps. Imagine that you are providing the list to a company that wants to make and sell your traps.

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NEWS FLASH . . . Scientists estimate that there are a billion insects for every human on the Earth! Occasionally we see spectacular displays of this abundance. In Morocco in 1931, a swarm of locusts formed that weighed between 70 000 and 80 000 tonnes altogether. This swarm swept down on an area of just 1000 m2. West Africa succumbed to a similar invasion in 2005, which caused famine and destruction over thousands of square kilometres.

4

Draw a diagram for each of your traps. Clearly indicate the equipment and material that you will need.

5

Have your teacher approve your list of equipment and material, your choice of traps and your diagrams.

6

Organize your hunt. In addition to animals, you must collect the following items: • enough soil to fill in the bottom of your terrarium • a number of plants with their roots (moss, clover, grass and so on) • some shelter (a rock, a piece of wood, dead leaves, a pine bough and so on)

7

Familiarize yourself with the observation and identification card in Figure 5, below. You must complete a card for each specimen that you capture. 1. Date and time of capture: For example: September 7, early evening 2. Place of capture: For example: A peat bog, in Blainville 3. Trap used: For example: A net 4. Biological notes (name of the plant that sheltered your animal, ambient temperature, soil humidity, animal’s way of life and so on): For example: The animal lives in water, it can fly,

it swims very quickly. 5. Identification: For example: a diving beetle Figure 5 A sample observation and identification card

8

Assemble your material.

9

Prepare your traps.

10

Set off on the hunt.

11

While waiting for the terrarium to be ready, keep your animals in a jar or a box with airholes. Provide some food and water.

I analyze my results and present them 1 In the field, for each specimen that you capture, provide the information in points 1 through 4 on an observation card like the one in Figure 5.

UNIT 1

2

Upon returning from the hunt, identify each animal (point 5) using the identification key that you used in the activity “Every Creature Has a Name” on page 6.

3

Were some traps more useful than others? Which ones? Why, in your opinion?

4

If you were to repeat this experiment, how would you change the procedure? Explain why.

12 The Diversity of Ecosystems: A Treasure

ACTIVITY 3 Experimentation Make Yourself at Home! Ecological Niches

I observe

ENCYCLOPEDIA, pp. 232–234

Biologists often reconstruct habitats or model phenomena in order to study them. Over the centuries, this method has enabled them to better understand nature. In this way, it has been possible to take steps to protect some of the planet’s living species and resources. Your terrarium is a model of a semi-aquatic ecosystem. The elements of your model must correspond as closely as possible to the elements in nature. For example, you will have to reproduce the habitats of your small tenants so they can occupy the same ecological niches that they did in the natural environment. The soil composition must allow for the circulation of air and water, the growth of plants, animal camouflage and the absorption of odours.

Types of Soil ENCYCLOPEDIA, pp. 307–310

How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

I develop research questions 1. “What characteristics of the natural environment do I need to reproduce in my terrarium?” 2. “How will I reconstruct each of these characteristics?” I define the variables 1. Your terrarium must mimic a semi-aquatic ecosystem. You must therefore pay attention to: • the composition of the soil • the presence of shelters or hiding places • the diets of the living organisms that it contains 2. You must be able to associate each part of your terrarium with an element in the natural environment.

I experiment

Cover

Hanging thermometer Small animals Plants A small container

Large container Soil Sand Charcoal

Equipment ent • an aquarium or a large transpar container with a solid base • a cover • a small container • a thermometer • a small shovel • a spray bottle Material • gravel • charcoal • sand ent • soil taken from a natural environm • water • absorbent cotton • a piece of string

Gravel Figure 6 The parts of a semi-aquatic terrarium

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13

JOB OPPORTUNITY Entomologist Are you fascinated by insects? Entomology may be the career for you! Professional entomologists are employed by the Ministère de l’Agriculture du Québec or by the Montréal Insectarium, or they are associated with research organizations. To practise this profession, you must first take a science program in Cégep, then complete a Bachelor’s degree in biology at university and, finally, specialize in entomology at the Master’s level. Amateur entomologists acquire their knowledge by studying subjects that interest them. Many end up working as entomological clerks, as technicians involved in raising insects or as guides.

Suggested Procedure Here is an example of a procedure for this experiment. You might want to suggest a different one. 1

Write the names of the members of your team on the large container.

2

Spread layers of gravel and charcoal as shown in Figure 6 on the previous page.

3

Choose a place for the aquatic zone, and put the small container there.

4

Spread the layer of sand. Make small hills in the sand with your fingers. Now add the soil.

5

Sow grass or clover seeds. Plant the vegetation you collected.

6

Water the land areas and fill the water container half full. Do not put too much water in the basin. You don’t want any of your tenants to drown in it.

7

Hang the thermometer using the string.

8

Add food (apple sections, oats, wet absorbent cotton balls and so on) and water.

9

Place your animals in the terrarium. Quickly close the lid.

10

Every week, collect new specimens. Add as many as possible to keep a good balance of the living organisms in your terrarium. As the environment is very small, carnivores (predators) will soon run short of food (prey). It’s up to you to find their favourite dishes!

Tip! From this point on, study the evolution of your terrarium and intervene as little as possible. Limit your activities to • watering the earth lightly, as needed • giving your carnivores food • adding living organisms

This Way to the Review Activity

Record the method that you used to build your terrarium, as well as the role played by each layer of soil. You will complete the analysis of your observations and present them in the review activity, “A Research Report.”

UNIT 1

I analyze my results and present them 1 Draw on what you have learned to describe the role played by the layers of gravel, charcoal, sand and soil in your terrarium. 2 Observe the phenomena that unfold in your miniature ecosystem over several weeks. Activities 5 to 7 (see pages 17 to 20) will guide your observations. 3 Complete the weekly observation chart that your teacher will give you. Instructions for filling in the chart can be found in Activity 5, “Weekly Observations” on page 17. 4 If you were to repeat this experiment, how would you change the procedure? Explain why.

14 The Diversity of Ecosystems: A Treasure

ACTIVITY 4 Research A Bug’s Life You know the common names of all the specimens in your terrarium. You will now conduct research on one of your insects. Following your teacher’s instructions, select an insect.

2

To learn more about your insect’s life cycle, read “The Life Cycle of Insects” on the next page.

3

Conduct research to find out: • your insect’s scientific (Latin) name • its physical description (size, eyes, antennae, buccal apparatus, wings, legs) • its ecological niche (habitat, shelter, diet, predators, social structure, role in nature) • its sexual characteristics and life cycle • its adaptations • its particular markings

SKILLS HANDBOOK, pp. 436–437

Write your research findings on the research worksheet handout that your teacher gives you.

5

Make a poster in the shape of your insect’s silhouette.

6

Glue your research worksheet on the back of your poster.

ENCYCLOPEDIA, pp. 250–256

How to Conduct a Research Project

1

4

Reproduction in Animals

You can use an encyclopedia or a CD-ROM database for your research. You can also download images or photographs to illustrate your poster. Don’t forget to reference your sources.

This Way to the Review Activity

Keep your poster about research on your insect. It will be helpful to you when you write up your research report.

Figure 7 The metamorphosis of an Old World Swallowtail butterfly

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The Life Cycle of Insects Life cycle The stages of development of a species, from conception to death.

Moult A phenomenon during which some animals renew their carapace, their external skeleton, their horns, their plumage, their fur and so on. The moult can occur at different points in the life cycle, depending on the animal.

Metamorphosis A change in the form, nature or structure of an animal. It is such a dramatic transformation that the animal is no longer recognizable as the same creature.

The life cycle of insects varies significantly, from a few days to a few years. Over this period, they undergo a series of transformations. Some are spectacular, such as moulting and metamorphosis.

Two Types of Metamorphosis Most insects (85 percent) undergo a complete metamorphosis, meaning that the larva is so different from the adult that it is often difficult to connect them. When a larva transforms into a pupa and then into an adult, this is called complete metamorphosis. If the larva transforms directly into an adult, this is called incomplete metamorphosis. Table 4 The stages of the two types of insect metamorphosis

Complete metamorphosis

Incomplete metamorphosis

Stage 1: egg The egg is produced when a male and a female gamete come together.

Stage 1: egg The egg is produced when a male and a female gamete come together.

Stage 2: larva The larva grows in a series of moults. Its only activity is to feed itself in order to develop.

Stage 2: larva The larva bears a strong resemblance to the the adult. However, it has no wings. It develops through a series of moults.

NEWS FLASH . . . The mayfly is a unique insect! Following its aquatic beginnings, the larva moves to the surface of the water, moults, and transforms into a winged individual. The mayfly is the only insect that has functional wings before reaching adulthood. At this stage, it is called a subimago or sometimes pre-adult.

Stage 3: pupa The insect generally encloses itself in a cocoon. Its organs rearrange themselves, and it becomes a pupa (also called a chrysalis in butterflies). This is the stage of real metamorphosis. Stage 4: adult (or imago) Once the metamorphosis is finished, the pupa’s envelope opens to free the adult insect. The insect is now able to reproduce.

UNIT 1

16 The Diversity of Ecosystems: A Treasure

Stage 3: adult (or imago) The adult’s wings form during the final moult. It will not grow any larger. It is now sexually mature.

ACTIVITY 5 Experimentation Weekly Observations pH

I observe

ENCYCLOPEDIA, pp. 186–187

Your specimens are now settled in your terrarium. But this does not mean they are safe from all danger! In fact, some will be devoured. Others will die of natural causes because they have a very short life cycle. As well, you may see animals appear that you did not think you had captured. Many discoveries await you. You must stay attuned to everything that happens in your terrarium. This activity will enable you to move to the next stage of the scientific method: the collection of data from observation. You will analyze your data in Activity 7, “Multiple Interrelations” on pages 19 and 20.

The pH Meter ENCYCLOPEDIA, p. 188

Ecological Niches ENCYCLOPEDIA, pp. 232–234

How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

NEWS FLASH . . . I develop research questions 1. “What are the physical conditions in my terrarium?” 2. “What are the relationships between the living things in my terrarium?” 3. “How does the number of specimens vary?” I define the variables You must collect information about: • the physical conditions in your terrarium: humidity, temperature, pH and so on • the relationships among living things, and between living things and their environment

The silk thread that a spider produces is five times stronger than a steel thread of the same diameter. It stretches more than nylon and is biodegradable. No other fibre possesses the same characteristics. Produced in large quantities, this thread could be used to make bullet-proof vests, suturing thread and fishing lines. Spider webs are attracting a lot of interest.

I experiment Suggested Procedure 1

Familiarize yourself with the observation chart that your teacher gives you.

2

Use the same equipment for each of your observations.

3

Once a week, fill in a weekly observation chart by following these steps: • Measure the physical conditions in your terrarium • Observe all of the elements in your terrarium • Take note of as many changes as possible that you observe • Take note of what has not changed • Make an inventory of the living things visible in your terrarium

4

Have your first weekly observation chart approved by your teacher.

Equipment • a soil pH meter • a soil thermometer • a hygrometer • a partial-immersion alcohol thermometer Material • a weekly observation chart

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ACTIVITY 6 Experimentation Microscopic and Primitive Plant and Animal Cells ENCYCLOPEDIA, pp. 278–279

How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

The Microscope SKILLS HANDBOOK, pp. 453–456

I observe You already know that all living organisms without exception are made up of cells. Animals and plants are multicellular, meaning they are made up of a collection of cells, each of which has its own function. A number of living organisms, however, are unicellular, meaning that they are composed of just one cell. Unicellular creatures, along with many multicellular creatures, are so small that you need a microscope to see them.

I develop a research question “In my terrarium, are there living organisms that are only visible under a microscope?” I define the variables 1. This experiment must enable you to use a microscope to observe living organisms in your terrarium that you cannot see with the naked eye. 2. You must also draw diagrams to record your observations. I experiment Suggested Procedure Here is an example of a procedure for this experiment.

Equipment • a microscope • two glass slides • a depression slide • a cover slide • a dropping pipette • a petri dish Material • adhesive tape • a piece of string

UNIT 1

1

Using a string and some tape, suspend a microscope slide in your terrarium.

2

Place another slide on the bottom of your terrarium.

3

Deposit a depression slide into your terrarium’s water basin.

4

Leave the slides in these positions for two or three days.

5

Take the slides out and observe each of them under the microscope. You must cover the depression slide with a cover slide.

6

Deposit some earth in the petri dish. Look at it under the microscope.

I analyze my results and present them 1 Draw a diagram to illustrate the most interesting phenomena that you observed. 2

Try to identify the living organisms that you observed.

3

If you were to repeat this experiment, how would you change the procedure? Explain why.

18 The Diversity of Ecosystems: A Treasure

ACTIVITY 7 Analysis Multiple Interrelations In Activity 5, “Weekly Observations,” you completed your observation charts. You saw that living organisms interact with each other and with their environment. These interrelations are connected to diet, social life and reproduction. For example, the frog that swims in the basin interacts with the water in the basin. In this activity, you must establish the greatest possible number of interrelations. 1

Look at your weekly observation charts. They will allow you to analyze the interrelations between the various elements in your terrarium. • Make an inventory of all of the living organisms and all of the nonliving elements that you observed in your terrarium. • Construct a classification network of the terrarium’s components, based on the model in Figure 8. This type of network is a tool for organizing your observations.

Ecological Niches ENCYCLOPEDIA, pp. 232–234

The Line Graph SKILLS HANDBOOK, p. 444

Interrelation A close relationship between two elements in an environment. These elements can be living or nonliving.

The Terrarium

Nonliving Elem ents

-Living Organisms

Consumers

Herbivores

Carnivores

Producers

Decomposers

Omnivores

Figure 8 A model of a classification network of the terrarium’s components

2

Using what you know, determine the role that each of the following elements plays in the lives of the living organisms in your terrarium: air, water, soil and light.

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19

R EVIEW

ACTIVITY

1

Analysis and Communication

A Research Report During their research, scientists carry out experiments or activities and record their observations. Then they must present results, observations and conclusions in a report or research article. This is the process that you have followed throughout this chapter. You must now present your results in a report. If your school were to have a science journal, your report should be suitable for publication in it. 1

Your research report should include, in this order, • a cover page • a table of contents • an introduction (that presents your work) • a description of the method that you used to build your terrarium (Activity 3)

2

Write up an analysis of your results that includes, in this order, • a description of the habitat that you aimed to re-create (Activity 2) • the observation charts and identification of your specimens (Activity 2) • your research sheet on the insect that you chose (Activity 4) • your weekly observation charts (Activity 5) • the diagrams of your observations with the microscope (Activity 6) • the classification network of your terrarium’s components (Activity 7) • your table of interrelations between the living organisms in your terrarium (Activity 7) • your food chain (Activity 7) • the answers to the analysis questions in the handout • your two line graphs (Activity 7)

3

Prepare your conclusion. It must answer the following question: “What did you learn from your observation of this re-created environment?”

How to Communicate Effectively SKILLS HANDBOOK, pp. 438–439

You could use word-processing and design software to format your research report.

Checklist This Way to the Review Activity

1. I drew conclusions based on my observations and the data that I obtained. 2. I included all of my observations and relevant documents in my report. 3. I presented my results in various forms (tables, diagrams, figures). 4. I respected the styles and conventions of science and technology.

Semi-aquatic ecosystems have specific characteristics that might attract tourists interested in ecology and the environment. How could you take advantage of these characteristics when it comes time to do the Unit Project, “My First Job”?

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C HAPTER 2 The Forest: An Ecosystem on a Natural Scale He Speaks for the Trees Way back in the days when the grass was still green and the pond was still wet and the clouds were still clean, and the song of the Swomee-Swans rang out in space. . . one morning, I came to this glorious place. And I first saw the trees! The Truffula Trees! The bright-colored tufts of the Truffula Trees! Mile after mile in the fresh morning breeze. And under the trees, I saw Brown Bar-ba-loots frisking about in their Bar-ba-loot suits as they played in the shade and ate Truffula Fruits. From the rippulous pond came the comfortable sound of the Humming-Fish humming while splashing around. But those trees! Those trees! Those Truffula Trees! All my life I'd been searching for trees such as these. The touch of their tufts was much softer than silk. And they had the sweet smell of fresh butterfly milk. Source: Dr. Seuss, The Lorax, 1971.

Dr. Seuss spoke of trees with a great deal of respect. In fact, trees are among the largest living organisms on the Earth, and they live longer than any other organism. Forests are vast ecosystems containing hundreds or thousands of trees. They have long been viewed as places that are barely accessible and sometimes even sacred.

UNIT 1

22 The Diversity of Ecosystems: A Treasure

1. What does the text tell you about the relationship between trees and other living organisms? 2. How useful do you find the forest in your daily life? 3. In your opinion, are the forests near you well protected? 4. Can studying forests teach you something? What, for instance?

KEY CONCEPTS IN CHAPTER 2 • acidity/alkalinity • air (composition)

Your challenge in Chapter 2 is to study the forests of the world, the forests of Québec and, finally, the trees that surround you. You will then see two important milestones in the life of a tree.

• asexual and sexual reproduction

• In Activity 1, “The Forest in My Life” on page 24, you will examine what a forest adds to your life and how it can be protected.

• design plan

• In Activity 2, “Forests of the World” on pages 25 to 27, you will see that trees’ various adaptations produce numerous forest types. • In Activity 3, “Who Lives Here?” on page 28, you will make an inventory of forest dwellers and draw a diagram of a food web. • In Activity 4, “Finding the Way Home” on pages 29 and 30, you will learn how a compass works. • In Activity 5, “Feeding the Birds” on pages 31 and 32, you will build a feeder for a species of bird. With it, this species will find food more easily, and you will have an easier time observing these birds. From the forest to the tree • In Activities 6 and 7, you will learn how to identify trees and uncover some of their secrets. – In Activity 6, “Identifying Trees” on pages 33 and 34, you will create a herbarium. – In Activity 7, “Discovering Trees” on page 35, you will research a tree of your choice.

• characteristics of living organisms • ecological niche • erosion • gametes • habitat • inputs and outputs (energy, nutrients, waste) • molecule • photosynthesis and respiration • physical and behavioural adaptation • population • reproduction in plants • reproductive organs • species • specifications • taxonomy • technical drawing

• In Activity 8, “An Oxygen Factory” on pages 36 and 37, you will discover a chemical reaction that is essential to life: photosynthesis. • In Activity 9, “A Variety of Colours” on pages 38 to 40, you will see how leaves change colour in autumn. Since the dawn of time, forests have inspired stories, poetry and paintings from artists around the world. In this chapter, you will notice that an artist’s work introduces each activity. At the end, in the review activity, “A Forest Story” on page 41, you must create an illustrated adventure story about a man or a woman who has chosen to live in the forest. CHAPTER 2

The Forest: An Ecosystem on a Natural Scale

23

ACTIVITY 1 Analysis The Forest in My Life NEWS FLASH . . .

It is Spring in the mountains. I come alone seeking you. The sound of chopping wood echoes Between the silent peaks. The streams are still icy. There is snow on the trail. At sunset I reach your grove In the stony mountain pass. You want nothing, although at night You can see the aura of gold And silver ore all around you. You have learned to be gentle As the mountain deer you have tamed. The way back forgotten, hidden Away, I become like you, An empty boat, floating, adrift.

Deforestation can have adverse effects when natural disasters strike. In 2004, Haiti experienced serious flooding. If the ground had not been destabilized through deforestation, much less damage (fewer landslides, for instance) might have occurred.

Source: Tu Fu, Written on the Wall at Chang’s Hermitage

For the Chinese poet Tu Fu, nature in springtime provided a backdrop for meditation. The forest is precious to humans. However, today the forest and its inhabitants are in danger. In this activity, you will use your knowledge to establish just how beneficial trees and forests are. You will also describe the threats that this ecosystem faces. Then, you will propose a solution to each of these threats. 1 2 3

Make a list of how people can use trees and the forest, as well as the advantages of such uses. Copy Table 6. Use your knowledge to complete the table. You must: • make a list of threats to the forest • propose solutions that you would put into practice if you governed the country • suggest concrete actions to fight these threats

Table 6 How to protect a threatened forest

This Way to the Review Activity What threats does the character in your adventure story face? What solutions can your heroine or hero apply to survive?

UNIT 1

Threats For example, fires due to carelessness

24 The Diversity of Ecosystems: A Treasure

Solutions If I were in power For example, I would conduct awareness campaigns

Concrete actions For example, avoid lighting fires in the forest

ACTIVITY 2 Analysis Forests of the World Erosion

“But that can only mean going into the Old Forest!” said Fredegar, horrified. “You can’t be thinking of doing that. It is quite as dangerous as Black Riders.” “Not quite,” said Merry. “It sounds very desperate, but I believe Frodo is right. It is the only way of getting off without being followed at once. With luck we might get a considerable start.” “But you won't have any luck in the Old Forest,” objected Fredegar. “No one ever has luck in there. You’ll get lost. People don't go in there.”

ENCYCLOPEDIA, p. 329

Source : J.R.R. Tolkien, The Lord of the Rings, 1. The Fellowship of the Ring, 1954–1956.

The forest described by the characters in The Lord of the Rings is very different from forests in Québec. In fact, forests are highly diversified. Because of this diversity, forests have been able to adapt to almost all terrestrial environments. Certain species of trees can withstand frost or the weight of snow. Others can withstand drought, heavy rainfall and sea salt. Still others adapt to different kinds of soil, different levels of acidity and so on. All these changes have produced the types of forests found on the Earth’s surface.

1

Study the map of the distribution of the world’s forests on pages 26 and 27.

2

Choose two of the types of forests. a) In your opinion, what conditions (heat, humidity, amount of sunlight) are favourable to the existence of these two types of forests? b) Name two species of tree found in these two types of forests.

3

Answer the following questions: a) What types of forest exist in Canada? b) What types of forest exist in Québec? c) The map shows places without forests. What are the climatic conditions in these places? d) In your opinion, do plants grow in these places? Explain your answer. e) In your opinion, what would be the impact of a forest’s disappearance (through clear-cutting, for instance)?

JOB OPPORTUNITY Park Warden The park wardens of Parks Canada are responsible for upholding the law and protecting public safety in Canada’s National Parks. These wardens conduct scientific and environmental research. In addition, they are involved in all matters related to the environment in the park: fire prevention and suppression, environmental management, and emergency protection of animals and plants. If this career interests you, you must obtain a bachelor’s degree in a discipline related to natural resources (biology, environment, forestry and so on), and then you have to take a training course given by the Royal Canadian Mounted Police and Parks Canada.

CHAPTER 2

The Forest: An Ecosystem on a Natural Scale

25

Tree savannah (450 million hectares)

Mediterranean forest (80 million hectares)

ARCTIC OCEAN

ASIA

AFRICA

PACIFIC OCEAN

ATLANTIC

INDIAN

OCEAN

OCEAN

OCEANIA

Scale at the Equator

ANTARCTIC OCEAN A N TA R C T I C A

CHAPTER 2

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27

ACTIVITY 3 Analysis Who Lives Here? Ecological Niches ENCYCLOPEDIA, pp. 232–234

A Population ENCYCLOPEDIA, p. 234

Marc-Aurèle Fortin Under the Elms, 1935

Photoperiod The length of the period of daylight in relation to the period of darkness. The photoperiod varies according to latitude and season. It regulates the activity period of living organisms.

As you can see from the painting by Marc-Aurèle Fortin, summer in Québec is a season of abundance. There is a profusion of food. The trees make the most of the photoperiod, and the soil is full of organic matter. Summer, too, is when the greatest number of inhabitants can be found in the forest. Ecologists regularly make an inventory of living organisms in a habitat. By observing living organisms, they can learn about the behaviour and interactions of various species. The inventory also helps ecologists pinpoint factors that can threaten the forest’s inhabitants. In this activity, you will make an inventory of the organisms that live in a maple forest in the summer. To do this, you will study a detailed picture of this typical Québec ecosystem. You will also recreate a food web.

This Way to the Review Activity Save your inventory and your food web. They will help you when writing your adventure story. UNIT 1

1

Study the picture provided by your teacher. Identify as many animal and plant species as possible.

2

Indicate the diet of each animal species that you identified.

3

Create the kind of food web that could be observed in such a habitat.

4

Compare your food web to those of your classmates. Correct it if necessary.

28 The Diversity of Ecosystems: A Treasure

ACTIVITY 4 Technology Finding the Way Home The woman led the children still deeper into the forest, where they had never been before. They made a great fire again, and the mother said, “Just sit there, children, and when you are tired you may sleep a little. We are going into the forest to cut wood, and in the evening when we are done, we will come and get you.” When it was noon, Gretel shared her piece of bread with Hansel, who had scattered his along the way. Then they fell asleep and evening passed, but no one came for the poor children. They did not awake until the middle of the night, and Hansel comforted his little sister and said, “Just wait, Gretel, until the moon rises, and then we shall see the crumbs of bread which I dropped along the way. They will show us our way home again.” When the moon rose, they set out, but they found no crumbs, for the many thousands of birds that fly about in the woods and fields had picked them all up. Source: Jacob Grimm and Wilhelm Grimm, “Hansel and Gretel,” in Children’s and Household Tales, 1812.

When you decide to explore the forest to observe various species, before going, you have to be sure that you can make your way home again! There are several ways of finding your way home. Of course, you can mark your path, like Hansel and Gretel did. There are other, safer ways to avoid getting lost, though. The simplest, most reliable way to find your direction is with a compass. Before using one, it is important to understand how they work. In this activity, you will learn about the compass. 1

Read “Magnetic North and Geographic North” on the next page.

2

Carefully study the compass that your teacher gives you.

3

Move the compass around a bar magnet (which represents the Earth). Observe the movement of the needle.

4

Using a design plan, describe how the compass works.

The Design Plan ENCYCLOPEDIA p. 382

How to Apply the Design Process SKILLS

HANDBOOK,

pp. 433–435

FURTHER STUDY If you don’t have a compass, you can still find north with the aid of a watch, the position of shadows, the North Star or any other star. Put yourself in the shoes of the ancient explorers. Discover and experiment with each of these methods of orientation.

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29

Magnetic North and Geographic North A magnet is an object that produces a magnetic field. Magnets have two poles: a north pole and a south pole. Opposite poles attract each other, while like poles repel each other.

Bar magnet A bar-shaped magnet. There are also horseshoe-shaped magnets, circular magnets and others.

DIRECTIONS IN TIME t 1269

Petrus Peregrinus observes that the opposite poles of a magnet are attracted to each other.

The Earth itself is an immense magnet because of the presence of a magnetic rock, magnetite, in its core. The planet can be compared to a magnet because it has two magnetic poles (called magnetic north and magnetic south) and because its magnetic field is similar to that of a bar magnet. A compass is also a magnet because its needle is magnetized and produces a magnetic field. In geography, we define magnetic north as the position indicated by the north pole of the magnetized needle of a compass. Magnetic north is not located at exactly the same place as geographic north (see Figure 9). Geographic north has a fixed position that corresponds to the Earth’s rotation on its axis. The site of magnetic north, however, varies from year to year. Right now, magnetic north is 1900 km from geographic north, toward Canada. The angle between these two norths is called the “magnetic declination.”

t 1302

Flavio Gioia perfects the compass and uses it regularly on his voyages. For a long time, other navigators who had never seen a compass considered him to be its inventor.

Magnetic declination

t 1934

Englishman Robert Watson-Watt defines the principle of modern radar.

Axis of the magnetic field Magnetic north

t 1960

The United States launches the first satellite navigation system (forerunner of the GPS).

Geographic north The Earth’s axis of rotation

Geographic south a) A bar magnet

b) The Earth’s magnetic field

Figure 9 The Earth resembles a bar magnet.

UNIT 1

30 The Diversity of Ecosystems: A Treasure

Magnetic south

ACTIVITY 5 Technology Feeding the Birds

5 The Technical Drawing ENCYCLOPEDIA, p. 383

How to Apply the Design Process SKILLS

Autumn Landscape in the Laurentians, unknown artist, circa 1860

1

Read the specifications on the following page.

2

Choose the species of bird for which you will be building your feeder.

3

Do some brief research on the feeding habits and anatomy of the bird that you have chosen. How will you adapt your feeder to the bird’s needs?

4

Make the technical drawing of your feeder.

5

Show your feeder’s characteristics to your teacher. In a few sentences, explain how you have adapted the feeder to the characteristics of the bird species that you have chosen.

6

Build your feeder.

7

Hang your feeder in an appropriate place. Add your bird’s favourite food. Evaluate the effectiveness of your creation.

pp. 433–435

NEWS FLASH . . .

In winter in Québec, birds must be patient when looking for food. Nature is barren, the ground is covered with a blanket of snow, and the days are short. Yet it is in winter that birds need more food to withstand the cold. You can make things easier for them by building bird feeders. The feeders must be adapted to the species that winter in your area. The best time to set up a feeder is autumn, when food becomes scarce. It is then best to leave the feeder up all year, because the birds will get used to having it around.

8

HANDBOOK,

Every second, a forest the size of a football field is destroyed. Nearly 80 percent of the world’s original forests are now gone. Those remaining are threatened by pollution and, above all, by logging that is carried out to meet the global demand for paper and wood.

This Way to the Project Bird-watching tours, during which people view birds and the places where they feed, are interesting attractions. The feeder that you make in this activity might be useful for the unit project.

CHAPTER 2

The Forest: An Ecosystem on a Natural Scale

31

FURTHER STUDY The wildlife of the forest leaves many signs of its presence. You can observe footprints, excrement, shelters, marks on tree bark and so on. You can also listen to sounds. This is how to learn the most about a forest’s inhabitants. Reconstruct an owl’s diet by analyzing the pellets that it drops on the ground. Your teacher will show you how.

Specifications Nature and Purpose of the Object A device allowing a species of bird to feed during the winter.

Construction From a physical perspective, the object must be: – made from inexpensive materials. From a technical perspective, the object must be: – built with sturdy materials – adapted to outdoor use, namely resistant to humidity, wind and cold – easy to fill with food – adapted to the chosen species of bird – transportable – light – protected from predators, such as cats – protected from animals that want the food, such as squirrels From an environmental perspective, the object must be made of materials that are: – not harmful to the environment – reusable, as much as possible

Use From a human perspective, the object must be: – attractive – easy to maintain and fill – easy to install

UNIT 1

32 The Diversity of Ecosystems: A Treasure

ACTIVITY 6 Analysis Identifying Trees Species

What is different about this tree? Of course, this sculpture does not look much like a tree in the forest. Observing trees helps you get to know them—a useful skill to have, for instance, when you want to find your way around the forest. In this activity, you will learn how to recognize certain species of tree. You will put together a herbarium with leaves that you collect and dry. You must then identify them using specific criteria.

First Part: Collecting and Drying Leaves 1 Collect tree leaves that are fairly dry, bright green, well developed and without any trace of disease. 2

3

ENCYCLOPEDIA, pp. 216–221

Herbarium A collection of dried, flattened and classified plants that can be preserved and studied.

Armand Vaillancourt, Arbre d’acier, steel sculpture, 1965

FURTHER STUDY

When you collect them, keep the following in mind: • Your leaves must come from trees, not bushes. • Collect leaves from at least 10 different species of trees.

Find a method of calculating the height of a nearby tree. Make sure no climbing is involved!

Dry your leaves according to your teacher’s instructions.

Second Part: Assembling a Herbarium When your leaves are fully dried, you can identify them. You can then also assemble your herbarium. 1

Read “The Unknown Tree” on the next page.

2

Using a glue stick, carefully paste each leaf of your herbarium to a thick piece of white paper.

3

Using the material that your teacher gives you, find the species of tree to which each leaf belongs.

4

Following the example in Figure 9 on the next page, write down relevant information under each leaf. The diagrams that your teacher shows you will help.

5

Create an original cover for your herbarium.

You can prepare an electronic herbarium by digitizing the leaves that you have collected.

This Way to the Review Activity The character in your adventure story must be able to identify trees. Now, you can choose the trees that your character will encounter from those species represented in your herbarium.

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33

The Unknown Tree Perennial A plant that lives longer than two years.

A tree is a perennial and ligneous plant. It is made up of organs, each with a specific function: stem, branches, roots, leaves, flowers, fruits and so on. Like any living organism, a tree develops, and it grows, reproduces, ages and dies.

Ligneous A ligneous substance is compact and fibrous. This substance forms the root, stem and branches of certain plants, including trees and bushes.

To identify a tree, we consider: • its adult height • its shape • the colour of its branches and bark

• • • •

the shape of its trunk the characteristics of its leaves its flowers, fruit and seeds its buds and so on

A tree is usually identified by the shape of its leaves. Table 7 Parts of the leaf that are used to identify a tree

Part

Description

Possible characteristics

Blade

The flat part of the leaf attached to the petiole

• Simple, composite • Narrow (in conifers) • Broad (in deciduous trees)

• Deeply veined, rounded, oval, oblong, triangular • Smooth, toothed, lobed

Twig

The small branch on which leaves grow

• Opposite

• Alternate

Lobe

An obvious separation in the blade, which is created by a deep or shallow sinus

• None • Rounded

• Toothed

Sinus

A shallow or deep gap separating two lobes

• None • Shallow

• Deep

Needles or scales

The narrow-bladed leaves on conifers

• Isolated

• Grouped in clusters

Type of tree: Deciduous Type of blade and position on twig: Simple, opposite Shape : Five lobes Contour: Toothed Type of lobe and sinus: Toothed lobe, deep sinus Date collected: September 25 Identification Common name : Sugar maple Latin name: Acer saccharum

Type of tree: Conifer Type of needle: Attached individually Shape : Narrow Date collected: September 25 Identification Common name : White spruce Latin name: Picea glauca Figure 10 Sample presentation of leaves in a herbarium

UNIT 1

34 The Diversity of Ecosystems: A Treasure

ACTIVITY 7 Research Discovering Trees Adapting through What and How They Eat

For three years he had been planting trees in this wilderness. He had planted one hundred thousand. Of the hundred thousand, twenty thousand had sprouted. Of the twenty thousand he still expected to lose about half, to rodents or to the unpredictable designs of Providence. Ten thousand oak trees remained to grow where nothing had grown before.

ENCYCLOPEDIA, pp. 227–229

Asexual or Sexual Reproduction ENCYCLOPEDIA, p. 240

Reproduction in Plants ENCYCLOPEDIA, pp. 240–249

How to Conduct a Research Project SKILLS HANDBOOK, pp. 436–437

low res

Source: Jean Giono, The Man Who Planted Trees, 1953.

The Man Who Planted Trees is a short story that inspired an animated film illustrated by Frédéric Back. As mentioned in the extract, not every seed becomes a mature tree. To develop, a tree must pass through several stages. Just like Jean Giono’s character, before reforesting an area, you must learn the various stages of a tree’s development. You also have to know the function of each part of a tree. 1

Choose a tree from the species in your herbarium.

2

Research your tree. You must know: • how its seeds germinate • • how it grows • how its fruits form • • how it disperses its seeds • its annual cycle • • how it adapts to winter

the parasites and other pests that harm the tree the name of its gametes and reproductive organs the kind of climate and soil to which it is adapted

3

Complete your research by specifying the function of certain parts of your tree: roots, bark, leaves, stem and stem interior, fruits, seeds and buds. Write your answers in a table.

4

Add to your herbarium the data that you collected in this activity. These data will be part of the introduction to your herbarium. Your introduction must also include a general outline of the contents of the herbarium.

5

Bind the pages and cover of your herbarium.

NEWS FLASH . . . To estimate a tree’s age, you can take a core sample from its trunk. (A core sample is a cylindrical sample extending from the tree’s bark to its centre.) You can then count the number of growth rings on the core sample. To estimate a fir tree’s age, you can also count the number of crowns that the branches form. Every crown represents a year. Add two or three years to your sum because the crowns of the first years leave no trace.

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35

ACTIVITY 8 Experimentation An Oxygen Factory Characteristics of Living Organisms ENCYCLOPEDIA, p. 277

A Grasshopper gay Sang the summer away, And found herself poor By the winter's first roar. Of meat or of bread, Not a morsel she had! So a begging she went, To her neighbour the ant, For the loan of some wheat, Which would serve her to eat, Till the season came round.

Inputs and Outputs ENCYCLOPEDIA, p. 280

Two Vital Functions of the Cell ENCYCLOPEDIA, pp. 284–285

The Composition of the Atmosphere ENCYCLOPEDIA, p. 293

Source: Jean de La Fontaine, “The Grasshopper and the Ant,” in Fables, Book 1, Fable 1, translated by Elizur Wright.

FURTHER STUDY In spring, a sweet sap can be extracted from a maple tree. This phenomenon is associated with photosynthesis. Study the way this sap is harvested and transformed into syrup.

I observe Unlike grasshoppers and ants, trees manufacture their own food. All summer long, they prepare food reserves in the form of sap. Trees benefit most from sunshine in the summer because that is when they are covered with mature leaves. Basically, leaves are the part that performs photosynthesis, the chemical reaction that enables trees to manufacture their own food. Summer is also the season when vegetation releases the most oxygen into the atmosphere, through photosynthesis. I develop research questions 1. “How does water circulate in plants?” 2. “How can I demonstrate that plants release oxygen?” 3. “Which gas in the atmosphere encourages plant growth?” I experiment 1 You will take part in the following three demonstrations: • transpiration of a plant • photosynthesis of an aquatic plant • growth factors of a plant

UNIT 1

2

Study Figures 11 to 13 on the next page. They will help you understand how to carry out each demonstration.

3

Study the results obtained in each demonstration.

36 The Diversity of Ecosystems: A Treasure

Figure 11 Transpiration of a plant

Figure 12 Photosynthesis of an aquatic

Figure 13 Growth factors of a plant

plant

I analyze my results and present them 1 Answer the following questions. They refer to the first demonstration. a) Where does the water that appears on the sides of the bag come from? b) Do all parts of the plant release water? Which part releases the most? c) In your opinion, what is the function of transpiration in plants? 2

Answer the following questions. They correspond to the second demonstration. a) Which conditions are necessary for bubbles to appear in the water? b) What gas is released in this experiment? How can it be identified?

3

Answer the following questions. They refer to the third demonstration. a) In what conditions have the plants been placed? b) Which plant seems healthiest? Why? c) Which factor most encourages plant growth?

4

Copy the diagram in Figure 14. Use your knowledge to complete it. INPUTS

input: origin:

In this space, draw the indispensable element that triggers the chemical reaction.

input: origin: input: origin: 5

OUTPUTS output: destination: output:

In this space, draw the part of the plant in which the chemical reaction occurs.

destination: output: Figure 14 The chemical reaction of

destination:

photosynthesis

In your opinion, what are the similarities and differences between photosynthesis and a plant’s respiration?

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37

ACTIVITY 9 Experimentation A Variety of Colours How to Apply the Experimental Method

The name—of it—is "Autumn"— The hue—of it—is Blood— An Artery—upon the Hill— A Vein—along the Road— Great Globules—in the Alleys— And Oh, the Shower of Stain— When Winds—upset the Basin— And spill the Scarlet Rain— It sprinkles Bonnets—far below— It gathers ruddy Pools— Then—eddies like a Rose—away— Upon Vermilion Wheels—

SKILLS HANDBOOK, pp. 430–432

Source: Emily Dickinson, “The name—of it—is ‘Autumn’”

I observe When you think of nature in autumn, you probably imagine the magnificent colours of the trees, as Emily Dickinson did in her poem. Have you ever wondered what the scientific principles are behind these phenomena?

Pigment A substance that is present in various tissues or organs and gives them their colouring.

Equipment • safety glasses • a petri dish • a mortar • a pestle • a pair of scissors Material • 5 g of fresh spinach leaves • 30 mL of sand • 25 mL of alcohol • a piece of filter paper cut in half

UNIT 1

I develop research questions “Where do the colours of autumn leaves come from? Is it the pigment that gives them their green colour that changes? Or are these colours present all year, but hidden by the green colour?” I define the variables Your experiment must enable you to observe the pigments that are present in a green spinach leaf. I experiment

PROCEDURE

1

Read “Paper Chromatography” on page 40.

2

Here are two clues that will help you to establish your procedure: • Paper chromatography is a procedure that separates chemical substances using absorbent filter paper. • With alcohol, you can extract coloured pigments from a purée of spinach and sand.

3

Using the partial equipment and material list on the left, develop a procedure for an experiment that will help you answer the questions in the “I develop research questions” section.

38 The Diversity of Ecosystems: A Treasure

NEWS FLASH . . . Certain sequoias in the Canadian and American west and certain Australian eucalyptuses are over 1000 years old. They can be over 100 m high and weigh up to 1000 tonnes. Can you imagine that? The elephant, the largest land animal, is 4 m high and weighs approximately 10 tonnes. The blue whale, the largest marine animal, is 40 m long and weighs approximately 100 tonnes.

4

Complete the equipment and material list.

5

Draw a diagram of your set-up.

6

Have your teacher approve your procedure, equipment and material list and diagram.

7

Conduct your experiment.

I analyze my results and present them 1 Draw your half of the filter paper after the chromatography. 2 Answer the following questions: a) What colour were the leaves at the beginning? b) What colours did you observe on the filter paper after the chromatography? c) Were the colours arranged in a specific order? Compare your results with those of the other teams. 3

Answer the questions in the “I develop research questions” section.

4

Read the excerpt from the article “An Exceptional Phenomenon” on the next page. It describes the delayed coloration of leaves in 2002.

5

Which factors trigger the coloration of leaves in fall?

6

Discuss your discoveries with your classmates.

7

If you were to repeat this experiment, how would you change the procedure? Explain why.

This Way to the Review Activity Make sure you are able to describe the functions of the parts of a tree (Activity 7). You must also be able to define the chemical reactions of photosynthesis and respiration (Activity 8). Furthermore, you must be able to explain the changes in colour that occur in leaves in the autumn (Activity 9). Each of these phenomena is important for life on Earth. They are also factors in your character’s way of life.

CHAPTER 2

The Forest: An Ecosystem on a Natural Scale

39

The Molecule ENCYCLOPEDIA, pp. 209–210

NEWS FLASH . . . Forest fires are very destructive. They are dangerous to animals and to people who work in the forest or live nearby. Did you know fires are a factor in the forest’s renewal, though? Certain trees, like the jack pine, cannot reproduce without fire. It makes their cones open, which releases their seeds.

UNIT 1

Paper Chromatography Every type of molecule in a pure substance has a characteristic mass. A water molecule, for instance, is lighter than a molecule of refined sugar. Paper chromatography uses this property to separate the different molecules in a substance. First, molecules can be dissolved in liquid, a little bit like salt in water. Next, filter paper can be dipped into this liquid. The paper Figure 15 Paper chromatography of gradually absorbs the liquid, and the dissolved a sample of India ink. molecules climb the filter. The heavier they are, the slower they climb. If the molecules are pigments, then, one by one, various colours will appear on the filter paper.

An Exceptional Phenomenon Pierre Gingras Our deciduous trees have decided to break with tradition this year. Many of them, it seems, have forgotten that in autumn a tree is supposed to lose its leaves. . . . Even the change of colours has not taken place as it should . . . . Contrary to popular belief, it is not frost that triggers the coloration process and the falling of leaves in autumn. . . . In fact, if an early frost occurs, the opposite happens: the leaves shrivel, turn brown and quickly fall. The change in colours is

40 The Diversity of Ecosystems: A Treasure

mainly due to the change in the photoperiod and the alternation of cool nights and warm, sunny days that usually begins in mid-August. This also explains why the change in colour takes place at about the same time all over Québec—even if another persistent myth has led many people to believe the contrary. Source: La Presse, November 9, 2002. (translation)

R EVIEW ACTIVITY 2

Communication

A Forest Story How to Communicate Effectively SKILLS HANDBOOK, pp. 438–439

This is the last activity in this chapter. In the form of an adventure story, you will use your new knowledge to describe a particular ecosystem: the forest. 1

Checklist 1. I described certain natural phenomena that occur in the forest. 2. I described the resources that my character uses, the threats to the ecosystem and the protective measures that my character takes. 3. I used the scientific and technological information found in every chapter activity. 4. I correctly used the vocabulary that I learned throughout the chapter. 5. I adapted my communication to the literary style of an adventure story, to the target audience and to grammatical conventions.

In 1541, Francisco de Orellana and his crew crossed an immense forest in Latin America. Their trek lasted a year and a half. In the course of their journey, the Spanish explorers nearly died of starvation. They described how tall women attacked them, and they called these women Amazons, like the women warriors of Greek mythology. Orellana then gave the name Amazon to the river that crosses the equatorial forest of Brazil.

CHAPTER 2

The Forest: An Ecosystem on a Natural Scale

SCIENCE

You must also illustrate your adventure story.

HISTORY OF

2

As you tell the story of a man or woman who has chosen to live in the forest, you must describe: • the characteristics of the forest and climate in which your story takes place • the annual cycle of the trees • the specific features of the trees • the animals that your character encounters • your character’s methods of finding their way around the forest • the forest resources that enable your character to live • the threats to these resources and the solutions that your character has devised

You can create an electronic slideshow to present your adventure story. Your slideshow can include photos, illustrations and even animation.

41

MY

DISCOVERIES

Chapter 1 • An identification key is very useful for identifying a species. Such keys exist for various groups of living organisms, such as insects, invertebrates and trees (page 6). • Insects are arthropods whose bodies are divided into three parts: the head, the thorax and the abdomen. The head has antennae. The thorax has three pairs of legs and often two pairs of wings (page 7). • A terrarium can be used to recreate an ecosystem in miniature (pages 13 and 14). • Living organisms are adapted to their environments and to their modes of life in various ways (page 15). • The life cycle of insects includes a complete or incomplete metamorphosis (page 16). • Condensation sometimes forms on the sides of a terrarium. This shows that the species that live in it are exhaling water vapour and transpiring. It is also because the water in the basin is evaporating (page 17). • For an ecosystem to be in equilibrium, it must contain producers, consumers (herbivores and carnivores) and decomposers (pages 17 to 20). • In a terrarium, the temperature is higher than in the classroom. This is caused by the respiration of living organisms and the fact that the terrarium is a tiny, living environment (pages 17 to 20).

Chapter 2 • Several factors threaten the forest. Governments and individuals must act to preserve this ecosystem, which is indispensable from so many points of view (page 24). • Plants adapt to the Earth’s various climatic conditions (pages 25 to 27). • The forest is an ecosystem that provides shelter for populations of living organisms. These living organisms belong to several classes of animals and plants (page 28). • A compass is an effective instrument for finding your way around a forest (pages 29 and 30). • Trees can be classified according to the principles of taxonomy, taking into account, for instance, the shape and distribution of their leaves (pages 33 and 34). • Leaves are true oxygen-production factories. Through photosynthesis, they use carbon dioxide in the air to manufacture the food that the plant needs. Oxygen, which is an output of this chemical reaction, is released into the air. This is why we say that green plants are the Earth’s lungs (pages 36 and 37). • Plant cells breathe, too (pages 36 and 37). • The coloration of leaves in the autumn is because of the diminishing photoperiod and the diminishing photosynthesis that comes with it. During this process, chlorophyll breaks down and the pigments that were hidden in the leaf all year become visible. Red coloration, however, results from a more complex reaction (pages 38 to 40).

42

U NIT

PROJECT

1

Communication

My First Job At the beginning of the unit, on page 3, you learned about a job offer. The tourist bureau in your area is seeking an advertising designer. The unit’s two chapters have taught you about two ecosystems: the semiaquatic environment and the forest. To boost your chances of being hired, you will now present an ecosystem of your choice. 1

Choose how you will present the ecosystem of your choice: as a radio or television show, a website, slides projected on a computer, a video, a script or in another format.

2

In your advertisement, cover the following points: • characteristics of the chosen ecosystem (location, visual appearance, natural elements present) • its inhabitants (plant, animal, human) • the threats that it faces • protective measures that must be applied • the benefits of the ecosystem to the living organisms within it

How to Communicate Effectively SKILLS HANDBOOK, pp. 438–439

KEY CONCEPTS IN UNIT 1 • acidity/alkalinity • air (composition) • asexual and sexual reproduction • cellular components visible under a microscope • characteristics of living organisms • design plan • ecological niche • erosion • gametes • habitat • inputs and outputs (energy, nutrients, waste) • molecule • photosynthesis and respiration

Checklist

• physical and behavioural adaptation • plant and animal cells • population

1. I demonstrated that I understand the natural phenomena occurring in and affecting the ecosystem that I am presenting. 2. I presented the information that I selected in a way that respects conventions and the scientific and technological vocabulary used throughout the unit. 3. I used information and communication technologies to respond to the job offer. 4. I completed my project. 5. In the presentation of my advertising message, I took into account both the readers and the grammatical conventions of the English language.

• reproduction in animals • reproduction in plants • reproductive organs • species • specifications • taxonomy • technical drawing • types of soil

43

Unit 2

The Balance of the Planet Summary Chapter 1 The Water Cycle . . . . . . . . . . . . . . . . . . 46 Chapter 2 Biking for a Greener Planet . . . . . . . . . 63 Chapter 3 Inventing Solutions . . . . . . . . . . . . . . . . 75

Being Aware of the Effect of Our Actions Every one of your actions has an effect on the environment. For example, when you ask your parents to take you somewhere by car, you contribute to gas consumption. Like it or not, the combustion of petroleum products is a probable cause of global warming, and the consequences of this warming are far reaching: desertification in certain regions and increased flooding in others. Of course, the simple decision to use a car does not make you alone responsible for such serious consequences. In many cases, though, you can choose to get to where you are going by bike, public transportation or simply by stretching your legs and walking. Each of these choices is an action that reduces your fuel consumption. Carefully study the pictures on the following page. 1. How do actions that humans perform every day disrupt the balance of the planet? 2. Discuss your answers with your classmates.

44

Project In the “Necessity Is the Mother of Invention” project at the end of this unit, you will design and build the small-scale prototype of a machine. To complete this project, you must apply the knowledge that you acquired in the unit’s three chapters about the water cycle and concepts of technology.

45

C HAPTER 1 The Water Cycle

Figure 1 Water and humans are in constant interaction.

KEY CONCEPTS IN CHAPTER 1 • atmosphere • conservation of matter • hydrosphere • layers of the atmosphere • light • mass • physical change • states of matter • system (overall function, inputs, processes, outputs, controls) • temperature • volume • water (distribution) • water cycle • winds

46

UNIT 2

The Balance of the Planet

What Happened? The media report natural disasters on a regular basis. Is the planet’s condition deteriorating? Or are we just better informed than in the past? Increasingly, we are recognizing that the planet is fragile. The pictures in Figure 1 show certain problems associated with the water cycle. Study these pictures carefully. Then, in teams, discuss your answers to the following questions: 1. To which situation does each picture in Figure 1 refer? 2. What similar situations have you experienced or observed? 3. Name some everyday occurrences in which you personally noticed disruptions of the water cycle. 4. What part did humans play in these occurrences? 5. Propose solutions to improve the situations you mentioned.

ACTIVITY 1 Analysis The Movements of Water The Hydrosphere ENCYCLOPEDIA, pp. 298–299

The Water Cycle ENCYCLOPEDIA, p. 332

How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

NEWS FLASH . . . On average, a molecule of water remains: • 1500 to 200 000 years in glaciers • 2500 years in the ocean • 1400 years in groundwater • 17 years in lakes • 1 year in the ground • 16 days in rivers • 9 days in the atmosphere

Figure 2 The Daniel-Johnson Dam on the Manicouagan River in northern Québec.

The Comings and Goings of Water Sometimes it rains or snows, and this varies the water level of lakes and rivers. Certain parts of the planet are very dry, while others are very humid. From time to time, the water cycle appears to be disrupted. That’s when natural disasters occur, as you saw in the opening of the chapter (see page 46). Water’s movements are complex. 1

First, read “The Water Cycle” on page 332 of the Encyclopedia.

2

Answer the following questions: a) When it does not rain for several days, where does the water that runs in rivers come from? b) Rivers are constantly emptying into oceans. Why is the water level of oceans stable? c) Where does the spring water found in mountains come from?

The Consequences of Our Actions As far back as 1 million years ago, the ancestors of human beings were making tools. Nowadays, people are constantly developing technology to satisfy their needs. Their accomplishments, such as the dam in Figure 2, have an impact on the environment. 1

Answer the following questions: a) What impact can a dam’s construction have on the water cycle? b) What other accomplishments and actions can modify the water cycle? c) How can we use the experimental method in our approach to the subject?

2

Discuss your answers with your classmates.

This Way to the Review Activity Keep your answers. They will be useful in the chapter review activity when you write your article.

48

UNIT 2

The Balance of the Planet

ACTIVITÉ 1 ACTIVITY 2 Experimentation Evaporation and Transpiration States of Matter ENCYCLOPEDIA, pp. 176–178

I observe Water can evaporate. That is a physical change. However, water does not always evaporate as quickly from one season to the next (see Figures 3 and 4). Evaporation and transpiration are two essential components of the water cycle. Water is present in the ground and the sea, and in plants and animals. Evaporation and transpiration allow water to reach the atmosphere in gaseous form.

Physical Changes ENCYCLOPEDIA, pp. 191–192

How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

How to Draw Diagrams SKILLS HANDBOOK, pp. 446–448

The Balance SKILLS HANDBOOK, p. 457

Evaporation The process by which water passes from a liquid state to a gaseous state.

Transpiration The release of water vapour by a living organism.

NEWS FLASH . . . Figure 3 In summer, the ground dries very

rapidly. Figure 4 In the autumn, the ground stays

wet for a long time.

I develop a research question “What factors affect the evaporation rate?”

I define the variables Your experiment must enable you to evaluate the effect of the following factors on the evaporation rate:

In the U.S. state of Louisiana, people wanted to make it easier to transport petroleum by boat. They diverted waterways and dried out wetlands at the mouth of the Mississippi River. These changes allowed the opening of a wide passage for navigation. It was through this opening that a gigantic wave was able to enter the city of New Orleans on August 29, 2005. Hurricane Katrina created the wave, and the rupture of a dike caused a catastrophic flood.

• temperature • wind speed • humidity of the air

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Equipment • four sponges or pieces of absorbent cloth • a graduated cylinder • a beaker or watch glass

I experiment PROCEDURE 1 Using the available equipment and material, determine a procedure for conducting this experiment. 2 Have your teacher approve your procedure. 3 Conduct your experiment.

a scale a fan a desk lamp a thermometer a stop watch a bell jar or large glass container Material • water

• • • • • •

FURTHER STUDY Using the results you obtained, explain how a hair dryer works.

I analyze my results and present them 1 Describe the influence of the factors you studied on the evaporation rate. 2 Illustrate your explanation with a diagram.

This Way to the Review Activity Keep your observations. They will be useful in the chapter review activity when you report on your work.

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3

Find an example that shows these factors at work in everyday life.

4

How would you repeat this experiment with plants?

5

Why are plant leaves thick in hot and dry climates?

6

Organize the results of your experiment into a table. Present your results to your classmates.

7

If you were to repeat this experiment, how would you change the procedure? Explain why.

ACTIVITY 3 Analysis Disturbing Data Volume ENCYCLOPEDIA, p. 180

Lessons from the Past Figure 5 shows how average world temperature has varied between 1856 and 2005, with a significant spike in the last 25 years of these recorded average temperatures. As you learned in the previous activity, temperature influences the atmosphere’s capacity for evaporating or transporting great quantities of water (see Figure 6 on the following page). How do temperature variations affect climate? This activity will help you understand the situation.

The Cartesian Plane SKILLS HANDBOOK, p. 441

The Line Graph SKILLS HANDBOOK, p. 444

Global Mean Temperature 0.6

0.2

Estimated actual global mean temperatures (°C)

Difference (°C) from 1856 – 2005

0.4

0.0 – 0.2

– 0.4 – 0.6

2000

1980

1960

1940

1920

1900

1880

1860

– 0.8

Year Source: Intergovernmental Panel on Climate Change

Figure 5 Change in average world temperatures between 1856 and 2005,

Average world temperature curve Average temperatures between 1980 and 2005

showing a significant spike between 1980 and 2005

1

Study Figure 5, and then answer the following questions: a) What does each of the two lines in the diagram represent? Explain in your own words. b) How has the average world temperature changed from 1980 to 2005?

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35

Water mass (g)

30

20 15 10

NEWS FLASH . . . The tufted puffin nests in great numbers on Triangle Island, which lies 40 km off the coast of British Columbia. In 1998, during a particularly hot summer, a great number of chicks were found dead. How can this phenomenon be explained? The puffins usually fed on rockfish, sand lance and Pacific saury. These species of fish are normally abundant near Triangle Island when the puffins reproduce. However, in 1998 El Niño modified sea currents, and very warm water flowed north, and the change in temperature drove these fish from the Triangle Island region at a critical period. The chicks born in 1998 died of starvation.

25

5 0

–20

–15

–10

–5

0

5

10

15

20

25

30

Temperature (°C) Figure 6 The maximum water mass in gaseous form that one cubic meter (m3) of air can

hold, in relation to temperature 2

Study Figure 6, and then answer the following questions: a) In winter, when the outside temperature drops to –20°C, what is the maximum water mass that 1 m3 of air can contain? b) In summer, when the outside temperature rises to 30°C, what is the maximum water mass that 1 m3 of air can contain? c) Why do clothes hanging on a clothesline dry quicker on a hot day? d) The heaviest snowstorms occur most often when the temperature is only a few degrees below freezing. How can you explain this phenomenon?

Tomorrow’s Forecast Scientists develop theoretical models to explain known phenomena. Then we use these models to make predictions. From what you know of the past, you can venture a prediction. You can then evaluate your understanding according to the accuracy of your predictions. Based on the information provided in Figures 5 and 6, answer the following questions: a) What climate changes do you foresee over the next 50 years? b) Specialists claim that global warming can produce droughts and floods. How do Figures 5 and 6 back up those claims? c) What personal observations might lead you to believe that the planet’s climate is warming?

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ACTIVITY 4 Experimentation Condensation How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

How to Draw Diagrams SKILLS HANDBOOK, pp. 446–448

a) Dew

c) Fog

b) Frost Figure 7 Three examples of ground-level condensation: dew, frost and fog

I observe When you take a glass container out of the refrigerator, water droplets appear on its surface. On winter mornings, the car’s windshield is often covered with frost. I develop a research question “What is the relationship between condensation of water vapour and the temperature of the air?”

Condensation The passing of water from a gaseous state to a liquid state. Dew, frost and rain are examples.

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I define the variables Your experiment must enable you to verify how temperature influences the condensation of water vapour in the air. Equipment • safety glasses • three 50-mL beakers • a 200-mL beaker • a hot plate • a retort stand • a ring clamp • mesh or wire gauze Material • 40 mL ice water • 40 mL lukewarm water • 250 mL boiling water

I experiment PROCEDURE 1 Using the available equipment and material, determine a procedure for conducting this experiment. 2

Draw a diagram of your set-up.

3

Have your teacher approve your procedure and diagram.

4

Conduct your experiment.

NEWS FLASH . . . There is always evaporation near bridges. Under certain conditions, this water vapour condenses into droplets near the ground. It then forms a fog that greatly reduces visibility and makes crossing bridges dangerous. Sometimes, when the temperature is below 0°C, another difficulty arises: the bridge surface becomes coated with ice. In other words, the water droplets forming the fog freeze.

I analyze my results and present them 1 Describe the relationship that you discovered between air temperature and the condensation of water vapour. 2 Illustrate your description with a diagram. 3 Answer the following questions: a) In winter, why does your exhaled water vapour condense? b) Why is dew best observed in the morning? 4 If you were to repeat this experiment, how would you change the procedure? Explain why.

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ACTIVITY 5 Experimentation The Movements of the Atmosphere The Layers of the Atmosphere

I observe

ENCYCLOPEDIA, p. 294

In the previous activity, you discovered the relationship between temperature and condensation. How does this relationship apply to the atmosphere as a whole? In terms of temperature, you know that certain places warm up significantly in the sun. (Think of a paved surface on a hot summer day.) However, other places, such as forests, warm up much less. When the sun has set, the ground temperature drops.

Winds

I develop research questions 1. “Could the unequal warming of the ground during the day cause movements of the atmosphere and certain cases of precipitation?” 2. “What causes atmospheric movements (also known as wind)?”

ENCYCLOPEDIA, pp. 334–337

How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

How to Draw Diagrams SKILLS HANDBOOK, pp. 446–448

Precipitation The different forms that water takes to return to the ground: rain, snow, hail, sleet or freezing rain.

I define the variables In this experiment, you will have to simulate atmospheric movements using a container of water. Your simulation must enable you to observe the effect of the following factors on the water’s movement: • temperature • altitude

Figure 8 Wind speed varies widely. Wind can sometimes be very violent.

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I experiment Suggested Procedure Equipment • safety glasses • a Pyrex dish • four Styrofoam cups • food colouring • a dropping pipette

Here is an example of a procedure for this experiment. You might want to suggest a different one.

Material • 500 mL boiling water • 500 mL ice water • lukewarm water

1

Fill two Styrofoam cups with boiling water.

2

Fill two Styrofoam cups with ice water.

3

Place the Pyrex dish on the four cups as shown in Figure 9.

4

Pour approximately 5 cm of lukewarm water into the Pyrex dish. This 5 cm of water represents the first 10 kilometres of the atmosphere. This layer is called the troposphere. It is here that meteorological phenomena occur.

5

Add a few drops of food colouring to the water in the Pyrex dish, just above one of the two cups of boiling water.

6

Observe the movement of the food colouring. It simulates the way air moves when it is warmed by the ground.

7

Put a few drops of food colouring in the water in the Pyrex dish, just above one of the two cups of ice water.

8

Observe the movement of the food colouring. It simulates the way air moves when it is cooled by the ground. Water representing the atmosphere

Two cups containing hot water

Two cups containing cold water

Figure 9 A simulator of atmospheric movement

I analyze my results and present them 1 Answer the following questions: a) Based on the results you obtained, in your opinion, is there a relationship between the unequal warming of the ground during the day and atmospheric movements? If so, explain this relationship. b) Is there a relationship between temperature, atmospheric movements and the onset of precipitation? 2 In a diagram of your simulator, illustrate the atmospheric movements produced by land breeze and sea breeze. 3 Discuss your results with your classmates. 4

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If you were to repeat this experiment, how would you change the procedure? Explain why.

ACTIVITY 6 Analysis Why the Difference? The Troposphere ENCYCLOPEDIA, p. 294

FURTHER STUDY The two sides of the island of Gran Canaria in the Atlantic Ocean present two very different landscapes. Yet Gran Canaria is a circular, mountainous island less than 50 kilometres in diameter. Do some research to explain the situation.

Figure 10 The Rocky Mountains

Study Figure 10. At the foot of the mountains, the temperature is high enough for trees to grow. However, certain peaks are covered in snow year-round. In Activity 2, “Evaporation and Transpiration” on pages 49 and 50, you learned that air can contain a maximum of water mass in the form of vapour. You also saw that this quantity depends on the air’s temperature. 1

Read the text “A Mountain Range’s Effect on Precipitation” on the next page.

2

Answer the following questions: a) How do you explain the presence of snow on certain mountain peaks? b) Can we predict heavy precipitation on the side of the mountain range that the wind comes from? c) Can we predict heavy precipitation on the side of the mountain range that the wind goes to?

3

Study the maps in Figures 12 and 13 on the next page. On these maps, the prevailing wind blows west to east. What is the relationship between the landforms and the precipitation observed on these maps?

4

Discuss your answers with your classmates.

This Way to the Review Activity Keep your answers. They will provide documentation for the newspaper article that you write for the Chapter Review Activity “A Special Supplement.”

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A Mountain Range’s Effect on Precipitation States of Matter ENCYCLOPEDIA, pp. 176–177

Temperature ENCYCLOPEDIA, pp. 181–183

Figure 11 A humid air mass passes over a mountain range

When a mass of warm, moist air arrives at the foot of a mountain range, it has to rise to clear the obstacle. As the air rises, it cools. The water vapour it contains condenses. When the water droplets that form clouds are too heavy, they fall back down in the form of precipitation. That is why the climate is wet on that side of the mountain. When the air goes down the other side of the mountain, it becomes warmer and drier. Therefore, there is little or no precipitation. The climate is quite dry. Southern Alberta, for instance, has a semi-desert climate.

Legend Average annual precipitation Over 4000 mm 2000 to 3999 mm 1600 to 1999 mm 1200 to 1599 mm 800 to 1199 mm 400 to 799 mm 0 to 399 mm

YUKON

YUKON

NORTHWEST TERRITORIES

NORTHWEST TERRITORIES

PACIFIC OCEAN

Fort Nelson

Queen Charlotte Islands

Prince Rupert

Dease Lake

ALASKA (U.S.)

Fort Nelson

Prince Rupert

Queen Charlotte Islands

BRITISH COLUMBIA

ALBERTA

Prince George

BRITISH COLUMBIA

N

W

E

E

Vancouver 0

Scale 250

S

Kelowna

Vancouver

Victoria 500 km

Vancouver Island

0

Scale 250

500 km

UNITED STATES

Figure 12 Average annual precipitation in British Columbia

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Kelowna

Victoria

UNITED STATES

Figure 13 Relief of British Columbia

iver

Vancouver Island

R bia lum Co

N

W

S

ALBERTA

Prince George

Fraser River

PACIFIC OCEAN

Dease Lake

ALASKA (U.S.)

ACTIVITY 7 Experimentation The Movement of Water in the Ground

Drinking Water ENCYCLOPEDIA, pp. 300–301

How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

How to Draw Diagrams SKILLS HANDBOOK, pp. 446–448

I observe When the ground contains too much water, it loses its cohesion, and landslides can occur.

I develop a research question “Where does rainwater go when it disappears from the surface of the ground?”

Figure 14 A landslide

Cohesion The force that keeps a substance’s particles together.

I define the variables Your experiment must enable you to determine the effect of the following factors on movement of water in the ground: • the type of ground • the ground’s relief

I experiment

PROCEDURE

Suggested Procedure Here is an example of a procedure for this experiment. You might want to suggest a different one. 1

Read the text “After It Rains, What Happens to the Water?” on page 61.

2

Place a 3-cm layer of gravel at the bottom of the container.

3

Push a straw into the gravel. Holding the straw, make a 3-cm layer of clay on top of the gravel.

4

Add clay to make a hill that covers the width of the container. Pack the clay well with your hands.

5

Push a straw halfway into the hill of clay.

6

Add a layer of sand on the clay so that it forms a slope approximately 6 cm deep at the thickest spot and approximately 3 cm deep at the thinnest.

Equipment m, • a transparent container (aquariu glass bowl, transparent plastic dish, etc.) Material • three straws • three wooden skewers • • • •

fine sand clay gravel water

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NEWS FLASH . . . Groundwater is often the only source of drinking water available to the people of developing countries. To get to it, however, people must dig a well. Although building a well does not cost much, many villages do not have the money to pay for one.

7

Push a straw into the thickest part of the layer of sand.

8

Place a skewer inside each straw.

9

Indicate which real phenomenon each material in your model represents.

10

Slowly pour water from the higher end.

A straw

Pour the water here.

Fine sand Well-packed clay Gravel

Figure 15 A simulation of the movements of water in the ground

Water table A body of groundwater formed by rainwater infiltration that feeds wells, springs and waterways.

This Way to the Project Keep all of the information you gathered. It will help you explain how to build an machine that transforms salt water into fresh water in the unit project “Necessity Is the Mother of Invention.” This machine will enable you to reduce the impact of climate change.

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11

With the skewers, check the water level in each straw. Record your results in a table.

12

Stop pouring the water when you see a layer of water approximately 1 cm high in the lower part of your container.

I analyze my results and present them 1 With the help of a diagram, explain why the water level is not the same in each straw. 2

With the help of a diagram, explain how water that disappeared under the surface can reappear on the surface elsewhere.

3

Discuss your results with your classmates.

4

Answer the following questions: a) Where does well water come from? b) How does the ground store water? c) What would happen if people extracted more water from the water table than what the water table actually received? d) How does water flow from the water table to the river? e) What does rainwater that falls to the ground become?

5

If you were to repeat this experiment, how would you change the procedure? Explain why.

After It Rains, What Happens to the Water? After a rainfall, a certain quantity of water returns to the atmosphere through transpiration or evaporation. This is what you learned in Activity 2, “Evaporation and Transpiration” on pages 49 and 50. What happens to the water remaining on the ground, though? This water circulates in two ways: by runoff and infiltration. A portion of the water flows over the surface of the ground as runoff, but the water can also enter a system of channels that ultimately brings it to lakes and rivers. This water causes the level of rivers to rise temporarily, but then the rainwater escapes from the region. When this happens, it cannot be used during a dry period unless the region includes systems such as dams that allow water to accumulate. The rest of the water infiltrates the soil to reach the water table. It will therefore be available during the next dry period and can be accessed via wells. Since this water runs very slowly, it helps keep the water level in rivers lower when it rains. Similarly, during dry periods, it keeps the water level higher.

Precipitation

Transpiration

Runoff

Evaporation

Infiltration

Figure 16 After a rainfall, water travels in different ways.

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R EVIEW

ACTIVITY

1

Communication

A Special Supplement How to Communicate Effectively SKILLS HANDBOOK, pp. 438–439

JOB OPPORTUNITY Journalist Are you a newshound? Do you like to communicate? The life of a journalist may be for you. To be a journalist, you should be ready to delve into news that touches on politics, culture, science or other fields. If you want to eventually practise this profession, you will have to graduate from high school. Following that, several options are open to you. For example, you can get a college diploma in the Arts, Media and Theatre program at Vanier College. You can also study for an honours degree in communications after two years of Cégep studies.

Some people believe that Canada could become the land of liquid gold. In fact, the demand for drinking water is so great that several countries would like to buy it from us. Some people are even talking of diverting a portion of our rivers’ waters to the United States. The local newspaper’s editorial board wishes to inform people in the area about the water cycle. It is therefore asking the students of your class to write a special supplement on the water cycle. 1

From the following questions, choose one or more that your team will answer in its article: a) What are the stages of the water cycle? b) How does an increase in the atmosphere’s temperature modify the quantity of water available? c) How is precipitation formed? d) Why does the atmosphere move? e) Why isn’t precipitation uniform everywhere? f) What happens to rainwater when it falls to the ground? g) What water-related dangers threaten us?

2

Each team must write an article of approximately 450 words, accompanied by a photograph or illustration of the chosen phenomenon.

Figure 17 In the U.S. state

of Colorado, canals have been built to transport drinking water. How might this action disturb the water cycle?

Checklist You can ask a Website to host an online version of your special supplement. You can also send an email to a list of potential readers to announce its publication.

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1. We appropriately integrated the scientific information found in the chapter activities. 2. We correctly used the scientific conventions and vocabulary seen in the chapter. 3. We wrote our text in the form of a news article.

C HAPTER 2 Biking for a Greener Planet

The Gift of a Bicycle Imagine that you recently received a bicycle as a gift. Now you can get around faster than you could on foot and get some exercise at the same time. In addition, on a bike, you can ride without using the fuel that produces greenhouse gases. You do not disrupt the water cycle when you ride a bike, nor do you disrupt the planet’s balance. Now, imagine that you went on a long bicycle trip with your friends. You explored the nearby hills. Twice, you had to walk your bicycle up a hill. You were out of breath and your legs hurt. What could you have done to make things easier? 1. On a bicycle, how can you make the following actions easier: a) covering long distances b) climbing hills c) pedalling against the wind

KEY CONCEPTS IN CHAPTER 2 • basic mechanical functions • components of a system • effects of a force • energy transformation • mechanisms that bring about a change in motion • mechanisms that transmit motion • physical and behavioural adaptation • simple machines • system (overall function, inputs, processes, outputs, control) • types of motion

2. Apart from using a bicycle, name two other ways of protecting the planet’s balance. 3. Discuss your answers with your classmates.

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Your challenge in Chapter 2 is to analyze the subsystems of a bicycle and to study certain features of the human body. This will enable you to use this means of transportation at maximum efficiency. In doing so, with each trip, you will contribute to the planet’s balance by avoiding the combustion of fuel. • In Activity 1, “The World of Levers” on pages 65 to 67, you will examine how levers make our lives easier. • In Activity 2, “Pedal Power” on pages 68 and 69, you will analyze how a bicycle’s components work. • In Activity 3, “The Human Body: A High-Performance Machine” on pages 70 and 71, you will discover the conditions that enable your body to work longer. • In Activity 4, “A Very Fragile Planet” on pages 72 and 73, you will see why using a bicycle contributes to the planet’s balance. Using a bicycle properly is a learned skill. At the end of the chapter, in the review activity “The Bicycle: A User’s Guide” on page 74, you will form teams and write a guide for beginners. In it, you will discuss beneficial attributes of the bicycle, for riders and the environment alike.

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ACTIVITY 1 Experimentation The World of Levers A bicycle requires several levers. Before studying some of the components of a bicycle and how they work, let us first examine a simpler kind of lever.

The Lever

I observe

ENCYCLOPEDIA, pp. 417–418

A direct-pull corkscrew firmly grips a cork and provides a handle for the hand that is pulling it from the bottle. The waiter’s corkscrew features a lever, as well. The lever reduces the effort required to pull the cork.

How to Apply the Experimental Method

ENCYCLOPEDIA, pp. 413–414

How Do Simple Machines Make Life Easier?

SKILLS HANDBOOK, pp. 430–432

The Line Graph SKILLS HANDBOOK, p. 444

The Dynamometer SKILLS HANDBOOK, p. 458

How to Use TechnologicaI Instruments SKILLS HANDBOOK, pp. 461–463

a) Direct-pull corkscrew

b) Waiter’s corkscrew

Figure 18 Two types of corkscrews

I develop a research question “Why is it easier to pull a cork from a wine bottle with a waiter’s corkscrew than with a direct-pull corkscrew?” I define the variables 1 Your experiment must enable you to compare the efforts required to pull a cork from a wine bottle, first with a direct-pull corkscrew and then with a waiter’s corkscrew. 2

You must build a simulator representing a waiter’s corkscrew.

3

Your simulator must allow you to calculate mechanical advantage.

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I experiment

Fulcrum Load arm

Lever arm

Effort (force exerted)

Load (cork) Lever arm Load arm

Load

Effort

Fulcrum Figure 19 A waiter’s corkscrew is an example of a second-class lever.

Equipment • a hand drill or power drill • drill bits • a backsaw and mitre box • a hammer • a dynamometer (cal ibrated from 0 to 5 N) • a dynamometer (calibrated from 0 to 30 N) • a metre stick • a vise • safety glasses Material • a 6.35-cm (2.5-inch) nail • two hooks • a piece of wood approximately 2.5 cm  5 cm  50 cm (1 in  2 in  20 in) in size

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This dynamometer represents the effort that the hand exerts. This dynamometer represents the resistance of the cork.

Effort (force exerted) Load arm

Load Lever arm Fulcrum Figure 20 Simulator of a waiter’s corkscrew

Suggested Procedure Here is an example of a procedure for this experiment. You might want to suggest a different one. 1

Study Figures 19 and 20.

2

Construct your simulator according to the model in Figure 20. You may have to adapt the dimensions to the available equipment and material.

3

Form teams of two. The first student holds the dynamometer closest to the fulcrum steady. Meanwhile, the other student pulls on the dynamometer farthest from the fulcrum.

4

In a table, record in newtons the measurement shown on each dynamometer. Conduct at least three trials.

5

Calculate the mechanical advantage using the following formula: Mechanical advantage 

Resistance force (dynamometer representing the cork) Force exerted (dynamometer representing the hand)

I analyze my results and present them 1 Give your teacher a report containing the following elements: a) a line graph representing mechanical advantage, in other words, showing the resistance force as a function of exerted force b) an explanation of how a waiter’s corkscrew works 2

Answer the question in the “I develop a research question” section.

3

Which other tools work along the same principle as a waiter’s corkscrew?

4

If you were to repeat this experiment, how would you change the procedure? Explain why.

FURTHER STUDY Why is it easier to carry a child in a wheelbarrow than in your arms? Explain this phenomenon using the lever principle. Illustrate your explanation with a diagram.

Figure 21 Several parts of the body can be

used as levers.

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The Design Plan ENCYCLOPEDIA, p. 382

Technological Systems ENCYCLOPEDIA, pp. 388–391

Basic Mechanical Functions ENCYCLOPEDIA, pp. 392–394

Connecting Rod and Crank ENCYCLOPEDIA, p. 424

Analyzing Technical Objects SKILLS HANDBOOK, pp. 434–435

A CTIVITY 2 Technology Pedal Power In the previous activity, you saw that levers can reduce how much effort you need to produce a movement. In this activity, you will apply this knowledge to analyze how a bicycle produces a movement by using your body’s energy.

What does a bicycle’s propulsion system do? The bicycle’s propelling system transforms the energy produced by the cyclist. It allows the bicycle to move forward without any kind of combustible fuel being used. So, bicycling is not just a recreational activity: it is a means of transportation that produces no greenhouse gases. 1

What do the gear-shift levers do (see Figure 22)?

2

Identify the fulcrum, load, effort, lever arm and load arm in each of the following levers (see Figure 23 on the following page): a) the lever that the pedal forms with each of a bicycle’s chainrings b) the lever that the back wheel forms with each of the sprockets

3

What should you do when you want to cycle up a steep hill?

4

What should you do when the wind is pushing you from behind?

Gear shift

HISTORY

The part of a bicycle that makes the chain slide from one sprocket to another, or from one chainring to another.

OF SCIENCE The German Karl Friedrich Drais invented the draisienne in 1817. This ancestor of the bicycle is equipped with two wheels. In 1861, Pierre Michaud added pedals to the front wheel fork.

Handlebars Seat Frame Brake

Brake

Tire Rim Spoke

Figure 22 The main parts of a bicycle

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Combined gear-shift and brake lever

Sprockets

Front derailleur

Pedal

Chainrings Chain Rear derailleur Figure 23 Components of the bicycle’s propulsion system

How does a bicycle’s propulsion system work? The bicycle is made up of a set of simple machines that use chemical energy supplied by the cyclist to produce a movement. 1

Study the various components of the bicycle’s propulsion system (see Figure 23). a) Name the components of this mechanical system. b) Identify the system’s inputs. c) Identify the system’s outputs.

2

Answer the following questions: a) Explain how the pedal levers increase the force applied to the load. b) Explain how the sprockets (which work like levers) increase the movement. c) Describe the various transformations that the movement undergoes, from the motion of the legs on the pedals to the rotation of the back wheel.

3

Draw a design plan showing how the motions of the legs cause the wheels to turn.

4

Explain the basic mechanical function of the derailleur.

How is the propulsion system constructed? 1 Identify the links between the components of the propulsion system. 2

Describe the role of each of these links.

FURTHER STUDY Study the two gear-shift levers on your bicycle. Try out every possible combination. In a table, record the results you obtained, meaning the distance that your bicycle covered when the pedal made a complete rotation. What was the variation in the force you applied to the pedals to obtain these results? What relationship can you establish between the force applied by your legs and the result obtained?

This Way to the Review Activity Keep your answers. They will help you to write your guide in the chapter review activity.

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ACTIVITY 3 Analysis The Human Body: A High-Performance Machine The Table SKILLS HANDBOOK, p. 440

The Line Graph SKILLS HANDBOOK, p. 444

FURTHER STUDY Jennifer weighs 50 kg. When she rides a bicycle at 15 km/h, she burns approximately 20 kJ of energy a minute. If she eats a cheeseburger consisting of a 100-g ground-beef patty and a slice of cheese, she assimilates 2000 kJ of energy. Calculate how long Jennifer must pedal to expend this energy.

You know now that the bicycle is a machine that uses the energy of your body. It enables you to move more quickly, with less effort, than on foot. Some people are stronger than others. In this activity, we learn the importance of knowing our capacities and factoring them in when riding a bike.

Figure 24 This triathlete is training

for a three-part competition: a cycling event, a running event and a swimming event.

You can use a spreadsheet program to create your line graph.

Cadence In cycling, the number of pedal revolutions a minute.

This Way to the Review Activity Keep your answers. You can use them to explain how to use a bicycle more efficiently. The explanations will be part of the guide that you write in the chapter review activity.

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Know Your Strength 1 First, read “At Your Own Pace” on the following page. 2 Using the standard formula, calculate the maximum heart rate for people aged 10 to 70. Calculate ages in increments of five (for example, 10, 15, 20, etc.). Record your results in a table. 3 Using the standard formula, calculate the heart rate corresponding to 85% of the maximum rate for people aged 10 to 70. Calculate ages in increments of five. Record your results in a table. 4 Use the data in your table to construct a line graph. Slow and Steady Wins the Race 1 What is the best way to ride a bicycle for a long time without getting tired? 2 What should you do if your heart rate is too high, but your cadence is right? Indicate how your speed will change. 3 What should you do to increase your effort without modifying your cadence? Indicate how your speed will change.

At Your Own Pace The heart beats at a pace that varies according to a person’s age and physical condition. This is called the heart rate. To produce a sustained effort, kinesiologists recommend maintaining a heart rate at 85% of the maximum rate. In the laboratory, kinesiologists can precisely evaluate a person’s maximum heart rate. However, you can obtain your approximate maximum heart rate using this standard formula:

Kinesiologist A person who specializes in promoting healthy lifestyles and preventing health problems. For example, this expert will prescribe physical activities to improve and maintain health and physical performance.

Energy What is used to produce work. For example, food provides humans with the energy to stay active. In the International System of Units, energy is measured in joules.

NEWS FLASH . . . Maximum heart rate: 220 – age For example, if you are 13 years old, you would calculate your maximum heart rate as follows: Maximum heart rate: 220 – 13 = 207 Your heart can therefore beat up to 207 times a minute. However, you cannot maintain this pace for long. It would be too exhausting. To maintain a pace for a long time, you should not exceed 85% of this value. In other words, if you are a 13-year-old on a bike trip, your heart rate should not exceed the following value:

It is not easy to measure your heart rate while pedalling. However, certain indicators can help you determine if your pulse is too high. Carry on a conversation as you pedal, for instance. If you cannot keep up your end of the conversation, then your heart rate is probably too high for you to keep that pace for very long.

Heart rate that should not be exceeded  207  85  176 100 According to kinesiologists, cyclists are efficient when the movements of their legs follow a certain cadence. For example, competitive cyclists must maintain a cadence of approximately 90 to 100 pedal rotations a minute. That’s not exactly an easy ride. When you use a bicycle for transportation, your cadence should range from 60 to 80 rotations a minute. This is how you will use your energy most efficiently to get around. Training leads to physical adaptation. The more you train, the stronger your body becomes, and your endurance will increase.

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ACTIVITY 4 Research A Very Fragile Planet How to Conduct a Research Project SKILLS HANDBOOk, pp. 436–437

Figure 25 The flooding of Prague (Czech Republic) in 2002

Figure 26 In Central Asia, the Aral Sea dried up.

The sea lies on the border of Kazakhstan and Uzbekistan.

Join an Internet discussion group to learn about concrete actions that can reduce your production of greenhouse gases. Do not forget the rules of Internet courtesy, or “netiquette.”

In Activity 3, “Disturbing Data” on pages 51 and 52 of the previous chapter, you analyzed a diagram showing the change in average temperatures from 1948 to 2005. You also saw that the increase in the planet’s average temperature can lead to natural disasters: • Regions can dry out because of greater evaporation (see Figure 26) • Floods can occur because the air has a greater capacity to transport water (see Figure 25) • Severe weather phenomena can occur because the increase in temperature causes the release of more energy 1

Read “Greenhouse Gases” on the following page. It will explain a possible cause of the climate changes that have been observed.

2

Research the answers to the following questions: a) What actions could you take from now on to reduce your personal production of greenhouse gases? Name at least five. b) Why do many people believe that using a bicycle helps solve environmental problems?

This Way to the Review Activity Keep your research results. They will help you explain how the bicycle contributes to maintaining the planet’s balance. You will use this information in the chapter review activity when you write your bicycle user’s guide.

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Greenhouse Gases Light ENCYCLOPEDIA, pp. 345–350

The Sun Space

4 1

1 Some of the Sun’s rays pass through the 1●

Earth’s atmosphere and reach the ground.

Greenhouse gases

2

2 The atmosphere reflects some of the 2●

Sun’s rays into space. 3 The energy of the Sun’s rays warms the 3●

The atmosphere

ground. It sends infrared rays (heat) into the atmosphere.

5

4 Some of the infrared rays pass through 4●

the atmosphere and reach space. 5 Greenhouse gases trap the rest of the 5●

3

infrared rays in the atmosphere.

The Earth Figure 27 The greenhouse effect

Legend

Look carefully at Figure 27. It shows what happens to the Sun’s rays when they reach the Earth. Certain gases in the atmosphere, including carbon dioxide (CO2) and water vapour (H2O), prevent infrared rays from returning to space. This phenomenon keeps the temperature of the Earth’s surface high enough to allow life to develop. We call this phenomenon the greenhouse effect.

1°C to 0°C 0°C to 1°C 1°C to 2°C 2°C to 3°C 3°C to 4°C 4°C to 5°C

As you probably already know, when we burn petroleum and carbon, we release great quantities of carbon dioxide into the atmosphere. As a result, the greenhouse effect increases, and the average temperature of the Earth’s surface rises. All countries must take strong measures to reduce production of greenhouse gases. If not, environmental organizations and government departments, such as Environment Canada, predict that the planet’s surface temperature will change considerably from now until the mid-21st century, as shown in Figure 28. To make these predictions, scientists used two types of data. They calculated the average temperatures from 1975 to 1995 with data measured directly in the field. These measurements are therefore accurate. Average temperatures from 2040 to 2060 are estimates, however, and so the accuracy of the data obtained is therefore reduced.

Figure 28 The temperature change between average

temperatures from 1975 to 1995, and average estimated temperatures from 2040 to 2060 (in ºC)

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R EVIEW

ACTIVITY

2

Communication

The Bicycle: A User’s Guide How to Communicate Effectively SKILLS HANDBOOK, pp. 438–439

Using a bicycle seems simple enough. However, if you want to cover long distances, you have to understand the process. This will enable you to ride with a minimum of effort. Many people prefer to use a car to get around. Unfortunately, the gas consumption that this involves has a disastrous impact on the planet. By making choices, we can contribute to the planet’s balance. 1

With your team members, write a user’s guide for beginner cyclists. In your guide, you must: a) use a design plan to describe the workings of a bicycle’s propulsion system b) use a line graph to explain how the human body sustains an effort for a long time c) provide clear instructions about proper bicycle use, taking into account the physical condition of beginning cyclists d) list reasons why people should travel by bicycle rather than using transportation that consumes fuel

2

Your guide must be approximately 10 pages long. It must also include • an eye-catching cover • an introduction

JOB OPPORTUNITY Family Doctor Do you like science? Are you interested in people’s health? Have you thought of studying medicine? To be a doctor, you must be very good at synthesizing and analyzing data. You must also have a keen sense of observation. To become a doctor, you need to finish high school and go on to Cégep. Following that, you must study at a university for four or five years to obtain a doctorate in medicine.

Checklist 1. We clearly described how a bicycle works and explained how the human body sustains an effort for a long time. 2. We explained how using a bicycle can help preserve the planet’s balance. 3. We correctly used the scientific and technological vocabulary seen in the chapter. 4. We used critical thinking with respect to the information that we learned in the chapter. 5. We wrote a guide that complies with the rules of presentation.

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C HAPTER 3 Inventing Solutions A History of Genius Inventions have often changed the course of human history. Just imagine what life would be like without the wheel! Human beings have run into many problems that seemed impossible to solve. Fortunately, our ingenuity has often enabled us to find solutions. Thanks to the compass, for instance, we can find our way at sea in foggy weather. Numerous inventions are changing the course of our lives today. The world around us is different from the one that your parents knew at your age. Take the arrival of email, for instance, and the development of the Internet. It is not surprising that parents are always asking their children how new technologies work! Since time immemorial, humans have faced obstacles that seemed insurmountable. Even today, we have a serious problem: the fragile balance of the planet is threatened by our actions. 1. Form teams and answer the following questions: a) What characterizes an invention? b) What drives people to invent something?

KEY CONCEPTS IN CHAPTER 3 • basic mechanical functions • design plan • effects of a force • equipment • manufacturing process sheet • mass • materials • mechanisms that transmit motion • specifications • technical drawing • universal gravitation • volume • winds

c) Name a problem for which a solution has not yet been invented. d) Can certain inventions disrupt the planet’s balance? If so, name one and describe the consequences of its use. 2. Discuss your answers with your classmates.

Figure 29 Human ingenuity

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Your challenge in Chapter 3 is to put yourself in the shoes of people who overcame numerous obstacles to develop their inventions. In conducting your own experiments, you will see how humans have handled the challenges of water transportation.

HISTORY

• In Activity 1, “The Paper Clip Challenge” on pages 77 and 78, you will discover the principle of buoyancy.

OF SCIENCE In the early 20th century, shipping between the Magdalen Islands and the mainland was impossible in winter. In fact, it halted from late December to early May. The only means of communication between the islands and the mainland was the telegraph. On January 6, 1910, an underwater cable broke, completely isolating the people of the Magdalen Islands. So the people invented their own solution. On February 2, 1910, they launched a small boat containing their mail. The boat’s hull was made of a barrel. The boat landed on the Nova Scotia shore during the night of February 12.

• In Activity 2, “Archimedes’ Principle” on pages 79 and 80, you will examine buoyancy in more detail. • In Activity 3,“Don’t Rock the Boat!” on pages 81 and 82, you will study the features that cause a boat to right itself after it has capsized. • In Activity 4, “Steadying the Course” on pages 83 and 84, you will learn how to design a boat that can maintain its direction on its own. At the end of the chapter, in the review activity “The Wind in Your Sails” on pages 85 and 86, you will use your ingenuity to design and build a small boat. This boat must be capable of transporting a cargo under very specific conditions. The discoveries that you make in the chapter will help you devise your solution.

306

Figure 30 A shipyard

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ACTIVITY 1 Experimentation The Paper Clip Challenge Volume ENCYCLOPEDIA, p. 180

Mass ENCYCLOPEDIA, pp. 178–179

How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

How to Draw Diagrams SKILLS HANDBOOK, pp. 446–448

Figure 31 In the 17th century, explorers travelled by canoe.

New France’s first colonists adopted the canoe as a means of transportation. This relatively light craft was able to transport very heavy loads. Moreover, like a bike, it was environmentally friendly. You too can design a boat, but first you must understand the concept of buoyancy.

I observe When I put a piece of wood in water, it floats. However, when I put a nail in water, it sinks.

I develop research questions 1. “What makes certain objects float on the water, while others sink?” 2. “Does an object that floats on water also float on any other liquid?” I define the variables 1. Your experiment must enable you to discover the principle of buoyancy. To understand this principle, you must examine the following factors: • the volume of the object that you want to float • the mass of the object that you want to float

Buoyancy The capacity of an object to float. Buoyancy results from the effect of two forces: the object’s weight (downward force) and the buoyancy force of the water on the object (upward force).

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mass ratio of the object that you want to float volume • the volume of the liquid on which the object must float • the

Equipment • safety glasses • a container (beaker, Pyrex dish, etc.) • paper clips • a scale • a graduated cylinder Material • 200 mL water • 200 mL alcohol • 25 g modelling clay

• the mass of the liquid on which the object must float mass • the ratio of the liquid on which the object must float volume 2. With modelling clay, build an object that is able to float on both water and alcohol.

I experiment

PROCEDURE

FURTHER STUDY A submarine can float on the water like a boat, or sink to navigate below it. Find out how submarine crews modify the buoyancy of their vehicle.

1

Using the available equipment and material, determine a procedure for conducting this experiment.

2

Have your teacher approve your procedure.

3

Form your object.

4

Try to make it float on the water.

5

Determine the maximum number of paper clips that your object can carry, while continuing to float. As is typical in science, you will probably have to make several attempts.

6

Record your results in three tables.

7

Repeat your experiment, replacing the water with the same volume of alcohol.

I analyze my results and present them 1 In your own words, explain the principle of buoyancy. This Way to the Review Activity In the chapter review activity, you will have to design a boat according to a list of specifications. Make sure you fully understand the principle of buoyancy. You will need it to build the hull of your boat.

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2

Illustrate your explanation with a diagram.

3

Record the maximum number of paper clips that your boat was able to carry: • on water • on alcohol

4

When you replaced the water with alcohol, did the buoyancy of your object change? If so, explain this difference.

5

Discuss your results with your classmates.

6

If you were to repeat this experiment, how would you change the procedure? Explain why.

ACTIVITY 2 Experimentation Archimedes’ Principle You already know that our planet exerts a force of attraction on all of the objects on its surface. By hanging an object on a dynamometer, we can measure the force with which the Earth is pulling this object. This force corresponds to the object’s weight. It is important to take weight into account when designing a boat.

Effects of a Force ENCYCLOPEDIA, pp. 410–411

The Law of Universal Gravitation ENCYCLOPEDIA, p. 351

How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

I observe In the water, you feel lighter. It is as if the water were exerting a force on you that opposes gravity and lifts you up.

The Table SKILLS HANDBOOK, p. 440

The Dynamometer SKILLS HANDBOOK, p. 458

I develop research questions 1.“If I drop objects into the water, what force does water exert on those objects?” 2. “If I drop objects into other liquids, will different liquids exert the same force on them as water does?”

The Graduated Cylinder SKILLS HANDBOOK, pp. 459–460

I define the variables Your experiment must enable you to: • measure the force that opposes the weight of an object in two different liquids • discover the relationship between this force and the weight of the displaced liquid • explain what enables an object to float

I experiment Suggested Procedure Here is an example of a procedure for this experiment. You might want to suggest a different one. 1

With a dynamometer, measure in newtons the weight of each of the objects on the equipment list opposite (cork, wood, etc.). Use elastics to attach each object to the dynamometer.

2

Mark the results in a table.

3

Now, measure the weight of the empty beaker and tray. The tray is used to suspend the beaker from the dynamometer.

4

Copy the set-up in Figure 32 on the next page.

5

Fill the overflow can to the top.

6

Place the empty beaker under the spout of the overflow can.

7

With the help of an elastic, hang an object in the liquid. In your table, a) note the force that the dynamometer records b) indicate whether the object floats

Equipment • safety glasses • an object made of cork • an object made of wax • an object made of copper • an object made of lead • an object made of wood • a dynamometer (calibrated from 0 to 5 N) • a graduated cylinder • an overflow can • a beaker • a retort stand • a tray Material • synthetic thread (fishing line) • elastic bands • water • alcohol

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NEWS FLASH . . . Luckily for fish, ice floats on water. If this were not the case, ice would sink to the bottom of the water as soon as it was formed. In no time, all of the water in the lake would freeze. Fish would have no free water to swim in during winter, and they would die.

8

Calculate the buoyancy force exerted by the water on the object. Use the following formula. Record the results in your table. Buoyancy force Object’s Force indicated on the dynamometer   of the water weight when the object is in the water

9

Calculate the weight of the water collected in the beaker. Use the following formula. Record the results in your table. Weight of the Weight of the water, beaker  displaced water  and tray

Weight of the empty beaker and tray

10

Repeat steps 4 to 8 with the other objects.

11

Repeat the experiment using alcohol instead of water.

FURTHER STUDY How does a life jacket prevent someone from sinking in the water?

Figure 32 This model allows you to measure the buoyancy force of a liquid on

an object and to collect the displaced liquid.

This Way to the Review Activity Keep the discoveries that you made in this activity. They will help you confirm the buoyancy of your boat in the chapter review activity.

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I analyze my results and present them 1 Explain in your own words the force that different liquids exert on objects that have been dropped into them. 2 Illustrate your explanation with a diagram. 3 Discuss your results with your classmates. 4

If you were to repeat this experiment, how would you change the procedure? Explain why.

ACTIVITY 3 Experimentation Don’t Rock the Boat! Sometimes all it takes is one false move, one big wave, or a gust of wind to capsize a boat. In order to design a boat that can maintain its balance, you must fully understand the principle of stability.

Basic Mechanical Functions ENCYCLOPEDIA, pp. 392–394

The Transmission of Motion ENCYCLOPEDIA, pp. 419–422

How to Apply the Experimental Method SKILLS HANDBOOK, pp. 430–432

The Dynamometer SKILLS HANDBOOK, p. 458

HISTORY OF

I observe

SCIENCE

Figure 33 The capsizing of a sailboat

The shape of the keel alone does not guarantee a sailboat’s stability. Gerry Roufs, a Montréaler, perished in the Antarctic in January 1997. He had been competing with 17 others in the Vendée Globe single-handed round-the-world race. His sailboat likely capsized, as did the boats of two other contestants, Tony Bullimore and Thierry Dubois. Their occupants narrowly escaped death. The criteria for sailboat stability in such races are stricter now.

Certain boats capsize easily. Others are very stable. After capsizing, certain boats right themselves on their own. Others are very difficult to right.

I develop a research question “What must I do to build a boat that is virtually capsize-proof and that will right itself easily if it does capsize?” I define the variables Your experiment must enable you to discover:

Hull

• how the shape of the hull influences a boat’s stability

The exterior surface of a boat and its framework. Fixtures, such as the mast, keel and rudder, are attached to it.

• how the distribution of a boat’s cargo can modify its stability • what the basic mechanical function of the keel is

Keel The flat, heavy structure attached to the bottom of a sailboat. CHAPTER 3

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81

Equipment • a glue gun • a hole punch for soft material • a retractable utility knife • a vise • a dynamometer • a set of weights • a protractor • a ruler Material • corrugated plastic • a wooden dowel 1 cm

I experiment PROCEDURE 1 Examine the available equipment and material, as well as Figure 34. 2 Determine a procedure for conducting this experiment. 3

Have your teacher approve your procedure.

4

Build your prototype.

5

Conduct your experiment.

Dynamometer

in diameter • a 7.5-cm (3-inch) roofing nail • synthetic thread (fishing line) • glue sticks

Wooden dowel representing the mast Nail representing the boat’s axis of rotation Corrugated plastic representing the hull and keel

NEWS FLASH . . .

Holes onto which to hook weights

This sailboat is nearly capsize-proof. When it does capsize, it rights itself on its own. Carefully study the shape of its keel. Coque

This Way to the Review Activity Keep your results and answers. You will be using them to build a boat that is stable and able to right itself after capsizing.

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Figure 34 Set-up for the experiment

I analyze my results and present them 1 Describe the ideal shape of a boat’s hull, one that allows the boat to right itself after capsizing. 2 Describe how you would arrange the cargo so that your boat could right itself after capsizing. 3 Answer the following questions: a) How does the direction and speed of the wind hitting a sail cause a boat to capsize? b) How can waves capsize a boat? 4 Describe the ideal shape of a boat’s keel, one that allows the boat to right itself after capsizing. 5 What is the basic mechanical function of the keel? Draw a diagram to illustrate it. 6

Discuss your results with your classmates.

7

If you were to repeat this experiment, how would you change the procedure? Explain why.

I experiment PROCEDURE 1 With the available equipment and material, complete the following manufacturing process sheet to build the prototype in Figure 36. • Drill four holes into your prototype. These holes must allow you to attach the corrugated plastic panel with a bolt. Using these holes, you can determine the ideal spot for the keel. • Hammer 12 nails into your prototype. You will use these to attach the thread that you will use to pull your prototype through the water. Using these nails, you can determine the ideal spot for the mast when the wind is blowing from the rear. 2

Equipment • safety glasses • a glue gun • a hand drill or power drill • a set of drill bits • a 5-cm (2-inch) bolt • two screws • a retractable utility knife • a Pyrex dish screws • a screwdriver appropriate for the • an adjustable wrench Material • a 8-cm x 4-cm plywood board s • 12 2.5-cm (1-inch) finishing nail ) line ing • synthetic thread (fish • a piece of corrugated plastic approximately 4 cm x 2 cm

3

Make the technical drawing of your prototype, and number each of the nails. Have your teacher approve your manufacturing process sheet and technical drawing.

4

Build your prototype.

5

Determine a procedure for conducting the experiment.

6

Have your teacher approve your procedure.

7

Conduct your experiment.

8

Record your results in a table.

The four holes represent the different possible spots for the keel. They are labelled A to D on the piece of plywood.

The 12 nails represent the different possible spots for the mast. They are labelled 1 to 12 on the piece of plywood.

The corrugated plastic represents the keel.

• water

The thread represents the force exerted by the backwind on the sails. a) Side view b) Top view Figure 36 The prototype for this experiment

I analyze my results and present them 1 How did you simulate the forces that are exerted by: a) the wind? b) the water? 2 Indicate where you should attach the thread and piece of corrugated plastic so that your prototype can maintain its course. Explain your choice. 3 Discuss your results with your classmates. 4

After the discussion, draw a diagram showing the ideal positions for the keel (piece of corrugated plastic) and the mast (nail) on your prototype in a backwind.

5

Explain the relationship between the position of the keel and the friction of the water.

6

If you were to repeat this experiment, how would you change the procedure? Explain why.

This Way to the Review Activity Keep your results. They will help you in the chapter review activity, when you design a boat that will maintain its course.

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REVIEW ACTIVITY

3

Technology

The Wind in Your Sails The state of the planet is a growing concern. Several factors are threatening its balance. However, every time we run into a problem, humans try to find solutions, even if we do not always succeed. With your team, you too must devise an environmentally friendly solution to the problem of cargo transport. 1

Examine the specifications on the following page.

2

Make an inventory of the equipment and material you will need.

3

Make the technical drawing of your boat.

4

Develop the manufacturing process sheet.

5

Create a procedure to test your boat.

6

Have your teacher approve your list of equipment and material, technical drawing, manufacturing process sheet and procedure.

7

Build your boat.

8

Test your boat. Adjust it as needed.

9

Prepare a report for your teacher. Your report must contain the following elements: • a design plan explaining the function of the following systems of your boat: buoyancy, ability to right itself after capsizing, and steering • your technical drawing • your manufacturing process sheet • your testing procedure • a record of results obtained during testing • a record of modifications made after testing

Checklist

Technical Diagrams ENCYCLOPEDIA, pp. 382–384

The Manufacturing Process Sheet ENCYCLOPEDIA, p. 385

How to Apply the Design Process SKILLS HANDBOOK, pp. 433–435

NEWS FLASH . . . On the night of April 14 and 15, 1912, the Titanic sank 640 km south of Newfoundland. It was crossing the Atlantic for the first time. Of the 2224 people on board, 1500 perished. The ship’s designers had believed that its 16 watertight compartments made it unsinkable.

1. We built a boat that complies with the specifications. 2. We clearly explained the function of each of our boat’s systems. 3. We correctly used the scientific and technological information seen in the chapter to improve our boat’s performance. 4. We made appropriate contributions to the work of our team.

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JOB OPPORTUNITY

Specifications

Naval Architectural Technician Do you like to work with advanced computers and software? Are you a stickler for accuracy? This line of work may interest you. To do this job, you must finish high school and, if you’re able to study in French, you can enroll in the Institut maritime du Québec in Rimouski. There, you will follow a three-year program. For those studying in English, Memorial University of Newfoundland offers the only undergraduate program in Canada.

Nature and Purpose of the Object A boat capable of transporting a 150-g load of 4-cm finishing nails.

Making It From a physical perspective, the boat must be capable of: – righting itself after capsizing – resuming its course in the same direction as the wind – surfacing after dipping below the waterline – keeping its cargo dry at all times – moving without human intervention after being launched From a technical perspective, the boat must: – be 8 to 12 cm long – have a maximum air draught of 10 cm – have a maximum draught of 3 cm – have a maximum width of 8 cm – be wind powered From an environmental perspective, the boat must: – be made of recycled materials

Air draught The vertical distance of a boat above the waterline.

Draught The vertical distance of a boat below the waterline.

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Using It From a human perspective, the boat must: – be aesthetically pleasing

MY

DISCOVERIES

Chapter 1 • The water cycle consists of a series of endlessly repeating stages. Water evaporates from the ground, bodies of water and living organisms (through transpiration). It then condenses to form clouds. Finally, it returns to the ground in the form of precipitation (page 48). • Evaporation is quicker when the air is warm, dry and in motion (pages 49 and 50). • The planet’s average temperature has risen approximately 0.45°C over the past 25 years. Annual temperature variations are much greater than average temperature variations, however (pages 51 and 52). • In some places, the hotter the air is, the more water vapour and precipitation it can carry. In other places, hot air is more likely to dry out the ground. Condensation occurs when the air cools and can no longer contain all the water in the form of vapour (pages 53 and 54). • The greater the temperature difference, the more powerful the winds (pages 55 and 56). • Hot air rises and cold air drops. The farther hot air rises, the cooler it becomes. The farther cool air drops, the warmer it becomes (pages 57 and 58).

Chapter 2 • If a lever arm is shortened, then the force applied to the load will be weaker. However, the movement obtained will be greater. If a lever arm is lengthened, then the force applied to the load will be stronger. However, the movement obtained will be smaller (pages 65 to 67). • A bicycle pedal increases the force applied to the chain. When this movement is transmitted to the gears, it increases the motion of the back wheel (pages 68 and 69). • To obtain maximum efficiency on a long bike journey, a cyclist’s heart rate must remain at less than 85% of its maximum rate. The cyclist must also maintain a cadence of 60 to 80 pedal rotations a minute (pages 70 and 71). • The consumption of petroleum products causes the release of large quantities of carbon dioxide into the atmosphere. This contributes to an increase in the greenhouse effect and can have disastrous effects on the environment (pages 72 and 73).

Chapter 3 • In a comparison of two objects with similar masses, the object with the larger volume floats more easily (pages 77 and 78). • An object that floats displaces a quantity of liquid that is equivalent to its weight. The immersed portion corresponds to the volume of the displaced liquid (pages 79 and 80). • The deeper a boat’s keel extends and the heavier a boat is at the stern, the less likely the boat is to capsize, and the easier it is to right after capsizing. The larger a boat’s hull, the harder it is to capsize. However, a large hull makes righting a capsized boat more difficult (pages 81 and 82). • The farther forward a boat’s mast is, the more easily a boat points in the direction of the wind. The presence of a keel under its hull, at the back, helps point the boat in the direction of the wind (pages 83 and 84). 87

U NIT

PROJECT

2

Technology

Necessity Is the Mother of Invention How to Apply the Design Process SKILLS HANDBOOK, pp. 433–435

KEY CONCEPTS IN UNIT 2 • atmosphere • basic mechanical functions • components of a system • conservation of matter • design plan • effects of a force • energy transformation • hydrosphere

How do the people in a region surrounded by sea water get drinking water locally? This is your next challenge. You will design and build the prototype of a machine that can transform salt water into fresh water. An invention of this kind would be useful in Thailand, for instance, which borders the ocean. It would enable the country to produce drinking water locally.

• light

1

Examine the specifications and Figure 37 on the next page.

• manufacturing process sheet

2

When water evaporates from the ocean, it essentially contains no salt. How can you imitate this phenomenon with your machine?

• mass

3

Design and build your machine using the design process. You can base it on the diagram in Figure 37 on the next page.

4

You must give your teacher a report containing the following elements: • a design plan of your machine • a technical drawing of your machine • a manufacturing process sheet for your machine • a testing procedure • a record of results obtained during testing • a record of modifications made after testing

• mechanisms that bring about a change in motion • mechanisms that transmit motion • physical and behavioural adaptation • physical change • simple machines • specifications • states of matter • system (overall function, inputs, processes, outputs, control) • technical drawing • temperature • types of motion • universal gravitation • volume • water cycle • water (distribution) • winds

88

Checklist 1. 2. 3. 4.

I designed a machine that meets the specifications. I proposed a solution that protects the planet’s balance. I tested my prototype and used my test results to improve it. I used effective work methods to develop my design process.

Specifications Nature and Purpose of the Object A machine that, with the help of powerful lighting, is capable of producing at least 5 mL of fresh water an hour from salt water.

Making It From a physical perspective, the machine must: – be made of corrosion-resistant material – be watertight – be able to desalinate water containing at least 3.5 g of salt for each 100 mL of water

Corrosion A chemical reaction causing the progressive destruction of an object. For example, in the presence of air or water, oxygen and iron react together to produce rust.

From a technical perspective, the machine must: – have a maximum volume of approximately 60 cm x 30 cm x 30 cm – collect fresh water automatically in a collection basin From an environmental perspective, the machine must: – be constructed from recycled materials as much as possible

Using It From a human perspective, the machine must: – allow the addition of salt water – allow the collection of fresh water – be easy to maintain

The Sun

Condensation

Glass

Trough Evaporation Figure 37 This diagram shows the Mexican method of desalinating

sea water. The black basin absorbs the sun’s light. The sea water in the black basin heats and quickly evaporates. The glass, however, does not absorb the sun’s light. It is therefore cooler than the black basin. The water condenses on it, and then drips into the trough. The apparatus rests on insulated material.

Black basin

Sea water

Insulation

89

C HAPTER 1 KEY CONCEPTS IN CHAPTER 1 • asexual and sexual reproduction • cellular components visible under a microscope • characteristics of living organisms • evolution • fertilization • gametes • genes and chromosomes • physical and behavioural adaptation • plant and animal cells • pregnancy • reproduction in animals • reproductive organs

A Fascinating Development Where Do Babies Come From? The passage below was taken from a book for children. It was written by a young person of your own age to explain the stages of human development. 1. In your opinion, is any information missing? Are any elements untrue because they have been oversimplified? 2. Rewrite the passage to make it correct. 3. Suppose you wanted to explain human development to a child of about eight years of age. a) What would you have to know about human development, from conception to birth? From birth to death? b) How would you present the subject to a young child?

• species • stages of human development

n have d a woma n a n a m A lations. sexual re h mixe s wit n e m e s ’s n’s The man t he w oma an o vum in v um g row s a nd o belly . Th e aby. ab becom es re has no mo y b a b e h lly, it When t other’s be if m s it in room learn . Then we t u o s e m o c l. y or a gir it is a bo

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Your challenge in Chapter 1 is to discover the stages of human development, from the formation of sex cells to death. • In Activity 1, “Reproducing and Evolving” on pages 94 and 95, you will be reviewing the concepts of evolution and adaptation, and the various reproductive mechanisms of living things. Why Do I Have My Father’s Eyes? • In Activities 2 and 3, you will see certain elements that affect the transmission of genetic traits. – In Activity 2, “Sex Cells” on page 96, you will examine gametes under a microscope. – In Activity 3, “Extracting DNA” on pages 97 and 98, you will extract and observe DNA from the cells of your cheek. • In Activity 4, “Puberty Already!” on page 99, you will learn more about the human reproductive organs. • In Activity 5, “The Cycle of Life” on page 100, you will discover the stages of human development. At the end of this chapter, in the review activity “Our Story” on page 101, you will explain human development in a small illustrated book written for elementary students of about eight years of age.

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ACTIVITY 1 Analysis and Communication Reproducing and Evolving Species ENCYCLOPEDIA, p. 216

Evolution ENCYCLOPEDIA, pp. 235–237

Natural Selection ENCYCLOPEDIA, p. 235

Genetic Mutation ENCYCLOPEDIA, p. 236

Reproduction in Animals ENCYCLOPEDIA, pp. 250–256

Figure 1 Diversity in the human species

Study the diversity of the human species in Figure 1. Certainly, differences between human beings are not as significant as those that exist between animals or between plants. But Homo sapiens has been on the Earth for only about 400 000 years. This might seem a long time to you, but, in reality, it is a very short time for such diversity to appear. In comparison, life appeared and began developing here on the Earth approximately 3.5 billion years ago. Homo sapiens boasted only a few tens of thousands of individuals 100 000 years ago. How could this species have become so numerous? How did people end up displaying so many differences? You will be able to answer these questions at the end of this activity. 1

In a few sentences, summarize what you know about each of the following subjects: • the evolution of species • natural selection • reproduction in animals

2

Read “The Cradle of Life” on the next page. It will tell you about the age of the Earth and the evolution of life.

3

Have a discussion with your classmates. Try to explain how the human species developed in the past 100 000 years. Also explain why, in your opinion, there are so many differences from one individual to another (see Figure 1).

FURTHER STUDY Make a comic book, banner or poster showing the evolution and diversification of an existing species over the past 100 000 years.

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The Cradle of Life The Earth is approximately 4.5 billion years old. Imagine that this period equals 12 hours (see Figure 2). Using our clock, let us say that our planet appears at midnight. The first forms of life appear at 2:45 a.m. (see Table 1). Animal life comes and goes many times over, as witnessed by the changes occurring between 10:25 a.m. and 10:37 a.m. The dinosaurs appear at 11:19 a.m. and die out at 11:48 a.m. The human species appears 24 seconds before noon (if we count the first Homo, who appeared approximately 2.5 million years ago). Modern humans (Homo sapiens) appeared approximately 400 000 years ago. On our clock, that is just two seconds before noon! Just as this 12-hour period is coming to an end, there is a tiny period of 1/20th of a second. In that short period are crammed the last 6000 years of our civilization. 11:59:58 11:59:36 11:58 11:24 From 11:19 to 11:48 10:37 10:36

Table 1 Some major events in life

development

Date 1:33 2:45 4:37

1:33

10:25

10:25 10:36 2:45

10:37 From 11:19 to 11:48 11:24 11:58 11:59:36

4:37

11:59:58

Figure 2 Clock showing

Event Oldest known rocks (4.016 billion years ago) First cells (3.8 billion years ago) Cyanobacteria (primitive algae) (2.8 billion years ago) Ediacaran fauna (600 million years ago) Tommotian fauna (530 million years ago) Burgess fauna (525 million years ago) Dinosaurs (appeared 230 million years ago and disappeared 66 million years ago) Mammals (200 million years ago) Hominids (6 million years ago) First Homo (2.5 million years ago) Homo sapiens (400 000 years ago)

the evolution of life

 Ediacaran fauna

 Tommotian fauna

 Burgess fauna CHAPTER 1

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ACTIVITY 2 Sex Cells The Cell ENCYCLOPEDIA, pp. 277–283

The Microscope SKILLS

HANDBOOK,

pp. 453–456

Gamete The male reproductive cell (spermatozoon) or female reproductive cell (ovum) that can unite with another, similar cell from the opposite sex, through the process of fertilization.

Analysis

Have you ever observed animal or plant cells under a microscope? If so, you will have noticed that these two types of cells have parts in common. You will also have seen that the plant cell has certain additional parts. The perpetuation of species and evolution are ensured by reproduction. In this activity, you will study the two human cells necessary for sexual reproduction: the male gamete and the female gamete.

Figure 3 Spermatozoon penetrating an ovum

96

1

Use a microscope to study the prepared slides your teacher will give you. These slides contain animal cells, specifically, male and female gametes.

2

Draw what you observed under the microscope. Specify the magnification used.

This Way to the Review Activity

3

Keep your sex cell diagrams and notes in a safe place. You can work the information into your booklet when you do the review activity.

Answer the following questions: a) What are the cells you observed called? b) What parts typical of animal cells did you observe in each cell? c) Did you see any parts not found in a typical animal cell? If so, try to name them.

4

In your diagrams, name each part you identified.

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ACTIVITY 3 Experimentation Extracting DNA Genes and Chromosomes ENCYCLOPEDIA, pp. 236–237

How to Apply the Experimental Method SKILLS

HANDBOOK,

pp. 430–432

The Microscope SKILLS

HANDBOOK,

pp. 453–456

HISTORY SCIENCE

The cell nucleus directs the cell’s activities and contains its genetic material. This material appears as long strands of deoxyribonucleic acid (DNA) in the form of a double helix. The transmission of information contained in the DNA is essential to the production of new cells, the reproduction of individuals, and the evolution of species.

OF

I observe

Rosalind Elsie Franklin (1920 –1958) projected an X-ray beam that had passed through DNA onto photographic film and, in this way, obtained images of DNA. From these images, James Watson and Francis Crick deduced that the DNA molecule had the form of a double helix. In 1962, they received the Nobel Prize in Medicine for the model they developed.

I develop a research question “How can I extract and observe my own cells’ DNA?”

I define the variables Your experiment must enable you to extract DNA from the cells of your cheek and observe them with a microscope.

I experiment The following procedure will enable you to perform this experiment. 1

Add 15 g of table salt to the spring water.

2

Reclose the bottle of spring water. Shake the bottle until the salt is completely dissolved. The water is now salted.

3

Pour 45 mL of this salted water into a plastic cup.

4

Gargle and rinse the insides of your cheeks well with 45 mL of salted water. Spit the water into a 250-mL beaker.

5

Dip the stirring rod in some dishwashing liquid and gently add a drop of the soap to the beaker’s contents.

Equipment • a plastic cup • a 250-mL beaker • a 250-mL graduated cylinder • a dropping pipette • a stirring rod • a microscope • a microscope slide • a cover glass Material • 500-mL bottle of spring water • 15 g of table salt (NaCl) • 125 mL of alcohol • blue food colouring • colourless dishwashing liquid

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GENETICS IN HISTORY t 1859

Charles Darwin proposes a theory of evolution.

6

Stir gently two or three times only. There should be as little foam as possible.

7

Measure 125 mL of alcohol into a graduated cylinder.

8

Add two drops of food colouring to the alcohol and stir well.

t 1865

Gregor Mendel defines the fundamental laws of heredity. t 1869

9

Friedrich Miescher isolates DNA for the first time. t 1953

Franklin, Watson and Crick discover that DNA has the structure of a double helix. t 1973

First cloning of an animal gene t 1982

First transgenic mammal. In the photograph, a baby mouse has a fluorescent green protein extracted from a jellyfish.

t 2003

Scientists finish decoding human DNA. It contains 30 000 genes.

FURTHER STUDY What have specialists in genetics been doing since they finished decoding human DNA? Do some research on the most recent developments in this booming sector. Also investigate some of the ethical and social issues involved in these discoveries.

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Using the dropping pipette, make the alcohol slide down the side of the beaker. Tilt the beaker roughly 20 degrees so that the alcohol sits on top of its contents, but does not mix. Pour enough alcohol to form a layer approximately 2 cm thick on top of the water.

10

Observe the strands of DNA clustered in the layer of alcohol.

11

Remove the DNA with the dropping pipette and place it on a microscope slide. Following your teacher’s instructions, place a cover glass over it.

12

Observe your DNA under the microscope.

13

Draw what you see in the microscope.

I analyze my results and present them 1 You used different products to perform this experiment. In your opinion, what is the purpose of: • the salt (NaCl)? • the soap? • the alcohol? 2 In your opinion, how could you have observed the double-helix structure of DNA in more detail? 3

How would you modify the procedure if you had to redo the experiment? Explain why.

4

How has the study of DNA influenced the history of science?

5

“DNA is the structure responsible for the evolution of species.” Research the subject briefly to obtain further information.

6

Write a summary of your research.

ACTIVITY 4 Research and Communication Puberty Already! Most animal species attain a stage of sexual maturity sometime in their life cycle. From that moment, they are able to reproduce and transmit their genetic material. In humans, this stage corresponds to puberty. Right from the start of puberty, physical and psychological changes occur. This activity will enable you to discover those changes. 1

With your classmates, discuss the physical and psychological changes seen at puberty.

2

Take note of the changes you have identified. Make sure you have understood the anatomy of the reproductive organs, and the changes associated with puberty.

3

Following your teacher’s instructions, choose a part of your reproductive system.

4

Do some research on the role and functions of this part of your anatomy.

5

Write up a fact sheet. It must contain an illustration, and a summary of what you have found.

6

Consult the other students’ fact sheets.

7

To check your knowledge, copy and label the diagrams your teacher gives you.

Reproduction in Humans ENCYCLOPEDIA, pp. 257–261

Adolescence and Puberty ENCYCLOPEDIA, p. 271

How to Conduct a Research Project SKILLS

HANDBOOK,

pp. 436–437

How to Communicate Effectively SKILLS

HANDBOOK,

pp. 438–439

Puberty A stage of sexual development in which a series of changes prepares the human body for reproduction.

This Way to the Review Activity Make sure you have fully understood the changes occurring at puberty. This will be useful to you in the chapter review activity. CHAPTER 1

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ACTIVITY 5 Analysis The Cycle of Life Pregnancy ENCYCLOPEDIA, pp. 262–267

Birth ENCYCLOPEDIA, p. 268

The Stages of Human Development ENCYCLOPEDIA, pp. 269–271

As you saw in the previous activity, the human body is ready to reproduce from the onset of adolescence. Sexual reproduction begins with the union of sex cells, or fertilization. A series of cell divisions follow. Now, continue your investigation into human development from pregnancy to old age. Your teacher has set up 10 stations around the classroom. Each contains information on human development.

FURTHER STUDY Certain factors have contributed to the increase in life expectancy in Canada over the last 100 years. Do some research on the subject. Show how Canada ranks on scales of life expectancy worldwide.

Figure 4 Different stages of human development

1

Study the review sheets your teacher gives you. They will tell you what you will be learning at each station.

2

Following your teacher’s instructions, visit the 10 stations.

3

At • • •

4

Form teams. Compare your review sheet with those prepared by the other members of your team.

This Way to the Review Activity Now, choose elements in your review sheet that you will work into your booklet in the review activity “Our Story.”

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each station, take the time to: read the information available study the models and diagrams, if any complete the corresponding section of your review sheet

R EVIEW ACTIVITY 1

Communication

Our Story In this chapter, you learned a good deal about human development. You must now present this knowledge in a small illustrated book. You can then transmit the knowledge to students about eight years of age in elementary school.

1

Your booklet must have an illustrated cover page and a catchy title.

2

Your booklet tells the story of life. It must therefore: • explain reproductive mechanisms in animals in general • summarize the evolution of living species • name the parts of an animal cell and describe their roles • briefly identify what is found in the cell’s nucleus • describe the human reproductive organs and sex cells (gametes) • explain every stage of human development

3

You must include at least one photo, illustration or diagram referring to your text on each page.

4

You must write a summary outline that can be used to market your booklet. Remember that marketing is a step in the design process.

The Design Process ENCYCLOPEDIA, pp. 376–377

How to Communicate Effectively SKILLS HANDBOOK, pp. 438–439

NEWS FLASH . . . Every second, the human body produces nearly 50 million new cells. Each cell contains approximately 2 m of DNA. Placed end to end, the DNA the body makes in one hour would more than cover the distance from the Earth to the Sun.

You can use layout software to create your booklet. Revise your text with a grammar checker. You can also digitize the photos and illustrations you have chosen and insert them in your booklet. Do not forget to indicate your sources.

Checklist 1. I described and explained complex phenomena clearly. 2. I used scientific information learned in each of the chapter’s activities. 3. I used scientific language and attractive visual elements appropriate for children about eight years old. 4. I cooperated with my team members to accomplish the work.

This Way to the Project You now know more about cell structure, reproduction and human development. You can work your new knowledge into the game show you create as part of the unit project “It’s My Life.”

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C HAPTER 2 KEY CONCEPTS IN CHAPTER 2

Healthy Habits for a Healthy Body

• acidity/alkalinity • chemical change • components of a system • design plan • equipment • manufacturing process sheet • material • molecule • osmosis and diffusion • physical change • respiration • specifications • stages of human development • system (overall function, inputs, processes, outputs, control) • technical drawing

Around the Campfire When you get together with your friends, activities often centre around sharing food or having a meal together. In the previous chapter, you learned about human development; this chapter looks at another important aspect of development: food and nutrition. 1. What factors make up a healthy lifestyle? 2. The time you spend with friends is usually a lot of fun. Take a look at the photograph on this page. Considering the context, what do you think of the food choices made by these young people?

Tip! Begin preparing your menu right away. At the end of the chapter, you will have a chance to make changes based on what you have learned.

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3. Describe a healthy diet that meets your daily needs. 4. What effects can your food choices have on the local economy? On the country’s agriculture industry? On the environment? On society at a global level? Imagine that your school is organizing a four-day camp at the end of the school year. The students are divided into teams, and each team must plan their meals. You are in charge of the menu. Your menu must meet all of your team members’ nutritional requirements. It should also provide them with enough energy to take part in the camp’s activities.

Your challenge in Chapter 2 is to learn what a balanced diet includes and why it is important for you to eat well. You will also learn about the effects your food choices have on your health. • In Activity 1, “A Look at What You Eat” on page 104, you will discover what your team members typically eat during the course of a day. • In Activity 2, “Canada’s Food Guide” on pages 105 and 106, you will learn more about a tool to help you plan your menus and physical activities. • In Activity 3, “Surprising Saliva” on pages 107 and 108, you will analyze the action of saliva on food and learn about its role in digestion. • In Activity 4, “Eating Well to Stay Healthy” on pages 109 and 110, you will learn that you need to eat a healthy diet for your cells to function properly. • In Activity 5, “Gateway into the Cell” on pages 111 and 112, you will learn how food reaches the cells in your body. • In Activity 6, “The Technology behind Our Food” on pages 113 and 114, you will design a piece of equipment used in food preparation. At the end of this chapter, in the review activity “Camp Cuisine” on page 115, you will make changes to your camp menu. You will take into account the needs of your team members and the recommendations contained in Canada’s Food Guide. You will also provide nutritional advice.

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ACTIVITY 1 Analysis A Look at What You Eat JOB OPPORTUNITY Dietitian/Nutritionist Dietitians, also known as nutritionists, work in the health field. They have a keen interest in food. They also possess strong interpersonal and communication skills. Dietitians must keep up to date on the latest scientific discoveries in the field of nutrition. If you are interested in a career as a dietitian, you must obtain a diploma of collegial studies (DEC) in health sciences. Then you must earn a bachelor’s degree in nutrition. You can also work in this field if you have technical training in dietetics, which is offered at the Cégep level.

Parents are generally the ones responsible for feeding their family. However, parents’ choices are influenced by their children’s tastes and requests. In this activity, you will take a close look at your daily menu. You will also discover the different kinds of foods your team members enjoy. 1

Record all the food you eat over the course of two days. You must choose a day on the weekend, as well as a school day. Record the quantity of each food you eat. Write down as much as you can about the ingredients of any prepackaged or restaurant meals.

2

Make a note of your preferences or any special food requirements (allergies, vegetarian, religion, tastes related to your country of origin, etc.).

3

Join the team assigned by your teacher.

4

Ask your team members to show you their food journals, and show them yours. Make a note of each member’s preferences and special requirements.

5

Answer the following questions based on what you already know: a) How would you improve your eating habits? Why? b) What effects can poor nutrition have on your health?

This Way to the Review Activity Hold on to your list and your notes on your team members’ preferences and requirements. They will be helpful in the “Camp Cuisine” review activity, where you will take into account the other students’ preferences as you make recommendations.

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ACTIVITY 2 Analysis Canada’s Food Guide

The first version of Canada’s Food Guide was published in 1942, during World War II when food rations were in effect. The purpose of the Guide was to prevent poor nutrition and to improve the health of Canadians. Since then, the Guide has been updated and transformed eight times following important scientific discoveries. However, its objective has remained the same: to help people make healthy food choices. 1

Your teacher will give you a copy of Canada’s Food Guide. Read it and pay attention to all the details: colours, examples of foods, examples of servings, advice, etc.

2

Copy the following table. Use the Guide to help you complete it.

FURTHER STUDY Compare the eight versions of Canada’s Food Guide published since 1942. How are they similar? How are they different? How do they fit in with important historical events?

Table 2 Healthy food profile of a teenager

Food groups

Examples of foods

Choices recommended for my age group and gender

Advice and tips from Canada’s Food Guide

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3

Answer the following questions: a) How does the Guide use illustrations and visual presentations to convey information? b) What does the Guide say about oils and fats? About the benefits of eating well and staying active? What does the Guide say about selecting beverages? c) List at least four ways that we can choose and prepare food to keep its fat content down. d) Are foods not listed in the four food groups unhealthy? e) Does everyone have the same nutritional requirements? Why, or why not? f) The Guide provides tips to help us follow its recommendations. Name at least five. g) Name at least three tips to help make wise choices when we buy groceries. h) How can we determine the number of servings of each food group contained in a meal that includes pizza, which is made from several different foods? i) What information does the Guide provide about food labels?

4

Describe the size of the recommended servings with quantities you know. For example, 15 mL of peanut butter is roughly equal to the size of your thumb.

5

Go back to the list you prepared in the previous activity, “A Look at What You Eat.” a) Analyze your list based on the recommendations contained in Canada’s Food Guide (number of servings of each food group, whether you have followed the advice it contains, etc.). Be sure to check your servings carefully. b) Which recommendations contained in the Food Guide might apply to the foods you ate on the two days you are analyzing?

6

Discuss your answers with your classmates.

FURTHER STUDY Some countries use pyramidshaped guides to present their nutritional recommendations. Analyze one of these pyramids with your teacher’s help.

This Way to the Review Activity Make sure you understand the recommendations contained in Canada’s Food Guide. They will come in handy when you make the changes to your menu in the review activity at the end of this chapter.

Figure 5 To which food groups do the foods in these photographs belong?

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ACTIVITY 3 Experimentation Surprising Saliva I observe

Acids and Bases

You consume solid and liquid food every day. Imagine that your last meal was a sandwich and a glass of orange juice. What happens to the sandwich after you eat it? What about the orange juice? Write down your answers. You will discuss them later. Digestion is a complex process that allows your body, through cellular respiration, to obtain the energy it needs to carry out its activities.

ENCYCLOPEDIA, pp. 183–188

Litmus Paper ENCYCLOPEDIA, p. 186

Physical and Chemical Changes ENCYCLOPEDIA, pp. 191 and 193

How to Apply the Experimental Method SKILLS

HANDBOOK,

pp. 430–432

The Table SKILLS

HANDBOOK,

p. 440

I develop research questions 1. “How is food transformed during digestion?” 2. “How can I observe the action of saliva on food?”

I define the variables Your experiment must allow you to: • distinguish the taste of salted crackers before and after you chew them for one minute • observe the physical and chemical changes that take place in your mouth; you will mix saliva with the mashed potatoes and let the mixture stand for 10 minutes • demonstrate the role of saliva in these changes; to do this, you will observe what happens when you add saliva to pure starch • determine whether saliva is acidic or basic

I experiment

PROCEDURE

As you suggest a procedure, remember that the iodine tincture turns starch dark blue. Starch is a complex sugar found in some foods, including grains such as wheat and corn. Starch is also found in certain vegetables, such as potatoes, and in several fruits, such as bananas.

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107

Equipment • a dropper bottle • a petri dish Material ent) • salted crackers (two for each stud er • six strips of litmus pap • • • • •

1

Using the available equipment and material, determine a procedure for conducting this experiment. You can use the questions in the section “I analyze my results and present them” as a guide.

2

Have your teacher approve your procedure.

3

Conduct your experiment.

cornstarch tincture of iodine a toothpick mashed potatoes saliva

I analyze my results and present them 1 Prepare a table to record your results and descriptions. 2

Answer the following questions: a) How did the taste of the crackers change after you chewed them? Describe this change in your table. b) How did the appearance of the crackers change after you chewed them? Describe their appearance in your table. c) How did the appearance of the mashed potatoes change after being in contact with saliva for 10 minutes? Describe their appearance in your table.

3

The chemical composition of the crackers changed after chewing. What proof do you have of this change?

4

Is saliva acidic or basic? In your opinion, is this the case for all of the substances your body secretes during digestion?

5

Describe the chemical and physical changes the mashed potatoes underwent in this experiment.

6

If you were to repeat this experiment, how would you change the procedure? Explain why.

FURTHER STUDY Take another look at the list of foods you prepared in Activity 1, “A Look at What You Eat.” Calculate (in kJ) whether what you ate in the course of a day corresponds to the energy needs of a person your age. Ask your teacher to help you with this question.

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ACTIVITY 4 Analysis Eating Well to Stay Healthy Since the beginning of this chapter, you have been reading about recommendations that have to do with food. You know that you need to make healthy food choices. However, eating is also an important social activity: it provides an opportunity to spend time with the people you care about and to relax, talk and sample foods from other cultures. Eating therefore goes hand in hand with other activities.

Cellular Respiration ENCYCLOPEDIA, p. 285

You learned in the previous activity that digestion begins in the mouth. What happens to food after that? What happens to the nutrients you absorb? How does your body use them? After this activity, you will be able to answer all of these questions. 1

One of the chemical reactions that takes place in your cells is called cellular respiration. Answer the following questions to help refresh your memory about this process: a) Where do the inputs of this reaction come from? b) In your opinion, how do the inputs travel to the cells? c) Aside from nutrients, what does the cell need for cellular respiration to take place? d) What might prevent this other input from entering the cell?

2

Read “An Overview of the Digestive System” on the next page. Study Figure 6 carefully. Answer the following questions: a) The mouth is not the only organ in the digestive system. What do you know about the reactions that take place in the other organs? b) What is the connection between the digestion of food, the particles it contains and the chemical changes that occur?

3

Now go back and answer the question at the beginning of the previous activity: “Imagine that your last meal was a sandwich and a glass of orange juice. What happens to the sandwich after you eat it? What about the orange juice?”

4

Discuss the following question with your teammates: If my diet consisted only of meal replacements, would my body get everything it needed for proper devel opment? Why or why not?”

NEWS FLASH . . . Aside from the fetal period and the first year of life, humans grow most rapidly during adolescence. Weight doubles, and you might grow between 8 and 12 cm a year for a few years. Girls between the ages of 13 and 15 need to consume an average of 10 358 kJ a day to meet their energy requirements. Boys between the ages of 16 and 19 need 12 771 kJ a day.

This Way to the Review Activity Make sure you understand how your digestive system works. This will help you to make recommendations for your camp menu in the review activity at the end of this chapter.

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An Overview of the Digestive System Physical and Chemical Changes ENCYCLOPEDIA, pp. 191 and 193

1 2 1 Salivary glands 2 Mouth or oral cavity 3 Pharynx 4 Esophagus 5 Liver 6 Gallbladder 7 Stomach 8 Pancreas 9 Small intestine

0 Large intestine ¡ Rectum Ô Anus £ Villus ¢ Food particle ˆ Capillary § Artery ¶ Vein

3 4

£

5

¢ ˆ

7 8

6

9 § ¶ 0 Ô

¡

Figure 6 Food: from consumption to cellular respiration

HISTORY

During digestion, the food you eat undergoes a series of physical and chemical changes that break it down into particles. These changes occur mainly in the mouth, stomach and small intestine (see Figure 6).

110

OF SCIENCE Alexis Saint-Martin was a Canadian trapper. On June 6, 1822, he was shot in the side. The bullet left an opening almost 2 cm across in his stomach. Dr. William Beaumont used SaintMartin’s case to study how the stomach works. SaintMartin died in 1880 … with a hole still in his stomach!

UNIT 3

The Adventure of Living Organisms

Physical changes take place primarily in the mouth, where food is cut and crushed through chewing. The stomach also plays a role in breaking down and mixing food. In the small intestine, bile, which is produced by the liver, breaks down lipids (fats). Chemical changes take place in all parts of the digestive system where secretions (saliva, digestive juices) are present. In the mouth, saliva transforms starch. In the stomach, gastric juices begin the digestion of proteins. In the small intestine, intestinal and pancreatic juices break down carbohydrates (sugars), proteins and fats. Once digestion is complete, the food particles are small enough for the body’s cells to use them. These particles are absorbed by the villi of the small intestine and diffuse toward the capillaries. Then the blood carries them to the cells. The food particles, called nutrients, are transformed into energy during cellular respiration, which is a form of combustion. The body can store the surplus energy, for example, in the form of fat. Nutrients are also used to build different molecules the body needs.

ACTIVITY 5

5

Experimentation

Gateway into the Cell I observe In the previous activity, “Eating Well to Stay Healthy,” you saw that the nutrients required by cellular respiration come from the food you eat. You also know that cells carry out exchanges with their surroundings through diffusion and osmosis. I develop research questions 1. “How can I reproduce the phenomena of diffusion and osmosis?” 2. “How can I explain diffusion and osmosis to someone who is not taking a science-and-technology class?”

I define the variables Your experiment must allow you to visualize the phenomena of diffusion and osmosis. I experiment

PROCEDURE

How Do Cells Work? ENCYCLOPEDIA, pp. 280–285

How to Apply the Experimental Method SKILLS

HANDBOOK,

pp. 430–432

How to Draw Diagrams SKILLS

HANDBOOK,

pp. 446–447

Equipment • a petri dish • a 250-mL beaker • a dropping pipette • an overhead projector • a knife Material • food colouring (red and blue) • one potato for each team • coarse salt • water (room temperature) • hot water (tinted red) • cold water (tinted blue) salt • saline solution (same mineral ) cells an concentration as hum • distilled water (containing no mineral salts)

The first hole contains distilled water. The second hole contains saline solution. a) Adding food colouring to water

The third hole contains coarse salt.

b) Adding hot water to cold water

c) Cellular exchanges in a potato

Figure 7 Developing a model of osmosis and diffusion

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JOB OPPORTUNITY Food Technician Food technicians perform many technical laboratory tasks in the food industry. They may determine the nutritional value of food or experiment with recipes. They may also monitor production quality or develop new food products, etc. If you are interested in a career as a food technician, you must obtain a diploma of collegial studies (DEC) in chemical-engineering technology, laboratory technology or food-processing technology.

1

Using the available equipment and material, determine a procedure for conducting this experiment. To help you, read the section “I analyze my results and present them.” You will prepare the three set-ups shown in Figure 7. The set-ups should allow you to explain diffusion and osmosis to someone who is not familiar with these phenomena.

2

Have your teacher approve your procedure.

3

Assemble your three set-ups and perform the experiment.

I analyze my results and present them 1 Answer the following questions: a) In the first set-up, you added a drop of food colouring to the roomtemperature water. What did you observe approximately three seconds after adding the food colouring? What did you observe one minute after adding the food colouring? b) In the second set-up, you mixed hot water (red) and cold water (blue) in a beaker. What did you observe when you mixed the two together? c) Use diagrams to illustrate what happened in the petri dish in the first set-up and in the beaker in the second set-up. d) What is the name of the phenomenon you observed in these two set-ups? 2

Use a diagram to illustrate what happened in each of the three holes in the potato.

3

Add a legend to each of your diagrams. The legends should contain explanations using the following words: diffusion, osmosis, cell and membrane.

4

Summarize the phenomena of diffusion and osmosis in your own words.

5

What is the connection between diffusion, osmosis and the passage of nutrients into the cell?

6

What is the connection between diffusion, osmosis, the passage of nutrients into your cells, your health and your level of physical fitness?

7

If you were to repeat this experiment, how would you change the procedure? Explain why.

Figure 8 Elodea cells in a saline solution

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ACTIVITY 6 Technology 6 The Technology behind Our Food The use of technology in the food industry is becoming increasingly common. Technology can be used to preserve, transform and even produce food. Biotechnology has given us cheese, yogurt, bread, certain beverages, etc. Although the word “biotechnology” is new, it refers to processes that have been around for a long time. Technical foodpreservation methods, such as pasteurization and canning, allow us to enjoy a wide variety of foods all year long. Cooking, drying, smoking, etc., are all technical processes for transforming food. In this activity, you will design and build an apparatus for drying food such as fruit. You may include this food in your camp menu in the review activity.

Technical Diagrams ENCYCLOPEDIA, pp. 382–384

The Manufacturing Process Sheet ENCYCLOPEDIA , p. 385

Material and Equipment ENCYCLOPEDIA , p. 387

Systems ENCYCLOPEDIA , pp. 389–390

How to Apply the Design Process SKILLS

HANDBOOK,

pp. 433–435

Pasteurization A process that uses heat to kill harmful bacteria sometimes found in liquids such as milk. Figure 9 Commercial dehydrator

1

Your teacher will give you a technical data sheet for a commercial dehydrator (see Figure 9). Read it carefully.

2

Read the specifications on the following page to learn about the design requirements of your apparatus.

3

Make a list of the equipment and material you need to build your dehydrator.

4

Draw a preliminary design plan for your dehydrator.

5

Draw a preliminary technical drawing for your dehydrator.

6

Have your teacher approve your list of equipment and material and your diagrams.

7

Build your dehydrator.

8

Adjust your design plan and technical drawing as needed.

9

Prepare a technical data sheet for your dehydrator, basing it on the one you read earlier. Include any necessary warnings.

10

Prepare a manufacturing process sheet for the mass production of your dehydrator.

11

Dry some fruit using your apparatus.

12

Summarize the features of your dehydrator, according to your teacher’s instructions.

FURTHER STUDY Not everyone is in favour of some methods used to preserve food, such as freeze-drying. Debate this topic after having researched one of these methods.

This Way to the Review Activity Make sure you understand the food-preservation technique called dehydration. It will help you make recommendations for your camp menu in the review activity at the end of this chapter.

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HISTORY

OF SCIENCE Louis Pasteur (1822–1895) was a French chemist and biologist. He invented many things, including the rabies vaccine. Back then, wine and beer used to sour quickly. This was extremely inconvenient and caused economic hardship. Pasteur established a connection between beverages turning sour and the presence of micro-organisms. He was able to destroy these microorganisms by heating the wine and beer and then letting them cool rapidly. Pasteurization was invented in 1865. In Québec, however, pasteurization of milk only began in 1926. Its introduction led to a decline in the infant-mortality rate.

Specifications Nature and Purpose of the Object A dehydrator for preparing dried fruit snacks.

Construction From a physical perspective, the object must be: – constructed from materials with a temperature resistance of approximately 65°C – constructed from materials that protect the food from contamination by micro-organisms – used in a clean area to avoid food contamination From a technical perspective, the object must: – be easy to dismantle (access to food, cleaning) – have a constant heat source – have good ventilation allowing water vapour to escape From an environmental perspective, the object must be: – constructed from materials that are not harmful to humans or to the environment – energy efficient

Use From a human perspective, the object must be: – easy to maintain – easy to operate – quiet – safe

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L-R

R EVIEW ACTIVITY 2

Communication

Camp Cuisine Throughout this chapter, you have read many tips about food and nutrition. You have also learned about the effects of food choices on your development. In this activity, you will make changes to your school camp menu. You will need to consider healthy food choices and the effects of your eating habits. 1

You will be presenting the menu you prepared at the beginning of the chapter, as well as your final menu.

2

Your final menu should: • include three meals and two snacks for each of the four days at camp • take into account the preferences and allergies (if any) of your team members • follow the principles contained in Canada’s Food Guide • fit the context (variety, cooking method, storage) • include the food you dried in class

3

Explain your choices based on the needs of the human body and how the digestive system works.

4

Explain the changes you made to your original menu.

How to Communicate Effectively SKILLS

HANDBOOK,

pp. 438–439

Checklist 1. I followed the recommendations contained in Canada’s Food Guide as I prepared my menu. 2. I made recommendations that took into account all of the information contained in this chapter. 3. I explained my choices, using good judgment with respect to food choices and considering the context and the special needs of each team member. 4. I used new vocabulary from this chapter.

This Way to the Project In this chapter, you have learned a lot of facts about food and nutrition. This knowledge will help you to prepare questions for your game show in the unit project.

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C HAPTER 3 Do Not Enter!

a) HIV virus

b) Gonorrhea bacteria

c) A parasite (pubic louse)

Figure 10 Micro-organisms responsible for certain STDs: a virus, bacteria and a parasite

Staying Safe KEY CONCEPTS IN CHAPTER 3 • contraception • methods of preventing the implantation of the zygote in the uterus • sexually transmitted diseases

Several viruses, bacteria and parasites cause diseases and infections, including sexually transmitted diseases (STDs), also known as “sexually transmitted infections” (STIs). Like all other living things, these microorganisms have adapted to their environment which, in their case, is the human body. For instance, their life cycles are relatively short and simple, and this allows them to reproduce rapidly. It also means that they are responsible for significant problems. If not treated, STDs can lead to serious diseases, infertility and even death. However, there are ways to prevent some of the micro-organisms that cause STDs from invading the body. 1. What would you do if you discovered you had an STD? 2. Do you know of any STDs? If so, which ones?

Giving Life At the beginning of this unit, you learned that the human body is ready for reproduction at puberty. However, most people are not prepared to become parents until many years later. 3. In the early 20th century, it was common to become a parent before the age of 18. What would change in your life if you had one or two children now? 4. “STDs and contraception are everyone’s concern.” Do you agree with this statement?

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Your challenge in Chapter 3 is to learn about STDs and contraception. • In Activity 1, “An STD? What STD?” on page 118, you will become familiar with different types of STDs. • In Activity 2, “At the Speed of Light” on page 119, you will discover how STDs spread, and you will take a look at methods used to prevent infection. • In Activity 3, “A Baby? Now?” on page 120, you will learn about the various contraceptive methods and devices available. At the end of this chapter, in the review activity “The Information Challenge” on page 121, you help out your local health centre. The centre has asked for your assistance in organizing an information-andawareness campaign on STDs and contraception. The campaign is aimed at kids your age. You will be creating a public-service message in the format of your choice: a radio or television broadcast, posters, brochures, etc.

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Do Not Enter!

117

Sexually Transmitted Diseases ENCYCLOPEDIA, pp. 274–275

How to Conduct a Research Project SKILLS HANDBOOK, pp. 436–437

How to Communicate Effectively SKILLS HANDBOOK, pp. 438–439

NEWS FLASH . . . Chlamydia and genital warts are the two most common STDs in Canadian teens. Almost 50 percent of Chlamydia infections occur in people between the ages of 15 and 24. Genital warts are caused by the Human Papilloma Virus (HPV). Twenty-one percent of HPV infections affect women under the age of 24.

ACTIVITY 1 Research and Communication An STD? What STD? The viruses, bacteria and parasites that cause STDs have become adapted to the human body. Therefore, it is important to consider both their short- and long-term effects (see Figure 11). For this reason, certain steps must be taken to outsmart their adaptation strategies. We tend to think that STDs will only happen to someone else. But Figure 11 Chlamydia bacteria what if that “someone else” turns out to be us? In this activity, you will learn about the different types of STDs. 1

Read the descriptions of the various STDs in the Encyclopedia section (see pages 274 and 275).

2

Divide into teams following your teacher’s instructions. Each team must choose a different STD.

3

Research the STD your team has chosen.

4

Prepare a poster on the STD you are studying. Your poster should contain the following information: • history of the disease • the micro-organism that causes it (the virus, bacterium or parasite) • how you can catch the disease and how it is spread • symptoms of the disease in men and in women • treatments available for curing or slowing the progress of the disease • best methods for preventing it

5

Present your poster to your classmates.

6

Copy the following table. Complete it using the information presented by your classmates.

FURTHER STUDY Prepare and conduct an interview with a health professional. Ask this person about STDs and contraceptive methods and devices. You can use this information in the review activity at the end of this chapter, where you will be preparing a public-service message.

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Table 3 Summary of various STDs

STD

Symptoms

Treatment

Prevention

ACTIVITY 2 Analysis At the Speed of Light You saw in the previous activity that it is not always easy to determine whether a person is infected with an STD. It is even more difficult to know whether your partner is infected. In this activity, you will discover how fast STDs can spread. You will also learn about the steps an infected person should follow. 1

Your teacher will give each student a test tube containing water. The water represents the bodily fluids exchanged during sex. One student will receive a different type of liquid. This liquid represents bodily fluid contaminated by a micro-organism that causes an STD.

2

Exchange the contents of your test tube with three other students. During each exchange, one student pours the test tube contents into another student’s test tube. Then this other student pours half of the combined liquid back into the first student’s test tube. Return to your seat after you have exchanged your test-tube liquid with three other students.

3

Once all of the students have exchanged their liquids, your teacher will perform a simple test. The test will show which liquids are now contaminated.

4

If your liquid is contaminated, stand up. Remain standing until all students with contaminated liquids are standing.

5

Next, as a class, determine who received the contaminated test tube at the beginning of the exercise.

6

Your teacher will give a second test tube to each student. This time, exchange the contents of your test tube with five other students.

7

Discuss the following questions as a class: a) How does the number of test tubes containing contaminated liquid in this activity imitate the spread of an STD? b) How did you determine who received the contaminated test tube at the beginning of the exercise? c) What steps should an infected individual take to obtain treatment? To avoid spreading the disease?

NEWS FLASH . . . In 1495, Charles VIII returned from Naples after liberating the city, and his army began spreading in Europe a new disease called syphilis. The entire continent became contaminated, and the disease hit all social classes. It was a real epidemic until the 20th century, when an effective treatment was finally developed.

This Way to the Review Activity Make note of the details you think are important to convey regarding STDs. This information will help you organize the awareness campaign in the review activity at the end of this chapter.

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Do Not Enter!

119

Family Planning ENCYCLOPEDIA, pp. 272–273

How to Conduct a Research Project SKILLS

HANDBOOK,

pp. 436–437

How to Communicate Effectively SKILLS

HANDBOOK,

pp. 438–439

NEWS FLASH . . . Contrary to popular belief, a woman may become pregnant the first time she has sex. According to The Canadian Journal of Human Sexuality, each year approximately 38 000 teenagers between the ages of 15 and 19 become pregnant.

ACTIVITY 3 Research and Communication A Baby? Now? Having a baby is a life-changing experience and should therefore be carefully planned. In other words, aside from protecting against STDs, people who are sexually active also need to consider contraception. In this activity, you will research a contraceptive method or device that is currently available on the market. You will also consider ways to increase the effectiveness of the method selected and to decrease its disadvantages. 1

Read about the various contraceptive methods and devices described in the Encyclopedia (see pages 272 and 273).

2

Based on what you already know, discuss the following question with your classmates: “Which contraceptive methods and devices are most effective?”

3

Choose a contraceptive method or device following your teacher’s instructions.

4

Briefly research the contraceptive method or device you have selected.

5

Present your information in table form. Your table should show: • how this contraceptive method or device works • how it is used • the group of people who could benefit from this method or device • the estimated effectiveness of the method or device • its advantages and disadvantages

6

Look for a picture of, or draw, this contraceptive method or device.

7

Write an introduction on the history of this contraceptive method or device.

8

Write about five lines explaining how you would improve the effectiveness of this contraceptive method or device. Describe how to reduce its disadvantages.

9

Present the contraceptive method or device to your classmates.

10

Copy the following table. Complete it using the information provided by the other students during their presentations.

This Way to the Review Activity Make note of the details you think are important to convey about the various contraceptive methods and devices. This information will help you organize the awareness campaign in the review activity at the end of this chapter.

Table 4 Summary of various contraceptive methods and devices

Contraceptive method or device

120

How it works How it is used

UNIT 3

The Adventure of Living Organisms

Target group

Estimated effectiveness (%)

Advantages

Disadvantages

R EVIEW ACTIVITY 3

Communication

The Information Challenge How to Communicate Effectively SKILLS

HANDBOOK,

pp. 438–439

FURTHER STUDY

In this chapter, you learned about many aspects of sexually transmitted diseases and contraceptive methods and devices. Now your local health centre is asking for your help with an information and awareness campaign on STDs and contraception. The campaign is aimed at kids your age. 1

Your job involves producing a public-service message that will be broadcast over the media or posted in public areas. You get to decide how to reach your target audience (radio, television, posters, brochures). Consult the resources available in your area: talk to doctors and nurses, contact your local CLSC, etc.

2

Whichever method you choose, your message must include: • a catchy slogan • general information on STDs • general advice on how to protect against STDs • recommendations for people infected with STDs • information on contraceptive methods and devices

Louise Brown was born in Great Britain in 1978. She was the first baby conceived by in vitro fertilization. Since then, over 1 million children around the world have been conceived with this technique (see image), which is used by infertile couples. While some couples worry about contraception, others are affected by infertility. Research some of the new reproductive techniques and the ethical problems they raise.

Checklist 1. 2. 3. 4. 5.

I conveyed accurate scientific information. I used information obtained from the various activities in the chapter. I used creativity in developing my public-service message. I cooperated with my teammates throughout the project. I adapted my message to the method I selected for conveying my ideas.

This Way to the Unit Project STDs and contraceptive methods and devices are excellent topics for the game show you will be working on in the unit project. What types of questions could you ask on these two topics?

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121

M Y D ISCOVERIES Chapter 1 • Natural selection is a theory explaining the diversity of species and their evolution (pages 94 and 95). • Reproduction is the basis for gene transmission and species evolution (page 96). • Gametes are reproductive cells. The male gamete is also called a spermatozoon, and the female gamete is called an ovum (page 96). • An individual’s genetic information is contained in the DNA of cell nuclei (page 97). • Physical and psychological changes occur during puberty to prepare the body for reproduction (page 99). • The function and anatomy of male and female reproductive organs are very different (page 99). • Human development is divided into four stages: infancy, childhood, adolescence and adulthood (page 100).

Chapter 2 • By following the recommendations in Canada’s Food Guide, most people will get everything their bodies need for proper development (pages 105 and 106). • The food we eat is broken down into nutrients by the physical and chemical changes that occur during digestion (pages 107 and 108). • The digestive system consists of the digestive tract (made up of several organs) and glands that secrete saliva and digestive juices (pages 109 and 110). • The nutrients and oxygen required for cellular activity are transported by the blood. They enter the cell through diffusion (pages 111 and 112). • Osmosis balances the concentrations of certain substances in cells (pages 111 and 112). • Technology helps to improve methods for destroying micro-organisms and for preparing and preserving food (pages 113 and 114).

Chapter 3 • STDs are caused by viruses, bacteria and parasites, and they produce many different symptoms (page 118). • Antibiotics are used to treat some STDs, while others can be prevented with vaccines. It is possible to reduce the symptoms of certain incurable STDs (page 118). • A person who is infected with an STD must be treated by a doctor and inform all past and present partners (page 119). • Limiting the number of partners and using a condom reduces the risk of infection by an STD (page 119). • The condom is the only contraceptive device that also protects against STDs (page 120). • Pregnancy may be prevented by natural contraceptive methods or by mechanical, chemical or surgical means (page 120).

122

U NIT P ROJECT 3 It’s My Life How to Communicate Effectively SKILLS

HANDBOOK,

pp. 438–439

KEY CONCEPTS IN UNIT 3 • acidity/alkalinity • asexual and sexual reproduction • cellular components visible under a microscope • characteristics of living organisms • chemical change • components of a system

In the three chapters of this unit, you learned about the various stages of human development. You also learned that it is important to eat well so your body will develop properly. You discussed two topics that have to do with sexuality: contraception and STDs. Now you will enter a contest sponsored by Life TV and prepare a game show. The theme of the show is human development. 1

Reread the contest rules on page 91.

2

Develop a concept for your game show.

3

Write the questions and answers for your program.

4

Prepare any necessary equipment.

5

Plan a rehearsal of your game show.

6

Host your game show during the rehearsal.

• contraception • design plan • equipment • evolution • fertilization • gametes • genes and chromosomes • manufacturing process sheet • material • methods of preventing the implantation of the zygote in the uterus • molecule • osmosis and diffusion • physical and behavioural adaptation • physical change

Checklist

• plant and animal cells • pregnancy • reproduction in animals

1. I conveyed accurate scientific and technological information as I prepared my questions and answers. 2. I used new vocabulary from the unit chapters. 3. I showed originality in developing and hosting my game show. 4. I used effective work habits from start to finish. 5. I used ICTs in the visual presentation of my game show and in preparing my questions and answers.

• reproductive organs • respiration • sexually transmitted diseases • species • specifications • stages of human development • system (overall function, inputs, processes, outputs, control) • technical drawing

123

Unit 4

Creating Your Own Perfume Contents Chapter 1 Soil: A Priceless Resource . . . . . . . . . . 126 Chapter 2 Solutions and Mixtures . . . . . . . . . . . .142 Chapter 3 Perfume Makes Perfect “Scents” . . . . . 154

A Short History of Perfume Over 5000 years ago, the Egyptians burned scented vegetable matter called aromatics as offerings to the sun god, Ra (see illustration below). The ancient Greeks also used perfumed substances to honour the gods and the dead, and cleansing oils and ointments when they bathed. As for the Romans, they believed that perfumes had medicinal powers. In the Middle Ages, when the Crusaders brought back perfumes from the Orient, their use in personal hygiene and for pleasure was rediscovered. It was at this time that the Queen of Hungary’s apothecary created the first perfume compound. It was made up of a mixture of different essences. An apothecary can be thought of as a kind of scientist, since it was he who would prepare medicinal syrups and medications in his shop (see illustration on the next page). In the 16th and 17th centuries, perfume consumption increased. In the 18th century, with the use of modern stills, the perfume industry developed in Grasse, in southern France.

124

That city is still the perfume capital of the world. In the 20th century, many haute couture houses launched perfumes. Film stars, singers and even athletes have had perfumes named after them. Perfume is a consumer product. The creation and marketing of perfume must follow a design process. In this unit, you will learn how to create a perfume. First, you will come up with a concept for your perfume. Then you will create it. Finally, you will produce and launch it. Take the first step in the design process now: think up a concept for your perfume. Form a team and brainstorm answers to these questions: 1. How will the steps in the design process help you to create, produce and launch your perfume? 2. What will the target audience be for your perfume? 3. What ingredients make up a perfume? Where can you get them? With your team, analyze each of the ideas that you came up with during your brainstorming session and choose one. Use this idea to plan how you will approach your procedure.

Project At the end of this unit, in the “Launching a New Perfume” project, you must present and promote the perfume that you have created. The three chapters in this unit will help you learn what you need to know to create a perfume and go through the steps of the design process.

125

C HAPTER 1 Soil: A Priceless Resource A Type of Soil for Every Plant KEY CONCEPTS IN CHAPTER 1 • acidity/alkalinity • characteristics • lithosphere • mass • physical and behavioural adaptation • types of rock (basic minerals) • types of soil

Flowers and aromatic plants are often the essential ingredients in perfume. To create a high-quality perfume, healthy plants must be used. If you want to grow healthy plants, you must take many factors into consideration. One of these factors is the type of soil. 1. What factors do you think contribute to the growth of a healthy plant? 2. What types of soil are you familiar with? 3. What criteria do you think can be used to identify different types of soil?

4. Name some plants that grow best in a particular kind of soil.

• volume

c) Heliotrope

a) Lavender b) Coleus Figure 1 These plants need very different types of soil to grow.

126

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Creating Your Own Perfume

Your challenge in Chapter 1 is to learn about the characteristics of different types of soil. This knowledge will help you better understand the needs of the aromatic plants that are used as basic ingredients in many perfumes. The Search for the Best Soil • In Activities 1 to 4, you will examine different types of soil. – In Activity 1, “Is All Soil the Same?” on pages 128 and 129, you will examine the characteristics of different soil samples. – In Activity 2, “What Is Soil Used For?” on pages 130 and 131, you will make a list of the different ways soil can be used. – In Activity 3, “Thirsty Soil” on pages 132 and 133, you will discover which type of soil offers the best drainage. – In Activity 4, “Too Much Salt in the Soil?” on pages 134 to 136, you will check different soil samples for the presence of mineral salts. Soil: An Environment Rich in Minerals • In Activities 5 and 6, you will study in greater depth the source of the mineral salts found in soil. – In Activity 5, “The World of Rocks” on page 137, you will assemble a file on different types of rocks and how they are formed. – In Activity 6, “Minerals,” on pages 138 to 140, you will learn more about a mineral of your choice. In the review activity at the end of this chapter, “Potted Flowers” on page 141, you will analyze the results that a horticulturist obtained from cultivating three flowering plants in four different types of soil. You will present your analysis of these results in a laboratory report.

CHAPTER 1

Soil: A Priceless Resource

127

ACTIVITY 1 Experimentation Is All Soil the Same? pH Encyclopedia, pp. 186–187

Universal Indicator Paper Encyclopedia, p. 188

Types of Soil Encyclopedia, pp. 307–310

How to Apply the Experimental Method Skills Handbook, pp. 430–432

The Table

I observe Soil covers almost the entire surface of the Earth. It is made up of rock particles and minerals. It also contains organic matter, such as debris from dead plants and animals. Soil contains microscopic life forms, as well as air and water. Soil is often essential to the cultivation of plants. I develop a research question 1. “What distinguishes one type of soil from another?” 2. “How can I classify different soil samples?”

Skills Handbook, p. 440

Porosity The percentage of free space in a given volume of soil.

a) Soil from a temperate region

b) Soil from an alpine region Figure 2 Flowering plants that have

adapted to different types of soil

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Creating Your Own Perfume

I define the variables 1. Your experiment must allow you to examine five soil samples: sand, black earth, peat moss, clay and the soil in your region. 2. Examine the following properties in the types of soil at your disposal: • the colour of the soil when it is dry • its texture when it is wet • its colour when it is wet • its structure • the average size of • its porosity its particles • its pH • its texture when it is dry 3. Use your results to propose a way of classifying types of soil. I experiment PROCEDURE 1 Collect a sample of local soil from a park in your neighbourhood, your garden or the schoolyard. If you cannot collect any soil, your teacher will provide some. 2 Note where the local soil sample was taken. 3 Examine the samples of the different types of soil that your teacher gave you. 4

Determine a procedure to discover the properties of your soil samples. Read “I analyze my results and present them” to help you do this.

5

Select the equipment and material needed to do this experiment from the list on the opposite page.

6

Have your teacher approve your procedure and your list of equipment and material.

7

Conduct your experiment.

I analyze my results and present them 1 In a table, note your data on the properties of each of the soil samples. 2 The texture of the soil depends on the size of its particles. Put your soil samples in order according to texture: a) Which is the most granular? b) Which has the finest particles?

3

The soil structure indicates the arrangement of the particles. Examine your sample of local soil. a) How does its structure compare to the other types of soil? b) What type of soil does it resemble when it is dry? When it is wet?

4

Soil structure tells us something about its porosity, that is, the free space found in a certain volume of soil. Describe the porosity of your local soil sample. Is your sample very porous? Or not very porous at all?

5

Establish the criteria that will help you classify the types of soil that you studied.

6

Compare your classification system with the ones that your classmates came up with.

7

Revise your criteria and your classification system if necessary.

8

Make up a list of your criteria for classification of types of soil and put it into a table.

9

Answer the following questions: a) What observations did you make using your senses? b) What observations did you make using observation instruments?

10

If you were to repeat this experiment, how would you change the procedure? Explain why.

11

Keep your soil samples. You will need them for later activities.

Equipment • safety glasses • a pH colour chart or • a magnifying glass, microscope ope binocular microsc • a sieve • a scale • 50-mL beakers • a spatula • a wash bottle • a stirring rod • a hot plate • an asbestos pad • two porcelain dishes • crucible tongs • a petri dish • funnels • a retort stand • a funnel stand • 100-mL graduated cylinders Material • water • distilled water • universal indicator paper • filter papers of soil • samples of five different types (sand, black earth, peat moss, clay, a sample of local soil)

This Way to the Review Activity Keep your classification table. It will help you when you analyze different types of soil in the review activity, “Potted Flowers.” CHAPTER 1

Soil: A Priceless Resource

129

ACTIVITY 2 Research and Communication What Is Soil Used For?

a) Construction

Figure 3 Some of the ways soil is used

b) Agriculture c) Mining

Types of Soil Encyclopedia, pp. 307–310

How to Conduct a Research Project Skills Handbook, pp. 436–437

How to Communicate Effectively

Human beings have always depended on soil and its riches for shelter, nourishment, making tools and so on. This activity will help you understand how important soil is to us. 1

Read “Different Types of Soil” on the next page.

2

Research one of the types of soil found in Canada. a) What is the composition of this soil? b) What are the different ways it can be used?

3

Make a list of the different ways this soil can be used. Give an example of each use from your own environment.

4

Choose one way we use soil. Represent this use in an illustration. a) Annotate your illustration. If necessary, add a legend. b) Give your illustration a title.

5

Look at your classmates’ illustrations.

6

Discuss the following questions with your classmates: a) What factors are bad for different types of soil? b) What can be done to preserve soil quality?

Skills Handbook, pp. 438–439

Use a search engine to find information on the Internet. You may also use software such as an illustration, paint or graphics program to produce your illustration.

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Different Types of Soil Types of soil are classified in different ways: according to their pH level, their texture, their colour, their structure and so on. Canada has its own soil-classification system. The map in Figure 4 gives definitions of types of soil and shows how they are distributed across the country.

Soil Profile Encyclopedia, p. 308

Permafrost The part of the ground that stays frozen all year long in colder regions.

Legend Types of Soil Chernozemic Soils: These soils favour the growth of grains and grasses (prairie vegetation) and are found in cool or cold regions. Accumulated organic matter blackens their surface layer (A horizon).

Luvisols: These soils are common in forested regions in moderate−to−cool climates. Organic Soils: These soils are made up of large quantities of organic matter (at least 30%).

Cryosols: Permafrost is found less than 1 m from the surface of these soils. The types of vegetation most often associated with them are tundra and boreal forest.

Podzols: The B horizon of these soils contains organic matter and metals (generally aluminum and iron).

Brunisols: The horizons of these soils are sufficiently formed to exclude them from the regosol category, but they cannot be classified under the other categories. They can be associated with a wide variety of types of rock, vegetation and climates.

Gleysols: These soils do not drain well. They are charac− terized by the prolonged presence of large quantities of water. Peat bogs tend to form at their surface.

Regosols: The horizons of these soils are either barely formed or absent.

Ice

Hudson Bay

PACIFIC OCEAN

ATLANTIC OCEAN

N W

Solonetzics: These types of soil favour the growth of prairie vegetation in semi−arid climates. Their B horizon isgenerally brown. Their C horizon contains mineral salts, especially sodium.

E

0

Scale 250

500 km

S

Source: Agriculture and Agri-Food Canada, The Canadian System of Soil Classification, 3rd edition, Soil Classification Working Group, 2002.

Figure 4 Map of the types of soil found in Canada

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ACTIVITY 3 Experimentation Thirsty Soil How to Apply the Experimental Method Skills Handbook, pp. 430–432

Drainage The removal of excess water from soil.

I observe The two preceding activities showed you that not all soil is the same. For example, certain types of soil retain water. Others provide good drainage. It is important to take these characteristics into consideration when cultivating plants.

I develop a research question 1. “What factors affect soil drainage?” 2. “What type of soil offers the best drainage?” I define the variables 1. Your experiment must allow you to calculate the drainage rate of the different soil samples that you used in Activity 1, “Is All Soil the Same?” 2. You must choose a volume of water (in mL) and a volume of soil (in mL) that you will use throughout your experiment. I experiment

Partial list Equipment • five plastic containers, approximately 300 mL each • a magnifying glass d • five 100-mL beakers or graduate cylinders Material • water • food colouring • five filter papers • the five soil samples from Activity 1

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PROCEDURE

1

Determine a procedure to calculate the drainage speed of the different types of soil from Activity 1. a) Measure in mL the volume of water drained off after 10 minutes. b) Divide this by 10 to get the drainage speed in mL/min.

2

Complete the list of equipment and material that you will need.

3

Have your teacher approve your procedure and your list of equipment and material.

4

Conduct your experiment.

I analyze my results and present them 1 Show your results in a table. 2

Compare the drainage speeds of your soil samples. a) Which one drains the fastest? b) Which one drains the slowest? c) Compare the drainage speed of your local soil sample to those of the other types of soil. In terms of drainage speed, which type of soil does it resemble the most?

3

Answer the following questions: a) What connection can be made between the porosity of a soil and its drainage speed? b) How can the volume of water drained from the soil be increased? c) How can it be reduced? d) Why is the volume of water drained from soil an important factor in agriculture?

4

If you were to repeat this experiment, how would you change the procedure? Explain why.

5

Keep your soil samples. You will need them for the next activities.

This Way to the Review Activity Keep in mind the factors that affect soil drainage. You need to understand this characteristic to analyze the results of the experiment in the review activity.

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ACTIVITY 4 Experimentation Too Much Salt in the Soil? pH Encyclopedia, pp. 186–187

How to Apply the Experimental Method Skills Handbook, pp. 430–432

The Table Skills Handbook, p. 440

I observe Soil is an essential component of many ecosystems. In soil, vegetable matter and dead animals decompose and are recycled in the form of various organic compounds. These in turn get mixed in with minerals to form the darkest part of the soil, which is called humus. Humus contains numerous mineral salts that are indispensable to plants: for example, nitrogen (N2), phosphorus (P), potassium (K) and sulphur (S). Mineral salts mix with rainwater as it soaks into the soil. Plants can then absorb this mineral-rich water through their roots.

I develop a research question 1. “How can I verify whether soil contains mineral salts?” 2. “Can mineral salts modify certain soil properties?” I define the variables

Equipment • safety glasses • a stirring rod • a 100-mL graduated cylinder • a spatula • a 5-mL graduated pipette s • three 10-mL graduated test tube • three rubber stoppers for the test tubes • a test-tube stand • a 1000-mL beaker Material • a soil-test kit • distilled water salt • a sample of soil whose mineralcontent you already know • a nitrogen-reactant packet • a phosphorus-reactant packet • a potassium-reactant packet • the five soil samples from Activities 1 and 3

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Your experiment must allow you to: • measure the quantity of nitrogen, phosphorus and potassium in different soil samples • verify the effect of the presence of mineral salts on the pH level and electrical conductivity of different soils

I experiment Part 1: Mineral Salts Found in Soil Suggested Procedure Here is an example of a procedure for this experiment. You might want to suggest a different one. 1 2 3 4 5 6

Read “Mineral Salts and Soil” on page 136. This will give you information about the mineral salts that are found in soil. Form a team, following your teacher’s instructions. With your teammates, choose one of the six soil samples at your disposal. With a spatula, take 100 mL of soil from your sample. Place it in a 1000-mL beaker. Pour 800 mL of distilled water into the 1000-mL beaker. Mix it all together with a stirring rod for one minute.

7

Let the mixture stand for approximately 30 minutes. Use this waiting period to conduct the second part of the experiment.

8

With the pipette, take 2.5 mL of the liquid from the top of the beaker. Drop this liquid into a test tube.

9

Repeat this last step twice, dropping the same quantity of liquid into two more test tubes.

10

a) Pour a nitrogen-reactant packet into the first test tube. b) Pour a phosphorus-reactant packet into the second test tube. c) Pour a potassium-reactant packet into the third test tube.

11

Put the stoppers on the three test tubes.

12

Vigorously shake each test tube for 30 seconds.

13

Let the test tubes stand for 30 seconds.

14

Compare the colour of the contents of each test tube with the colour scale from the test kit.

15

Write the quantity of nitrogen, phosphorus and potassium in your sample in a table.

Part 2: Soil pH Level and Electrical Conductivity PROCEDURE 1 With the help of the equipment and material listed on this page, suggest a procedure that will allow you to determine the pH level of your soil sample and another procedure to establish its electrical conductivity. 2 Have your teacher approve your procedure. 3

Conduct your experiment.

I analyze my results and present them 1 Present your results in a table. 2

Compare the results that you obtained from both parts of this experiment with those of the other teams.

3

Describe how the presence of the mineral salts that you examined modified the pH level and the electrical conductivity of each type of soil.

4

Compare the sample of the local soil with the other samples. What can be said about the mineral salts contained in the local sample?

5

If you were to repeat this experiment, how would you change the procedure? Explain why.

6

Keep your soil samples. You will need them for the next activity.

Equipment • safety glasses • a 250-mL beaker • a 100-mL graduated cylinder • a conductivity meter • a test tube • a test-tube stand • a rubber stopper for the test tube Material • the five soil samples from Activities 1 and 3 • distilled water • a soil-test kit • universal indicator paper

FURTHER STUDY What happens to plants when soil contains too many mineral salts? When it doesn’t contain enough? Think of an experiment that could verify this.

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Mineral Salts and the Soil NEWS FLASH . . . Bacillus anthracis bacteria live in soil. They can infect animals with anthrax. The bacteria can also contaminate humans, if they come into contact with a wound or are ingested or inhaled. This noncontagious illness can affect the skin, the lungs, the mouth, the throat and the digestive tract.

Figure 5 In agriculture, to obtain a good harvest, it is important to control soil quality.

For this reason, the pH level and mineral-salt content of soil are checked regularly. This makes it possible to choose crops that are appropriate for a particular type of soil. Fertilizer can also be added (as in the photo) or the soil composition may be modified to adapt it to certain crops.

Plants need water and light for photosynthesis to occur. They also need mineral salts in the soil to grow well. Nitrogen is essential to photosynthesis because it allows the leaves to play their part. Phosphorus helps the plant to develop flowers, leaves and roots. Potassium facilitates the absorption of water through its roots and keeps the sap circulating. Nitrogen (N2), phosphorus (P) and potassium (K) are the principal ingredients of commercial fertilizers. Formulas, such as 20-20-20, 10-45-15 or 11-27-11 are often seen on fertilizer packages. The first number indicates the proportion (or percentage) of nitrogen in the product; the second, that of the phosphorus; and the third, that of the potassium. Plants modify the physical, chemical and biological properties of the soil. As they grow, they absorb mineral salts from the soil to meet their needs. As photosynthesis takes place, the plants produce glucose (a kind of sugar). Glucose is a source of carbon (C). When the plants die, they decompose. In this way, the carbon and mineral salts that they contained are returned to the soil. When the roots decompose, they leave behind tunnels that run through the soil. These tunnels help aerate the soil and let water drain away. They also make possible the development of bacteria that play a big role in decomposing organic material in the soil. This fertilizer is 11% nitrogen, 27% phosphorus and 11% potassium. The rest is made up of neutral matter and other trace elements necessary for good plant growth.

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ACTIVITY 5

Analysis and Experimentation

The World of Rocks When you go on a hike, you sometimes see little pebbles on the ground. In general, rocky soil is not very good for cultivating flowers. There are, however, species of flowers that grow in essentially rocky landscapes. Edelweiss, the national flower of Austria, is one example. This activity will help you to better understand the properties of rocks and how they are formed.

1

You must follow your teacher’s instructions for this activity. Join a team.

2

Use all the resources at your disposal to answer the following question: “What do you know about the world of rocks?” The members of your team should help each other. Answer the question on the worksheet provided by your teacher.

3

Use the documentation in the envelope that your teacher gave your team. You will find articles about three types of rocks: igneous, metamorphic and sedimentary.

4

Each member of your team should familiarize themselves with one of these three types of rocks. Read the text that is about the type of rock you have chosen. By studying it, you will become your team’s expert on this type of rock.

5

Join the other rock experts. Together, conduct the experiment described in your documents. Note your results in a table.

6

Go back to your original team. One by one, each of your teammates should present his or her discoveries.

How Are Rocks Formed? Encyclopedia, pp. 303–307

How to Apply the Experimental Method Skills Handbook, pp. 430–432

The Table Skills Handbook, p. 440

FURTHER STUDY Prepare an information sheet that presents the different types of rocks in your region. Your sheet should also include a classification key. To create it, imagine that you have a quarry and that you want to sell different types of rocks from this quarry to your clients.

NEWS FLASH . . . Calcium carbonate is a mineral found in some types of rocks. Certain marine mollusks, such as mussels and oysters, use calcium carbonate to make their shells. When mollusks die, their empty shells accumulate on the ocean floor. Over centuries, they are transformed into sedimentary rock, called limestone.

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ACTIVITY 6

Research

Minerals How to Conduct a Research Project Skills Handbook, pp. 436–437

How to Communicate Effectively Skills Handbook, pp. 438–439

Ore A substance taken from the subsoil or underlying rock that has a high enough concentration of saleable mineral products that it can be mined and processed for profit.

THE STUDY OF MINERALS THROUGH HISTORY tAround 300 BCE The botanist and geological scientist Theophrastus (372–287 BCE) created one of the first classification systems for minerals. t1669 The Danish anatomist and geological scientist Nicolaus Steno (1638–86) proved that the deepest layers of rocks are the oldest, and that the shallowest are the most recently formed. t1812 The German mineralogist Friedrich Mohs (1773–1839) created a scale that classified minerals according to their hardness. t1896 The French physicist Antoine Becquerel (1852–1908) discovered radioactivity,

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Aromatic plants are often used as perfume ingredients. Perfumes are consumer products. Rocks and minerals are also a basic component of many consumer products. The preceding activity gave you a better understanding of different types of rocks. They are made up of one or more minerals. This activity will help you learn more about a mineral that you choose. 1

First, read “What Lies Hidden Underground?” on page 140.

2

Look at Figure 6 on the next page. It is a map of minerals mined in Québec.

3

Locate the different minerals on the map.

4

Choose a mineral that interests you.

5

Research your mineral. Find out about the following subjects: • the places where this mineral is found • the methods used to extract this ore • the properties of this mineral • its uses • any other interesting characteristics of this mineral

Legend Geological Regions Canadian Shield Hudson Bay Lowlands Great Lakes and St. Lawrence Lowlands Appalachians Mining Activities ATLANTIC OCEAN

Hudson Bay

Metallic Minerals

Metal

Copper

Industrial Mineral

Gold

Industrial Minerals Asbestos

NE

Salt

Iron Silver Zinc

O WF UN DL uted)

till disp

D AN

LAB

y

Boundar

cision (s

de Council

D AN

James Bay

27 Privy set by 19

RAD

OR

St.

wre La

River nce

Gulf of St. Lawrence PRINCE EDWARD ISLAND

NEW BRUNSWICK

W

A

ONTARIO

UNITED STATES

A OV

I OT SC

Scale

N

Figure 6 The principal minerals mined in Québec

a) Gold

b) Copper

Figure 7 Two metallic minerals found in Québec

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139

What Lies Hidden Underground? Soil Profile Encyclopedia, p. 308

The Earth’s subsoil is rich in minerals, rocks and other materials, including many kinds of metals and water. These materials are essential to the growth of plants. Minerals are often used by humans. We use granite in construction. We use sand to make glass. Mineral resources are divided into four categories:

31.2% 52.7% 16.1%

Metallic Minerals

• • • •

metallic minerals: iron, nickel, copper, gold, etc. industrial minerals: salt, asbestos, silica, etc. construction materials: clay, sand, rock, etc. combustible materials: natural gas, petroleum and coal

If a mineral is beautiful, pure and rare, it is called a precious stone. Diamonds, emeralds, rubies and sapphires are some examples of these. There are also semiprecious stones, such as topaz, jade and opal. The value of these stones depends on their size, their transparency, their rarity and fashion. If a mineral or a rock is unusual, it is called a mineral specimen. The desert rose is one example of a mineral specimen.

Industrial Minerals Construction Materials Figure 8 The principal mineral

resources mined in Québec. Combustible materials are not included in the diagram, because they are not mined in significant quantities in Québec.

NEWS FLASH . . . The fruit of the carob tree tastes a little like chocolate. Over the centuries, carob seeds were used to weigh precious stones. The weight of one of these seeds was given the value of one carat. In 1907, it was decided that five carats would equal one gram. The carat is still used today to measure the mass of precious stones.

a) Precious stone: a diamond

b) Semi-precious stone: an amethyst

c) Mineral Specimen: a desert rose Figure 9 Some highly prized minerals

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R EVIEW ACTIVITY 1

Experimentation

Potted Flowers Your teacher will give you a table showing the results of an experiment conducted by a horticulturist who cultivated three plants in four different types of soil. These three plants are lavender, coleus and heliotrope. The four types of soil used were sand, black earth, peat and clay. You must analyze these results and present them in a laboratory report. 1

Prepare a laboratory report explaining and justifying the effects of the different factors you have studied on the growth of the three plants.

2

In your report, you must indicate: • the best type of soil for each of the three plants • the effects of the following factors on the growth of the plants in the ideal type of soil for each plant: – the texture of the soil – its structure – its porosity – its drainage rate – its mineral composition – its pH level – any other elements that you think influenced the growth of the plants studied

3

Draw a vertical-bar graph showing the growth of each plant in each type of soil.

How to Apply the Experimental Method Skills Handbook, pp. 430–432

Bar Graphs Skills Handbook, p. 442

Checklist NEWS FLASH . . . 1. I identified the best type of soil for each plant. 2. I used the scientific knowledge that I acquired from the activities in this chapter to analyze the results. 3. I justified my explanations, taking into consideration the soil properties, water and the presence of mineral salts. 4. I presented my results, my analysis and my bar graph in a laboratory report.

At the Papineau-Labelle Wildlife Reserve in the Outaouais, the predominant type of soil is podzol. This type of soil is most often found in cold, humid regions, such as Québec. It is named for the ashy quality of one its layers. In Russian, pod means “under” and zola means “ash.”

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C HAPTER 2 Solutions and Mixtures

Figure 10 Mixtures are part of everyday life.

KEY CONCEPTS IN CHAPTER 2 • characteristics • mixtures • separation of mixtures • solutions • temperature

Mixtures around Us Our planet is full of natural mixtures, made up of two or more pure substances. Ground, air and seawater are all natural mixtures. Over the centuries, people have developed techniques to classify substances and, by doing so, have created new mixtures. They were also able to separate mixtures in order to isolate components. Perfume is an example of a mixture created by people—in this case, using alcohol and the essence of flowers. Use your knowledge to answer the following questions: 1. Under what circumstances do people make mixtures? 2. Under what circumstances do people separate mixtures? 3. How is the scent of a flower extracted in order to create perfume? 4. Why is alcohol used in the making of perfume?

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Your challenge in Chapter 2 is to learn to distinguish between different types of mixtures and discover different processes for separating mixtures. This knowledge will be useful when you create your very own perfume. In Chapter 3, you will extract the essential oil from an aromatic plant. You will use various separation processes to create your own perfume.

Essential oil An oil obtained through the distillation of a plant’s aromatic substances.

• In Activity 1, “Preparing Mixtures” on pages 144 and 145, you will identify different types of mixtures. • In Activity 2, “Heterogeneous or Homogeneous?” on pages 146 to 148, you will closely examine and classify three types of drinks. • In Activity 3, “Separating Mixtures” on pages 149 and 150, you will discover that mixtures sometimes need to be separated. • In Activity 4, “Mixtures in Everyday Life” on page 151, you will study a mixture of your choice. In the review activity at the end of this chapter (“Hidden in a Mixture” on pages 152 and 153), you will separate the components of an unknown mixture and detect the presence of water.

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Solutions and Mixtures

143

ACTIVITY 1 Experimentation Preparing Mixtures Mixtures Encyclopedia, p. 196

How to Apply the Experimental Method Skills Handbook, pp. 430–432

How to Work Safely Skills Handbook, p. 428

I observe Liquid, solid and gaseous mixtures are found in nature. The milk in your cereal, the dressing on your salad and your favourite fruit juice are perfect examples of liquid mixtures that are made up of particles from different substances. The perfume that you will create at the end of this unit is another example of a liquid mixture. During this activity, you will examine liquid mixtures more closely.

I develop a research question “How will the appearance of various liquids change if they are mixed together?”

Equipment • safety glasses • five test tubes • a test-tube stand • five rubber stoppers • a 10-mL graduated cylinder • a dropping pipette Material • 10 different liquids

I define the variables The experiment will allow you to observe the appearance of different liquids before and after they are mixed. I experiment Suggested Procedure Here is an example of a procedure for this experiment. You might want to suggest a different one. 1

Describe the 10 liquids provided for you (for example, their colour, transparency, viscosity, the presence of particles, etc.). Do not touch or taste any of the substances directly. Write down your description in a table similar to Table 1, shown below.

2

Prepare five mixtures. For each mixture, pour two of the 10 starting liquids into a test tube and mix well.

120

Table 1 The appearance of 10 different liquids

Name of the liquid

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Appearance

Describe the composition and appearance of the five mixtures. Write your description in the three first columns of a table like Table 2, shown below. Table 2 The composition and appearance of five mixtures

Mixture

Appearance Composition Appearance 10 minutes after (names of the imme diately mixing two liquids used) following mixing

4

Let the five mixtures rest for 10 minutes.

5

Describe the new appearance of your mixtures. Write your observations in the last column of your table.

NEWS FLASH . . . Soap was invented in antiquity, over 2500 years ago. It was made by mixing animal fat with ashes.

I analyze my results and present them 1 Present your results in the form of a diagram. For each of the five mixtures, draw four diagrams. • Draw the appearance of the two starting liquids before they were mixed (two diagrams). • Draw the appearance of the liquid immediately after mixing. • Draw the appearance of the liquid 10 minutes after mixing. 2

Did the appearance of the liquids change during the experiment? If so, explain how and why.

3

For each of the five mixtures, indicate if it consists of a homogeneous mixture (solution) or a heterogeneous mixture.

4

Compare your answers with those of another team.

5

If you were to repeat this experiment, how would you change the procedure? Explain why.

This Way to the Project As you know, perfume is a mixture of several ingredients. How would you describe the appearance of this mixture? Write down your answer; it will help you describe the mixture that you will propose at the end of the unit. CHAPTER 2

Solutions and Mixtures

145

ACTIVITY 2 Experimentation Heterogeneous or Homogeneous? Pure Substances and Mixtures Encyclopedia, pp. 195–197

How to Apply the Experimental Method Skills Handbook, pp. 430–432

How to Use Observation Instruments Skills Handbook, pp. 452–456

I observe Many of the foods you eat are made up of mixtures. Many of your favourite drinks are also mixtures. In the previous activity, you saw that there are two types of liquid mixtures: homogeneous and heterogeneous. During this activity, you will learn more about these two types of mixtures. I develop a research question “What characteristics allow me to determine whether drinks are heterogeneous or homogeneous mixtures?”

Equipment • three test tubes • a test-tube stand • a magnifying glass • a microscope or binocular microscope • three dropping pipettes • three petri dishes • three slides • three cover glasses • dye Material • three different drinks, labelled A, B and C • a perfume sample

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I define the variables 1. The experiment lets you observe the characteristics of three different drinks. 2. You must determine if each drink is a homogeneous or heterogeneous mixture.

I experiment Suggested Procedure Here is an example of a procedure for this experiment. You might want to suggest a different one. 1

Read “Heterogeneous Mixtures” on p. 148.

2

Copy Table 3, shown below. This will be your results table.

Drink A

Observation method

Homogeneous Observations or heterogeneous? Reason for this classification

With the naked eye Under a magnifying glass Under a microscope or binocular microscope

3 4 5

6

7 8

Pour 20 mL of drink A into a test tube. Clearly label your test tube. First, examine drink A with the naked eye. Write your observations in your results table. Using a dropping pipette, transfer one drop of drink A onto a petri dish. Examine it using the magnifying glass. Once again, write your observations in your results table. Transfer a small amount of drink A onto a slide. Protect your sample with a cover glass. Examine your sample under the microscope or the binocular microscope. Begin observing at the lowest magnification. Then, observe your sample under the highest magnification. Write down your observations in your results table. Repeat steps 3 to 6 for drinks B and C. Observe the perfume sample that your teacher provided. View it first with the naked eye, then with a magnifying glass and a microscope. Write your observations in your results table.

I analyze my results and present them 1 Answer the following questions: a) What did you see with the magnifying glass that was not visible to the naked eye? b) What new observations did you make using the microscope or binocular microscope? c) Did drinks that seemed homogeneous to the naked eye appear heterogeneous through a more precise instrument? If so, which ones? d) How did observation instruments improve your observations? e) Before saying that a mixture is homogeneous, what observations must you make? 2 Following your observations, would you classify the perfume sample as a homogeneous or heterogeneous mixture? Explain your answer. 3 If you were to repeat this experiment, how would you change the procedure? Explain why.

Mixtures are made up of different substances. In antiquity, carbonated water came from springs, where it bubbled out of the ground. Scientists later discovered that, by adding carbonated gas to water, they could reproduce the same sparkling effect. Sugar, flavouring and food colouring can also be added to carbonated water. Many soft drinks found in stores today are made this way.

SCIENCE

Liquid

HISTORY OF

Table 3 Observation and classification of mixtures

This Way to the Review Activity Write down your observations on how to distinguish between homogeneous and heterogeneous mixtures, as well as contributions made by the observation tools. These will help you when you separate the different components of an unknown mixture in this chapter’s review activity. CHAPTER 2

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147

NEWS FLASH . . . Homogenized milk is a solution, a suspension and a colloidal mixture all at the same time. Whole milk is a solution of water and sugar (lactose). It is also a suspension because it contains suspended particles of fat (cream). Finally, milk is a colloidal mixture because it contains particles of casein. Casein is a protein and also the main ingredient in cheese.

Heterogeneous Mixtures Heterogeneous mixtures are classified into three categories: simple heterogeneous mixtures, suspensions and colloidal mixtures. In a simple heterogeneous mixture, the particles of the two substances do not mix. Some particles float on the surface, while others quickly sink to the bottom. A suspension is a mixture with particles small enough to remain suspended for a long time. In a colloidal mixture, the particles are so small that they cannot be seen by the naked eye. In this type of mixture, particles can remain suspended for a very long time. Table 4 lists characteristics of the three types of heterogeneous mixtures.

Table 4 Characteristics of heterogeneous mixtures

Centrifugation

observation

Suspension

Colloidal mixture

Visible to the naked eye.

Different parts are usually visible to the naked eye.

Different parts usually impossible to see with the naked eye.

Particles separate quickly.

Particles separate after a certain amount of time. The mixture is cloudy.

Particles separate after a very long period of rest. The mixture is cloudy.

Components separated by decantation.

Components separated by filtration.

Components separated by centrifugation.

Salad dressing

Grapefruit juice

Mayonnaise

Example

A process that separates the components of a mixture by rapid rotation.

Separation process

Naked-eye

Simple heterogeneous

FURTHER STUDY In addition to casein, milk contains other proteins. One is used to make a type of plastic. Find out about this protein and come up with an experiment to extract it from milk.

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Unlike solutions, heterogeneous mixtures will separate if left at rest too long. They must therefore be shaken or stirred before use; this is the case for paint, which is a colloidal mixture. This is a clue to help you distinguish between a solution and a heterogeneous mixture.

ACTIVITY 3 Experimentation Separating Mixtures I observe In the two previous activities, you learned that substances could be combined to create mixtures. However, mixtures can also be separated into their various components. Do you know of any examples? During this activity, you will visit four stations; each one has a different mixture to be separated.

Characteristic Properties of Matter Encyclopedia, pp. 188–189

Separation of Mixtures Encyclopedia, pp. 198–201

How to Apply the Experimental Method Skills Handbook, pp. 430–432

I develop a research question “How can I separate components of a mixture?”

I define the variables The experiment will allow you to separate the components of the four mixtures, using the procedure of your choice.

I experiment PROCEDURE 1 Observe Figure 11. In your opinion, what is the best method for separating the components of each mixture? 2 Find out the different methods of separating mixtures by reading pages 198 to 201 in the Encyclopedia. Also read “Using Distillation to Extract the Essence of Aromatic Plants” on the following page. 3 Visit the four stations set up in your class and perform the following tasks: • At each station, choose the most appropriate process to separate the mixture. • Choose the equipment and material that you will need. • Separate the components of the mixture. I analyze my results and present them 1 Present your results in a table. Give it a title. 2 Compare your results with those of your classmates. 3 Answer the following questions: a) What is the best separation method for each mixture? b) Which kinds of mixtures is each separation method best suited to? c) How would you detect the presence of water in a mixture? 4 If you were to repeat this experiment, how would you change the procedure? Explain why.

Oil + water

Seawater

Water + earth

Water + sand

Figure 11 Mixtures to be separated

This Way to the Review Activity Make sure that you properly understand the different methods for separating mixtures. During the chapter review activity, you will need to know these methods in order to separate the different components of an unknown mixture.

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Using Distillation to Extract the Essence of Aromatic Plants Distillation is an ancient separation process, known to the Greeks and Egyptians in antiquity. The process was widely dispersed by the Arabs between the 8th and 10th centuries following the invention of a coil that improved the instrument used for distillation, the still. Stills are used to extract perfumed oils found in different parts of plants. A still is used to distill, the essential oils from plants using the following method: 1

A boiler boils water until heat emitted by the flame transforms it into vapour. The water vapour then travels through a tube connecting the boiler to the plant chamber.

2 The plant chamber contains flowering plants, from which essential oils will be extracted through distillation. The water vapour from the boiler passes

through these plants, breaking down the essential oils and carrying them along. 3 The perfumed water vapour evaporates in the swan neck and passes through a chamber of extremely cold water containing a frozen coil. When it comes

in contact with the cold, the perfumed vapour condenses and becomes liquid again. The water temperature in the container also causes the liquid to separate into two components: water and essential oil.

Figure 12 Two types of stills

NEWS FLASH . . . Up to 6000 kg of flowers are sometimes necessary to collect 1 kg of an essential oil.

4 When released from the coil, the liquid pours into a Florentine flask vase.

In this vase, the essential oil floats to the surface of the water that has been distilled by decantation. The only thing left to do is collect it. swan neck perfumed water vapour

2

3 frozen water chamber

plants water vapour

coil

cold water faucet

distilled liquid (water and oil) essential oil

boiling water plant chamber

boiler

water

1

4

Figure 13 The diagram of a still used to distil, essential oil from aromatic plants

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Florentine flask vase

ACTIVITY 41

Research

Mixtures in Everyday Life In this chapter, you studied the different properties of mixtures. You learned that some mixtures are natural, while others are artificial. You will now choose a mixture and conduct a documentation search to learn more. 1 2

How to Conduct a Research Project Skills Handbook, pp. 436–437

Following your teacher’s instructions, choose the mixture that you will examine. Conduct research on your mixture so that you can answer the following questions: a) What are the components of your mixture? b) Is your mixture natural or artificial? c) How can your mixture be used? d) What is the best way to separate the components of your mixture? e) Does your mixture have other characteristics? If so, what are they?

JOB OPPORTUNITY Chemical process technician Have you ever wondered how soap, fuel or kinds of medication are created? Did you know that toothpaste, ink and cosmetics are all made in a laboratory, often by a chemical process technician? Technicians supervise the different steps that transform chemical substances into products and take care of quality control. Technicians make sure the technical instruments used are functioning properly. To do this job, you need a college diploma in chemical process technology.

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R EVIEW ACTIVITY 2

Experimentation

Hidden in a Mixture How to Apply the Experimental Method Skills Handbook, pp. 430–432

I observe In this chapter, you acquired the knowledge and competencies required to separate the components of an unknown mixture.

HISTORY

I develop a research question “How will I separate the components of an unknown mixture?”

152

OF SCIENCE In 1853, Canadian Abraham Gesner (1797–1864) developed a process for separating tar. With this process, Gesner obtained a new liquid fuel that he called “kerosene.” The new fuel was ideal for lighting, and emitted almost no smoke. Since kerosene could not be used in the lamps available at the time, Gesner invented a new kind of lamp. Today, kerosene lamps are more often used for decoration than lighting.

UNIT 4

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I define the variables The experiment will allow you to: • choose the best method for separating the components of an unknown mixture • detect the presence of water in an unknown mixture I experiment PROCEDURE 1 Determine a procedure for separating the components of an unknown mixture. Indicate all the safety measures that you will follow in your procedure. 2

Make a list of the equipment and material that you will need to conduct this experiment.

3

Draw a diagram of your setup.

4

Have your teacher approve your procedure, your list of equipment and material and your diagram.

5

Conduct your experiment.

I analyze my results and present them 1 Prepare a report outlining the steps you followed to conduct this experiment and the results you obtained. 2

Using a diagram, describe the steps necessary to separate the components of the unknown mixture.

3

In your diagram, label the different components that you separated. Identify the process or processes that you used in each step.

4

Explain how the presence of water is detected in an unknown mixture.

5

If you were to repeat this experiment, how would you change the procedure? Explain why.

Checklist

NEWS FLASH . . . Oil and water do not mix. A quantity of petroleum the size of a coin is enough to kill a seabird when spilled in the ocean, where it contaminates the surface of the water. In 1989, the oil tanker Exxon Valdez ran aground in Alaska. Over 48 million litres of crude oil spilled into the Pacific Ocean. Imagine the devastation!

1. I chose one separation process (or more) appropriate for this unknown mixture. 2. I was adequately prepared for the experiment: I made a list of the necessary equipment and material, and I planned the steps of the process. 3. I conducted my experiment taking the necessary safety precautions. 4. I relied on a diagram to identify the separation process or processes used in each step, as well as the components of the unknown mixture. 5. I used the appropriate vocabulary, which I learned in this chapter.

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C HAPTER 3 Perfume Makes Perfect “Scents” KEY CONCEPTS IN CHAPTER 3 • equipment • material • mixtures • physical and behavioural adaptation • manufacturing process sheet • raw materials • separation of mixtures • solutions • temperature

“The Nose” and the Music of Perfume Some of the many people who work creating perfume are informally known in the industry as “noses.” Unlike most of us, “noses” possess an olfactory organ that can recognize a palette of several hundred kinds of different scents. They correlate, analyze and devise scents, labouring until these new creations achieve the perfect balance. This is how original perfumes are made. “Noses” are part artist, part technician. Their sense of smell is their main tool. These people spend their days smelling strips of blotting paper called mouillettes that are saturated with perfume. Doing so gives them the expertise to create a harmony of scents in the same way that a harmony of colour or sound is created. An experienced “nose” can distinguish up to 1000 different scents. Right now, there are approximately 250 “noses” in the world. Do you think you could be a “nose”? 1. What do you feel when you smell the perfume of a flower or the odour of a skunk? 2. In what daily activities do you use your sense of smell? 3. How would each of these activities be changed if you lost your sense of smell? 4. What pleasant memories do you associate with odours? 5. What odours represent unpleasant memories for you?

Figure 14 Your daily life is full of all sorts of odours.

Some are pleasant, while others are not.

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Here is your challenge for Chapter 3. In the perfume industry, scent is king. In this chapter, you will become familiar with the principles behind the sense of smell. You will also conduct an experiment in which you create your own perfume. The Sense of Smell in Daily Life • In Activities 1 and 2, you will learn more about your sense of smell. – In Activity 1, “Do You Have Flair?” on pages 156 to 158, you will discover if you have the flair of a “nose” and can describe and classify different odours. – In Activity 2, “Taking Care of Your Nose” on pages 159 and 160, you will discover that the olfactory organ requires proper hygiene and protection. Extraction of Perfumed Essences • In Activities 3 to 6, you will design your own perfume. – In Activity 3, “A Field Survey” on page 161, you will interview 10 people. This will allow you to create a perfume that will meet your target clientele’s needs. – In Activity 4, “Extracting a Delicate Flower” on pages 162 and 163, you will extract the essence you use to create your own perfume. – In Activity 5, “The Birth of a Fragrance” on pages 164 and 165, you will create a perfume. – In Activity 6, “A Production Line of Scents” on page 166, you will describe the steps that enable the mass production of your perfume in a factory. During the review activity at the end of this chapter (“Perfume: The Work of a ‘Nose’” on page 167), you will explain the different steps in the design process used to create your perfume.

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ACTIVITY 1

Analysis

Do You Have Flair? Technique for Smelling Substances in the Laboratory Skills Handbook, p. 428

NEWS FLASH . . . In movie theatres, the enticing smell of popcorn is sometimes artificially diffused to encourage people to buy the snack.

What would life be like without smell? A life without colour or flavour! The sense we use to perceive odours is smell. The sense of smell is not always given as much attention as sight, hearing and taste. How would you describe odour to a person who has never smelled? It would be very difficult, because every person perceives odours in an individual fashion. To become a “nose,” you must possess a very delicate sense of smell. Do you think you have this flair? To find out, conduct the activity. You will form a team that analyzes different odours from a palette and groups them by families. Here are the equipment and material you will need: • a palette of different odours in dropper bottles • strips of blotting paper to saturate with different odours • a blindfold

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1

First, read “Perfumes of the World” on page 158. It describes seven families of perfumes.

2

Form a team following your teacher’s instructions.

3

With the equipment and material available to you, describe the different odours in your palette. • Have one of your teammates cover his or her eyes with the blindfold. • Place a drop of the bottle’s contents on a strip of blotting paper. Wave it under the nose of the blindfolded student. • The blindfolded student should use their sense of smell to describe the odour perceived. Another student writes down the description. • Switch roles, and repeat the experiment using another bottle.

4

Answer the following questions: a) With what known odour do you associate each of the odours you just smelled? b) Which odour did you prefer? c) Which odour did you like the least? d) How many different odours did you identify correctly?

5

Classify the odours based on the families of scents in Table 5 (on the following page). a) How would you describe each family of scents in your own words? b) What odours did you associate with each family? c) How many families of scents did you find? d) Was your classification different from those of the other members of your team? If so, how?

6

Keep your descriptions and classification of the scents. You will need them for Activity 3, “A Field Survey.”

FURTHER STUDY Make a list of odours found in your environment that would be difficult to put in a bag or bottle. How would you replicate these odours and put them in a paper bag?

This Way to the Project These descriptions and your classifications will help you present your perfume in the unit project. CHAPTER 3

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Perfumes of the World Perfumes are grouped in seven families. Table 5 lists the seven families of perfume, as well as a description of their scents.

Table 5 The seven families of perfume

Family

NEWS FLASH . . . Did you know that Canada is the main exporter of castor beaver scent? It is an aromatic secretion obtained from beavers. This oily substance is used in the perfume industry. It works as a fixative, helping the scents stay on the skin.

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Description

Example

Citrus

These are fresh scents based on citrus zest and juice.

Floral

This is the most important family in perfumes for women. The floral base is made up of one of several flowers: rose, lily of the valley, violet, jasmine, etc.

Woody

This family mainly consists of masculine scents like cedar wood and vetiver roots.

Oriental and amber

These perfumes carry the scent of vanilla.

Vanilla

Fougere

These perfumes often contain lavender and woody scents.

Lavender

Chypre

The base of this family is oak moss. This is accompanied by other scents, such as dry wood, fruit and flowers.

Oak moss

Leather

This family reproduces the scent of kinds of leather. Considered masculine, the scents of these types of perfumes carry smells like honey, essence of birch, smoke and tobacco.

Leather

Citrus fruit

Jasmine

Vetiver

ACTIVITY 2 Interpretation and Communication Taking Care of Your Nose In the previous activity, you learned to better recognize the world of odours. The different odours are captured by the olfactory receptor cells located in the nose—your olfactory organ. They are then analyzed by your brain. Your nose is therefore very important. Do you know how to take care of it?

How to Conduct a Research Project Skills Handbook, pp. 436–437

FURTHER STUDY Conduct research to describe three illnesses or conditions that affect the sense of smell.

1

Read “The Perception of Odours” on the following page.

2

What methods can you use to preserve the efficacy of your sense of smell?

3

Discuss your list of methods with other students in your class.

4

Add to your list of methods, if necessary.

5

Prepare an information sheet to provide advice on basic hygiene preserving the sense of smell.

NEWS FLASH . . . Several gases cannot be perceived by the sense of smell. Carbon monoxide (CO) is a deadly gas that does not emit an odour. To detect the gas, a carbon monoxide detector must be used. Another well-known gas that is odourless is natural gas. To detect leaks, companies add thiol to natural gas before delivery. This chemical smells like rotten eggs.

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The Perception of Odours The nose is the organ responsible for smell. Smell is made possible due to tiny odour detectors, called olfactory receptor cells. These cells are located in the nasal cavities. Smells are produced by molecules present in the air in a gaseous state that enter the nose through the nostrils. When the molecules reach the nasal cavities, the olfactory receptor cells are activated.

Hypothalamus This area located at the base of the brain is responsible for several functions, such as hunger, thirst and emotions.

The nasal cavities are covered with mucus. Mucus is essential, because it works as a filter to hold particles contained in the air, and breaks downs the molecules of fragrant substances. When they perceive an odour, the olfactory receptor cells send a message to the brain through the olfactory nerve. The brain then causes you to experience a sensation that corresponds to the odour perceived. In many cases, the brain also sends a message to the hypothalamus. This is why you experience emotions, such as pleasure or disgust, when faced with certain odours. olfactory nerve

brain

olfactory receptor cells mucus

hypothalamus

nasal cavities nostrils molecules of fragrant substances

FURTHER STUDY Propane leaks are dangerous in trailers, which are often safeguarded by propane detectors. Why are they placed nearer to the ground than the ceiling? Conduct research to find out the answer.

Figure 15 The organs associated with the perception of smells

The olfactory receptor cells gradually get used to smells after a certain length of time. To observe this fact, just visit a barn housing livestock. At first, the strong odour is disturbing but, after a few minutes, the olfactory perception lessens. Occasionally, the sensitivity of the sense of smell decreases or disappears. This can be caused by an infection of the olfactory receptor cells or the olfactory nerve, dietary deficiencies, cranial traumas, etc. Like all of the other senses, olfactory abilities also decrease with age. Table 6 lists diseases and conditions that specifically affect the sense of smell. Table 6 Diseases and conditions affecting the sense of smell

Name

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Description

Anosmia

Loss of olfactory sensitivity

Parosmia

Inability to accurately distinguish odours

Hyperosmia

Oversensitivity to scents

Hyposmia

Decrease in olfactory sensitivity

Sinusitis

Inflammation of the sinuses caused by bacteria or allergic reactions

ACTIVITY 3 Communication A Field Survey How to Communicate Effectively Skills Handbook, pp. 438–439

Before a new product is created, the target market should be studied. Studying the market is an important step in the design process. The creation of a new perfume is no exception to this rule. Before creating your perfume, you will therefore conduct a field survey to find out the preferences and expectations of your target clientele. 1

Determine what market you wish to target with your perfume (men, women, teens, etc.). Consult the notes you took during the brainstorming session at the beginning of this unit (see page 125).

2

Create a questionnaire. a) Come up with a few questions to find out the preferences of your target clientele regarding perfume. b) Use samples of different scents. Your teacher will provide them.

3

Conduct your survey by interviewing 10 people among your target clientele.

4

Answer the following questions: a) Which sample is preferred by most of the people interviewed? b) To which family of perfumes does this sample belong? c) What conclusions can be drawn from your survey?

5

Using the results from your survey, choose the essence or essences that will be included in the composition of your perfume. You will be extracting one of these essences in the next activity.

Put your questions into a database, then note the answers of the people you interviewed.

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ACTIVITY 4 Experimentation Extracting a Delicate Flower Distillation Encyclopedia, p. 200

How to Apply the Experimental Method Skills Handbook, pp. 430–432

You are now deep into the design phase of a design process: the creation of your prototype perfume.

I observe As you learned in the previous chapter, perfumes are mixtures. They are made up of natural and artificial products. The natural products are often extracts of flowers, spices, herbs, citrus fruit and even animal secretions. The artificial products are scented essences created in a laboratory.

I develop a research question “How will I extract the essence of the substance I chose to create my perfume?”

I define the variables In your experiment, you will have to extract your essence through the process of distillation. I experiment

Equipment • safety glasses • a peeler or grater • a 250-mL round-bottom or Erlenmeyer flask • a 500-mL beaker • a hot plate • a retort stand • combination pliers • a thermometer • a thermometer clamp • beaker tongs • a rubber stopper Material • three lemons • 250 mL of canola oil • water

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PROCEDURE

1

Reread “Using Distillation to Extract the Essence of Aromatic Plants” on page 150.

2

Consult the list of equipment and material, as well as the procedure suggested below and on the following page.

3

Determine a procedure for conducting your experiment. You can modify the suggested procedure.

4

Have your procedure approved by your teacher.

5

Perform your extraction.

Suggested Procedure Here is an example of a procedure for this type of experiment. It deals with extracting the essence of a lemon. You should modify this procedure to extract the essence of your choice.

Part 1: Maceration 1 Collect the zest from three lemons with a peeler or grater. 2

Put the zest in a round-bottom flask.

3

Add 250 mL of canola oil.

4

Fill a 500-mL beaker with water and place it on the hot plate.

5

Place the round-bottom flask containing the zest and oil in the beaker filled with water. Affix the round-bottom flask using the combination pliers and the retort stand.

6

Heat everything for one hour. Try to maintain the temperature of the oil at around 95°C.

7

Remove the round-bottom flask from the beaker of hot water using the beaker tongs. Cap the round-bottom flask with the rubber stopper. Let the liquid cool.

Part 2: Distillation 1 Take the cooled liquid you obtained following the maceration. 2

Separate the lemon zest from the rest of the liquid, using a sieve. Pour the oil back into the 250-mL round-bottom flask.

3

Pour 30 mL of alcohol into the round-bottom flask.

4

Cap the flask and mix the two liquids for approximately five minutes.

5

Proceed with the distillation. Make sure there is no leak in your setup. Pour the distillate into a test tube.

6

Cap the test tube to avoid evaporation.

7

Keep the distillate, which consists of a mixture of alcohol and essential oil. This is what you will use to create your perfume in the next activity.

Equipment • safety glasses • two 250-mL round-bottom or Erlenmeyer flasks • a 500-mL beaker • a sieve • a rubber stopper • a hot plate • two retort stands • two combination pliers • two test-tube tongs • a stopper with two holes • a thermometer • a 90° glass elbow • a condenser • two rubber tubes • a test tube • a 50-mL graduated cylinder Material • 250 mL of liquid to be distilled (collected from the maceration) • 30 mL of alcohol • water

I analyze my results and present them 1 What quantity of distillate (in mL) did you extract from the substance you chose? 2 What separation techniques did you use in this experiment? What are the advantages of each one? 3

If you were to repeat this experiment, how would you change the procedure? Explain why.

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ACTIVITY 5

Experimentation

The Birth of a Fragrance How to Apply the Experimental Method Skills Handbook, pp. 430–432

Equipment • safety glasses • a dropping pipette • a test tube • a test-tube stopper • a graduated cylinder Material ration • strips of blotting paper for satu • distillate collected during the previous activity • samples of essential oils

In this activity, you will proceed with the creation of your perfume.

I observe All the perfumes sold in stores contain a minimum of 70 percent of alcohol. Your perfume will be a mixture made up of alcohol and essential oils extracted from different scented substances. However, it will contain a lot less alcohol than perfumes sold in stores. In fact, those perfumes contain a type of alcohol that has been treated to make it unscented, which is not the case with the alcohol you will be using in class. I develop a research question 1. “How will I combine the essential oil extracted in the previous activity with other essential oils to create my perfume?” 2. “What role does alcohol play in perfume?”

I define the variables Your experiment should allow you to combine the distillate you extracted with other essential oils in order to create a perfume that meets the needs of your target clientele. I experiment

PROCEDURE

1

Using the equipment and material available to you, outline your procedure for conducting the experiment.

2

Have the procedure approved by your teacher.

3

Conduct your experiment.

I analyze my results and present them 1 Answer the following questions: a) What volume of distillate (in mL) did you use in your perfume? b) What other ingredients did you add to your distillate? c) What is the volume (in mL) of the other ingredients you used? 2 Explain why your distillate contains a certain amount of alcohol. 3

Read “The Music of Perfume” on the following page.

4

In your own words, describe the role that alcohol plays in perfume.

5

Along with your team members, design the shape of the bottle that will contain your perfume.

6

Remember to choose a name for your perfume.

7

If you were to repeat this experiment, how would you change the procedure? Explain why.

This Way to the Project Keep your perfume sample. You will need it when you present your perfume during the unit project.

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The Music of Perfume A Harmony of Scented Notes Any “nose” in the perfume business has a personal collection of the many different scented substances that can be combined to create a perfume. Each substance has a “note” or specific scent. A “nose” searches for the notes that produce the best harmony. Notes are natural products, either animal or vegetable, or can even be artificial products. Artificial products are now used more often because they replace natural products that are rare or expensive, or whose use harms endangered species.

Fragrant Notes As soon as perfume is applied, the alcohol begins to evaporate. Only the concentrate of scented substances remains on the skin. This concentrate will diffuse its scent over an entire day as its molecules evaporate. In addition to diluting scented substances, which are usually very concentrated, alcohol holds and fixes the essence of a perfume. Without alcohol, perfume would not be stable enough to be applied and worn. In France, the perfume industry uses alcohol from beets. It is treated to make it unscented.

NEWS FLASH . . . Cologne first appeared in the late 17th century in its namesake city of Cologne, Germany. It became popular because it was the perfume industry’s least expensive product.

Over time, a perfume’s scent changes. Once it has been applied to skin, different notes can be smelled. First the “top note” is experienced for less than an hour. This note is an attention grabber usually made of citrus fruits and lavender. The “heart note” is smelled next as it evaporates more slowly. This note determines the family of the perfume and is made mostly of flowers. It can last up to three hours. Finally, the “base note” is experienced for up to 24 hours. This note is usually derived from mosses, woods and animal products.

The application of a perfume

The top note 10 min.

1 hr.

The heart note 2 hr.

3 hr.

The base note 24 hr.

Figure 16 The three notes of a perfume

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6

ACTIVITY 6 Technology A Production Line of Scents

The Design Process Encyclopedia, pp. 376–377

The Manufacturing Process Sheet Encyclopedia, p. 385

How to Draw Diagrams Skills Handbook, pp. 446–449

Use a computer-aided design (CAD) application to help you with your design.

You have finished the design phase of the design process. You are now ready to enter the production phase. Before putting a new product on the market, you must be able to make enough of your product to meet demand. This is an important step. Now that you have created your perfume, the time has come to move into mass production. Among other things, you will have to formulate a manufacturing process sheet. This will allow you to mass-produce your perfume in a plant.

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1

List in order the production steps that have to be followed to mass-produce your perfume.

2

Using a table, describe the equipment and material necessary to perform each one of the steps listed in the previous question.

3

Draw a diagram to illustrate each step of the production of your perfume. Include legends with your diagrams, and add notes. Make sure that you clearly indicate all the details so that a person unfamiliar with perfume could recreate your product.

R EVIEW ACTIVITY 3

Communication

Perfume: The Work of a “Nose” In the different activities in this chapter, as well as those in Chapters 1 and 2, you used a design process to create a new perfume. In a team, you had to:

How to Apply the Design Process

• determine who your target clientele will be

How to Communicate Effectively

• analyze different design scenarios

Skills Handbook, pp. 433–434 Skills Handbook, pp. 438–439

• draw up an inventory of ingredients and equipment necessary to create your perfume • survey the target clientele before deciding on the essences that will make up your perfume • extract the essence from raw materials • create your perfume • describe the production steps to make your perfume You must now look back at the process you used and write a report. This step will help you prepare the launch of your perfume. 1

Explain how you applied each step of the design process listed above to create your perfume.

2

Assess the design process using the worksheet given to you by your teacher.

3

If necessary, recommend improvements that could be made to your perfume or the design process used.

Checklist 1. I used the scientific and technological information from the activities of this chapter to assess my design process. 2. I explained how the different steps of the design process contributed to the creation of my perfume. 3. I used the appropriate vocabulary, which I learned in this chapter. 4. I recognize the successes and difficulties of my design process.

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M Y D ISCOVERIES Chapter 1 • Soil is made up of particles of rocks and minerals, organic matter, microscopic organisms, air and water (pp. 128–129). • Soil is an essential resource used for housing, for growing food, for producing goods, etc. (pp. 130–131). • There are several ways to classify soil based on its pH levels, its texture, its colour, its structure, etc. Canada has its own classification system for soil (pp. 130–131). • The texture and composition of soil influence the speed of drainage (pp. 132–133). • The speed of drainage should be controlled to allow for the growth of most plants (pp. 132–133). • Mineral salts dissolve in water. Plants then absorb this water through their roots (pp. 134–136). • Soil-test kits are used to determine the pH level and concentration of nitrogen, phosphorus and potassium (pp. 134–136). • The presence of mineral salts in the soil may modify some of its properties (pp. 134–136). • There are three types of rocks: igneous, metamorphic and sedimentary (p. 137). • Mineral resources can be classified into four categories: metallic minerals, industrial minerals, construction materials, and combustible materials (pp. 138–140).

Chapter 2 • When they clump together, particles of matter form heterogeneous mixtures or homogeneous mixtures called solutions (pp. 144–145). • A mixture can be identified as a homogeneous or heterogeneous mixture by studying it with the naked eye, or by using more precise instruments, such as a magnifying glass, a binocular microscope or a microscope (pp. 146–148). • There are several processes for separating the components of a mixture, for example, decantation, filtration, distillation and centrifugation (pp. 149–150). • Some mixtures are natural, while others are artificial (p. 151).

Chapter 3 • Perfumes can be classified in seven families (pp. 156–158). • Odours are captured in olfactory receptor cells that are located in the nasal cavities. These then transmit messages through the olfactory nerve to the brain (pp. 159–160). • The separation process used most often to extract the essence from flowers is distillation (pp. 162–163). • Perfume is a homogeneous mixture of extracts from odorant substances, alcohol and water (pp. 164–165). • After a perfume has been applied, the alcohol evaporates quickly. Only the odorant substances remain on the skin. These diffuse their scent throughout the day as the scented molecules evaporate (pp. 164–165). 168

U NIT P ROJECT 4

Communication

Launching a New Perfume You have reached the end of the unit! You have completed the design and production phases of the design process. With your team, you will now launch your perfume on the market. Review all the activities in this unit. Choose the information that you find interesting or essential for the launching of your perfume. In your presentation, you should:

The Design Process Encyclopedia, pp. 376–377

How to Communicate Effectively Skills Handbook, pp. 438–439

KEY CONCEPTS IN UNIT 4

1

Report on the findings of the survey that you conducted with your target clientele to choose the basic essence of your perfume.

2

Describe the basic ingredients of your perfume and the processes you used to extract them.

• acidity/alkalinity

Describe all the other ingredients used in your perfume and the methods applied to mix them with the basic ingredient.

• equipment

3

• characteristics • erosion • lithosphere

4

Present the production steps for your perfume.

5

Include the promotional text that will accompany your product when it is put on the market.

• mass

6

Unveil the name of your perfume, as well as the shape of the bottle.

• physical and behavioural adaptation

7

Provide a sample of your perfume in a container or on a strip of blotting paper.

• raw materials

• manufacturing process sheet • material • mixtures

• types of rock (basic minerals) • separation of mixtures • types of soil • solutions • temperature • volume

Checklist 1. I used the scientific and technological information found in the activities in the three chapters in this unit. 2. I clearly presented the design process (design, production, marketing). 3. I justified the decisions I made during different steps in the creation of my perfume. 4. My presentation was original. 5. I used different types of communication in my presentation.

169

NG

WORLD EA

D

T HE

L WO R L

THE L IVI

MA

THE

170

RIA TE

H RT

AND SPA CE

THE TEC H

D RL

GICAL W LO O O N

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THE MATERIAL WORLD Matter: Natural and Synthetic Substances Take a look around you. Whether you are in class, at home or on your way to school, you see many objects of different shapes and sizes. Everything you see is matter. Some matter is natural, other matter is synthetic. A lot of matter is essential to life. You cannot live without natural matter like water and air. Synthetic matter can be important as well. What would you do if there were no chairs in your class, no buses to take you to school or no telephones? However, the production and use of matter can have negative effects on the air we breathe and the water we drink. It is important to be aware of these effects and to use matter responsibly.

SECTION 1 The Properties of Matter

The Material World

p. 174

SECTION 2 Transformation of Matter

p. 190

SECTION 3 Organization of Matter

172

p. 202

Non-Characteristic Properties of Matter

p. 175

Characteristic Properties of Matter

p. 188

Physical Changes

p. 191

Chemical Changes

p. 193

Conservation of Matter

p. 194

Pure Substances and Mixtures

p. 195

The Atom

p. 203

The Elements

p. 204

The Molecule

p. 209

Here is an overview of what you will be learning in “The Material World”:

• In Section 1, “The Properties of Matter,” you will see that substances exist in different states. We use these substances for different purposes depend ing on their properties or characteristics.

• In Section 2, “Transformation of Matter,” you will learn that substances can be transformed naturally or modified by human beings. After studying this section, you will have a better understanding of the advantages and disadvantages of these transformations.

• In Section 3, “Organization of Matter,” you will discover what matter is made up of and learn about the smallest particles in the Universe. This section will provide you with a good understanding of the structure and compo sition of substances.

173

S ECTION 1 The Properties of Matter States of Matter p. 176

Mass

p. 178

Volume

p. 180

Solids

p. 176

Liquids

p. 176

Gases

p. 177

Particle Theory

p. 177

The Celsius Scale p. 181

Temperature

p. 181

Non-Characteristic Properties of Matter p. 175

Temperature and Particle Theory p. 183

Measuring Acidity or Alkalinity p. 185

SECTION 1 The Properties of Matter Acids and Bases

SECTION 2 The Material World

p. 183

Transformation of Matter

p. 186

pH

p. 186

Universal Indicator Paper p. 188

Organization of Matter The Melting Point Characteristic Properties of Matter

ENCYCLOPEDIA

Litmus Paper

Different Degrees of Acidity p. 187

SECTION 3

174 The Material World

Temperature and Atmospheric Pressure p. 182

The pH Meter p. 188

p. 188

The Boiling Point p. 188

p. 188

OVERVIEW If you look around your class, you will notice that none of the students look exactly alike. Each student has certain characteristics or properties that help to identify them. For example, one student might have brown hair. However, this property alone is not enough to recognize the student because many of your classmates also have brown hair. This is called a non-characteristic property. On the other hand, no two fingerprints are alike, so they can be used to specifically identify someone (see Figure 1). A person’s fingerprints are a characteristic property.

Figure 1 Fingerprints are a charac-

teristic property because they can be used to specifically identify a person.

Non-Characteristic Properties of Matter There are many substances in your class. Although there are numerous differences between them, they can be divided into three categories: solids, liquids and gases. This is what we refer to as states of matter. It takes more effort to lift a desk than to lift a pencil. Why? One reason is that a desk contains more matter than a pencil. The quantity of matter of a substance is expressed by its mass. The mass of a desk is greater than the mass of a pencil. Look at the objects in your class. Your chair takes up more space than your pencil case. The space that matter occupies is called volume. The chair has a greater volume than a pencil case. Matter is anything that has mass and volume. Your body is able to feel things that are hot and cold. For example, you can easily distinguish hot water from cold water. The temperature indicates the quantity of heat an object or matter contains. In the next few pages, you will learn how to measure a few non-characteristic properties of matter. These properties are mass, volume and temperature. We will also discuss another non-characteristic property of substances: acidity and alkalinity.

SECTION 1

The Properties of Matter

175

States of Matter Room temperature The temperature of the surrounding air. In a room, this temperature is approximately 20°C.

At room temperature, matter can exist as a solid, a liquid or a gas. The furniture, walls and floor of your classroom are solids. Water and other beverages are liquids. The air you breathe is a gas.

Solids Solids are made up of particles held together by invisible bonds. These bonds are so strong that the particles cannot move around freely. All they can do is vibrate, like cell phones on quiet mode. This is why solids have a specific shape and occupy a measurable volume. Therefore, using a ruler, you can easily measure the space your desk occupies. Also, the strength of the bonds between the particles makes it difficult to deform a solid (see Figures 2 and 3).

Figure 2 Particles of solids cannot

Figure 3 A solid placed in a container keeps its shape.

move around freely. They can only vibrate.

Liquids The bonds that hold together the particles of a liquid are weaker than the bonds holding together the particles of a solid. Unlike the particles of a solid, the particles of a liquid can move around slowly. They move around like people talking and dancing at a party. Individuals can move around on their own within the group. Also, small groups of people can move around a little, or the entire group can move from one place to another. Unlike particles of solids, particles of liquids do not form rigid structures. As a result, the particles of a liquid do not keep their shape, and the liquid takes the shape of its container (see Figures 4 and 5).

Figure 4 Particles of liquids can

move slightly with respect to each other.

ENCYCLOPEDIA

176 The Material World

Figure 5 A liquid takes

the shape, but not the volume, of its container.

Gases At room temperature, many substances exist in their gaseous state. For example, the air we breathe is a gas. The bonds between particles of gas are even weaker than the bonds connecting particles of liquids. Particles of gas can therefore move around much more freely than particles of liquids and solids. There are large, empty spaces between them. Think of a baseball stadium with only two people who are sitting at opposite ends. Particles of gas move around easily with respect to each other. They have so much freedom of movement that they can travel in all directions. As a result, the gas expands to fill the entire container or room (see Figures 6 and 7).

Figure 7 Gas particles are very Figure 6 A gas expands

to completely fill its container.

Particle Theory Scientists today use particle theory to explain the structure of matter. According to this theory, matter is composed of particles that are invisible to the naked eye.

The main principles of particle theory: 1. All substances are made up of very small particles. 2. A substance consists of particles that can be similar or different. 3. There is space between the particles. 4. The particles are constantly moving; the speed of these movements depends on the temperature of the substance. 5. The particles of a substance either attract or repel each other; the strength of the attraction or repulsion depends on the type of particles in the substance.

far apart from each other; they can move freely in all directions.

NEWS FLASH . . . The fourth state of matter is plasma, which usually takes the form of ionized gas. This means that one or more electrons have been removed from some or all of the atoms and molecules of the gas. Scientists estimate that 99% of all matter is plasma. The Sun and the stars are made up of plasma. On the Earth, plasma occurs in its natural state in lightning and in the upper atmosphere. We can also see it in the polar auroras. Plasma has many applications and is used in flat-screen televisions and fluorescent tubes.

SECTION 1

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177

Memory Check 1. Name the state of matter described in each of the following cases: a) The matter takes the shape, but not the volume, of its container. b) The matter expands to fill all the available space. c) The matter has a specific shape and occupies a volume that can be measured. 2. A substance has a defined volume but an undefined shape. Is it a solid, liquid or gas? 3. How would you explain the difference between a solid, a liquid and a gas to a student your age who is not taking a science and technology class?

NEWS FLASH . . . People often confuse mass and weight. If you say, “I weigh 40 kg,” this is incorrect. It is not your weight but rather your mass that is 40 kg. Weight is a force that is expressed in newtons (N). On the Earth, the force exerted on an object is 9.8 N/kg. Your weight is therefore 392 N. If you were on the Moon, your weight would be different. It would be one sixth of your weight on the Earth, or 65 N. Your mass does not change. In “The Technological World” (see page 410), you will study the concept of force in greater detail.

Mass: A Question of Quantity According to particle theory, matter is made up of small particles. Since these particles are tiny, we can neither see them nor count them. A single drop of water contains billions of water particles. Just imagine how many particles there are in the human body! The mass of a substance tells us how much matter it contains. For example, an object such as a car contains much more matter than your bicycle. The car therefore has a greater mass than the bicycle. To determine the mass of different substances or objects, we need a measuring instrument. To express the measurement, we need a unit of measure. Scientists generally use the units of the International System of Units (also called SI units from the French name Système International d’Unités) and the units that are derived from them (see Table 1). Table 1 Basic units of measure of the International System of Units (SI units)

Unit of measure

ENCYCLOPEDIA

178 The Material World

Symbol

Measurement

Metre

m

Length

Kilogram

kg

Mass

Second

s

Time

Kelvin

K

Temperature

Mole

mol

Quantity equal to 6.02 x 1023 particles of matter

Candela

cd

Light intensity

Ampere

A

Strength of an electric current

The kilogram is the basic unit of measure for mass. Table 2 provides a few examples of objects, as well as their masses. Table 2 Masses of various objects and of a person

Unit of measure

Examples

Large masses

kilogram (kg) 1 kg = 1000 g

250 kg

60 kg

Smaller masses

1000 kg gram (g) 1 g = 0.001 kg or 1000 mg

25 g 1g

Much smaller masses

100 g milligram (mg) 1 mg = 0.001 g or 0.000 001 kg

100 mg

20 mg

The scale is the measuring instrument used to measure mass (see Figure 8).

Figure 8 A quad beam

balance SECTION 1

The Properties of Matter

179

Volume: A Question of Space Look around at the objects in your class: they are big or small, wide or narrow, thick or thin. When you make these types of comparisons, you are considering the space the objects occupy, or their volume. It is possible to measure the volume of solid, liquid and gaseous substances. Like mass, volume is expressed in units of measure. However, the unit of measure and the measuring instrument used for volume differ depending on the state of the matter. In other words, we do not use the same units or instruments for measuring a regular solid as we do for an irregular solid or a liquid (see Table 3). The units of measure for volume are derived from the metre. One litre (1 L) is equal to one cubic decimetre (1 dm3). The litre is therefore derived from the unit of measure of length. Table 3 Various methods for measuring volume

Unit of measure

Regular solid

Cubic metre (m3) Cubic centimetre (cm3) (1 cm3 = 0.000 001 m3)

Illustration Use the following formula:* Volume = length  width  height

Ruler, tape measure

height Cubic millimetre (mm3) (1 mm3 = 0.000 000 001 m3)

length width

Irregular solid

Millilitre (mL) Cubic centimetre (cm3) (1 mL = 1 cm3)

Graduated cylinder, overflow can

Place the object in a graduated cylinder containing water and measure the volume of the water that is displaced.

Litre (L) (1 L = 1 dm3)

Liquid

Measure the volume of water that flows out of an overflow can.

Pour the liquid into a graduated cylinder.

Graduated cylinder

Millilitre (mL) (1 mL = 0.001 L)

* This formula applies to rectangular prisms and to cubes. Different formulas apply to other regular solids, such as spheres and cones.

ENCYCLOPEDIA

180 The Material World

Temperature: The Higher the Heat, the Greater the Movement  Do you often listen to weather forecasts? When the forecast is calling for 30°C, you can spend the day at the beach. However, if the temperature is –15°C, you will be in the mood for something a little different.

 Heating and refrigerating foods are part of our daily activities.

The Celsius Scale

NEWS FLASH . . .

The everyday unit of measure for temperature is the degree Celsius (°C). The degree Celsius is derived from the kelvin. To calibrate a thermometer in degrees Celsius, which involves putting the increment marks in the right place, scientists rely on the properties of water. Water exists in three states: solid, liquid and gaseous. The temperature at which water freezes is given the value 0. Next, the temperature at which water turns into vapour is given the value 100. Then, the space between these two reference points is divided into 100 units (or degrees) of equal length. Figure 9 illustrates this process.

a) The level of liquid in a thermometer placed in a container of water and ice is given the value 0 when ice crystals begin to form in the water.

b) The level of liquid in a thermometer placed in a container of boiling water is given the value 100.

We often confuse temperature and heat. Heat is one of the forms of energy that is measured with an apparatus called a calorimeter. Heat is measured in joules. However, temperature is an indirect indication of the amount of energy. The unit of measure for temperature is the degree Celsius.

c) The space between these two numbers is divided into 100 equal parts of 1 degree each.

Figure 9 Method for calibrating a thermometer in degrees Celsius.

SECTION 1

The Properties of Matter

181

Temperature and Atmospheric Pressure

Pressure The force exerted on a surface. For example, when you press down on your pencil as you write, you are applying pressure to the paper.

NEWS FLASH . . . Body temperature provides an important indication of a person’s state of health. For all warm-blooded animals, maintaining a constant body temperature is essential for the body to function properly. Average human body temperature is 37°C. A drop of only a few degrees will trigger hypothermia. When hypothermia occurs, blood circulation becomes dangerously slow. In contrast, if a person’s body temperature rises by a few degrees, that person will experience a fever, or even hyperthermia.

The calibration of Celsius thermometers is always based on the properties of water at sea level. This is important to keep in mind because water particles behave differently at different altitudes. Liquid water boils at 100°C at sea level. However, at an altitude of 1600 m, water boils at about 94°C. This difference is due to atmospheric pressure. To understand atmospheric pressure, imagine that you are sitting on the ground and three students are pressing down on your shoulders with all of their strength. You will have trouble getting up because their hands are exerting a force on you. In the atmosphere, air particles also exert a force. At sea level, the thickness of the atmosphere is at its maximum. In other words, that is where there are the most air particles above you. The atmospheric pressure is at its maximum. However, the higher the altitude, the thinner the atmosphere. There are fewer air particles above you, and the atmospheric pressure decreases. It is as if only one student were pressing down on your shoulders. At sea level, the force exerted by atmospheric pressure limits the transformation from the liquid state to the gaseous state. Particles of water must reach a temperature of 100°C before they have enough energy to transform into a gas. This is why water boils at 100°C at sea level. At high altitudes, the atmospheric pressure is lower. For example, at an altitude of 1600 m, water particles have enough energy to transform into a gas once they reach a temperature of 94°C. This is why water boils at 94°C at an altitude of 1600 m (see Figure 10). The greater the atmospheric pressure, the higher the temperature needed for water to transform from the liquid state to the gaseous state. In contrast, the lower the atmospheric pressure, the lower the boiling point.

Top of the atmosphere

94°C

Figure 10 At an altitude of 1600 m, water boils at 94°C rather than 100°C because the atmospheric pressure is lower than it is at sea level.

ENCYCLOPEDIA

182 The Material World

100°C

1600 m

Temperature and Particle Theory Particles that make up matter are constantly moving. In solids, particles do not travel; they vibrate in place. In liquids, particles move around more freely. For example, in a glass of water, particles can move around, but in a piece of ice, they are almost immobile. Water in a glass is warmer than it is when frozen into ice cubes because of the speed of the particles. It is almost impossible to directly measure the speed of particles in matter. Particles are too small, and they travel too quickly. However, the temperature of a substance provides an indication of the average speed of motion of these particles.

United States

212 °

Boiling point of water

100 °

98.6°

Human body temperature

37 °

32 °

Freezing point of water

0°

Acids and Bases: We Can’t Live Without Them You can taste acidity when you bite into a lemon or a salad that has dressing on it. The sourness, or tartness, is a property of acidic substances. You can also taste the alkalinity of a substance while sitting in your dentist’s chair. The bitterness you taste when the dentist gives you a needle to numb the pain is what a base (an alkali) tastes like. Or, ask an adult you know to let you taste baking powder, another basic (alkaline) substance. Your own body produces strong acids and bases. Your stomach secretes hydrochloric acid, which breaks down and dissolves food to extract the nutrients. We sometimes experience heartburn after eating food that is hard to digest. This sensation is caused by excess acid in the stomach or by acid reflux in the esophagus. The stomach itself is protected from the effects of this acid by its thick lining. As food exits the stomach, it is mixed with strong bases. These are bicarbonates secreted by the pancreas. The bicarbonates neutralize the effects of the acid when the food is in the small intestine (see Figure 11).

Canada

Fahrenheit scale

Celsius scale

 Canada and the United States use different temperature scales.

Esophagus

Stomach Pancreas Small intestine Figure 11 The human digestive system produces

strong acids and bases. SECTION 1

The Properties of Matter

183

The venom produced by some insects is another example of an acidic substance. Bees, wasps and some ants produce a very acidic liquid to defend themselves (see Figure 12). When they bite or sting, the acidity of the venom reacts with the water in your skin cells, and you experience a burning sensation. You can relieve the pain by applying to your skin a mixture of baking soda and water. Since baking soda is basic, it neutralizes the acidity of the venom. Some plants, such as poison ivy, produce a basic substance as a defence mechanism (see Figure 13). When water from your skin comes into contact with this substance, a severe irritation occurs. The itching can be relieved with a slightly acidic substance like vinegar or lemon juice. Figure 12 The bee uses its stinger

to inject acid into its enemies.

Table 4 shows some common acidic and basic products.

Figure 13 Poison ivy produces

a basic substance. Table 4 A few acidic and basic products

Name

Acidic substances

Basic substances

Hydrochloric acid

Sulphuric acid

Vinegar (acetic acid)

Ammonia

Baking soda (sodium bicarbonate)

Bleach (sodium hypochlorite)

• Concrete stripper

• Production of plastics, fertilizers and dyes

• Cooking ingredient

• Household cleaner

• Cooking ingredient

• Disinfectant

• Food-preservation agent

• Production of fertilizers • Antacid and explosives

Products

Uses

• Toilet-bowl cleaner

ENCYCLOPEDIA

184 The Material World

• Electrical conductor for car batteries

• Bleaching agent

Measuring Acidity or Alkalinity

BLEACH

Acidic and basic substances are very useful, but they can also be very dangerous. It is therefore important to know their degree of acidity or alkalinity, which is expressed as their pH. The pH of a substance indicates whether it is very acidic or mildly acidic, very basic or somewhat basic. When the degree of acidity or alkalinity of a substance changes, it reacts differently with other substances. For example, rainwater usually has a pH of 5.6. This value is considered mildly acidic and represents little danger for humans. However, when rain mixes with certain pollutants in the air, its acidity increases. You do not feel a difference on your skin, but the leaves of trees will be damaged. Also, the acidity of soil and bodies of water increases, which is harmful to many plants and several species of fish.

CAUTION: May irritate eyes and skin. This product produces a dangerous gas when mixed with an acid. Do not mix with a toilet-bowl cleaner, stripper, ammonia or acid. Never mix undiluted bleach directly with other household products. Avoid contact with eyes and skin. Follow instructions. Keep tightly capped and in upright position. Keep out of reach of children. FIRST AID: Contains sodium hypochlorite. If swallowed, call a doctor or the Poison Control Centre immediately. Do not induce vomiting. If in contact with eyes, rinse with water for 15 minutes. If in contact with skin, rinse well with water.

It is extremely dangerous to try to determine the acidity or alkalinity of a substance by tasting it. Read the labels on cleaning products you have in your home. You will see warnings about the dangers of products that are highly acidic or highly basic (see Figure 14). You can use an indicator to measure the acidity or alkalinity of a substance. An indicator is a substance that changes colour in the presence of an acid or base. Some flowers are natural indicators (see Figure 15). Lichens, red-cabbage juice, tea and grape juice also change colour in the presence of acidic or basic substances.

Figure 14 Labels on some household

cleaning products contain warnings about the dangers of strong acids and bases.

Figure 15 Hydrangea blossoms are blue

when the plant is cultivated in acidic soil and pink when it is cultivated in neutral or basic soil.

SECTION 1

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185

HISTORY

Litmus Paper: A Useful Indicator OF SCIENCE Alfred Nobel (1833–1896) was a Swedish chemist and entrepreneur. During his time, nitroglycerin, which is very sensitive to shock, was used as an explosive. It is a thick, colourless liquid that is toxic and extremely volatile. After his brother died following a nitroglycerin explosion, Nobel set out to find a safer way to handle it. In 1867, after many attempts, he discovered that when he mixed nitroglycerin with other substances, he obtained a product that was less sensitive to shock and much more powerful. He had just invented dynamite.

Litmus paper comes in two colours: red and blue. You need to use both of them to get a good indication of the acidity or alkalinity of a substance. Table 5 shows how to interpret their colour after you have used them. When you soak both of these papers in an acidic or basic liquid, one of the papers will change colour (see Figure 16). If neither paper changes colour, the substance is neutral; in other words, it is neither an acid nor a base. Litmus paper does not allow you to measure the degree of acidity or alkalinity, but it does provide a useful indication.

Figure 16 Litmus paper is one of the oldest indicators and the most common one used to determine whether a substance is acidic or basic.

Table 5 How to interpret the colour of litmus paper

Blue litmus paper

Red litmus paper

Acidic substance

Turns red

Stays red

Basic substance

Stays blue

Turns blue

Neutral substance

Stays blue

Stays red

pH: An Accurate Measurement Scale You saw that litmus paper turns red or stays red when it is soaked in an acidic substance, but it will not tell you whether the substance is mildly acidic or very acidic. However, this information can be very important. For example, if water in a lake is too acidic, the eggs of certain species of fish will not develop. The adults will not be replaced by younger fish, and the population will disappear. In your laboratory experiments, you will need a more accurate method of measuring acidity and alkalinity. You will use a pH scale (see Figure 17 on the next page). This scale classifies substances according to their acidity or alkalinity. The pH scale ranges from 0 to 14. Acidic substances have a pH below 7. Basic substances have a pH above 7. Substances with a pH of 7 are neither acidic nor basic. They are neutral.

ENCYCLOPEDIA

186 The Material World

Look at Figure 17. Pure water has a pH of 7. As you move along the scale to the left, the substances become increasingly acidic. The most acidic substance on the scale has a pH of about 0. The acid in a car battery (sulphuric acid) is so strong that it can burn skin. As you move to the right of pure water, the substances become increasingly basic. The most basic substances have a pH of about 14. Very basic substances react very strongly with human tissues and with various substances.

Different Degrees of Acidity An apple has a pH of 3, and a lemon has a pH of 2. Does this mean that a lemon is only slightly more acidic than an apple? Actually, every increment on the pH scale represents a factor of 10. In other words, a lemon is 10 times more acidic than an apple. To compare degrees of acidity, you need to multiply by 10 every time the value of the pH decreases by one. Similarly, you must divide by 10 every time the pH increases by one. Figure 17 compares the pH of different substances.

Battery acid 0.2

Stomach 1.2

0

1

Lemon juice Vinegar Apple 2.0 2.2 3.0

2

3

Tomato 4.2

4

Rain 5.6

5

Milk 6.6

6

Pure water 7.0

7

Human blood 7.4

8

Baking soda 8.2

Water from Milk of the Great magnesia Lakes 8.5 10.5

9

10

11

12

Ammonia 11.1

Oven cleaner 13.9

13

14

10 times 10 times more acidic more basic 100 times more acidic

100 times more basic

1000 times more acidic 10 000 times more acidic 100 000 times more acidic 1 000 000 times more acidic 10 000 000 times more acidic

Acidic substances

1000 times more basic 10 000 times more basic 100 000 times more basic 1 000 000 times more basic 10 000 000 times more basic

Neutral substances

Basic substances

Figure 17 Comparison of various degrees of acidity and alkalinity on the pH scale

SECTION 1

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187

Universal Indicator Paper: An Accurate Tool Universal indicator paper (see Figure 18) is much more practical and accurate than litmus paper. Each degree of acidity or alkalinity corresponds to a different colour. Universal indicator paper therefore provides the specific pH of a substance, whereas litmus paper indicates only whether a substance is acidic or basic.

Check colour against the chart after 30 seconds . pH 0 to 14

Figure 18 We can determine

the pH of a substance by comparing to a colour chart the colour of the universal indicator paper that has been soaked in the substance.

The pH Meter The pH meter is an electronic instrument (see Figure 19) that directly provides the pH of a substance. It uses the capacity of these liquid substances to conduct electrical current. The more acidic or basic the substance, the better it conducts electrical current.

Characteristic Properties of Matter Figure 19 The pH meter uses the

electrical conductivity of a substance to determine its pH.

We saw earlier that the state of matter is a non-characteristic property. However, the temperature at which a substance changes state is a characteristic property. For example, a particular kind of paraffin is the only known substance that transforms from its solid state to its liquid state at a temperature of 71°C; this is therefore a characteristic property of that type of paraffin.

The Melting Point When a substance melts, it passes from its solid state to its liquid state. The temperature at which this occurs is called the melting point. For example, the melting point of aluminum is 660°C. This characteristic property distinguishes aluminum from other substances.

The Boiling Point The boiling point is also a characteristic property of matter. It is the temperature at which a substance passes from the liquid state to the gaseous state. In contrast, the transformation from the gaseous state to the liquid state is called condensation. Condensation occurs at the same temperature as the boiling point. ENCYCLOPEDIA

188 The Material World

Table 6 shows the melting points and the boiling points of various substances. Table 6 Melting points and boiling points of various substances

Substance

Melting point (°C)

Boiling point (°C)

Oxygen

–218

–183

Mercury

–39

357

0

100

Tin

232

2602

Lead

328

1740

Aluminum

660

2519

Table salt

801

1413

Silver

962

2162

Gold

1064

2856

Iron

1535

2861

Water

 Candle wax melts under the heat produced by the flame. It starts out in the solid state and changes to the liquid state. Then the heat causes the liquid wax to vaporize and transform into the gaseous state.

Memory Check 1. What is the difference between a characteristic property and a non-characteristic property? Give examples. 2. What does mass tell us about a substance? 3. Name an object that has a mass of approximately: a) 10 g b) 10 kg c) 5000 kg 4. a) What does volume measure? b) What units of measure express volume? c) What instruments measure volume? 5. Explain how you would measure the volume of the following objects: a) a box of tissues b) an apple c) the amount of juice in an orange 6. a) What does temperature tell you about the particles of a substance? b) What instrument allows you to measure temperature? 7. Name an object that has a temperature of about: a) –5°C b) 20°C c) 60°C

8. What is the name of the scale that is used to measure the degree of acidity or alkalinity of a substance? 9. a) What is an indicator? b) Which is more accurate: litmus paper or universal indicator paper? Why? 10. A student places a drop of an unknown solution on red litmus paper. She notices that the litmus paper does not change colour. a) What can she conclude from this? b) What can she do to determine whether her conclusions are accurate? 11. Sea water has a pH of approximately 8.2. Cheese has a pH of about 5.5. a) Which of these substances is more acidic? Why? b) Which is more basic? Why? 12. Is it possible for a substance to be neither acidic nor basic? Explain your answer.

SECTION 1

The Properties of Matter

189

S ECTION 2 Transformation of Matter Physical Changes

p. 191

Chemical Changes

p. 193

Conservation of Matter

p. 194

Changes of State and Particle Theory p. 192

SECTION 1 The Properties of Matter

SECTION 2 The Material World

Transformation of Matter

Mixtures

SECTION 3

Solutions

p. 196

Dissolution

p. 197

Sedimentation

p. 198

Decantation

p. 199

Filtration

p. 199

Distillation

p. 200

p. 196

Organization of Matter Pure Substances and Mixtures p. 195 The Separation of Mixtures p. 198

Overview Humans tend to make a lot of changes to their environment. For example, imagine the transformations a city has undergone since the time when it was only a village or, before that, natural relief. Humans transform matter to meet their needs. The objects you use are made from matter that has been manufactured or transformed. Aluminum or plastic juice or soft-drink containers are made from transformed materials. When you send off these empty containers to be recycled, they are transformed again.

Compost A mixture of organic and mineral substances resembling black earth. Compost results from the decomposition of plant and animal residues.

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190 The Material World

Transformation of matter also occurs naturally. In the winter, water changes into snow and ice; on hot summer days, it evaporates. In the fall, trees lose their leaves, which are transformed into compost and serve to enrich the soil the following spring. In this section, you will learn that transformations of matter can be divided into two categories: physical changes and chemical changes. In addition, you will discover that the majority of substances exist in the form of mixtures. You will also learn a few techniques for separating different substances contained in mixtures.

Physical Changes: Reversible Transformations

ion osit Dep

lim a Sub

on

sati den

Changes in states of matter are physical changes. In physical changes, the particles of the substance remain the same. The only thing that changes is the appearance of the substance. Appearance is a non-characteristic property. For example, water is SOLID always made up of water particles, whether it is in the form of ice, liquid water or water vapour. It retains its characteristic properties. In addition, physical changes are reversible; the substance that undergoes the change can return to its initial state. For example, ice turns back into water when it melts.

Con

tion

GAS

or ling Boi ration po eva

At the end of the previous section (see page 192), we discussed two characteristic properties of matter: the melting point and the boiling point. These properties involve changes to the state of matter. We also saw that certain substances can pass from the solid state to the liquid state, then to the gaseous state if they are heated sufficiently. Conversely, when certain substances are cooled, they go from the gaseous state to the liquid state, and then to the solid state. Figure 20 illustrates these transformations. Table 7 provides a list of the various changes in states of matter and a few examples.

Melting

Solidification

LIQUID

Figure 20 Changes in states

of matter

Table 7 Changes in states of matter

Change of state

When the substance is heated

When the substance is cooled

Explanation

Example

Melting (or liquefaction)

Transition from the solid state to the liquid state. The temperature at which this transition takes place is called the melting point.

• Melting ice • Melting candle wax

Boiling (or fast vaporization)

Quick transition from the liquid state to the gaseous state. The temperature at which this transition occurs is the boiling point.

• Boiling water • Boiling wax

Evaporation (or slow vaporization)

Gradual transition from the liquid state to the gaseous state. The transition occurs at a temperature below the boiling point.

• Clothes drying • The odour of gasoline when we fill up our vehicles

Sublimation

Direct transition from the solid state to the gaseous state.

• Ice cubes gradually “disappearing” in the freezer

Condensation (or liquefaction)

Transition from the gaseous state to the liquid state. The temperature at which this transition occurs is the condensation point. It is the same temperature as the boiling point.

• Water vapour that condenses to form clouds

Solidification (or freezing)

Transition from the liquid state to the solid state. The temperature at which this transition occurs is the freezing point. It is the same temperature as the melting point.

• Liquid water that freezes and transforms into ice • Liquid wax that runs down a candle and stays in place once it becomes solid

Deposition

Direct transition from the gaseous state to the solid state.

• Water vapour freezing to form frost

SECTION 2

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191

Changes of State and Particle Theory D ● B●

Particle theory can help you understand what happens to particles when a substance passes from one state to another. E●

C●

A ● Time

A ●

A● Consider a solid substance. It has a specific shape. Its particles are very close

together, and they cannot move around easily. The only thing they can do is vibrate. When the solid is heated, its temperature increases. Its particles vibrate faster and stronger. The volume of the solid increases gradually. B● If heat continues to be applied to the solid, there will be a point at which the

particles vibrate so strongly that the bonds holding them together change. This is the melting point. The solid melts and gradually becomes a liquid. As the solid melts, all of the heat it receives goes into transforming the bonds between the particles. This is why the temperature stops increasing until the entire solid has melted. On a graph plotting temperature over time, this phenomenon takes the form of a plateau, which can be called the “melting plateau.”

B●

C● The solid has become a liquid. It takes the shape of its container. Its particles

are farther apart. They are able to move around a little. When the liquid is heated, its temperature rises and its particles move around faster and more freely. The volume of the liquid gradually increases. D ● If we continue to heat the liquid, the particles’ movements become very strong

and very fast, and the bonds holding them together break. The particles can even escape from the container. The liquid reaches its boiling point; it becomes a gas. During this entire time, heat goes into breaking the bonds between the particles. The temperature stops increasing until all of the liquid has become a gas. This is the second plateau of the graph of temperature over time. It can be called the “boiling plateau.”

C●

E● The substance has become a gas. The particles escape from their container

D ●

and disperse quickly in all directions. The bonds between them are weak, and the particles move around easily.

Memory Check E●

1. a) Name the three states of matter. b) Name the six changes in states of matter. c) Give an example of each of these changes in states of matter. 2. What is a physical change? 3. Are new substances produced during a physical change? Explain. 4. What happens to the characteristic properties of a substance during a physical change? ENCYCLOPEDIA

192 The Material World

Chemical Changes: Radical Transformations Paper that burns and fuel that is consumed in a car engine are two examples of chemical changes. Unlike physical changes, chemical changes result in new substances that have their own properties. In the case of burning paper, many new substances are created, including ashes and carbon dioxide. These two substances are very different from paper. Paper is white, whereas ashes are grey. Paper is a solid, but carbon dioxide is a gas. It is often difficult or impossible to reverse a chemical change. Ashes and carbon dioxide cannot be combined back together to produce paper. Fuel that is consumed in a car engine is another example of a chemical change. When fuel burns in the presence of oxygen, different substances are produced, such as water vapour and carbon dioxide. The gases produced do not resemble the original liquid at all. In addition, it is impossible to recreate fuel from the newly formed substances. Here are four signs that a chemical change has occurred:

1. A gas is formed (e.g. bread baking).

2. A residue is formed (e.g. stalagmites and stalactites).

3. Heat or light is produced (e.g. fireworks).

 Paper that burns is transformed into ashes and smoke.

4. A colour change occurs (e.g. rust).

Memory Check 1. What is the difference between a chemical change and a physical change? Provide some examples. 2. Are new substances produced during a chemical change? Explain your answer. 3. What happens to the characteristic properties of a substance when a chemical change occurs?

SECTION 2

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HISTORY

OF SCIENCE Antoine Laurent de Lavoisier, a French chemist (1743–1794), identified 23 chemical elements. However, he did not work alone. His wife, Marie-Anne Lavoisier, was a big help in his research. She read and translated many English articles for him. Teamwork is often an important part of science!

Conservation of Matter: Nothing Is Lost, Nothing Is Created Antoine Laurent de Lavoisier was a French scientist who lived in the 18th century. He performed many experiments involving transformations of matter. In order to have a clear understanding of what was going on, he took very accurate measurements. As a result, he observed that the mass of substances that undergo a transformation is always equal to the mass of the resulting substances. He called this phenomenon the law of conservation of matter. Consider the case of a physical change, such as water freezing. If you place a hermetically sealed glass filled with water in the freezer, what happens? The container will explode as the expanding ice breaks the glass. However, the mass of the water remains the same whether it is in a liquid or solid state. Since the mass is the same before and after the transformation, it is the volume that changes. Water pipes that burst in the winter illustrate this phenomenon. Now let us consider a chemical change: fuel that is consumed in a car engine. During combustion, fuel combines with oxygen in the air and is transformed into different products, including carbon dioxide and water vapour. The mass of the fuel and of the oxygen that are used up is the same as the mass of all the new gases produced. Lavoisier said that nothing is lost and nothing is created; everything is transformed. This means that the original substances do not disappear. In the case of a physical change, the particles change state, mix with other particles or separate. In the case of a chemical change, the particles themselves undergo a transformation. They combine with other substances, or they divide into two or more new substances. In Section 3, “Organization of Matter,” we will take a closer look at what is inside particles of matter.

 Carbon monoxide is very dangerous because it is odourless, invisible and can cause asphyxiation.

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194 The Material World

Pure Substances and Mixtures Have you ever gone to the beach? Look carefully at Figure 21. Beach sand is made up of grains from different minerals. It also contains animal and plant debris. What about air and water? Are they also formed from mixtures of different particles, or are they pure substances? On the next few pages, you will see that many familiar substances are actually mixtures. You will learn the difference between a pure substance, a homogeneous mixture and a heterogeneous mixture.

Pure substances

Mixtures

Homogeneous mixtures (solutions)

They contain only one type of particle. Examples: salt, sugar, iron, diamond, oxygen, carbon dioxide, distilled water, pure alcohol

They are made up of at least two types of particles. These particles are uniformly distributed throughout the mixture. To the naked eye, there appears to be only one substance. Examples: air, tap water or bottled water, sugar water, salt water, steel, gold jewellery

Heterogeneous mixtures

They are made up of at least two types of particles. These particles are not uniformly distributed throughout the mixture. At least two different substances are visible to the naked eye or through a microscope.

a mixture?

HISTORY An alloy is a metallic substance made up of a metal that is combined with another metallic or nonmetallic substance. It may be a solid or liquid. Bronze was one of the first alloys ever manufactured. It is a mixture of copper and tin. Bronze jewellery, tools and weapons from 3500 to 800 BCE have been discovered in France and Germany. Alloys are very important in industry. For example, steel is an alloy of iron and carbon, and brass is a mixture of copper and zinc. Alloys are often harder and stronger than the pure substances they are made from.

SCIENCE

Matter

Figure 21 Is sand a pure substance or

OF

Observe Figure 22. It shows that the difference between a pure substance and a mixture is due to the composition of the substance. A pure substance contains only one type of particle, whereas a mixture contains at least two types of particles.

Examples: smog, muddy water, concrete, $2 coin

Figure 22 Classification of matter based on its composition

SECTION 2

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Mixtures: Heterogeneous or Homogeneous? Nobody wants to breathe the polluted air shown in Figure 23. Like most people, you would probably prefer the fresh air depicted in Figure 24. What is the difference between the two? The air shown in Figure 23 is an example of smog. If you are in the middle of a smog cloud, you might not be able to distinguish the pollutants. However, if you look at smog from a distance, the pollutants in the air form a greyish cloud. Smog is a heterogeneous mixture. The air in Figure 24 is invisible. You know that air is a mixture of different gases, but these gases cannot be distinguished from each other. Pure air is a homogeneous mixture. Homogeneous mixtures are also called “solutions.” Figure 23 Smog is a

heterogeneous mixture of air and various pollutants.

Figure 24 Pure air is a

homogeneous mixture of nitrogen, oxygen and carbon dioxide.

Solutions: Homogeneous Mixtures Soluble substance A substance whose particles have the ability to separate until they are uniformly distributed in another substance. For example, sugar is soluble in water.

Solvent The part of a mixture that dissolves the other substances.

Solute The part of a mixture that is dissolved.

Solutions are homogeneous mixtures containing two or more substances. Unlike heterogeneous mixtures, the different types of particles of a homogeneous solution cannot be distinguished from each other. A solution has the same appearance as a pure substance, which only contains one type of particle. In a solution of sugar water, represented in Figure 25, the particles of sugar are evenly distributed among the particles of water. The sugar does not disappear in a mixture. Rather, the sugar dissolves in the water, which means it is soluble in water. In a mixture of sugar water, there are more particles of water than particles of sugar. The substance present in the larger quantity is called the solvent. The substance present in the smaller quantity is called the solute. In the example shown in Figure 25, water is the solvent, and sugar is the solute.

A sugar particle Figure 25 In a solution of sugar water, the

particles of the two substances are uniformly distributed. Each particle of sugar retains all of its sugar properties. Each particle of water retains all of its water properties. The solution possesses the properties of the two substances. ENCYCLOPEDIA

196 The Material World

A water particle

In a solution, there is only one solvent. However, the solution can contain several solutes. For example, air is a solution that contains three main gases. In air, the solvent is nitrogen. The other gases are solutes (see Figure 26).

Nitrogen (78%) Oxygen (21%)

Dissolution When you stir salt into a glass of water, it forms a homogeneous mixture: a solution of salt water. When two or more substances mix to form a solution, dissolution occurs. The solute (salt) dissolves in the solvent (water). However, the mixture of several substances does not always form a solution. For example, if you pour sand into water, you do not obtain a solution. Instead, you get a heterogeneous mixture where you can clearly distinguish the various substances. Why does salt dissolve in water while sand does not? Each grain of salt is made up of billions of particles. These particles attract each other to form a grain. When the grain of salt is placed in water, changes occur. The attraction between the water particles and the salt particles is very strong. It is stronger than the attraction of the salt particles to each other. First, the water particles attract a salt particle at the surface of a grain of salt. They detach it from the grain and keep it away from the other salt particles. Then, other water particles attract other salt particles. This process continues until all of the particles of the grain have been detached and dissolution is complete. The salt particles are uniformly distributed in the water (see Figure 27). A grain of sand placed in water does not dissolve. Why? The attraction between the water particles and the sand particles is weaker than the attraction of the sand particles to each another. The grain of sand therefore stays intact.

a) A grain of salt placed in water.

Other gases (about 1%) Carbon dioxide (less than 0.1%) Figure 26 The main

components of air

NEWS FLASH . . . Rain might seem harmless at first glance. However, if it is acidic, it can be harmful to living organisms and cause damage to buildings. The process of dissolution transforms rainwater into a solution called “acid rain.” The water particles in the air act as the solvent. The particles of gas (pollutants) are the solutes. Water becomes acidic when it dissolves the gas particles produced, for example, by car exhaust and industrial pollution.

b) The grain of salt dissolves: c) The salt is dissolved: the the water particles detach salt particles uniformly the particles at the surface disperse in the water. of the grain of salt.

Figure 27 The dissolution of salt in water

SECTION 2

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The Separation of Mixtures At home, you use simple procedures for separating mixtures. For example, you use a colander to separate pasta from the water it was boiled in. Your parents use a filter to separate coffee grounds from brewed coffee. Mixtures can be separated easily using these simple processes. However, you might also find it useful to combine the ingredients of a mixture. For example, you might want to shake orange juice before drinking it because the pulp has settled to the bottom of the carton. The same applies to salad dressing because the oil and vinegar separate from each other. Why separate mixtures? Here are a few examples of situations in which it is necessary to separate the components of a mixture. Petroleum is a heterogeneous mixture. It must be distilled to obtain the various substances it is made up of. One of these is gasoline, which cars run on. Jewellery is often made from metals found in rocks. These rocks are heterogeneous mixtures. They need to be crushed and heated for the metal to be extracted. The same process is used to manufacture aluminum cans. In its natural state, the metal aluminum is not found in its pure form. It must be extracted from a rock called bauxite, which is a heterogeneous mixture. Fresh water can be a homogeneous mixture, or it can be a heterogeneous mixture. Often, it must be filtered and treated before it is safe to drink. When we manufacture or use various products, mixtures are sometimes formed that are harmful to the environment or to our health. This is the case when water is mixed with industrial waste, or air is mixed with the exhaust from cars or factories. In these last two examples, separating mixtures is beneficial to people’s health and to the environment.

Sedimentation: Slow but Sure Figure 28 shows a heterogeneous mixture of muddy water. After a while, the mixture’s particles separate. Solid substances that are heavier than water particles deposit at the bottom of the beaker. They form a sediment. This separation process is called sedimentation.

Figure 28 Sedimentation of muddy

Sediment

water. The sediment gradually separates and settles at the bottom of the beaker. a) First day ENCYCLOPEDIA

198 The Material World

b) Second day

Sedimentation occurs in orange juice, when the pulp deposits at the bottom of the container. In salad dressing, the oil and vinegar eventually separate through sedimentation. The vinegar particles settle at the bottom of the container, and the oil particles float on top of the vinegar. Sedimentation is a process that occurs naturally; the mixture simply needs to sit. For example, sedimentation is an effective process for treating water. The water to be treated passes through a sedimentation basin, which allows the debris to separate from the water. In water-treatment plants, sedimentation is often one of the steps carried out to make the water safe to drink.

Decantation: From One Container to Another Decantation is often used after sedimentation. With decantation, a heterogeneous mixture that has layers can be separated into distinct substances. Decantation involves pouring out one of the layers into another container (see Figure 29). Consider again the example of the muddy water. If mud particles are at the bottom of the beaker, you can pour out the water into another container to separate the water from the mud.

Filtration: Fast and Effective

Figure 29 A method for decanting

A vacuum cleaner is an example of an apparatus that uses filtration. If you open it, you will see a filter, which traps the dust and residue that is vacuumed up. A colander is also a filter; it holds the food and allows the cooking water to pass through.

two liquids

Filtration separates different substances of a heterogeneous mixture. It can replace sedimentation and decantation. Sometimes a heterogeneous mixture contains substances in the form of droplets suspended in the liquid. It can take a very long time before the droplets separate out from the mixture through sedimentation. The separation process can be accelerated with filtration (see Figure 30). You can pour the muddy water mixture through filter paper. Filter paper has many tiny holes in it. The paper holds back the bigger particles (the residue), while the smaller particles (the filtrate) pass through.

Residue

Mixture

Filtrate Figure 30 A method for filtering the

contents of a beaker SECTION 2

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199

NEWS FLASH . . . The cells of the human body produce waste each day. Some of this waste accumulates in the blood. The kidneys clean the blood by filtering it. The residue collected by the kidneys is evacuated from the body in the form of urine. Each day, the 5 L of blood in the human body pass through the kidneys about 330 times. When a person’s kidneys do not function properly, the blood must be filtered by an artificial kidney, called a “hemodialysis machine.”

Water intake (filtration cycle)

Intake: wash water and air Filtration cycle

Discharge of wash water toward sewers

a)

Filtration bed

b)

a) carbon b) sand Outlet to filteredwater basin

Nozzles False floor Wash cycle

In water-treatment plants, the water passes through layers of carbon and sand. The carbon and sand trap the impurities.

Distillation: Separating the Invisible How would you go about separating the components of a salt-water solution? Could you use sedimentation, decantation or filtration? Since it is a homogeneous mixture, none of these processes would work. However, you could use distillation, which is another method for separating the components of a mixture. Distillation relies on a characteristic property of substances: their boiling point. To separate water and salt through distillation, the salt-water solution must first be boiled. When water reaches a temperature of 100°C, it begins to boil. It transforms into vapour and passes through a tube called a “condenser.” In this tube, water vapour cools and returns to its liquid state. In other words, it condenses and accumulates in the beaker. The salt stays behind in the roundbottom flask. 1 Hot plate 1● 2● 2 Salt (residue) accumulates at the bottom of the roundbottom flask as the water evaporates.

3 Salt water 3● 4 Water vapour 4● 5 Condenser 5● 6 Cold-water outlet 6● 7 Cold-water intake 7● 8 Vapour condenses as it 8● cools

8

9 Pure water (distillate) 9●

6 7 4

Figure 31 This laboratory set-up is used

5

3

to distill solutions. 2 ENCYCLOPEDIA

200 The Material World

1

9

A distillate is the substance obtained from condensation (see Figure 31 on the previous page). In this case, it is water. The substance that does not move into another container after distillation is called the residue. In our example, the salt is the residue. The boiling point of salt (1413°C) is much higher than the boiling point of water. The salt would have to be heated to a much higher temperature to transform from its solid state to its liquid state and then to its gaseous state. Is it possible to separate two liquids through distillation? Consider the example of water and ethanol. Ethanol is an alcohol and is used, among other things, in laboratory thermometers. It is coloured red to make the thermometer easier to read. Ethanol is actually a transparent, colourless liquid, like water. By mixing ethanol and water, we obtain an alcohol-water solution. Here is an example of how distillation can be used to separate the two components of this homogeneous mixture. First, the alcohol-water solution must be heated. Ethanol reaches its boiling point at 78.3°C. It passes from the liquid state to the gaseous state. Ethanol in the gaseous state enters the condenser, cools and condenses. The recipient container holds the liquid ethanol, which is the distillate. Since water has not yet reached its boiling point, it stays in the original container. It is the residue of the distillation process.

Memory Check

NEWS FLASH . . . Petroleum extracted from the ground is a thick, brown liquid. In this form, it is an unusable mixture. However, when petroleum is refined, it is separated into many useful substances. An important step in the refining process is distillation. Some of the substances obtained through refining include natural gas, gasoline, heating oil, kerosene, diesel, tar and asphalt. The distillation process used in other steps produces several kinds of plastic.

1. a) Provide an example of a heterogeneous mixture. b) Provide an example of a homogeneous mixture. 2. a) What is the difference between a pure substance and a homogeneous mixture? b) Is tap water a pure substance or a homogeneous mixture? Explain your answer. 3. You are in a science lab, and you are looking at several beakers containing the unknown substances described below. Before identifying them, you must separate the components of each mixture. How would you go about separating the components? What is the name of the process you would use? a) Beaker A contains a heterogeneous mixture. You can clearly see brown particles suspended in it. You also see a deposit at the bottom of the beaker. b) Beaker B contains a blue solution. There are no visible particles in the liquid. c) Beaker C contains a heterogeneous mixture. The suspended particles are very fine. There is no visible deposit at the bottom of the beaker. 4. In filtration plants, the water to be treated passes through a layer of sand. Is this sedimentation or filtration? Explain your answer. 5. In landfill sites, liquid collects in a leaching basin. What is the purpose of this process? SECTION 2

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201

S ECTION 3 Organization of Matter SECTION 1 The Properties of Matter The Atom

p. 203

Atomic Theory

p. 204

The Periodic Table

p. 205

Chemical Symbols

p. 208

Chemical Formulas

p. 210

SECTION 2 THE MATERIAL WORLD

Transformation of Matter The Elements

p. 204

SECTION 3 Organization of Matter

The Molecule

p. 209

Overview The particles of matter we have been discussing throughout “The Material World” are made up of atoms. Atoms are like letters of the alphabet. With only 26 letters, we can make thousands of words. Do you know how many different particles are necessary to make up the millions of living and non-living organisms in the world? In your opinion, are there as many different particles as there are substances? Let us take another look at our alphabet example. The words ape, elephant and partridge have the letters a, p and e in common. However, these words refer to very different life forms. Is it possible that substances, even very different substances, share certain particles? In this third section, you will learn that there are 90 stable atoms, called elements. They are classified into the periodic table of elements. Atoms joins together to form molecules. All the matter surrounding us is made up of molecules.

ENCYCLOPEDIA

202 The Material World

The Atom: From Visible to Invisible When you look around, your eyes perceive very different substances. However, all of them are made up of particles of matter, called atoms, which cannot be seen with the naked eye.

The word atom comes from the Greek word atomos, which means “indivisible.”

The 26 letters of the alphabet form words as different as zoo and anticonstitutionally. Atoms are like letters of the alphabet; they form all existing substances. There is a wide variety of substances because atoms are very different from each other, as are the letters of the alphabet. In addition, atoms can combine in many ways to form molecules, just as letters combine to form the words of a language. Atoms are like letters, and molecules are like words. We saw earlier that matter is made up of a very large number of particles. Scientists have discovered that these particles, in turn, are made up of molecules, and that molecules are made up of something even smaller, called atoms. If you pass an electrical current through water for a certain amount of time, two gases are produced: hydrogen and oxygen. This process, call electrolysis, breaks up the water particles. Electrolysis shows that the water particles are made up of two types of atoms (see Figure 32). Each water particle is a molecule made up of two atoms of hydrogen and one atom of oxygen. All pure substances contain a combination of specific atoms. An infinite number of combinations exists, and each combination is a different molecule. This explains why there are so many different forms of matter.

Hydrogen

Oxygen

Water

Current source

Figure 32 The electrolysis of water

demonstrates that it is made up of hydrogen and oxygen.

SECTION 3

Organization of Matter

203

Atomic Theory Earlier in this chapter we discussed particle theory. Next, we will discuss atomic theory, which will explain the structure of matter even further.

HISTORY

The main principles of atomic theory:

OF SCIENCE Humphry Davy (1778–1829) was a British scientist. He was the founder of a field of science called “electrochemistry.” Electrochemistry involves passing an electrical current through a solution to separate its elements. Using this process, Davy discovered another method for separating the elements potassium (K), sodium (Na) and calcium (Ca).

1. All matter is made up of tiny particles called atoms. 2. Atoms are made up of even smaller particles called protons, neutrons and electrons (see Figure 33). 3. Atoms can be distinguished from each other by their number of protons, neutrons and electrons. 4. A set of atoms, each of which has the same number of protons, is called an “element.” 5. Atoms combine to form molecules. Electron

Proton

Nucleus

Neutron

Figure 33 The atom as we

know it today

The Elements: Different Atoms Elements are the building blocks of the Universe. An element is a group of atoms that have the same number of protons. The number of protons is therefore a characteristic property of elements. Atoms of a given element can, however, differ in the number of neutrons they contain. In many cases, some of their electrons are given to, received from, or shared with other atoms. Hydrogen is the simplest element. It has only one proton and only one electron. It is also the lightest element. If we filled an Olympic-sized swimming pool with hydrogen, the total mass would be about 1 kg. Hydrogen is also extremely explosive; in its liquid state, it is used as rocket fuel.

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204 The Material World

In 1937, as the Hindenburg dirigible was travelling through the air, its hydrogen fuel caught fire. Thirty-five of the 97 people on board were killed in the disaster.

The Periodic Table: Ingredients of Matter Suppose your teacher asks you to find the missing numbers in this table. How would you solve this problem?

0 10 20

2 12

3

4 5 11 14 15 21 23 24 25 31 32 33 34 35 40 41 42 43 45 50 51 52 53 54 You have probably already noticed that the information contained in the table is organized in numerical order. The numbers in each row increase by one. The numbers in a column increase by 10. This pattern helps you find the missing numbers quickly. If you had received a list of numbers that were unorganized instead of in table form, you would probably have found the problem much more difficult to solve. In science, a similar situation occurred when the information about the elements was first compiled. Was there a way to organize them so that their properties would become more apparent and easier to understand? A Siberian chemist, Dmitri Ivanovitch Mendeleev provided the best solution to this question in 1869.

Dmitri Ivanovitch Mendeleev (1834–1907) was the creator of the periodic table. SECTION 3

Organization of Matter

205

Table 8 Periodic table of elements 1 1

H

1

Hydrogen

3

Li Lithium

11

Na

Mg Magnesium

19

20

3

4

21

22

Name of element

5 23

6 24

7 25

8 26

9 27

K

Ca

Sc

Ti

V

Cr

Mn

Fe

Co

Potassium

Calcium

Scandium

Titanium

Vanadium

Chromium

Manganese

Iron

Cobalt

4 37

38

39

40

41

42

Rb

Sr

Y

Zr

Nb

Rubidium

Strontium

Yttrium

Zirconium

Niobium

5 55 6

56

57

72

73

43

44

Mo

Tc

Molybdenum Technetium

74

75

45

Ru

Rh

Ruthenium

Rhodium

76

77

Cs

Ba

La

Hf

Ta

W

Re

Os

Ir

Cesium

Barium

Lanthanum

Hafnium

Tantalum

Tungsten

Rhenium

Osmium

Iridium

87 7

Chemical symbol

Hydrogen

Beryllium

Sodium

(equal to the number of protons)

H

Be 12

3

Solid

Atomic number

4

2

State at room temperature

1

2

88

89

104

105

106

107

108

109

Fr

Ra

Ac

Rf

Db

Sg

Bh

Hs

Mt

Francium

Radium

Actinium

Rutherfordium

Dubnium

Seaborgium

Bohrium

Hassium

Meitnerium

Gaseous Liquid

58

59

Ce

6

Cerium

90

Artificial elements

7

60

Pr

61

Nd

62

Pm

Praseodymium Neodymium Promethium

91

92

93

63

Sm

Eu

Samarium

Europium

94

95

Th

Pa

U

Np

Pu

Am

Thorium

Protactinium

Uranium

Neptunium

Plutonium

Americium

Mendeleev wrote down on cards the main properties of the 63 elements that were known at the time. Then he hung the cards on a wall. He studied them for several months and moved them around, trying to discover a model based on the properties of the elements. When he put the cards in increasing order of atomic mass, he noticed that some properties recurred at regular intervals. Then he placed the cards with similar properties in a column, and the periodic table was born. Mendeleev’s classification was quickly adopted because it allowed predictions to be made. There were empty spaces in the table, and Mendeleev said that, one day, elements would be discovered that corresponded to these empty spaces. He even predicted many properties of these new elements. Other chemists later discovered these elements and confirmed Mendeleev’s predictions. The periodic table contains all natural and artificial elements known to date (see Table 8). These elements form all of the visible and invisible matter

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206 The Material World

18 2

He 13 5

6

28

11 29

12 30

15 7

16 8

9

10

C

N

O

F

Boron

Carbon

Nitrogen

Oxygen

Fluorine

14

15

16

17

Al

Si

P

S

Cl

Silicon

Phosphorus

Sulphur

Chlorine

32

33

34

Ne Neon

18

Aluminum

31

Helium

17

B 13 10

14

35

Ar Argon

36

Ni

Cu

Zn

Ga

Ge

As

Se

Br

Kr

Nickel

Copper

Zinc

Gallium

Germanium

Arsenic

Selenium

Bromine

Krypton

46

47

48

49

50

51

52

53

54

Pd

Ag

Cd

In

Sn

Sb

Te

I

Xe

Palladium

Silver

Cadmium

Indium

Tin

Antimony

Tellurium

Iodine

Xenon

78

79

80

81

82

83

84

85

86

Pt

Au

Hg

TI

Pb

Bi

Po

At

Platinum

Gold

Mercury

Thallium

Lead

Bismuth

Polonium

Astatine

110 (no name)

64

111 (no name)

65

112

114

(no name)

66

116

(no name)

67

68

70

(no name)

Tb

Dy

Ho

Er

Tm

Yb

Lu

Gadolinium

Terbium

Dysprosium

Holmium

Erbium

Thulium

Ytterbium

Lutetium

97

98

99

100

101

102

Metals (representative elements) Metals (transition elements)

71

Gd 96

Radon

118

(no name)

69

Rn

103

Cm

Bk

Cf

Es

Fm

Md

No

Lr

Curium

Berkelium

Californium

Einsteinium

Fermium

Mendelevium

Nobelium

Lawrencium

Metals (actinides and lanthanides) Metalloids (semi-metals) Non-metals

around us. The periodic table contains the ingredients of all matter on the Earth and in the Universe. In the periodic table, the elements are laid out in rows and columns. First let us consider the rows. The elements are organized in ascending order of atomic number. The atomic number corresponds to the number of protons. Each row of the table is called a period. Hydrogen is the first element because it has only one proton. The next element, to the right, is helium, which has two protons. Now look at the columns. Each column of the table represents a family or group. Each family contains elements that have similar properties. For example, all of the elements in the first family (Column 1) form compounds with those of the second-to-last family (Column 17). The last family (Column 18) is made up of elements that rarely form compounds with the elements of the other families. They are called “rare gases” or “noble gases.”

SECTION 3

Organization of Matter

207

Chemical Symbols: A Universal Code Table 9 The symbol for hydrogen

is international

Name

Symbol

English

hydrogen

H

French

hydrogène

H

German

Wasserstoff

H

Italian

idrogeno

H

Portuguese

hidrogênio

H

Spanish

hidrógeno

H

Whatever language they speak and wherever they come from, scientists use a universal code to refer to the same element: its chemical symbol. The elements do not have the same name in all languages, and a name may be pronounced differently in different countries. However, the symbols of the elements are the same all over the world. Table 9 illustrates the universality of the symbol for hydrogen. In Japan and China, people write with characters called ideograms. However, students learn the same chemical symbols as we do. Each element in the periodic table has its own symbol (see Table 8 on the previous page). For some elements, it is the first letter of the name, which is written in upper case. For other elements, the first letter of the name is used (in upper case), followed by the second letter in lower case. Sometimes three letters are used to designate an element. The origins of the names of the elements are very varied. Some come from Latin, Ancient Greek or other languages. Others are named after scientists (see Table 10).

Table 10 The origins of the names of a few elements

Atomic Chemica Element number l symbol

ENCYCLOPEDIA

208 The Material World

Origin of name

Year of discovery

1

Hydrogen

H

Named by Lavoisier. Derived from the Greek words hydro and genes, which together mean “water-forming.”

1766

6

Carbon

C

Derived from the Latin word carbo, which means “charcoal.”

Antiquity

7

Nitrogen

N

Derived from the Greek words nitron and genes, which mean “nitre” (saltpetre or potassium nitrate) and “forming.”

1772

8

Oxygen

O

Named by Lavoisier. Comes from the Greek words oxys and genes, which together mean “acid-forming.”

1774

19

Potassium

K

Discovered by Humphry Davy. From the English word potash. The symbol is derived from its Latin name, Kalium.

1807

84

Polonium

Po

Named by Marie Curie, in honour of her country of origin, Poland.

1898

96

Curium

Cm

Named in honour of Pierre and Marie Curie.

1944

The Molecule: A Group of Atoms

O2

CO2

H2O

dioxygen

carbon dioxide

water vapour

CO

NO2

SO2

carbon monoxide

nitrogen dioxide

sulphur dioxide

Henry Cavendish (1731–1810) was a British scientist. Cavendish was one of the first scientists to generate water molecules by exploding oxygen and hydrogen in the gaseous state. He also demonstrated that water is not an element, but a molecule composed of oxygen and hydrogen atoms.

SCIENCE

When two or more atoms join together, they form a molecule. Molecules, in turn, combine to form all visible objects. Molecules also make up invisible matter, such as the air we breathe (see Figure 34).

HISTORY OF

In nature, elements rarely exist in the form of individual atoms. Most of the time, they bond with one or more other atoms of the same or different elements. This is what happens with the element hydrogen, which is the most common substance in the Universe. It is usually found in the form of dihydrogen molecules, which are two hydrogen atoms that are joined together. The same thing occurs with carbon. This element is found in certain gases in the air, such as carbon monoxide (CO) and carbon dioxide (CO2). Carbon is also found in all living things.

a) Some components of air

b) Some atmospheric pollutants Figure 34 Some molecules usually present in the air

SECTION 3

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209

Chemical Formulas: A Practical System Symbol for hydrogen

Symbol for oxygen

H 2O The number 2 shows that there are two hydrogen atoms

No number means that there is only one atom of oxygen

Figure 35 The chemical formula for

The elements are represented by chemical symbols. A system also exists for molecules: a chemical formula represents the molecules and indicates which elements the molecules contain. The chemical formula contains the symbols of the elements and the number of atoms in the molecule. Figure 35 shows the formula for a molecule of water, which is H2O. This formula tells us that each molecule of water contains two atoms of hydrogen and one molecule of oxygen. Table 11 shows the chemical formulas for a few other molecules. Table 11 Chemical formulas for a few molecules

Molecule

Chemical formula

Molecular model

Atomic composition

Silica (sand)

SiO2

1 atom of silicon 2 atoms of oxygen

Glucose (sugar)

C6H12O6

6 atoms of carbon 12 atoms of hydrogen 6 atoms of oxygen

Sodium chloride (table salt)

NaCl

1 atom of sodium 1 atom of chlorine

Acetic acid (vinegar)

CH3COOH

2 atoms of carbon 4 atoms of hydrogen 2 atoms of oxygen

water

Memory Check 1. How are atoms like the letters of the alphabet? 2. How are molecules like words? 3. Imagine that you are in the science lab and your teacher asks you to build a model of an atom. a) Explain how you would go about doing this. b) Describe your model. 4. What is the name of a group of atoms that have the same number of protons? 5. Imagine that Mendeleev had never been born and that you had just created the first periodic table of elements. What arguments would you use to convince your colleagues of the importance of the periodic table? 6. The periodic table groups together elements by families and periods. What do the elements of the same family have in common?

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210 The Material World

THE ATOMIC MODEL OVER TIME LE MODÈLE ATOMIQUE DANS LE TEMPS t 1808

John Dalton (1766–1844), a British scientist, was the first person to propose an atomic theory. Dalton believed that atoms were the smallest particles of matter. He believed that atoms were similar to billiard balls of different sizes and masses.

t 1897

Joseph John Thomson (1856–1940) was a British scientist who discovered that the atom itself was made up of even smaller particles. He described the atom as a ball charged with positive electricity. The ball also contains electrons, which are charged with negative electricity. His atomic model resembled a raisin muffin, where the raisins represent the negative areas and the rest of the muffin represents the positive area.

t 1911

Ernest Rutherford (1871–1937) was born in New Zealand. He taught science for a number of years at McGill University in Montréal. Rutherford said that atoms were made up of electrons (negatively charged particles) revolving around a very small nucleus. This nucleus contains protons (positively charged particles). His model resembles the solar system, where the sun represents the nucleus, and the planets orbiting around the sun represent electrons.

t 1914

Niels Bohr (1885–1962), originally from Denmark, was Rutherford’s student. Bohr proposed that the electrons did not revolve around the nucleus like planets around the sun. Rather, the electrons moved around the nucleus in orbitals. These orbitals resembled clouds more than orbits. An orbital is the zone in which the electron can travel.

F

t 1932

James Chadwick (1891–1974) was a British scientist who discovered the neutron. The neutron is a third type of particle. The first two are the electron (negatively charged particle) and the proton (positively charged particle). The neutron has neither a negative charge nor a positive charge; it is neutral. It is found in the atom’s nucleus. It is thought to act like cement between the protons.

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THE LIVING WORLD We Are Not Alone There are eight known planets in our solar system. The Earth, however, seems to be the only one with the necessary conditions to sustain life. Not only does life exist on the Earth, it also comes in an amazing variety of shapes! Imagine trying to list all the living species on the Earth. One lifetime would probably not be long enough to complete it. We have now identified about 1.8 million species of living organisms and new ones are continually being discovered. Human beings are one of these life forms. We share the water, land and air with all the other living organisms. These resources, however, are not always distributed equitably. Human beings greatly transform their environment. The following pages will help you better understand the living world. You may learn ways to make a more equitable use of the water, land and air and you will be reminded that human beings are not alone on the Earth.

SECTION 1 The Diversity of Life Forms

p. 214

SECTION 2 The Living World

Reproduction of Living Organisms

p. 238

SECTION 3 Life-Sustaining Processes

212

Species

p. 216

Habitat

p. 224

Evolution

p. 235

Asexual or Sexual Reproduction

p. 240

Reproduction in Plants

p. 240

Reproduction in Animals

p. 250

Reproduction in Humans

p. 257

Characteristics of Living Organisms

p. 277

The Cell

p. 277

Two Vital Functions of the Cell

p. 284

p. 276

“The Living World” will help you make the following discoveries:

• In Section 1, “The Diversity of Life Forms,”

you will come to understand why there is such an incredible variety of living organisms. To do so, you will study different habitats, which are the places where species live. You will discover that the diversity of life forms is the result of a long evolutionary process.

• In Section 2, “Reproduction of Living Organisms,” you will discover that reproduction is the reason why living organisms continue to exist after billions of years. You will learn about human reproduction.

Animals (over 2 million species) Plants (between 350 000 and 400 000 species) Fungi (about 100 000 species) Protists (about 70 000 species) Monerans (at least 10 000 species)

• Finally, in Section 3, “Life-Sustaining Processes,” you will discover how to tell the difference between living and non-living things. You will then delve into the heart of living organisms to study the cell. Finally, you will discover two vital cellular functions: respiration and photosynthesis.

213

S ECTION 1 The Diversity of Life Forms Taxonomy

p. 217

Scientific Names p. 218 Species

p. 216

The Plant Kingdom

p. 219

The Animal Kingdom

p. 222

Adaptations

p. 225

The Maple Family

p. 220

Adaptations to Climate

p. 225

Adapting Through How They Move

p. 226

Adapting Through What and How They Eat p. 227

SECTION 1 The Diversity of Life Forms

Habitat

p. 224

SECTION 2 The Living World

Reproduction of Living Organisms

SECTION 3 Life-Sustaining Processes

Ecological Niches

A Population

Natural Selection

Evolution

ENCYCLOPEDIA

214 The Living World

p. 232

p. 234

p. 235

Genetic Mutation

p. 236

Genes and Chromosomes

p. 236

p. 235

Adapting Through The Way They Communicate

p. 230

Adapting Through The Way They Reproduce

p. 231

The Role of Species in Food Chains p. 232 Producers

p. 233

Consumers

p. 233

Decomposers

p. 233

The Ecological Niche

p. 234

The Blueprint of Life p. 236 Blue or Brown Eyes?

p. 237

Overview We have been sharing our homes with cats for a very long time. Certain wild animals, such as the lion, tiger and lynx, belong to the same family as the domestic cat. These animals are called felines and belong to the family Felidae. The dog, along with other animals such as the wolf and fox, belongs to another family called the Canidae. Carefully observe Figures 1 and 2. You will notice similarities among animals of the same family, yet each animal is different from other family members.

Figure 1 The cat is a member of the family Felidae

Figure 2 The dog is a member of the family Canidae

Where did the diversity of living organisms come from? Certain animals have feathers, whereas others have fur or scales. Some walk or fly and others climb, jump, crawl or swim. In this section, you will first learn that every living organism belongs to a species. The great diversity of species has led us to develop a classification system called taxonomy. Next, you will learn that species are adapted to the habitat in which they live. In other words, species have physical and behavioural adaptations that are tailored to the various limitations of their habitat. You will then discover that individuals of the same species form populations within the same habitat, which facilitates reproduction between two individuals. During sexual reproduction, genes are exchanged and shuffled. This creates new physical and behavioural characteristics that might improve the chance of survival of the population. In fact, all existing life forms are the result of successful adaptations. This long process of natural change is called evolution. It is the reason why more effective adaptations have appeared, and continue to appear, in response to changes in habitat. However, evolution is a slow process. Some species disappear because their habitat changes too quickly and they do not have enough time to adapt.

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Species By observing the diversity of living organisms, it is easy to see that they do not all belong to the same species (see Figure 3). Every living organism has distinct physical characteristics. Those that share similar characteristics belong to the same species. Physical resemblance is the first criterion for grouping living organisms into species. However, sometimes physical characteristics are not enough to determine to which species a living organism belongs. Figure 4 shows several animals belonging to the “domestic dog” species. You can see by their size, shape, fur and colour that these dogs are very different.

Figure 4 There is a great

diversity of shapes, sizes and colours among the members of the “domestic dog” species.

There are three more criteria that help determine whether two animals belong to the same species. These three criteria must be met to confirm that certain animals belong to the same species.

1. Two individuals of the same species but opposite sexes can mate to reproduce in their natural habitat. 2. The female gives birth to one or more young that survive. 3. Upon reaching maturity, these young can also reproduce successfully.

Figure 3 The diversity of living

organisms

ENCYCLOPEDIA

216 The Living World

Taxonomy: Classifying Life

Great-great-grandmother

Great-grandmother

You

Father

Sister

Great-great-grandfather

Great-grandfather

Grandmother

Mother

Aristotle lived in Greece from 384 to 322 BCE. He spent a great deal of time observing plants and animals. He divided living organisms into two categories: in the plant category, he identified trees, shrubs and grasses. In the animal category, he distinguished between animals that live on land, in water and in the air.

SCIENCE

Classifying living organisms is a bit like creating a family tree. Take a close look at Figure 5. Pretend that it represents your family tree. You are at the bottom of the tree along with your brothers, sisters and cousins. Each of these people has a mother and a father. Your father, for example, may also have brothers and sisters who would be your aunts and uncles. Further up the tree are your grandparents, great-aunts and great-uncles, then your great-grandparents and so on.

HISTORY OF

We have so far identified about 1.8 million species living on the Earth. We know that there are still many species yet to be discovered. How can we make sense of all these different species? They can be divided into groups and classified. This helps us to understand both the relationships between species and their origin.

Brother

Grandfather

Aunt

Uncle

Cousin

Cousin

Figure 5 Example of a family tree

In theory, your family tree can be traced back to the very first humans. A tree can even be created to represent all the individuals of the human species, either living or dead. This family tree could help you determine your degree of kinship to every single person on the Earth. This is exactly what scientists hope to achieve with the classification of living organisms, also known as taxonomy. Although a lot of information they would need to classify all species is still missing, new discoveries are being made every day that help them improve or correct the current taxonomy.

The word taxonomy comes from the Greek words taxis, which means “order,” and nomos, which means “law.”

There is yet another reason for classifying living organisms. Taxonomy helps people communicate using a common language. In fact, scientists from all over the world can talk about species using the same names and categories. This is very useful in furthering our knowledge of life and its origins.

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217

Scientific Names For a classification system to be meaningful, the names of species must be accepted by all scientists. It was Carl Linnaeus who, in 1735, developed our current method for naming species. Living Organisms are divided into six kingdoms are divided into phyla are divided into classes are divided into orders are divided into families

Fungi are divided into genera

Organisms, such as yeasts and moulds, that feed on organic matter (and are therefore incapable of photosynthesis) and reproduce by means of spores.

Protists Unicellular organisms with a nucleus. Some, such as algae, can perform photosynthesis and others, such as the amoebae, feed on organic matter.

Monerans Unicellular organisms, such as Escherichia coli, that lack a nucleus. This kingdom is now divided into Bacteria and Archaeans.

are divided into species

Figure 6 The current taxonomy of living organisms

Every species is given a scientific name. These names are usually in Latin, so for example, the scientific name for the sugar maple is Acer saccharum. The first part of the name, Acer (maple), indicates the genus of the living organism. The second part, saccharum (sugar), designates the species. By convention, the genus and species are always in italics and the genus always takes a capital letter. The common name of a species can therefore vary from one language to another, whereas its scientific name always stays the same. The diagram in Figure 6 illustrates the taxonomy of living organisms. Living Organisms ARE DIVIDED INTO SIX KINGDOMS

Animals

Plants

Figure 7 The six kingdoms of living organisms

ENCYCLOPEDIA

218 The Living World

Fungi

Protists

Bacteria

Archaeans

Before classifying a new species, scientists study its anatomy, behaviour and fossil ancestors. They also compare the characteristics of this species with those of other species that have already been named and classified.

Anatomy The study of the structure and organization of humans, plants or animals.

Living organisms are divided into six large kingdoms (see Figure 7). Each of these kingdoms is made up of living organisms that share certain characteristics.

Fossil ancestors Long-dead organisms for which whole or partial body imprints have been found.

The Plant Kingdom Figure 8 presents a summary of the physical and behavioural characteristics of the five classes of the plant kingdom. Living Organisms are divided into six kingdoms

Animals

Plants

Fungi

Protists

Bacteria

Archaeans

are divided into five classes • They produce their own food. • They cannot move on their own.

Algae Algae do not have roots, stems or leaves. They form a type of branchlet that may be more or less broad, depending on the species. They usually live in water.

Mosses and Liverworts Mosses do not have true roots.

Ferns

Conifers

Flowering Plants

Ferns, conifers and flowering plants have roots, stems and leaves. They have channels for conducting sap.

They have a stem and leaves. They do not have channels for conducting sap. (Sap is the liquid that contains plant nutrients.) They live on the ground or attach themselves to objects.

Ferns and conifers do not have flowers for reproduction.

Flowering plants reproduce by means of flowers.

Ferns do not produce seeds.

Flowering plants produce seeds that are protected inside a fruit.

They reproduce by means of spores.

Conifers produce naked seeds that are usually protected inside a cone. They have needle-like or scale-like leaves. They do not usually shed their needles in the winter.

Figure 8 The five classes of the plant kingdom

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219

The Maple Family The following example will show you how the taxonomy of living things helps us understand the relationship between species. The maple family, well known in Québec, is a member of the class of flowering plants. There are seven species of maple trees in our province. Figure 9 shows the leaves of Québec maples. It describes the common characteristics of these leaves. The shared characteristics lead us to group these seven tree species in the same family. It also demonstrates the differences between each leaf. These differences have, among other things, prompted scientists to classify these maples as different species.

Flowering Plants are divided into families

The Maple Common characteristics of maple leaves: • The leaf has a long petiole. • The veins extend outward from the petiole. • The leaf has three to nine lobes. • The leaf has a toothed edge. divided into species

Sugar Maple (Acer saccharum) • The leaf has five lobes. • Each lobe has a pointed tip. • It has large, sparse and irregular teeth.

Black Maple (Acer nigrum)

Carl Linnaeus (1707-1778) developed our current method for naming species.

ENCYCLOPEDIA

220 The Living World

• The leaf has three lobes and has a wilted appearance. • The underside of the leaf is covered in brown down • It has few teeth.

lobe

vein tooth petiole

Red Maple (Acer rubrum) • The leaf has three to five shallow lobes. • It has small, numerous and irregular teeth.

Silver Maple (Acer saccharinum) • The leaf has five to seven deep lobes. • The underside of the leaf is silver. • It has large and irregular teeth.

HISTORY

Manitoba Maple or Box Elder (Acer negundo) • The leaf is divided into three to seven leaflets. • The leaflets have irregular teeth.

Striped Maple (Acer pensylvanicum) • • • •

The leaf is very large. The leaf has three shallow lobes. Each lobe has a pointed tip. It has small and regular teeth.

The Montréal Botanical Garden was born of the dream of a man with both a religious and a scientific vocation, Brother Marie-Victorin (1885–1944). Having always been enthralled with nature, he founded the Botanical Institute of the Université de Montréal in 1920. At that time, he was already dreaming of creating a great botanical garden for Montrealers. In 1925, Brother Marie-Victorin made his plan public. Six years later, after much hard work to convince politicians and members of the local scientific community, his plan finally took shape on the site of an abandoned landfill.

SCIENCE

• The leaf has three shallow lobes. • It has irregular teeth.

OF

Mountain Maple (Acer spicatum)

Figure 9 The leaves of the seven maple species of Québec

SECTION 1

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221

Habitat: Tell Me Who You Are and I’ll Tell You Where You Live NEWS FLASH . . . Unlike traditional zoos, the Centre de Conservation de la Biodiversité Boréale (CCBB) in Lac-Saint-Jean has no cages. Animals roam free while visitors are caged in vehicles that take them through the different habitats. These habitats mimic the Arctic and Boreal regions of Québec.

You now know that there is a great variety of different species. Each species can survive only in an environment to which it is adapted. The environment in which a specific species lives is called a habitat. Several different species can share the same habitat. Your neighbourhood is your habitat. It provides you with a house for shelter and stores to buy what you need. It also has entertainment facilities and a school where you can gain new knowledge. Your friends also share your habitat. In the same way, animals live in a habitat that meets their needs. To survive, they need: • to meet other animals of the same species in order to reproduce • a shelter • food and water • a climate to which they are adapted Table 1 gives a description of the beaver and its habitat. The physical and behavioural characteristics of this animal help it survive in a wetland habitat.

Table 1 The Canadian beaver and its habitat

Beaver habitat The Canadian beaver (Castor canadensis) lives in the wetlands and lakes of North America.

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224 The Living World

Beaver behaviour This rodent builds lodges out of branches and mud. Beavers start by building the inside of the lodge, then the outside. All the adults participate in this task. They cover their lodge with clay to help protect them from the harsh winter climate and from predators. Beavers also build long dams 30 m or more in length. These dams help maintain the water at a level high enough to hide the entrance to their lodge.

Physical adaptations of the beaver The body of a beaver is adapted to aquatic life. It has • a broad, flat tail • thick, oily fur • webbed hind feet Beavers cut down trees with their long front teeth, called incisors. They feed on leaves and the bark from branches. They use the rest of the tree to build or repair their lodges and dams.

Adaptation Species must be adapted to their habitat. Individuals of a species must protect themselves from the heat and cold, move about, feed themselves, communicate and reproduce within this habitat. They therefore have physical and behavioural adaptations that help them do all these things.

Adaptations to Climate

Figure 11 The Korok River Valley in Nunavik. The Torngat Mountains can be seen in the

background.

Observe Figure 11. It shows a landscape in the Arctic region of Québec. What adaptations might a mammal living in this habitat have? It will surely need a thick coat of fur to protect it from the cold. Its fur might change colour with the seasons so that it can better camouflage itself.

a) The red fox

b) The Arctic fox

Figure 12 Physical differences between the red fox and the Arctic fox

Compare the red fox, which lives in more southern ranges, with the Arctic fox (see Figure 12). You can see that the Arctic fox depends on physical adaptations other than the colour and thickness of its fur to survive in this habitat. Compared to its cousin the red fox, the Arctic fox has shorter, rounder ears. It also has a shorter tail. Its more compact body exposes a smaller surface area to the air; this helps minimize heat loss. SECTION 1

The Diversity of Life Forms

225

Adapting Through How They Move Every animal species has its own unique way of moving. Some species run, whereas others fly, glide, jump, crawl or swim. Animal movement is adapted to specific habitats. Table 2 gives examples of adaptations related to movement. Table 2 Adaptations of some species according to their method of movement

Species

Adaptation

Habitat

The oblong-winged katydid has long V-shaped legs that help it jump long distances from one shrub to the next.

This grasshopper lives in the trees and shrubs of deciduous forests and gardens.

The fins of the walleye help it move through the water. Its elongated body creates little water resistance when swimming.

This fish lives in the cold, clear water of lakes and rivers. In the summer, it seeks the cooler waters of rapids. At night, it goes into deeper water to feed on other fish.

Bullfrog

This amphibian uses its V-shaped legs to leap great distances on the ground. It has webbed feet that help it swim.

The bullfrog lives in lakes and ponds that have enough vegetation to provide shelter.

Smooth green snake

The snake has no legs. It slithers across the ground.

It lives in areas, such as fields, where plants can provide good shelter.

Semipalmated plover

This little bird can fly, but it prefers using its long legs to walk along the shores. It can move quickly, despite the obstacles on the ground or in shallow water.

It can be found on the shores of the oceans, lakes and rivers.

It lives in coniferous and deciduous forests.

Red squirrel

The red squirrel uses its paws a bit like hands to hold the seeds on which it feeds. It has small claws that help it climb safely through the trees.

Oblong-winged katydid

Walleye

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226 The Living World

Adapting Through What and How They Eat Wild animals spend lots of time searching for food. Every animal species has physical adaptations that help it eat. We will look at two examples: mammals and birds. Every mammal species has a jaw that is adapted to its diet. There are four types of teeth: incisors, canines, premolars and molars. Each one has a specific function (see Figure 13). Observe Table 3. It will help you see how the teeth of certain mammals are adapted to their diet. Molar (grind, crush) Premolar (grind, crush) Canine (tear) Incisor (shred, cut)

Figure 13 Human teeth and their functions

Table 3 Examples of mammalian teeth according to diet

Deer

Beaver

Human

Diet

Type of teeth

Jaw

Cat

The canines are particularly well developed.

The molars are well developed. Deer have no canines.

The incisors are well developed. Beavers have no canines.

Humans have all four types of teeth. These teeth are all equally developed.

Cats are carnivores: they eat meat. They use their canines to tear meat.

Deer are herbivores (ruminants): they eat plants and, more specifically, leaves. They use their molars to crush and chew leaves.

Beavers are herbivores (rodents): they eat plants and, more specifically, the bark of small branches. They use their incisors to cut down trees in order to reach this bark.

Humans are omnivores: they eat both meat and plants. Human teeth are adapted to a varied diet.

SECTION 1

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227

Table 5 shows certain plants’ dietary adaptations in different habitats.

Table 5 The dietary adaptations of certain plants

Plant Lichen

Moss

Fern

Water hyacinth

Adaptation Lichens consist of algae and fungi living in symbiosis. The algae produce the food required by the fungi, while the fungi protect the algae from drought and temperature variations.

Symbiosis A mutually beneficial relationship between two living organisms.

This moss species uses a tree trunk to capture a maximum amount of light, which it uses to produce its food through photosynthesis.

This epiphytic species also uses the elevation offered by tree trunks to capture a maximum amount of light.

Epiphytic plant A plant that grows on another plant without harming it.

Water hyacinths grow in ponds. Their roots are not attached to the soil. They absorb minerals and water directly from the pond.

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Adapting Through the Way They Communicate Like diet and respiration, communication is extremely important. It helps individuals make contact with other individuals of the same or different species. Animals must be able to tell other animals when they are searching for a mate, defending their territory or protecting their young. Table 6 provides examples of animal communication.

Table 6 Means of communication and their goals

Means of communication Visual signals

Goals Examples of species

Colours

Gestures

Light

Male birds have brightly coloured feathers.

Bees perform a dance-like movement in the hive.

White-tailed deer raise their tail.

Fireflies produce light.

Attract females.

Indicate the location of a new flower patch.

Warn other deer of danger.

Attract a mate.

Olfactory signals

Goals Examples of species

Odours Wolves, dogs, moose and minks leave their urine or musk (a glandular secretion) on plants and rocks.

Skunks spray a liquid from their anal glands.

Mark their territory.

Ward off predators.

Auditory signals

Goals Examples of species

Cries, growls and clicks

Howls

Songs

Sounds

Dolphins whistle.

Coyotes howl.

Birds sing.

Beavers slap their tail on the water.

Stay in contact with other dolphins.

Stay in contact with other coyotes over great distances.

Mark their territory. Attract a mate.

Warn other beavers of danger.

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230 The Living World

Adapting Through the Way They Reproduce Flowering plants have strikingly beautiful physical adaptations. Since these living organisms cannot move about, they sometimes use insects to help them reproduce. Insects carry the pollen (containing spermatozoa) of one flower to the pistil (containing ovules) of another flower (see Figure 29 on page 248). The members of the orchid family have many different ways of attracting insects (see Table 7).

Table 7 Reproductive adaptations of the flowers of different species of orchids

The lady’s slipper (Cypripedium acaule) is a type of orchid found in Québec. An insect that lands on its flower must slip under the stamen to reach the nectar. Its body then becomes covered in pollen, which it carries over to the next flower.

The bee orchid (Ophrys apifera) can reproduce only with the help of certain species of wild bees. Its flowers look a lot like the female bee of these species. The male bees are therefore tricked into carrying the pollen from flower to flower.

Some orchids such as the Angraecum sesquipedale (also known as the star of Bethlehem orchid) store their nectar at the bottom of a spur. Only butterflies with very long snouts can reach this nectar and therefore pollinate the flower.

Some orchids have pleasant scents like chocolate, vanilla, coconut, cinnamon, cloves, corn chips, leather, or honey. Others have unpleasant odours like fish, rotting fruit, manure, or rotting meat. Some relase their perfume only at night to attract moths.

Memory Check 1. Give two physical or behavioural adaptations of the Arctic fox to the Arctic climate. 2. Goats of a certain species have soft pads under their hooves that stick to rocks. Is this an adaptation to climate, the way they move, or the way they communicate? 3. You are given the skull of an unknown animal. You notice that it has incisors only in its lower jaw and has no canines. On the other hand, its premolars and molars are very large and flat. What do you think this animal ate?

4. a) How can a male bird communicate its desire to mate with a female? b) How does a pack of wolves indicate to another pack of wolves the limits of its territory? c) How can a bee tell the other bees in its hive where to find food? 5. Describe the physical adaptations orchid species use to attract insects.

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Ecological Niches

Herbivore Feeds on plants.

Carnivore Feeds on animals.

Scavenger An animal that feeds on the bodies of already dead animals.

The ecological niche represents the combination of all the conditions that promote the development and survival of a species. The ecological niche includes the living environment of a species (in other words, its habitat), as well as its diet and cycle of activity. In fact, animals interrelate with their environment in many different ways. These interrelationships describe their function in the ecological niche. In an ecosystem, such as a forest, several species share the same habitat. Every species occupies a different ecological niche, however, since each has a unique cycle of activity and position in the food web. This distribution maintains the balance of the ecosystem by helping species share the available food and space among themselves. For example, if you observe species living in a forest, you will realize that some are active during the day and others are active at night. Some species live on the ground, whereas others live underground or in the trees. Some species are herbivores and others are carnivores or scavengers.

The Role of Species in Food Chains Every species is part of a food chain. A food chain illustrates the flow of energy from one organism to another. Plants grow by using sunlight to produce and store their food. Cattle, for example, then store this energy by eating plants. Humans, in turn, absorb this stored energy when they eat beef. Figure 15 gives other examples of food chains. The arrows indicate the direction of energy flow.

Lawn

Forest

Pond

Grass (producer)

Wild cherry (fruit of a producer)

Floating alga (producer)

Grasshopper (primary consumer)

Caterpillar (primary consumer)

Mosquito larva (primary consumer)

American robin (secondary consumer)

Wood thrush (secondary consumer)

Minnow (secondary consumer)

Domestic cat (tertiary consumer)

Northern goshawk (tertiary consumer)

Yellow perch (tertiary consumer)

Earthworm (decomposer)

Turkey vulture (scavenger)

Bacterium (decomposer)

Figure 15 Examples of food chains

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232 The Living World

Producers: In First Place The food chains in Figure 15 show that plants are at the bottom of the energy chain. Plants are producers. They use sunlight, water and carbon dioxide to manufacture food. Through photosynthesis, producers make life possible for other organisms. You will learn more about photosynthesis on page 284 of Section 3.

Consumers: In Second Place Animals are consumers. They are given this name because they absorb the food manufactured by producers.

Decomposers: Recycling Pros When plants and animals die, decomposers feed on their detritus and bodies by breaking these down into tiny particles. In this form, primary substances such as carbon, nitrogen and minerals are once again made available to producers. Decomposers therefore play a vital role by recycling waste. Table 8 shows the position occupied by different species in the food chain. For example, herbivore consumers eat the producers. Herbivores are then devoured by carnivores. Carnivores are then recycled by decomposers. Table 8 The position of different types of organisms in the food chain

Type of organism Producers

Position in the food chain

Examples

They produce organic matter by photosynthesis.

Plants, phytoplankton

Primary consumers (herbivores)

They feed on producers.

Grasshopper, squirrel, hare

Secondary consumers (carnivores)

They feed almost exclusively on primary consumers.

Frog, weasel, fox

Tertiary consumers (carnivores)

They feed almost exclusively on secondary consumers.

Brown snake, owl, wolf

Omnivores

They feed on producers and on primary, secondary and tertiary consumers.

Human, black bear

Scavengers

They feed on the bodies of consumers.

Fly, crow, turkey vulture

Decomposers

They recycle plant and animal matter into organic matter.

Fungi, monerans, protists and certain animals (earthworms, insects)

The turkey vulture found in Québec is an example of a scavenger.

Consumers

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The Ecological Niche: More Than Just a Dietary Role Every species plays a specific role in its habitat. You can easily imagine that if all consumers were herbivores, producers would eventually disappear. As you have learned, however, an ecological niche also depends on how a species shares space, looks for food and builds a shelter. Different species living in the same habitat can therefore play the same role, for example, that of a carnivore consumer. Since individuals do not obtain their food from the same place, at the same time or in the same way, equilibrium is reached in the habitat.

Figure 16 Yellow-rumped warbler

Table 9 lists the ecological niches of a family of small birds called warblers (see Figure 16). These birds live in Québec. They share the same habitat: the forest. They are also all insectivorous consumers.

Table 9 Some characteristics of the ecological niches of warblers

Ecological niche

Species

Diet

Nest

Tennessee warbler (Vermivora peregrina)

Insects, spiders and fruit

On the ground

Blackpoll warbler (Dendroica striata)

Insects, spiders, seeds and berries

In spruce trees

Magnolia warbler (Dendroica magnolia)

Insects and spiders The bird forages in trees, at low to medium elevations.

On tree branches

Yellow-rumped warbler (Dendroica coronata)

Insects and berries

In conifer trees, anywhere from 1.5 m to 15 m above the ground

Black-throated green warbler (Dendroica virens)

Insects and berries The bird forages in trees, at medium to high elevations.

High up in conifers

Cape May warbler (Dendroica tigrina)

Insects

In fir or spruce trees

Black-throated blue warbler (Dendroica caerulescens)

Insects, seeds and fruit

Low in conifer trees

Bay-breasted warbler (Dendroica castanea)

Insects on leaves

In conifer trees

Black-and-white warbler (Mniotilta varia)

Insects under bark

At the base of trees

American redstart (Setophaga ruticilla)

Insects often caught in flight

In the forks of small trees

A Population: Individuals of the Same Species A population is made up of all the individuals of the same species that share the same habitat at the same time. Several populations can live in a habitat. A forest, for example, can support a white-tailed deer population, a black bear population and a wolf population. It may also shelter various bird, reptile and insect populations, as well as many different plant populations. These populations are all connected to one another.

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234 The Living World

HISTORY

Evolution: Adapting to Change

SCIENCE

1. a) What is the difference between a habitat and an ecological niche? b) Describe your habitat and ecological niche. 2. Explain what a food chain is. 3. a) What is the role of producers? b) What is the role of consumers? c) What is the role of decomposers? 4. Indicate whether each of the following species is a producer, a consumer or a decomposer. a) a rose bush c) a fox e) a mushroom b) a mouse d) a moose f) a human being

Charles Robert Darwin was born in England on February 12, 1809. As a young boy, he enjoyed hunting, fishing and collecting insects, rocks and plants. In 1831, after graduating from university at the age of 22, Darwin was invited to serve as a naturalist aboard the HMS Beagle on a science expedition around the world. This five-year voyage was a great achievement for science. It was during his stay on the Galapagos Islands that Darwin began developing his theory of natural selection.

OF

Memory Check

Biologists believe that all living organisms originate from a primitive life form that appeared on the Earth about 4 billion years ago. Evolution is the sum of all transformations undergone by this primitive life form over time.

Natural Selection Natural selection is a theory developed by Charles Darwin to explain the evolution of species. According to this theory, individuals whose physical and behavioural characteristics are best adapted to their habitat have better chances of reproducing and passing on their characteristics to future generations. The following story is an example of natural selection. There is a small moth in England called the peppered moth. During the day, this insect sleeps on birch trunks. As illustrated in Figure 17, its light colour blends in with the birch so that it becomes almost invisible. This camouflage is very effective. It prevents birds from finding the peppered moth and eating it. Sometimes, however, a black peppered moth is born. Imagine one of these black peppered moths on the trunk of a birch tree! What a great deal for the birds! This peppered moth has very little chance of surviving and reproducing. Now imagine a heavily polluted city where the tree trunks have turned black from all the factory smoke. In this environment, it is the black peppered moth that would go unnoticed. The light-coloured peppered moths would be quickly devoured by the birds. Over time, almost all the peppered moths would be black, since they would be the only ones to survive and therefore reproduce. The light variation of peppered moth is therefore best adapted to living in the country, whereas the dark variation is best adapted to living near factories. Only individuals that are well adapted to their habitat can survive and reproduce. This is the principle of natural selection. Figure 17 Peppered moths

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Genetic Mutation Continuing with the example of the peppered moth, we can ask ourselves why black moths ever came into being. It was actually the result of a mutation in the gene responsible for wing colour. When a mutation occurs in the gametes, it can be transmitted to future generations. It then becomes part of the genetic heritage of the individuals who inherit it. Certain mutations go unnoticed, whereas others lead to beneficial or harmful changes. Individuals who carry a beneficial mutation have a better chance of survival and, consequently, a greater chance of transmitting their gene mutation to their descendants. In a way, the theory of gene mutation completes the theory of natural selection to explain the evolution of species.

Genes and Chromosomes: Vive la différence ! Observe your classmates. You notice that the boys and girls share all the physical characteristics of the human race. Unless they have a physical disability, all students have two arms and two legs. They have the ability to walk, talk, think and learn. Every person is also different. Their heights are different, as well as their hair and eye colour. Nucleus

Genes (can vary in size)

Chromosome

Cell

These similarities and differences are called genetic characteristics. They are transmitted by genes located in the chromosomes. Figure 18 shows that chromosomes are found in the nucleus of the cells of living organisms. The cell will be discussed further on page 277 of Section 3, “Life-Sustaining Processes.”

DNA double helix

The Blueprint of Life

Figure 18 A chromosome and the

genes that determine individual characteristics

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236 The Living World

Chromosomes contain all the genes required to produce an individual. They can be compared to balls of yarn that, when completely unrolled, measure about 2 m long. Genes are small segments with specific locations on the chromosomes. They determine the unique characteristics of a species. For example, a set of genes controls height and another controls fur and feather colour. If any living organism were described by listing its characteristics, there would be a set of genes for each characteristic.

Blue or Brown Eyes? Take the example of two human parents and their child. The child inherited genes from each parent. Suppose that the mother’s eyes are blue and the father’s are brown. If the child inherited the “blue-eye” gene from his mother and the “browneye” gene from his father, what colour will his eyes be? They will be brown, since the “brown-eye” gene is dominant over the “blue-eye” gene. Dominant genes are the ones that are expressed and visible. Can this child one day have a blue-eyed child? Yes, this is possible, since he will give his child one of his two genes: the brown or the blue. There is therefore one chance out of two that he will pass on the “blue-eye” gene. If the other parent also passes on the “blue-eye” gene, their child will have blue eyes (see Figure 19). Every individual receives two copies of each gene: one from the mother and the other from the father. If one of these genes is dominant, it is the one that is visible in the individual. The other gene, however, is still present (even though it is hidden), and has just as many chances of being passed on to the next generation.

BROWN blue

BROWN blue

BROWN BROWN

BROWN blue

blue BROWN

blue

blue

Figure 19 Even though the “brown-eye” gene is dominant, two brown-eyed

parents can still give birth to a blue-eyed child.

Memory Check 1. Which of these two statements applies to the theory of evolution? a) Species evolve because adults pass their knowledge on to their young. b) Species evolve because new characteristics appear in individuals and because natural selection promotes the reproduction and survival of the species best adapted to their environment. 2. Some peppered moths have a light colour and others a dark colour. How does this moth species benefit from this colour variation?

3. a) What is the difference between a chromosome and a gene? b) What part of the cell contains our chromosomes and genes? 4. Imagine that crossing a yellow-pea plant with a green-pea plant produced the following results: three-quarters of the young plants are yellow-pea plants and only a quarter are green-pea plants. What conclusions can you draw?

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S ECTION 2 Reproduction of Living Organisms Asexual and Sexual Reproduction p. 240

Reproduction in Plants

Asexual Reproduction p. 240

Reproduction in Flowering Plants

p. 244

Pollination and Fertilization

p. 244

Seed Development

p. 245

The Diversity of Life Forms

Seed Dispersal

p. 246

SECTION 2

Reproduction in Conifers

p. 247

Sexual Reproduction

SECTION 1

The Living World

Asexual Reproduction

Life-Sustaining Processes Reproduction in Animals

Reproduction in SporeProducing Plants p. 248 p. 250

p. 250

Sexual Reproduction

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p. 242

Reproduction of Living Organisms

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238 The Living World

p. 241

p. 250

Mating

p. 251

Fertilization

p. 252

Types of Fertilization

p. 252

External Fertilization

p. 253

Internal Fertilization

p. 254

Hermaphrodites

p. 256

Le système The Reproductive reproducteur System p. 258 p. 262

Puberty

p. 258

Male Reproductive Organs

p. 259

Female Reproductive Organs p. 260 The Menstrual Cycle p. 261

Pregnancy

Reproduction in Humans

p. 262

p. 257

Birth

The Stages of Human Development

p. 268

p. 269

Family Planning

p. 272

Sexually Transmitted Diseases

p. 274

Embryo and Placenta

p. 263

From Embryo to Fetus

p. 264

First Trimester

p. 265

Second Trimester

p. 266

Third Trimester

p. 266

Risks During Pregnancy

p. 267

Changes in Body Proportions

p. 269

The Early Years

p. 270

Adolescence and Puberty

p. 271

Aging

p. 271

Contraception

p. 272

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Reproduction of Living Organisms

239

Overview Life on Earth has now existed for 4 billion years. It is reproduction that has made the continuation of life possible over such a long period of time. In the first part of this section, you will discover that organisms can reproduce asexually or sexually. You will then learn about plant and animal reproduction. You will become familiar with the reproductive organs and the stages of development of various organisms. Next, you will learn more about human reproduction. You will explore pregnancy and the stages of human development. Humans are the only living organisms who have the ability to control certain aspects of their own reproduction. You will discover the various methods of birth control. There are also some health risks involved in having a sexual relationship. You will therefore also read about sexually transmitted diseases (STDs).

Asexual and Sexual Reproduction Reproduction ensures the survival of species. Although the life span of an individual is actually relatively short, successful reproduction can guarantee the existence and evolution of a species over millions of years. There are, however, many different forms of reproduction. In fact, each species reproduces using its own unique method. Some species reproduce by asexual reproduction and others by sexual reproduction. Asexual reproduction requires the involvement of only one living organism. It does not depend on the presence of male and female parts. This form of reproduction produces offspring that are identical to their parent. Parent and offspring therefore share the same genetic material, or physical and behavioural characteristics. The species can nevertheless continue to evolve by genetic mutation. Sexual reproduction requires the involvement of a male and a female parent. Although offspring share many similarities with their parents, they each possess a unique genetic makeup consisting of a combination of genes from both parents. Figure 20 A lilac tree can reproduce

both asexually (new shoots at its base) and sexually (flowers).

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Reproduction in Plants Plants can reproduce both sexually and asexually. The growth of several shoots at the base of a tree, such as a mature lilac, is an example of asexual reproduction. In the spring, this tree also grows many flowers that will produce seeds. This is an example of sexual reproduction. The lilac therefore uses both forms of reproduction (see Figure 20).

Asexual Reproduction Many plant species can reproduce from a part of their own organism, such as a root, a stem or even a leaf. Duckweed provides a good example of frond multiplication. These tiny plants (from 4 mm to 5 mm) float on the surface of ponds. Each duckweed plant produces a frond that matures and then detaches to form a new plant. Duckweed can cover the entire surface of a pond after only a few weeks (see Figure 21).

Figure 21 Duckweed multiplies by growing new fronds.

Figure 22 shows how a plant can use its stems for asexual reproduction. This is one form of reproduction of the wild strawberry. When its stems arch over and reach the ground, they begin to take root. New stems and new leaves eventually emerge to form a new strawberry plant that is identical to the first one.

Figure 22 Strawberry plants can use

their stems to reproduce.

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Figure 23 shows an example of plant reproduction using roots. The trembling aspen forest you see here is actually a single individual. The roots of this one tree produced shoots that grew into the thousands of trees in this forest. Figure 23 The trembling aspen

reproduces from its roots.

Sexual Reproduction There are three forms of sexual reproduction in the plant kingdom: reproduction by means of flowers, reproduction by means of cones and reproduction by means of spores. These forms of reproduction have been added to the classification of the plant kingdom in Figure 24. Conifers and flowering plants produce seeds, whereas ferns, algae and mosses produce spores. A seed contains everything it needs to produce a new plant. First, it carries a small immature plant called an embryo. It also consists of food reserves, the cotyledon, and a protective covering called the seed coat (see Figure 33 on page 245).

Living Organisms are divided into six kingdoms

Animals

Plants

Fungi

Protists

Bacteria

Archaeans

is divided into five classes

Algae

Mosses

Ferns

Conifers

• produce cones and naked seeds • also known as gymnosperms • produce spores

• produce spores

Figure 24 Forms of reproduction in the plant kingdom

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242 The Living World

• produce spores

Flowering Plants

• produce flowers and seeds protected by a fruit • also known as angiosperms

Conifers and flowering plants do not protect their seeds in the same way. They are therefore divided into two categories: gymnosperms and angiosperms (see Figures 25 to 28). A conifer is a gymnosperm, which means “naked seed,” since its seeds are protected only by a seed coat. A flowering plant is an angiosperm, meaning “enclosed seed.” Its seeds can be enclosed in a pod (e.g. beans), a shell (e.g. nuts), or pulp (e.g. apples).

Figure 25 Certain angiosperms, such as the

Figure 26 A pea pod is actually a fruit consisting of

sunflower, produce large flowers.

the ovary (peas) and flower (hull) that have reached maturity.

Figure 27 Gymnosperm seeds are well protected inside

Figure 28 Ferns do not need seeds to reproduce.

the cone. When they fall to the ground, however, the cone offers them little protection.

Instead, they reproduce by means of spores.

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Reproduction in Flowering Plants Over half of all known plant species belong to the angiosperm family. Some of these plants produce large flowers. Others, such as grasses and many tree species, produce tiny flowers. All of these flowers contain the reproductive organs of the plant (see Figure 29).

Stamen Male reproductive organ

Pistil Female reproductive organ Stigma Sticky surface of the pistil that captures pollen grains Style Long thin stalk that supports the stigma Ovary Swollen base of the pistil that contains female gametes (ovules) Ovules Female gametes

Anther Part of the stamen where pollen is produced and stored Pollen grains Cases that contain male gametes (spermatozoa) Filament Long thin stalk that supports the anther

Some flowers only have male reproductive organs (stamens), whereas others only have female reproductive organs (pistils). Flowers often have both male and female reproductive organs.

Figure 29 Reproductive system of

a typical angiosperm (flowering plant)

Pollination and Fertilization Pollen grains (see Figure 30) are produced by anthers. They must land on the stigma of the pistil in order to fertilize the flower so that it can produce seeds. This process is called pollination. Self-pollination occurs when pollen is transferred to the pistil of the same flower. For most angiosperms, however, pollen is carried to the pistil of a different flower: this is called cross-pollination. The wind and insects are the two key agents of cross-pollination (see Figure 31).

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244 The Living World

Figure 30 Pollen grains magnified

Figure 31 Pollen sticks to flower-visiting

300 times

insects. This is how pollen is transferred from one flower to another.

Pollination leads to fertilization. During fertilization, the male and female gametes combine. The male gamete is one of the spermatozoa in the pollen sac and the female gamete is one of the ovules in the ovary. Each gamete contains a single gene for each physical characteristic of the parent plant (see page 236). These two gametes fuse to form the first cell containing complete genetic material. This cell is called a zygote. Figure 32 illustrates the fertilization process of angiosperms. Stigma

Pollen grain Spermatozoon

Pollen tube

Style Ovule

Pollen tube

Ovary

2 A pollen tube develops on the style then enters the ovary and ovule.

1 Pollination occurs when

A spermatozoon fertilizes an ovule

3 Spermatozoa travel through

a pollen grain lands on the stigma.

the pollen tube to fertilize the ovule.

Figure 32 Fertilization process of flowering plants

Seed Development When the male gamete (or spermatozoon) enters the ovule, a zygote is formed. This is the first stage of seed development. This first cell divides many times to form more cells that eventually become specialized. Some play a role in embryo development. Some become food storage cells called cotyledons. Others form the protective envelope called the seed coat. Figure 33 shows all the parts of a seed. Seed coat (envelope) Future leaf Future stem

Embryo

Future root Cotyledons (food storage) Figure 33 The seed contains everything

it needs to become a plant.

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Seed Dispersal Fruit are the primary means of seed dispersal in flowering plants. Figures 34 to 37 illustrate different types of seed dispersal. The five main agents of seed dispersal are animals, water, wind, the plant itself (such as when plants “shoot” their seeds out of seed pods) and humans (such as by sowing seeds). It is important that the seeds be dispersed far from the parent plant. A seed that lands near the parent plant must compete with it for its share of light, nutrients and water. Seed dispersal provides the young plant with a greater chance of survival and, eventually, reproduction.

Figure 34 Birds eat small berries but cannot digest the

Figure 35 Burdock fruits hook onto the fur of mammals seeds. They therefore eliminate the whole seeds in their that then disperse the fruits and their seeds. droppings.

Figure 36 When milkweed pods burst open, they release Figure 37 Seeds that fall at the base of the parent plant

seeds with long, silky filaments. Even the slightest breeze can carry these seeds far away.

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246 The Living World

can be carried far away by waterways and heavy rainfall.

Reproduction in Conifers The life cycles of gymnosperms and angiosperms share many similarities. The gymnosperms, however, do not produce flowers. Most of these plants reproduce by means of cones. Male cones contain male gametes and female cones contain female gametes (see Figure 38). Seeds develop in the female cones once the ovules have been fertilized.

Figure 38 Leaves (or needles) and cones

a) The small male cones of the fir tree grow on the tips of its branches.

of a typical gymnosperm

b) The female cones of the pine tree point toward the ground. When they reach maturity, they open and release their seeds.

Some conifer species produce male and female cones on different trees; however, most species produce both types of cones on the same tree. Figure 39 illustrates the process of gymnosperm reproduction.

1 The adult plant produces male and female cones.

2 a)

3 Pollination: Carried by the wind,

Female cones produce ovaries on the top surface of their scales.

a pollen grain lands on an ovary where it produces a pollen tube

Female cone

Ovary Ovary Scale

Scale

Fertilized egg (zygote)

Pollen tube

b) Meanwhile, male cones produce pollen in sacs located on the lower surface of their scales.

Winged pollen grains Male cone

4 Fertilization:

Winged seed Adult plant

5 The female cone releases a winged seed that, under

A spermatozoon travels through the pollen tube to fertilize the ovule and produce a zygote.

favourable conditions, will eventually germinate and transform into a young plant. Figure 39 Reproduction in gymnosperms (conifers)

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Reproduction in Spore-Producing Plants Many plants that grow on the forest floor, such as mosses, ferns and liverworts, do not produce seeds. These plants reproduce by means of spores (see Figures 40 to 42). Spores are cells that contain complete genetic material. A spore can therefore transform into a young plant without fertilization. Male spores develop into plants that produce spermatozoa and female spores develop into plants that produce ovules. Figure 43 on the next page illustrates the sexual reproduction of spore-producing plants.

Figure 41 Liverworts are small, slow-growing plants that live in very damp

environments. They reproduce by means of spores.

Figure 40 Soft, thick green moss grows

in damp environments.

Figure 42 The fern is a spore-producing plant. Some ferns produce their spores in tiny

sacs called sporangia located on the underside of their fronds.

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248 The Living World

1 Spores are released into the air. 5 The zygote develops on the

Male and female spores

female plant. It will produce spores when it reaches maturity.

Male plant

Spermatozoa Zygote

4 Fertilization

Female plant

2 On moist ground, a spore Ovule

produces a zygote.

3 Once released, the spermatozoa swim in the film of water that covers the plant until they reach the ovary.

can develop into a plant that can produce spermatozoa (male gametes) or ovules (female gametes). The spore does not need to be fertilized.

Figure 43 Sexual reproduction of moss

Memory Check* 1. Explain this statement in your own words: “Reproduction ensures the survival of species.” 2. a) What is asexual reproduction? b) What is sexual reproduction? 3. Why do forms of reproduction differ from one plant species to another? 4. Name a plant species that can reproduce by: a) its leaves b) its stems c) its roots 5. Describe the cycle of sexual reproduction of: a) flowering plants b) conifers c) ferns, mosses and algae

6. a) What is the difference between a seed and a spore? b) What is the difference between a gamete and a zygote? 7. a) Why is it important for seeds and spores to be carried far from their parent plant? b) Name at least four agents of seed and spore dispersal. 8. What will happen if you plant pollen in the ground and water it regularly? Explain your answer. 9. The beech tree produces small green flowers. Which do you think is the main pollination agent of the beech tree: the wind or insects?

* Questions 5 through 9 help verify your knowledge of concepts introduced in the units in Textbook A.

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Reproduction in Animals Animal species are classified into two groups: vertebrates and invertebrates. A vertebrate has a backbone, whereas an invertebrate does not (see Figure 10 on pages 222 and 223). Invertebrates make up about 97 percent of all animal species. They reproduce either asexually or sexually. As for vertebrates, most of these species reproduce sexually.

Asexual Reproduction In asexual reproduction, a single living organism can produce one or many identical individuals. For example, sponges and hydras reproduce by budding (see Figure 44). Individuals produce buds that develop directly on the parent. When these individuals reach maturity, they may break off and become independent.

Figure 44 Budding:

a form of asexual reproduction

a) The buds of the sponge remain attached to the parent. This leads to the formation of sponge colonies.

b) Hydras are tiny organisms that live in the water. They reproduce by budding.

Sexual Reproduction Although vertebrates include a great diversity of species, most of these reproduce sexually. Male animals produce male gametes, or spermatozoa. Female animals produce female gametes, or ova. Spermatozoa and ova each contain half the genetic material of the future offspring. These are the steps of vertebrate reproduction: 1. A male gamete fuses with a female gamete. 2. This fusion produces an initial cell called a zygote that contains complete genetic material. 3. The zygote divides and transforms into an embryo consisting of many cells. 4. The embryo develops into a small animal. 5. When the animal becomes an adult, it will produce gametes and therefore also be capable of reproduction (see Figure 45 on the next page).

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250 The Living World

2 A spermatozoon enters the ovum and

1 The male and female glands

fertilization occurs.

of the parents produce gametes.

Ovum Spermatozoon Ovum

Spermatozoon

Zygote (fertilized ovum)

Growth and development (cell division)

Embryo

Growth and development

4 The embryo eventually becomes an adult capable of producing gametes.

3 The embryo develops through cell division.

Figure 45 Cycle of sexual reproduction in animals

To be successful, sexual reproduction must meet the following two conditions: 1. The male and female gametes must be in the same place at the same time. 2. The zygote must obtain the nutrients and protection it needs to survive. It must also get the warmth and moisture needed for its development.

Mating During mating, two individuals of an animal species unite to combine their gametes and achieve fertilization. Many animals have only one mating period each year. In this case, eggs usually hatch or young are born in environmental conditions that are ideal for their development. Québec mammals mostly mate in the fall. Embryos develop during the winter and the young are born the following spring, when the climate and food supply are most favourable for their growth. Birds mate in the spring and their young hatch a few weeks later.

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Fertilization Fertilization occurs when a spermatozoon and ovum of a single species combine (see Figure 46). Fertilization must take place in a moist environment since male and female gametes are very fragile cells that die if they dry out. Moisture also keeps the egg membrane more supple, which allows the spermatozoon to penetrate it more easily. Finally, spermatozoa can only move in a moist environment.

Figure 46 Spermatozoa meeting an

ovum as seen under a microscope (magnified 64X).

Types of Fertilization There are two main types of fertilization in animals. In external fertilization, the gametes combine outside the bodies of both parents. This method is common in aquatic animals, such as fish (see Figure 47). Most land animals reproduce by internal fertilization. Spermatozoa enter the female and migrate toward the ovum or ova.

a) Pacific salmon

b) Salmon eggs Figure 47 The female Pacific salmon lays her eggs on the bottom of the river. The male

then fertilizes the eggs by releasing milt (semen containing spermatozoa) over them. Very young fish, called fry, later emerge from the eggs.

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External Fertilization Most aquatic animals reproduce by external fertilization. Some species of sea anemones are examples of animals that use this type of fertilization.

Figure 48 Certain species of anemones

Adult anemones do not move around to find a mate (see Figure 48). Some species of anemones still reproduce sexually, however, by releasing their gametes directly into the water. Spermatozoa and ova are then brought together by sea currents. The resulting zygotes transform into larvae that can swim and find their own food. The larvae sometimes travel great distances before settling on the ocean floor and developing into adults. Figure 49 illustrates the reproductive cycle of the sea anemone.

belonging to the same colony all release their eggs and semen at the same time. This increases the probability that their gametes will combine. This reaction is generally caused by an environmental trigger, such as a full moon.

Larva

Chance, however, does not always play such a major role in fertilization. For example, female fish usually lay a cluster of eggs. The male then releases his milt directly onto the eggs. This form of external fertilization is known as spawning.

In certain animals, such as amphibians and insects, the stage of development prior to becoming an adult.

3 A ball of cells undergoing

A zygote

cell division

4 A larva capable of swimming

2 A spermatozoon penetrates an ovum

5 An attached organism

1 The male and female gametes are released

Adults

6 An organism capable of catching and eating prey Figure 49 The reproductive cycle of sea anemones consists of several stages.

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Tadpoles use their tails to swim.

Young frogs have well-developed legs.

An adult frog

Frogs use another type of external fertilization. During mating, the male clasps onto the female. As soon as the female has laid her eggs, the male releases his semen over them. The young anemones, fish and frogs that emerge from the eggs do not look much like their parents. They must undergo several stages of development before maturing into adults capable of reproduction. Anemones and fish spend their entire adult lives in the water. Frogs, however, live both on land and in the water. They are amphibians. Figure 50 illustrates the stages of development of the frog.

Fertilized eggs

Figure 50 Stages of development of

the frog

Internal Fertilization Most species of land animals reproduce by internal fertilization. For example, all reptiles, such as the snake and turtle, reproduce by internal fertilization. Males and females usually have an opening called the cloaca through which semen, urine and feces can be released. During mating, the male and female join their cloacas. The male releases semen into the female’s cloaca. The spermatozoa then travel up a canal to reach the ova (see Figure 51).

Digestive and urinary organs Reproductive organs Figure 51 The cloaca of a reptile.

This opening is used to excrete waste (urine and feces). The male also releases semen through his cloaca into the female’s cloaca. ENCYCLOPEDIA

254 The Living World

Cloaca

Shell membrane Shell Egg white (albumen) Carbon dioxide Oxygen Air cell Yolk membrane (vitelline membrane) Embryo Yolk

The majority of reptiles, birds and amphibians and most fish and insects are oviparous, meaning they lay eggs. Bathed in a liquid environment inside the shell, the zygote transforms into an embryo. The egg contains all the necessary nutrients for the development of the embryo (see Figure 52). When its development is complete, the young animal hatches from its shell (see Figure 53).

Figure 53 Young reptiles are

miniature replicas of their parents. As soon as they emerge from their shells, they are able to find their own food and defend themselves against predators.

Like reptiles, birds also have cloacas through which gametes can combine. Birds care for their young, however, which makes them different from most reptiles, amphibians and fish. Male mammals have penises. The male uses this organ to deposit semen inside the female. Except for the duck-billed platypus and spiny anteater, female mammals do not lay eggs. All other mammals are viviparous, meaning that the fertilized ovum completely develops inside the mother’s body. This is where the zygote obtains the nutrients it needs to transform into an embryo and continue its development. In this form of reproduction, the future offspring develops more completely before birth. It is well protected inside its mother’s body. Having given birth to her young, the female produces milk to feed them (see Figure 54 on the next page). You will learn more about the reproduction of mammals when studying human reproduction on page 257.

Figure 52 The inside of a

reptile egg

NEWS FLASH… We can now produce a living organism without the involvement of male and female gametes. This method of reproduction is called cloning. In 1997, a sheep named Dolly became the first cloned mammal. She was created from a cell taken from an adult sheep. Since this cell was not a gamete, it did not have to combine with another gamete in order to develop. Dolly is therefore an exact replica of the donor parent instead of a unique organism that, like other mammals, carries the traits of both its father and its mother. On March 8, 2005, the General Assembly of the United Nations declared a ban on human cloning.

Finally, there are also ovoviviparous animals, such as certain species of snakes. Ovoviviparous females keep their eggs inside their bodies until they hatch. The incubation period therefore occurs inside the female’s body, and the young are then born live.

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Figure 54 The reproductive cycle

of mammals and birds requires that one or both parents expend large amounts of energy. This is why they give birth to fewer young at a time than most other animals.

Hermaphrodites Several species are known as hermaphrodites. Each of these animals is equipped with both male and female reproductive organs. These living organisms reproduce by a particular type of internal fertilization. Worms and snails are examples of hermaphrodites. When two worms mate (see Figure 55), they each inject their semen into the genital opening of the other. Each worm then lays fertilized eggs. Two individuals can therefore produce eggs after only one act of mating.

Figure 55 Hermaphrodites produce

both male and female gametes, but must exchange semen in order to reproduce.

Memory Check* 1. Explain how certain animals can reproduce asexually. Give one example. 2. Why must the spermatozoa and ova combine in a moist environment? 3. What is the difference between: a) mating and fertilization? b) internal fertilization and external fertilization? c) a cloaca and a penis? 4. During a full moon, the entire population of a colony of sea anemones release their spermatozoa and eggs at the same time. Why do they do this? 5. Turtles lay hundreds of eggs at a time. Birds usually lay fewer than 10. How can you explain this difference? 6. Describe the fertilization process of hermaphrodites. * Questions 3 through 6 help verify your knowledge of concepts introduced in the units in Textbook A.

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Reproduction in Humans From elephants to humans, all mammals begin their life as a tiny fertilized egg. This new life develops within a few weeks or months. It transforms into the collection of tissues and organs that make up a baby elephant or a baby human. These two babies may be quite different, yet they go through similar stages of development. In this part of Section 2, you will discover how a women’s body changes during pregnancy. A woman must protect the new life growing inside her body and also help it grow. You will learn how people practise family planning using different methods of contraception. You will also learn how individuals can protect themselves from sexually transmitted diseases (STDs).

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The Reproductive System The human reproductive system is similar to that of sexually reproducing plants and animals. It produces and combines male and female gametes in order to reproduce. As in other mammals, reproduction occurs by internal fertilization. It all begins with sex hormones. Like messengers, these hormones travel through the bloodstream and tell the testicles (in boys) and ovaries (in girls) when to begin producing gametes.

Puberty The majority of girls and boys start to feel the effects of sex hormones at the beginning of or during adolescence. This period, called puberty, begins when hormones cause changes in their bodies. These changes are designed to prepare them for reproduction. Pituitary gland A gland located at the base of the brain. In humans, it is about the size of a pea.

At puberty, the pituitary gland starts to release sex hormones (see Figure 56). In males, the main hormone is testosterone. In females, the two main hormones are progesterone and estrogen. These hormones travel in the bloodstream until they reach the testicles or ovaries. They send a signal to the testicles to produce spermatozoa and a signal to the ovaries to produce ova. During each menstrual cycle, an ovum develops and is released by the ovaries. Puberty also leads to other physical changes. For example, pubic hair and other body hair begins to grow. Girls start developing breasts. As for boys, changes to the larynx cause their voices to become deeper.

Pituitary gland (triggers the production of sex hormones)

Larynx

Ovary (produces progesterone and estrogen)

Figure 56 The pituitary gland regulates

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258 The Living World

Testicle (produces testosterone)

Male Reproductive Organs The male reproductive organs produce a very large number of spermatozoa. Figure 57 illustrates the anatomy of the male reproductive organs. Table 10 describes the role of each organ. Bladder Epididymis Vas deferens

Seminal vesicles Prostate gland Cowper’s gland

Testicle

Penis

Epididymis Urethra

Testicle

Seminiferous tubules

Scrotum

a) Cross-section of the male reproductive organs

b) The inside of a testicle

Figure 57 Male reproductive organs

Table 10 The male reproductive organs and their roles in the production of spermatozoa

Reproductive organ

Purpose

Scrotum

Pouch that contains the testicles. It holds the testicles away from the body. In order to produce gametes, testicles must actually be kept at a temperature slightly lower than body temperature.

Testicles

They contain the seminiferous tubules.

Seminiferous tubules

They produce an average of 400 million male gametes a day.

Epididymis

The spermatozoa produced are stored in this small, elongated organ lying above the testicles.

Vas deferens

The spermatozoa enter the vas deferens before being released outside the body during ejaculation.

Prostate and seminal vesicles

They produce semen, the fluid that contains spermatozoa. Semen helps the spermatozoa move and is rich in sugar. It provides male gametes with the energy for swimming after they are released into a woman’s vagina during ejaculation.

Urethra

The semen flows through this tube during male ejaculation. The urethra also carries urine from the bladder outside the body.

Cowper’s gland

Cowper’s gland releases a fluid into the urethra, which neutralizes the acidity caused by any remaining traces of urine that could threaten the survival of spermatozoa.

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Female Reproductive Organs The female reproductive organs are designed to produce female gametes called ova. Figure 58 illustrates the anatomy of the female reproductive organs. Table 11 describes the role of each organ.

Ovary Fallopian tube

Uterus Cervix

Bladder Urethra

Vagina

a) Side view

Fallopian tube Follicle Ovary Uterus Cervix Vagina Figure 58 Cross-section of the female

reproductive organs, front view (a) and side view (b)

b) Front view

Table 11 The female reproductive organs and their roles in ova production.

Reproductive organ

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Purpose

Ovaries

A woman has two ovaries. They take turns releasing one ovum about every 28 days: this is called ovulation.

Follicles

They are located in the ovaries. Each follicle contains a single ovum, and brings it to full maturity.

Fallopian tubes

The ovum released by the follicle travels through the fallopian tubes to reach the uterus. An ovum survives between 24 and 48 hours in the fallopian tubes, where it can be fertilized.

Uterus

A hollow, pear-shaped organ. A zygote develops in the uterus if the ovum is fertilized by a spermatozoon.

Vagina

The passage into which the penis penetrates to release its sperm. The baby also leaves the uterus through the vagina during birth.

The menstrual cycle causes changes to the female reproductive organs. This cycle lasts about 28 days. One ovum reaches maturity during every cycle. The body then reacts as though the ovum was about to be fertilized and an embryo about to develop. Among these changes, the lining of the uterus thickens to help the zygote implant in the uterus and begin its development.

Temperature (in °C)

The Menstrual Cycle 37.3

36.7

1

3

5

7

Figure 59 illustrates how a women’s body temperature Menstruation changes in relation to her menstrual cycle. This figure shows that a woman’s body temperature increases during ovulation. If the ovum is not fertilized after a few days, it is expelled from the body along with the cells that lined the uterus. This process is called a woman’s period, or menstruation (see Figure 60).

Menstruation

Possibility of fertilization

Ovulation: optimum time for fertilization

9

11 13 15 17 19 21 23 25 27 1

Ovulation

3

5

7

Menstruation

Day of cycle Figure 59 Relationship

between body temperature and menstrual cycle

Possibility of fertilization

The unfertilized ovum dies

Ovulation

Variation in thickness of uterine lining Shedding of endometrium and unfertilized ovum Day

1

2

3

4

Follicle development: the lining of the uterus starts to thicken 5

6

7

8

9

Ovulation

The lining of the uterus continues to thicken

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Figure 60 Menstrual cycle

Memory Check 1. a) What is the role of sex hormones? b) Name at least two sex hormones. 2. Describe the changes to the bodies of girls and boys during puberty. 3. a) Describe the life of a spermatozoon from its birth in a testicle to its death in a fallopian tube.

b) Describe the life of an unfertilized ovum, from birth to death. 4. Why does the lining of the uterus thicken during the menstrual cycle?

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Pregnancy When male gametes are deposited into a woman’s vagina, they swim first toward the uterus, then the fallopian tubes. Of the several million spermatozoa released, only a few thousand will reach the ovum (see Figure 61). Only one of these will succeed in fertilizing the ovum.

Figure 61 This photo shows the size of a spermatozoon compared

to that of an ovum. The mature ovum is the largest cell in the human body (magnified about 64).

3 Cell division Nucleus of a spermatozoon Four-cell zygote

Two-cell zygote Nucleus of the ovum

Eight-cell zygote Layer of external cells Embryoblast

2 Fertilization Fallopian tube

Uterus

4 Implantation in

Ovary

the uterus

1 Ovulation

Figure 62 Human development

from ovum to embryoblast

You have seen what happens to a woman’s uterus when the ovum is not fertilized. Now what happens when the ovum is fertilized, that is, when a spermatozoon unites with the ovum to form a zygote? After fertilization, the zygote moves from the fallopian tube to the uterus (see Figure 62). As it travels down the fallopian tube, the zygote undergoes a series of cell divisions. When it reaches the uterus, the zygote has already become a clump of about 16 cells. By the time it begins to implant in the uterus, the zygote has taken the shape of a fluid-filled ball. It contains a group of cells called the embryoblast. The external cells of the zygote will form the placenta, which we will discuss later. The embryoblast will become the embryo.

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Embryo and Placenta Two important tissues are formed between the tenth and fourteenth days of development (see Figure 63). The first tissue, called the amnion, develops into the amniotic sac, containing the embryo and amniotic fluid. This fluid protects the embryo from shock. The second tissue gives rise to the placenta. This organ carries nutrients and oxygen from the mother to the fetus through the umbilical cord. The umbilical cord is also used by the fetus to expel its waste products.

Umbilical cord

Placenta

Uterine wall

Embryo

Amniotic sac Figure 63 The top part of the photo represents the placenta. The embryo is in the

amniotic sac. The umbilical cord can be seen between the embryo and the placenta.

During initial cell division, embryonic cells are almost all identical. During the second week, however, these cells begin to differentiate. They form the gastrula, which consists of three layers or sheets: the ectoderm, mesoderm and endoderm. This change is shown in Figure 64. Amniotic cavity The cells of the ectoderm will form the skin and nervous system. The cells of the mesoderm will form the kidneys, skeleton, muscles, blood vessels and glands. The cells of the endoderm will form the lungs and the walls of the digestive system. Vitelline sac Uterine wall

Development of the three embryonic layers at the gastrula stage. Each layer will form different tissues.

Figure 64

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From Embryo to Fetus The three layers of the gastrula form the different parts of the body. This process is called cell differentiation, which means that certain cells specialize to perform the functions of various body tissues and organs. For example, the heart begins to beat at around three weeks even though there is not yet any blood for it to pump! By the end of the fourth week, the embryo has grown to 500 times its initial size. Known as gestation, the period of development before birth lasts 38 to 40 weeks. Gestation can be divided into three trimesters, as shown in Figure 65. Each trimester lasts about three months, or 13 weeks. Several major changes occur during each of these trimesters.

First trimester (week 1 to week 13)

a) During the first trimester, the embryo takes on a recognizable human shape. The placenta develops.

Second trimester (week 14 to week 26)

b) During the second trimester, the fetus goes through a period of growth and maturation.

Figure 65 Development of the embryo and fetus during pregnancy

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Third trimester (week 27 to week 40)

c) During the third trimester, the fetus takes up all the space in the uterine cavity.

First Trimester : Week 1 to Week 13 Table 12 describes the key aspects of the unborn baby’s development during the first trimester. For the first eight weeks, the baby is referred to as an “embryo.” From the end of the eighth week onward, it is called a “fetus.” Table 12 Development of the embryo and fetus during the first trimester

Embryo or fetus

Key aspects It measures 1 cm long.

Week 4

The brain, heart, limbs (legs and arms), eyes and spinal column begin to form.

An embryo at 28 days It measures 3 cm long. The embryo is now called a “fetus.” The first bone cells are produced.

Week 8

The fetus has legs and arms, but no fingers or toes yet.

A fetus at eight weeks It measures 8 to 10 cm long. The main organs begin to sprout: liver, stomach, brain and heart.

Week 12

The sex of the fetus can be determined. The fetus can now move.

A fetus at 12 weeks

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Second Trimester : Week 14 to Week 26 Figure 66 shows the fetus during the second trimester. At week 24, the fetus measures about 30 cm long. The mother can now begin to feel her baby moving, especially its legs (see Table 13).

Figure 66

A fetus at 24 weeks

Key aspects

Table 13 The key aspects of fetal development during the second trimester

Week 16

Week 20

Week 24

The fetus measures about 16 cm long. The skeleton begins to form. Fingers and toes become differentiated and nails start to grow. Genital organs are formed. The brain develops quickly. The nervous system begins to work. Most organs are present, although not fully developed.

The fetus measures 25 to 30 cm long. Hair has begun to grow on its head. The buds of permanent teeth appear beneath the milk teeth. It begins to hear sounds from outside the womb. It can suck its thumb. The fetus begins to use its digestive system by swallowing a little amniotic fluid.

The fetus measures 27 to 35 cm long. Although its lungs have just been formed, the fetus still cannot breathe on its own. It develops fingerprints. The fetus jumps when it hears a sudden noise.

Third Trimester : Week 27 to Week 40 Figure 67 shows a fetus in the last few months of development. The fetus develops rapidly during this period. The rapid growth of the fetus, and especially of its brain, requires a large quantity of nutrients. It is therefore crucial for the mother to eat a healthy diet. In the ninth month, the fetus usually settles into a head-down position in the uterus. The mother feels its movements becoming more frequent and vigorous (see Table 14).

Table 14 The key aspects of fetal development during the third trimester

Figure 67

A fetus at 32 weeks

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Key aspects

Week 28 The fetus measures about 38 cm long The immune system develops. This allows the fetus to fight off harmful viruses and bacteria. Bones begin to harden. The fetus can open its eyes.

Week 32 It measures about 42 cm long and grows about 1 cm a week. The lungs and brain continue to develop. The fetus is beginning to run out of room in the uterus. It settles into a head-down position in preparation for birth.

Week 36 The fetus measures about 50 cm long. It can distinguish between light and dark. It recognizes its mother ’s voice. Its nails and hair continue to grow. It often gets the hiccups.

Risks During Pregnancy During its development, the fetus gets all the nutrients and oxygen it needs from its mother’s blood. This blood flows through the placenta and then the umbilical cord. Hazardous substances can therefore also reach the fetus. Everything that the mother eats, drinks or breathes can end up in the blood of the fetus. The first trimester is a critical stage of embryonic development. The risk of fetal malformation is greatest during this period (see Figure 68). 3 weeks

4 weeks

5 weeks

6 weeks

7 weeks

8 weeks

9 weeks

10 weeks

20–26 weeks

38 weeks

Central nervous system Heart Arms Eyes Legs Teeth Palate External sex organs Ears Risk of major malformations

Risk of minor malformations Figure 68 The critical stages

Certain substances, such as cigarette smoke, alcohol and drugs, interfere with the normal development of the fetus. These substances can even cause permanent damage.

of embryonic and fetal development. The stages in red indicate when organs are most vulnerable to external factors.

Cigarette smoke can prevent the fetus from getting enough oxygen. This can affect its growth and organ development. Alcohol can impair the function of the brain and nervous system of the fetus, as well as its physical development. In fact, alcohol stays longer in the blood of the fetus than in that of the mother. Traces of hazardous substances, such as certain medications, have been found in fetal blood. These substances can cause physical defects or mental illness.

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Birth Pregnancy ends 38 to 40 weeks after fertilization of the ovum by a spermatozoon. A new being is then ready to make its way into the world. The birth signal (or the signal to expel the fetus) is sent by the pituitary gland. During puberty, this gland secreted hormones to trigger the production of male and female gametes. During birth, it produces another hormone called oxytocin that stimulates contractions of the uterus. This is the start of labour (see Figure 69). Uterus Umbilical cord

Separation of the placenta

Vagina Cervix

Umbilical cord

3 Delivery of the placenta. The

1 Dilatation. Uterine contractions and oxytocin cause the cervix to open and dilate. During this stage, the amniotic membranes rupture and the amniotic fluid leaks through the vagina. This stage usually lasts from 2 to 20 hours.

placenta and umbilical cord are expelled from the uterus. This usually occurs 10 to 15 minutes after birth.

2 Expulsion. Uterine contractions become very strong. The baby moves through the cervix and into the vagina. This stage lasts from 30 minutes to 2 hours. As the baby starts to move into the vagina, its head rotates to help its body pass more easily.

Figure 69 The three main stages of labour

Memory Check 1. Tell the story of a spermatozoon that fertilizes an ovum. Continue your narrative up to the moment when the embryo is implanted in the uterus. 2. Create a three-dimensional model of the gastrula. You could, for example, choose to make your model out of modelling clay. 3. What is the role of the: a) amniotic fluid? b) placenta? c) umbilical cord?

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4. At what point during pregnancy does the embryo become a fetus? 5. Make a diagram that summarizes the key changes during each of the three trimesters of pregnancy. 6. What special precautions must a woman take during pregnancy to prevent damage to the developing fetus? 7. What hormone triggers labour? 8. Describe the stages of labour.

The Stages of Human Development After birth, humans go through early childhood, childhood and adolescence, before finally reaching adulthood. These are the stages of human development. Each of these stages involves significant changes to a person’s body and behaviour. Early childhood and childhood are characterized by rapid growth. This growth slows down during adolescence and stops completely at adulthood. The body then begins to age and its capacities to diminish. Finally, death occurs when there is a loss of one or more vital body functions.

Changes in Body Proportions Different body parts grow at different rates. Figure 70 clearly illustrates the changes in body proportions using images of children and young adults. These images were enlarged until every person seemed to be the same size. For example, compare the size of each head. You will notice that the head makes up 2/8 of a baby’s body, whereas it only makes up 1/8 of the body in young adults.

2 months

2 years

4 years

7 years

12 years

20 years

55 cm

86 cm

110 cm

120 cm

145 cm

175 cm

Figure 70 Changes in body proportions from childhood to young adulthood

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The Early Years Humans develop quickly during the two first years of life. At six weeks, babies are completely dependent on their parents for food, shelter and mobility. Before the age of two, however, children can eat by themselves, walk and talk. These stages of learning are described in Figure 71.

6 weeks Other than at mealtimes, babies sleep most of the time. They cry to express hunger, discomfort or distress. They can follow people with their eyes and listen to them speak.

Figure 71 Physical and behavioural development in the early years

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6 months

88 months months

10 months

Babies can sit as long as their head and back are supported. They can hold objects. They babble and make high-pitched screams.

Babies can sit on their own and try to crawl. They can stand while supported. They recognize voices and can imitate simple sounds.

Babies can crawl quickly and use their hands to pull themselves up. They can point to things and grab small objects. They say their first words, which are usually “mama” and “dada.”

14 months

2 years

4 years

Children can stand and walk on their own. They know several words and try to make themselves understood.

Children can run and jump. They can turn the pages of a book, identify familiar pictures and objects and say short sentences.

Children have a good sense of balance and can stand on one foot. They can draw simple shapes and write several letters.

Adolescence and Puberty Adolescence marks the passage from childhood to adulthood. It is a time of physical and psychological change. The body grows and transforms during puberty. The pituitary gland secretes certain sex hormones that give boys and girls the ability to reproduce. Figure 72 shows the physical changes that occur in adolescence.

a) In girls, puberty usually begins between the ages of 10 and 14. Body curves appear, breasts develop and menstruation begins.

b) In boys, puberty usually begins between the ages of 12 and 16. They show an increase in muscle mass, their testicles begin to produce spermatozoa and their voices deepen.

Figure 72 Physical changes during puberty

Aging Aging is a normal part of the life cycle. It is a time when various body functions begin to slow down. Organs such as the heart, stomach, intestines and liver weaken. The body dies when vital organs stop working. The signs of aging are usually more noticeable after the age of 40. The body becomes less mobile and grey hairs and wrinkles begin to appear. Bones also become more brittle. Although the process of physical aging is inevitable, certain factors can help slow it down. Regular exercise and a healthy diet are two factors that can help delay the effects of aging.

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Family Planning The reproduction of most living organisms is triggered by external factors. Take Québec plant species, for example. As the hours of sunlight increase, their reproductive organs begin to develop and produce gametes. Animals also produce gametes as a result of a change in climatic conditions. Other factors that trigger animal reproduction are the quantity and quality of food available.

NEWS FLASH… Overpopulation causes serious problems in many countries. Although birth control seems to be a possible solution, the lack of information and inaccessibility of birth control methods are two major challenges that must still be overcome. Québec is faced with the opposite phenomenon: a declining birth rate. In fact, the average birth rate in Québec is about 1.5 children for each woman, whereas an established average of 2.1 children for each woman is needed to maintain a stable population. In this context, immigration helps compensate for the low birth rate.

In humans, however, gamete production is not influenced by environmental factors. In women, one ovum reaches maturity every month regardless of the season. A young girl can therefore become pregnant after her first menstruation. As for men, they produce spermatozoa every day of the year.

Contraception Contraception causes temporary or permanent sterility in men and women. Certain methods of contraception prevent fertilization, or the union of a spermatozoon with an ovum. Others prevent the zygote from implanting in the uterus. Table 15 describes different contraceptive methods and devices.

Table 15 Contraceptive methods and devices

Billings method This is a method of natural birth control. A substance called cervical mucus forms on the cervix before ovulation. This clear fluid has the texture of an egg white. Women must watch for the presence of cervical mucus to know when their ovulation begins. This is the period when women are fertile. They must therefore use one or more methods of contraception or abstain from having sexual intercourse during this period. They must start using these methods five days before ovulation and continue to use them until five days after ovulation has ended. This is because spermatozoa can survive several days in the uterus or fallopian tubes.

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Basal body temperature method

Female condom

This natural method is based on the fact that there is a slight increase in body temperature during ovulation. Women can therefore determine the date of their ovulation by taking their temperature. This method is most effective for women who know their cycle well and for whom the cycle is very regular.

The female condom is a method of contraception that helps prevent fertilization. It consists of a sheath that women insert in their vaginas to prevent sperm from reaching the uterus.

Table 15 Contraceptive methods and devices (cont.)

Male condom

Diaphragm

Spermicides

Intrauterine device (IUD)

The male condom works the same way as the female condom, except that the sheath is used by the man to cover his penis. Use of flexible condoms is the only way of preventing sexually transmitted diseases (STDs)

The diaphragm is a method of contraception used to prevent spermatozoa from reaching the ovum. This membrane is inserted into the vagina over the cervix and can stay in the vagina for 24 hours. It can then be cleaned and used again.

A spermicide is a chemical substance that kills spermatozoa. Used together with a diaphragm or condom, this method is effective for preventing fertilization.

The IUD is a small device that is inserted into the uterus by a healthcare provider. Although some of the spermatozoa may still reach the ovum, the IUD prevents the zygote from implanting in the uterus. This method is generally recommended for women who have already had children since it is more likely to cause infections in women who have never been pregnant.

Oral contraceptive

Birth control patch Contraceptive injection

Tubal ligation

Vasectomy

This surgical procedure consists of tying off the fallopian tubes to prevent fertilization but not ovulation. As a result, the ova produced are prevented from following their natural path in the fallopian tubes. The spermatozoa therefore cannot reach them. This procedure is usually irreversible.

This surgical procedure for men involves cutting the vas deferens of each testicle to prevent spermatozoa from reaching the urethra. Men who undergo this procedure can still ejaculate, but their semen does not contain any spermatozoa. This procedure is usually irreversible.

The birth control pill is a chemical method of contraception. It contains female hormones that prevent ovulation and therefore the production of ova. Women must take one pill every day.

The birth control patch is a chemical method of contraception. It contains two female hormones that prevent the ovaries from releasing ova. A new patch must be applied every week. The contraceptive injection is a chemical method of contraception. The injection contains a female hormone that prevents ovulation. Women are given one injection every three months.

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Sexually Transmitted Diseases Sexual activity can carry certain health risks. AIDS is one example of a sexually transmitted disease (STD) that can lead to death. Although not all STDs are quite that serious, they are all harmful to one s health. Since it can take a long time for an infected person to begin experiencing symptoms, these diseases are sometimes referred to as STIs (sexually transmitted infections).

STDs can: • cause sterility in men and women, in other words, prevent them from having children • cause damage to the nervous system or the cardiovascular system, if left untreated • be especially dangerous for pregnant women, since they can put the health of their baby at risk • be extremely contagious. They are easily and quickly transmitted between individuals during sexual intercourse

Health authorities emphasize the need for both young and older members of the population to use effective protection against STDs. This protection is even more crucial since many people with STDs do not show any symptoms. Condoms usually provide effective and useful protection against STDs. They act as a barrier against bacteria and viruses during sexual relations. Table 16 describes the most common STDs, their symptoms, methods of prevention and treatments. Table 16 Most common STDs

STD

Symptoms

Methods of prevention and treatment

Bacterial infections Syphilis

First stage Painless sores appear in the vagina or on the penis 9 to 90 days after infection. Second stage This stage lasts from six weeks to six months. Flu-like symptoms may appear. Skin rashes appear and disappear. Third stage Years later, if left untreated, syphilis may cause cardiac problems, blindness, damage to the nervous system and, eventually, death. It can cause sterility in women.

Prevention: Condom use Treatment: Antiobiotics are very effective.

Gonorrhea

The following symptoms appear three to five days after infection: • abnormal vaginal discharge • burning sensation when urinating • painful intercourse • thick, yellowish discharge from the penis • painful or swollen testicles

Prevention: Condom use Treatment: Antiobiotics are very effective.

Chlamydia

Symptoms appear one to three weeks after infection. Apart from a whitish discharge, the symptoms are the same as in gonorrhea. They also include itchiness inside the penis.

Prevention: Condom use Treatment: Antiobiotics are very effective.

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274 The Living World

Table 16 Most common STDs (cont.)

STD

Methods of prevention and treatment

Symptoms Viral infections

Hepatitis B

This is a virus that attacks the liver and is transmitted through saliva, semen or blood. The following symptoms appear two to six months after infection: • loss of appetite • nausea • vomiting • jaundice (yellowing of the eyes and skin) • headaches • dark urine (tea-coloured) • pale feces

Prevention: Condom use. This is the only STD that can be prevented by a vaccine. Treatment: Rest, and a healthy diet that does not include alcohol. Treatment is complex and can require antiviral medication.

AIDS (acquired immunodeficiency syndrome)

This disease attacks the immune system and renders it ineffective. (A healthy immune system protects the body from infectious bacteria and viruses.) The virus is transmitted through blood or fluids from the vagina or penis. It can be detected about 12 weeks after infection. A person can carry the disease for several years before experiencing any symptoms.

Prevention: Condom use Treatment: There is no treatment that can destroy the AIDS virus. It is, however, possible to slow the progression of the disease by taking several medications.

Condyloma

Symptoms appear two to eight weeks after infection. Condylomata are painless warts with a cauliflower-like appearance that develop in moist areas, such as the penis, vagina, cervix and mouth.

Prevention: Condom use Treatment: Since this is a viral infection, the virus stays in the body. The warts can be treated by applying a cream or having them removed by a physician.

Genital herpes

Symptoms appear several days to one week after infection. These consist of a tingling sensation on or around the genital area. Small blisters then appear which eventually burst and develop into painful ulcers.

Prevention: Proper bodily hygiene and condom use Treatment: Always keep infected areas dry and clean. Since this is a viral infection, the symptoms can disappear and reappear.

Memory Check 1. What are the stages of human development? 2. Why are contraception methods used? Give at least two reasons. 3. Name a method of contraception for each of the following effects: a) helps prevent STDs b) prevents the zygote from implanting in the uterus c) prevents fertilization d) prevents ovulation e) leads to permanent sterility 4. What health risks are associated with STDs? 5. What is the most effective method of preventing STDs?

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275

S ECTION 3 Life-Sustaining Processes SECTION 1

The Living World

The Diversity of Life Forms

Characteristics of Living Organisms p. 277

SECTION 2

The Cell

p. 277

Reproduction of Living Organisms

Plant and Animal Cells How Do Cells Work?

Inputs and Outputs

p. 280

Exchanges Between the Cell and Its Environment

p. 280

Diffusion

p. 281

Osmosis

p. 282

p. 278

p. 280

SECTION 3 Life-Sustaining Processes Photosynthesis Two Vital Functions of the Cell p. 284

p. 284 Cellular Respiration

p. 285

Overview What do a whale and a unicellular organism in a pond have in common? Their cells! In a single spoonful of pond water, countless living things are found. Many of them are formed of a single cell, like the amoeba, which has been magnified 64 times in the photograph on this page. The enormous body of the whale is also formed of cells—trillions of them. Since the invention of the microscope, scientists have been able to study the details of the structure of living organisms. According to their observations, the cell is the smallest self-sustaining component of all living organisms. Scientists have theorized that every living organism is made of cells. By studying cells and their functions, you can better understand what makes all life forms possible. In fact, the presence of cells is one of the characteristics of a living organism. In this section, you will discover the characteristics of living organisms. You will delve into the heart of life to observe cells and their functioning. Each cell is a small system. Substances enter the cell (inputs) and exit it (outputs). These exchanges are carried out by several processes, including osmosis and diffusion. The cells accomplish vital functions for themselves and the living organisms they are part of. At the end of the section, you will see two of these functions: photosynthesis and cellular respiration.

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276 The Living World

Characteristics of Living Organisms

The Cell The cell is like a tiny city made up of different parts. Each part plays a role in the functioning of the whole. Cells do not all have the same size, shape or function. In an animal’s body, for instance, the cells of the brain and those of the skin and eyes are very different. Figure 73 shows some examples of these differences. Regardless of their functions, though, most cells are made of the same elements, and these elements have the same roles.

Louis Pasteur (1822–1895) contributed to our understanding of micro-organisms. In 1879, Pasteur injected into chickens cholera microbes that had been considerably weakened. He then observed that the chickens were immunized against the disease. In 1885, Pasteur successfully tested his rabies vaccine and proved the effectiveness of vaccination in humans. Pasteur’s discoveries about the role of microorganisms in infectious disease save millions of lives each year.

a) Onion skin cells (magnified 200)

b) Human skin cells (magnified 400)

c) Root cells (magnified approx. 400)

d) Human heart cells (magnified 125)

e) Human nerve cells (magnified approx. 400)

f) Human blood cells (red corpuscles) (magnified 2600)

SCIENCE

Scientists have discovered an essential characteristic of life: all living organisms are composed of cells. The cell is the smallest living unit that exists. Crystals and puddles of oil are not living organisms because they are not made of cells.

HISTORY OF

Movement is one of the signs of life. However, it is not always easy to discern the differences between living organisms and inanimate objects. In fact, certain objects have characteristics similar to those of living beings, such as movement, growth and reproduction. For example, the crystals of many minerals can increase or grow; puddles of oil floating on water can divide into several smaller puddles. However, they are not living organisms.

Figure 73 Cellular diversity

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277

HISTORY

OF SCIENCE

Plant and Animal Cells: What Are They Made Of?

Sir Alexander Fleming (1881–1955) was a British physician and microbiologist. In 1928, he was studying the antibiotic effects of bacteria. In his absence, one of his bacterial cultures became infected with mould that was being cultivated in a nearby laboratory. When he returned, Fleming noticed that a bacteriafree area had formed around the mould. He concluded that the mould had produced a substance that inhibited bacterial growth. He named the substance penicillin. Today, penicillin is mass-produced and saves millions of lives.

Cells are like factories that never shut down. Each cell must accomplish certain tasks to stay alive. Among other things, the cell must breathe, nourish itself, repair itself, reproduce, and eliminate waste. Cells accomplish these tasks thanks to certain fundamental structures. The internal structures of the cell are called “organelles.” Each organelle has a role to play. Figures 74 and 75 show diagrams of the organelles of an animal cell and a plant cell. Table 17 lists these organelles and their roles. 2 2

3

1● Cell (or plasma) membrane 2● Cytoplasm 3● Nucleus 4● Vacuole 5● Endoplasmic reticulum 6● Mitochondrion

4 6

1

5

Figure 74 Diagram of an

animal cell

7

3 8

2

4 1 6 5

1● Cell (or plasma) membrane 2● Cytoplasm 3● Nucleus 4● Vacuole 5● Endoplasmic reticulum 6● Mitochondrion 7● Cell wall 8● Chloroplast Figure 75 Diagram of a plant cell

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278 The Living World

Table 17 Cell organelles and their roles

Organelle

Roles

1. Cell (or plasma) membrane

Like the skin covering our bodies, this membrane surrounds and protects the contents of the cell. Its structure helps control how substances enter and exit the cell.

2. Cytoplasm

A large portion of the cell is occupied by the cytoplasm, which has a gelatinous texture. Like blood circulating in the body, the cytoplasm is always in motion. It allows substances, such as oxygen and nutrients, to be distributed to the different parts of the cell. It also holds the organelles in place.

4. Vacuoles

These are located in the cytoplasm. They are balloon-like spaces in the cytoplasm that store nutrients and other substances that the cell does not use immediately (fat for instance). Vacuoles also contain waste that has not yet been eliminated.

5. Endoplasmic reticulum

This is a folded membrane that forms a network of canals. Substances travel down these canals to the various parts of the cell, or to leave the cell. The reticulum plays an important role in cellular transport.

6. Mitochondria

These absorb nutritive elements and, with them, produce the energy needed for the cell’s activities. The mitochondria play an important role in cellular respiration.

Organelles present in plant cells only 7. Cell wall

This is a thicker, more rigid wall than the cell membrane. It is formed mainly from a resistant material called “cellulose.” This wall serves as support for the cell. It is formed on the exterior of the cell membrane.

8. Chloroplasts

Photosynthesis—the production of sugar from solar energy and carbon dioxide—takes place in these structures. Each chloroplast contains a green pigment called chlorophyll that absorbs the energy of the sun.

Antoni van Leeuwenhoek (1632–1723) invented the microscope. With this device, Robert Hooke (1635–1703) was able to observe plant cells in 1655. A few years later, in 1661, Marcello Malpighi (1628–1694) described human cells for the first time. In 1673, the Danish anatomist and physician Nicolaus Steno (1638–1686) and the Dutch physician Reinier de Graaf (1641–1673) observed ovarian follicles. These structures, called “DeGraaf follicles” when mature, contain the ova. In 1677, van Leeuwenhoek observed sperm cells.

SECTION 3

Life-Sustaining Processes

SCIENCE

This is generally the easiest structure to see in a cell. The nucleus directs the cell’s activities. It contains chromosomes—structures made of genes that enable the cell to grow and reproduce. The nucleus is surrounded by a nuclear membrane. This membrane controls the entry and exit of substances in the nucleus.

OF

3. Nucleus

HISTORY

279

How does the membrane perform this function? It is a question of structure. Take, for instance, a plastic bag and a cotton bag. Water does not pass through a plastic bag, but does pass through a cotton bag (see Figures 76 and 77). Plastic is impermeable to water, while cotton is permeable. The materials making up each of these bags are different.

Figure 76 Plastic is impermeable to water because

Figure 77 Cotton is permeable to water because of its

of its structure.

structure.

Diffusion The structure of the cell membrane controls what enters the cell and what exits. To enter the cell, substances must move. How do they do it? Figure 78 gives you a clue. If we put a drop of ink in a container of water, the ink disperses.

Figure 78 After diffusion, the ink particles are uniformly dispersed in the water particles.

The entire solution seems to be tinted with ink.

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Imagine you are at a dance. Everyone is dancing on the dance floor. Each person tries to avoid colliding with the others. After a certain amount of time, the people dancing have shifted position on the dance floor so that there is a maximum amount of space between them. They are uniformly distributed over the dance floor.

NEWS FLASH… Osmosis and diffusion are two of the ways in which an array of substances can enter human body cells. An alcohol molecule, for instance, easily crosses the cell membrane. When there are too many alcohol molecules in the nerve cells of the brain, they slow its activity. Alcohol also impairs memory and slows reflexes.

Ink reacts the same way in water. It is composed of minuscule particles that move in every direction and continually collide (see The Material World on page 177). Because of these collisions, the ink particles are dispersed (see Figure 78, on the preceding page). They go into zones where there are fewer ink particles, and therefore fewer collisions. This process is called diffusion. Diffusion is the movement of particles when they shift from a region where they are concentrated to a region where they are less concentrated. The cell membrane is permeable to certain substances only. Diffusion is how substances enter the cell and exit it. Carbon dioxide, for instance, is waste produced by the cell. Imagine a cell containing this gas in great quantity. Since the gas particles are numerous within the cell, they try to move to a place where they are less numerous, outside the cell (see Figures 79 and 80).

Figure 79 There is a greater concentration of Figure 80 There is an equal concentration

carbon dioxide particles inside the cell than outside. The particles exit the cell more rapidly than they enter it.

of carbon dioxide particles on each side of the cell membrane. The particles enter the cell and exit it at the same rate.

Osmosis Water is the most abundant substance both inside and outside the cell. In fact, approximately 70 percent of a cell is water. Most cells die rapidly when they are deprived of water. Water is essential, in part, because it is a solvent. It is sometimes called “the universal solvent” because it can dissolve a great many substances. In the cell, the water contains various dissolved particles (nutrients, carbon dioxide, waste). The water particles are also small: they can enter and exit the cell easily. The water particles move from areas with low amounts of dissolved substances into areas of higher amounts. This dilutes the dissolved substances. In other words, the water moves from one side of the cellular

ENCYCLOPEDIA

282 The Living World

membrane to the other so that it can re-establish the equilibrium of the concentrations of dissolved particles. The passage of water across a membrane that only allows certain substances to pass is called osmosis. We can observe the phenomenon of osmosis in our day-to-day lives. For example, if you leave celery on a counter, unwrapped, it becomes limp. When celery is left in the open air, the water particles in the cells move, by evaporation, into the surrounding air. The surrounding air is less humid than the celery cells. The cells are therefore emptied of their water little by little and become increasingly soft. On the other hand, if you place this celery in a glass of water, it will firm up again. The water particles enter the celery through osmosis. Here, the celery is an environment containing more dissolved particles than the glass of water (see Figures 81 and 82). Now let us return to the cell membrane. It has selective permeability. In other words, it lets water and certain specific substances pass, but blocks the passage of other substances. When you expend a lot of energy, you discharge a lot of water into the air by exhaling and sweating. Water is pulled from your cells. When there is less water in Figure 81 Limp stalks of celery a cell, the particles (nutrients, carbon dioxide, waste) are more concentrated. To re-establish equilibrium, you must drink water. This water enters your cells by osmosis until the concentration of particles is the same on the interior and exterior of your cells. Figure 83 shows how a membrane with selective permeability works.

Figure 82 The same celery stalks,

a few hours later

A membrane with selective permeability

Before osmosis, 125 the particles 100 are more 75 concentrated on side A than 50 side B.

125

After osmosis, the concentration of particles is the same on side A as it is on side B.

100

25

75 50

A Particles (nutrients, carbon dioxide, waste) Water (measured in mL)

B

25

A

B

Figure 83 Water moves by osmosis

from side B to side A.

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283

Two Vital Functions of the Cell All cells need energy to grow and function. Where do most organisms get this energy? From the food they consume. Energy contained in the food is released during a chemical reaction called cellular respiration. Plants produce their food themselves with a function called photosynthesis. Cellular respiration and photosynthesis are thus complementary functions (see Table 18). Table 18 Photosynthesis and cellular respiration: a complementary relationship

Animals (including humans)

Plants LaPhotosynthesis photosynthèse

Cellular respiration

Cellular respiration

Plant cells produce carbohydrates Plant cells use carbohydrates as an Animal cells use carbohydrates as (sugars) from solar energy, carbon energy source to perform their an energy source to perform their dioxide and water. activities. activities. This reaction releases oxygen. Plant cells store the carbohydrates they produce.

The cells release energy contained in the carbohydrates with the help of oxygen.

The cells release energy contained in the carbohydrates with the help of oxygen.

This reaction produces carbon dioxide and water.

This reaction produces carbon dioxide and water.

Photosynthesis Plants use sunlight as a source of energy. When sunlight is present, they manufacture sugars called carbohydrates from water and carbon dioxide. The water comes from the roots, which draw it from the soil. The leaves absorb carbon dioxide present in the air (see Figure 84). Photosynthesis is very important because carbohydrates manufactured by plants are at the root of everything that living organisms eat. You absorb carbohydrates when you eat plants, such as fruit, vegetables and grains. When you eat meat, you indirectly absorb the carbohydrates that came from plants the animal ate.

Inputs

Outputs

Carbon dioxide

Water

Chemical reaction occurring in the plant cell (chloroplasts)

Solar energy Figure 84 Inputs and outputs of photosynthesis

ENCYCLOPEDIA

284 The Living World

Oxygen

Carbohydrates

Cellular Respiration In living organisms, cellular respiration is vital. Among other things, it transforms carbohydrates into energy. This transformation is performed by the mitochondria (see Figures 74 and 75 on page 278). They absorb carbohydrates and oxygen. Then, a chemical reaction causes the oxygen to release the energy present in the carbohydrates. This energy can then be used by the cells (see Figure 85). Inputs

Outputs Carbon dioxide

Oxygen

Carbohydrates

Chemical reaction occurring in the animal or plant cell (mitochondria)

Water

Energy

Figure 85 Inputs and outputs of cellular respiration

Memory Check 1. What distinguishes living organisms from nonliving things? 2. Explain the similarities and differences between a plant cell and an animal cell. 3. A cell can be compared to a tiny city. Draw a diagram of a “cellular city.” Factor in the following elements: a) Assign a role to each of the cell’s organelles. For instance, indicate which organelle will govern your “cellular city,” and which organelles will be in charge of traffic, garbage removal, power generation, etc. b) Explain how your “cellular city” works. 4. In each of the following cases, indicate whether it is an example of diffusion or osmosis. a) A sugar cube dissolving in a glass of hot milk

b) Water sprayed on a rack of fresh vegetables c) Water you drink when you are very thirsty d) The air in a closed room becomes fresher when a window is opened 5. Observe Figure 83 on page 283. a) Explain why, after osmosis, the water level is higher on side A than side B. b) Using a membrane with selective permeability and the principle of osmosis, how would you design a pipe in which water could rise? c) In your opinion, how do trees get the water drawn in by their roots to rise up to their leaves? 6. What are the similarities and differences between photosynthesis and cellular respiration? 7. Why are trees said to be the lungs of the Earth?

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THE EARTH AND SPACE Once upon a Time . . . The Earth is an immense stretch of water and land housing millions of life forms. Space is an immense void, cold and black, sprinkled with points of light. At first glance, they do not seem to have much in common. However, as they began to observe the stars and the planets, human beings made some surprising discoveries. Gradually, they understood that the Sun that warmed them and lit their way was in fact a star, similar to the points of light in the night sky. They realized, too, that the place in which they lived, the Earth, was also a planet. The Earth and Space, therefore, have several characteristics in common. Scientists are continually fine-tuning their instruments and observation methods. With them, we can reconstruct both the history of the Universe and that of our planet, the Earth. In “The Earth and Space,” you will fathom some of the mysteries that the blue planet and solar system hold.

SECTION

1

General Characteristics of the Earth p. 288 SECTION

The Earth and Space

2

Geological Phenomena SECTION

3

Astronomical Phenomena

286

p. 312

p. 344

The Earth’s Internal Structure

p. 290

The Biosphere

p. 291

The Atmosphere

p. 292

The Hydrosphere

p. 298

The Lithosphere

The Earth in Motion

p. 313

Volcanoes

p. 322

Earthquakes

p. 325

p. 302

Orogenesis

p. 328

Light

p. 345

Erosion

p. 329

The Law of Universal Gravitation

p. 351

The Water Cycle

p. 332

The Birth of the Solar System

p. 352

Winds

p. 334

The Earth

p. 359

Natural Energy Sources

p. 340

The Moon

p. 368

This is what you will discover in “The Earth and Space”: • In Section 1, “General Characteristics of the Earth,” you will embark on a voyage to the centre of our planet. The visit will help you discover that the Earth is not just a solid block of stone; on the contrary, it has a complex structure. You will then travel from the surface of the Earth to the topmost layers of the atmosphere. There, you will notice that our planet has a solid crust almost entirely covered with water and surrounded by a gaseous layer. You will see that each of these three components has its own characteristics. But they are also constantly interacting and—most importantly—provide a home for a multitude of living things. • In Section 2, “Geological Phenomena,” you will discover that volcanoes and earthquakes can be harmful and destructive in the short term. However, they play an important role in landscape evolution. You will also learn about the many natural sources of energy. • In Section 3, “Astronomical Phenomena,” you will explore the solar system. You will study several natural phenomena, such as the succession of day and night, the cycle of the seasons, and the phases of the moon. By studying eclipses, the appearance of comets, polar auroras and meteoroid showers, you will also be able to explain the more uncommon events that frightened our ancestors.

287

S ECTION 1 General Characteristics of the Earth The Earth’s Internal Structure p. 290 The Biosphere

p. 291 The Composition of the Atmosphere p. 293

The Atmosphere p. 292

The Layers of the Atmosphere p. 294

The Troposphere p. 294 The Stratosphere p. 295 The Mesosphere p. 295

SECTION 1 General Characteristics of the Earth

The Thermosphere p. 295

A Hole in the Ozone Layer

p. 296

Fresh Water

p. 300

Drinking Water

p. 300

Is It a Rock or a Mineral?

p. 302

The Hydrosphere p. 298

SECTION 2 The Earth and Space

Geological Phenomena

Igneous Rock

p. 304

Sedimentary Rock

p. 305

Metamorphic Rock

p. 306

The Formation of Soil

p. 307

Soil Profile

p. 308

SECTION 3 Astronomical Phenomena

How Are Rocks Formed?

p. 303

The Lithosphere p. 302 Types of Soil

p. 307

Soil Texture and Structure p. 309

Relief

ENCYCLOPEDIA

288 The Earth and Space

p. 310

Soil Inhabitants

p. 310

Overview On the Earth, certain landscapes change slowly at a regular pace. The coastlines of the Magdalen Islands (Îles-de-la-Madeleine), for instance, are retreating in certain places by several metres a year. Other landscapes never seem to change. However, all it takes is for a volcano to erupt, the earth to shake, or a tsunami to be unleashed, and the landscape is suddenly altered. Do you know what force is at the root of these phenomena?

Tsunami An isolated, very high wave caused by seismic or volcanic activity. This wave, also called a tidal wave, washes far inland.

If you could observe the Earth over a period of several million years, as in a fast-forwarded movie, you would see things completely differently. Continents would barrel into each other and violently collide. Mountains would rise from the ground. Wind and water would erode mountains and fill valleys. In short, you would discover that the Earth’s surface is constantly changing. What force do you think produces these transformations? Part of the answer is found under the Earth’s surface. Do you think our planet has the same composition from its surface to its centre? Unlike the Jules Verne novel (see Figure 1), no human has ever succeeded in visiting the Earth’s depths. We therefore cannot say for certain what there is at the centre of the Earth. However, scientists have inferred our planet’s structure by studying the waves produced by earthquakes. We now know, for instance, that it is divided into three main layers: the crust, the mantle and the core.

Figure 1 The adventures of

the characters in Jules Verne’s novel, Journey to the Centre of the Earth, are the stuff of science fiction rather than reality.

SECTION 1

General Characteristics of the Earth

289

The Earth’s Internal Structure Geologist A person who studies the nature and history of the Earth’s crust. They study the composition and structure of the Earth. They also analyze rocks, minerals, and plant and animal fossils.

The Earth has a solid surface called its crust. This crust envelops many layers that are increasingly hot, the closer they are to the Earth’s centre (see Figure 2). The total radius of the Earth is approximately 6400 km. The internal structure of the Earth is difficult to study. Geologists can dig into the crust, but it is presently impossible for them to excavate beyond a dozen kilometres. Table 1 lists the characteristics of each part of the Earth’s internal structure.

Table 1 The internal structure of the Earth

Layer Name

The Earth’s crust is solid. Its thickness varies: – between 5 and 10 km beneath the oceans – between 30 and 65 km beneath the continents

Crust

Mantle

Core

Main characteristics

Upper mantle (or asthenosphere)

• It can be up to 670 km thick. • This layer is semi-fluid. It is composed of partially melted rock. • It is believed that this layer causes continental drift (plate tectonics).

Lower mantle

• This layer is solid despite its high temperature because the pressure there is very high. • It is composed mainly of silica, oxygen, iron and magnesium.

Outer core

• The outer part of the core is liquid. • This layer gives rise to the Earth’s magnetic field. • It is approximately 2270 km thick.

Inner core

• Despite its very high temperature, the inner part of the core is solid because of the enormous pressure prevailing there.

670 km

28

Upper mantle (1000 to 1800°C)

85

Earth’s crust (5°C) 5 to 65 km

km

Lower mantle (1800 to 3700°C)

m

k 70

22

Outer core (3700 to 4500°C)

Figure 2 As shown in the diagram, the

temperature of the layers increases the closer one gets to the Earth’s centre. ENCYCLOPEDIA

290 The Earth and Space

Inner core (above 4500°C) Earth’s centre

1216 km

At its birth, the Earth was liquid. This was due to the large amount of energy present in the solar system. Our planet was an immense ball of melted matter. In this liquid matter, the heaviest elements, such as iron (Fe) and nickel (Ni), were drawn to the centre of the Earth. They formed the core. The lighter elements, such as silicon (Si), oxygen (O) and aluminum (Al), were massed on the planet’s surface. They formed the mantle and crust. Then the Earth’s average temperature dropped. This caused the crust to solidify.

Crust

Memory Check*

Mantle

1. What are the three main layers that form the Earth’s internal structure? 2. How is the structure of the Earth similar to that of an egg? 3. Why is it difficult to explore the Earth’s interior?

Core

Shell Albumen Yolk

The internal structure of the Earth can be compared to that of an egg. The shell represents the Earth’s crust, the white (or albumen) the mantle, and the yolk the core.

* These questions allow you to check your knowledge of concepts covered in the units of Textbook A.

The Biosphere The Earth is the only planet in the solar system that has surface water in liquid form. This is important because liquid water is indispensable for the appearance and continuation of life as we know it. It is thought that life first appeared in the oceans, then took hold on solid ground and in the air.

Some of the organisms living in the biosphere SECTION 1

General Characteristics of the Earth

291

In “biosphere,” the root “bio” comes from the Greek bios, meaning life.

Abyss A place where the ocean is extremely deep. An abyss is also called an “oceanic trench.”

The regions in which life can exist on the Earth are called the biosphere. In the biosphere, living things interact with each other and their environment. The biosphere includes the lower atmosphere, the seas and the upper layer of the Earth’s crust. Certain living organisms even inhabit places like hot springs, volcanoes, ice caps, abysses, etc. These places are therefore also part of the biosphere. The biosphere has three parts (see Figure 3). Each corresponds to one of the three states of matter: • The gaseous part makes up the atmosphere (air) • The liquid part is the hydrosphere (water) • The solid part is called the lithosphere (rock and sediments) Atmosphere

The Biosphere

Sea level

Hydrosphere

Lithosphere

Figure 3 The biosphere includes all

areas in which life can exist.

The Atmosphere: A Protective Envelope Imagine that the Earth is an orange. The fruit’s flesh would be the solid and liquid parts of the Earth. The peel would be the envelope of gas that surrounds the Earth, or atmosphere. It protects the Earth by blocking the harmful rays of the Sun (ultraviolet rays). Thanks to friction, moreover, the atmosphere destroys meteoroids directed toward us. And because of the greenhouse effect, the atmosphere reduces temperature differences on the Earth. Without the gases and water vapour in the atmosphere, life would be impossible on our planet. During the day, the temperature would rise to 80°C. Moreover, all of this heat would be lost at night because the temperature would drop to –140°C. The atmosphere therefore acts as an insulator. The atmosphere can be over 1000 km thick. But most of its mass is found at an altitude of 10 km or less. There is no real border separating the atmosphere from the empty reaches of space. The number of gas molecules just diminishes gradually the farther from the Earth they are.

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292 The Earth and Space

The Composition of the Atmosphere

Nitrogen (approx. 78%) Oxygen (approx. 21%)

At the end of the 18th century, scientists such as Lavoisier, Scheele and Priestley discovered that air is a mixture of several gases. Fresh air is a homogeneous mixture (a solution) whose two main gases are nitrogen and oxygen (see Figure 4). Water vapour and carbon dioxide are also present in air, but in very small quantities. However, they are essential to sustaining life (see Table 2). Although we consider air a solution, it is rarely of ideal purity. It often contains dust in suspension. A sample of polluted air can be described as a heterogeneous mixture if it contains suspended solid particles.

Water vapour (0 to 3%) Carbon dioxide (0.03%)

Figure 4 The proportion of gases

that make up the atmosphere

Ozone (0.000 003%) Other gases (less than 1%)

Table 2 The principal constituents of pure air

Name

Chemical formula

Percentage in air

Role

Nitrogen

N2

Approximately 78%

• Plants and animals need it to develop. • Plants cannot use atmospheric N2 directly. It is absorbed only when bacteria transform it into ammonium (NH4+) or nitrate (NO3–). • Animals consume nitrogen by eating plants that contain it.

Oxygen

O2

Approximately 21%

It is indispensable for the survival of most living things.

Water vapour

H2O

0 to 3%

• The quantity of water vapour in the air varies. • The presence of water in the atmosphere reduces differences in temperature.

Carbon dioxide

CO2

0.03%

• It is considered a greenhouse gas because it traps heat in the atmosphere. • Over some large cities, the air contains more CO2 because of pollution.

Ozone

O3

0.000 003%

• It forms a gaseous layer in the stratosphere. • The ozone absorbs most ultraviolet rays. It thus protects living organisms from the rays’ harmful effects.

Other gases

—

Less than 1%

Air contains traces of neon (Ne), helium (He), krypton (Kr), hydrogen (H), xenon (Xe), argon (Ar), etc.

NEWS FLASH… Scientists believe that most of the oxygen (O2) in the troposphere was formed in the oceans. Some 2.8 million years ago, the first forms of life, called cyanobacteria, began to perform photosynthesis. In other words, they used solar energy and carbon dioxide (CO2) to manufacture their food and emit oxygen. Around 400 million years BCE, there was enough oxygen in the atmosphere for animals to appear.

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The Layers of the Atmosphere The four layers of the atmosphere are the troposphere, the stratosphere, the mesosphere and the thermosphere. Each has its own characteristics. 180 170 160 150

re ratu

pe Tem

140 130

Thermosphere

120

Altitude (km)

110

The division of the atmosphere into four layers is based, among other things, on its variations in temperature. In the troposphere, the temperature drops with altitude. It then rises in the stratosphere. It drops once again in the mesosphere and then rises yet again in the thermosphere (see Figure 5). Let’s take a closer look at the layers of the atmosphere. We will start with the one closest to the Earth’s surface: the troposphere.

Polar aurora

100 90 80 Mesosphere

70 Meteoroid

60 50 40

Stratosphere Ozone layer

30 20

Figure 5 The four layers of the

10 -100

Troposphere -50

0

50

100

150

atmosphere. The curve indicates the temperature as a function of altitude.

200

Temperature (°C)

The Troposphere The troposphere varies in thickness. It measures up to 17 km in equatorial regions, but is only 7 to 8 km thicle in polar regions. Its temperature is also very variable, because it is subject to the thermal radiation of the ground. Certain parts of the soil absorb the sun’s rays and then emit the accumulated energy in the form of heat, which warms the air. The troposphere is the most important layer for living things because it contains over 80 percent of all air in the atmosphere. In fact, the farther from the Earth, the scarcer air is. The troposphere also contains almost all of the water vapour in the atmosphere. Water vapour produces numerous weather phenomena, such as rain and clouds. It also determines climate. The average temperature of the troposphere drops approximately 6°C with each kilometre of altitude.

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294 The Earth and Space

The Stratosphere The stratosphere is approximately 40 km thick. It is located just above the troposphere. The ozone layer is found here (see Figure 6). This layer of gas absorbs the ultraviolet rays coming from the Sun. In doing so, it protects us from these rays, which cause skin cancer (see “A Hole in the Ozone Layer” on the following page). Ultraviolet rays also heat the stratosphere: the farther from Earth, the higher the temperature.

a) Ozone

Large airplanes usually fly through the stratosphere, just above the cloud layer. Air is thinner at this altitude. Airplanes encounter less friction there and can therefore fly faster using less fuel.

The Mesosphere The mesosphere is the third layer of the atmosphere. It also is approximately 40 km thick. Air molecules are very scarce and absorb little of the Sun’s warmth. This leads to wide variations in temperature. Minimum temperatures can reach –120°C. Maximum temperatures range from 0°C to 27°C. In the mesosphere, gas molecules are scarce. Yet this atmospheric layer protects the Earth from meteoroids that have managed to break through the thermosphere. When the meteoroids come in contact with the air molecules, the friction heats them to the point that they catch fire and break up.

b) Oxygen Figure 6 Ozone (above) is a gas

molecule composed of three oxygen atoms (O3 ). Oxygen (below), which we breathe, is formed from two oxygen atoms (O2 ).

The Thermosphere The fourth and last layer of the atmosphere is the thermosphere. This layer is the thickest. It measures over 90 km. The Sun’s rays are fierce in this zone. They create extremely high temperatures that can exceed 1000°C. Within the thermosphere, at an altitude of 90 to 300 km, the ionosphere is found. The ionosphere is particularly useful for the Earth’s communication systems. This is because it contains a large quantity of electrically charged particles. These particles have the capacity to bounce back radio waves. A radio message sent from Montréal, for instance, can rebound on the ionosphere and land in Sydney, Australia. Most meteoroids heading toward the Earth are burnt up in the thermosphere. We then see them in the form of shooting stars (see page 366). The thermosphere is also the site of a magnificent natural phenomenon: the polar auroras (see page 363).

Ultraviolet rays (or UV rays) An invisible portion of the Sun’s radiation. The ozone layer prevents UV rays from reaching the Earth’s surface.

Friction (atmospheric) The force that slows down two bodies in contact.

Meteoroid A fragment of rock or ice that comes from space. A meteoroid, whose size can vary from a grain of dust to a stone block of a tonne or more, can hit the Earth at very high speed.

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A Hole in the Ozone Layer

Cataract An eye disease that causes the crystalline lens to become completely or partially opaque. This prevents light from passing through it.

Mucous membranes The layer of cells lining the inner walls of the digestive and respiratory tracts. These cells secrete mucus, which lubricates the wall and keeps it moist.

Since 1975, satellite images have shown that the thickness of the ozone layer is shrinking (see Figure 7). The main causes of this thinning appear to be chlorofluorocarbons (CFCs) and aerosol products. CFCs are given off by refrigeration equipment, such as refrigerators and air conditioners. When the CFCs reach the stratosphere, the chlorine they contain reacts with the ozone. The latter is then transformed into oxygen (O2). The consequences of this phenomenon are especially visible over the Antarctic. Cold temperatures stimulate this atmospheric reaction. CFCs, now banned, have been replaced with various substitutes. The thinning of the ozone layer is worrying because it is what protects us from the ultraviolet rays of the Sun. This phenomenon threatens to increase cases of skin cancer and cataracts around the world. Ironically, the increase in ozone at low altitude, i.e. in the troposphere, is also worrying. Ozone irritates the mucous membranes, which can cause serious health problems. The increase in ozone at low altitude is caused by pollution.

1979

2004

Antarctica

Figure 7 These satellite images show the progression of the hole in the ozone layer over

the Antarctic from 1979 to 2004. The most affected region is in violet. The difference in the two graphics is due to the improvements in imaging technology over time.

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Memory Check* 1. What do we call the regions on the Earth where life is possible? 2. The surface of the Earth is divided into three large parts. a) Name these parts. b) Indicate what state of matter is associated with each of these parts. c) Name some living organisms that can be observed in each of these parts. 3. Explain why the atmosphere is indispensable to life. Give at least two reasons. 4. a) What are the four main gases that form the atmosphere? b) What importance does each of these gases hold for living things? 5. Imagine that you are travelling in a rocket to the upper reaches of the atmosphere. a) Name the four layers of the atmosphere you zoom past. b) Indicate the changes in air temperature occurring as you rise in altitude. 6. On the aforementioned rocket ride, you observe different phenomena. Indicate the atmospheric layer in which you have the greatest chance of observing each of the following events: a) You see an airplane flying above the clouds. b) You find yourself in the middle of a polar aurora. c) You narrowly miss a meteoroid breaking up in a burst of light. d) You get caught in the rain. e) Your instruments show you are crossing the ozone layer. 7. a) What is the main cause of the thinning of the ozone layer? b) Why should we worry about a decrease in the ozone layer? c) Why does ozone increase at low altitude?

NEWS FLASH… Ozone is a gas that protects us, when it is in the stratosphere, from the ultraviolet rays of the sun. In the troposphere, however, it becomes a dangerous pollutant. Ozone is produced from the transformation of gases discharged by automobiles, among other things. It mixes with other pollutants and water vapour in the air to produce smog. Yet ozone is also useful for purifying air. When used in the treatment of drinking water, it is less dangerous than chlorine. It is also used to destroy certain harmful bacteria.

* Questions 1, 6 and 7 allow you to check your knowledge of concepts covered in the units of Textbook A.

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The Hydrosphere: The Distribution of Water on the Earth The hydrosphere is formed by all bodies of water on the Earth’s surface. Oceans, rivers, streams, lakes and all other waterways are a part of it. It covers approximately 75 percent of the Earth’s surface (see Figures 8 and 9). Water is vitally important for living things. It’s simple: without water, there would be no life.

1 ●

3 ●

5 ●

4 ● 2 ●

North America South America Europe Africa Asia Oceania Antarctica

1 ● 2 ● 3 ● 4 ● 5 ● 6 ● 7 ●

6 ●

7 ●

Figure 8 Water covers nearly 75% of the Earth’s surface.

Oceans and seas (salt water) (97.2%) Glaciers (2.15%) Underground water (0.63%) Rivers, lakes, ponds, etc. (available fresh water) (0.02%) Figure 9 The distribution

of water on the Earth

Water present on the Earth is either fresh or salty. The water of the seas and oceans is salty because of the great quantity of mineral salts dissolved in it. These mineral salts come from rocks. Every time it rains, a certain amount of the minerals that form rocks dissolves. These minerals then run into the oceans, where they accumulate. The quantity of salt dissolved in the seas varies according to the region of the world (see Table 3 on the following page). ENCYCLOPEDIA

298 The Earth and Space

Table 3 Percentage of salts dissolved in certain bodies of water

Body of water

Site

Salinity

Dead Sea

Saltwater lake in the Middle East

27%

Great Salt Lake

Near Salt Lake City, Utah, in the United States

5 to 27%

Red Sea

Gulf of the Indian Ocean, between Africa and Asia

4.1%

Arabian Sea

Between Pakistan and India. It is also called the “Sea of Oman.”

3.7%

Pacific Ocean

Between America and Asia

3.7%

Atlantic Ocean

Between America and Europe

3.2%

Baltic Sea

Northern Europe

1% or less

Water (96.5%)

Chlorine (55%) Sodium (30.6%) Sulphur (7.7%) Magnesium (3.7%) Calcium (1.2%) Potassium (1.1%) Figure 10 Mineral salts present

Other salts (0.7%)

in sea water containing 3.5% salt

Salts (3.5%)

Certain organisms cannot live in salt water: they are incapable of absorbing the large quantity of mineral salts it contains (see Figure 10). These organisms, including humans, therefore need fresh water to survive. However, fresh water covers only 3 percent of the Earth’s surface. Moreover, most of the fresh water on the Earth is frozen. The ice caps and glaciers hold three-quarters of the world’s freshwater reserves. In other words, human beings and other living organisms that cannot live in salt water have less than 1 percent of the planet’s water at their disposal. This water gets more polluted every day!

Glacier An accumulation of snow transformed into ice that slowly descends into a valley.

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Fresh Water: Its Distribution and Use Table 4 The distribution of fresh water

on the Earth

Country

Volume of fresh water

Brazil

18%

Canada

9%

China

9%

United States

8%

All other countries

56%

Fresh water is a natural resource that is distributed very unequally around the world. In many areas where the climate is very dry, there is a permanent lack of water. People must make do with very small quantities. Elsewhere, however, there is water in abundance. Yet many people waste this resource (see Figure 11). Table 4 shows that four countries alone possess nearly half the planet’s reserves of fresh water. No wonder it is difficult to procure enough fresh water for every human on the Earth! And the difficulty only increases with the fact that humans need water that is not only fresh, but drinkable as well.

Figure 11 While some people have water in abundance, others have barely enough to

meet their needs.

Drinking Water The quality of fresh water is important to health. If people drink polluted water, they can become infected by serious diseases. In certain countries, water quality is so poor that it cannot even be used for washing. Drinking water is water that is fit for consumption; in other words, it is safe to drink (see Figure 12). It is not the same as pure water. Instead, it is a mixture of water molecules and certain dissolved substances. The principal mineral salts dissolved in drinking water are calcium, magnesium and sodium.

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To be drinkable, water must have the following characteristics: • It must be perfectly transparent (limpid) • It must not contain suspended particles • It must not have an unpleasant odour • It must contain only a small quantity of dissolved minerals • It must contain dissolved oxygen • It must not contain micro-organisms that can cause disease Tap water must have all of the characteristics listed above. That is why chlorine is usually added to water to destroy bacteria. Fluoride is sometimes added as well to lower the risk of cavities.

Figure 12 Would you

drink a glass of this water? Why or why not?

Memory Check 1. a) Why is sea water salty? b) Where do the mineral salts present in water come from? 2. a) What is the difference between fresh water and salt water? b) What is the difference between fresh water and drinking water? 3. Why are so many living things unable to use three-quarters of the world’s reserves of fresh water? 4. Water covers nearly 75 percent of the planet’s surface. Why, then, is it considered a precious resource that should not be wasted?

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The Lithosphere The lithosphere is a rigid structure that comprises the Earth’s crust and part of the upper mantle. It encompasses mountains, plains, volcanoes, and more. The thickness of the lithosphere ranges from 70 km (beneath the oceans) to 150 km (beneath the continents). The lithosphere, too, is essential to life. It enables plants to send down roots and provides them with the minerals they need to grow and develop. It offers a range of habitats to animals. The lithosphere is also very useful for human beings. It holds natural resources, such as oil and natural gas. It gives us the matter we need to build the things on which our well-being depends. The lithosphere is constantly evolving due to the influence of several factors, such as climate and human activity.

Is It a Rock or a Mineral? Figure 13 The various minerals that

make a rock are like the different types of material that make up a house.

When you take a walk outside, you often see pebbles. You might suppose that they come from the Earth’s crust or have broken off a rock. But are they rocks or minerals? A rock is a heterogeneous blend of variously sized grains of different kinds. Each of these grains is a mineral (see Figure 13). A mineral is a pure, natural and inorganic (non-living) substance. It is formed within or on the surface of the Earth’s crust. In general, there are several kinds of minerals in a rock. Granite, for instance, is a rock formed from four minerals: feldspar, quartz, mica and hornblende (see Figure 14). Quartz

Mica

Feldspar

Hornblende

Granite

Figure 14 Granite is a rock made of various

minerals. The shiny grains seen in it are feldspar. The transparent crystals are quartz. The grey-green flakes are mica, and the dark specks are hornblende.

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How Are Rocks Formed? There are three types of rock, classified according to their origin (see Figure 15). • Igneous rock results from the cooling and solidification of magma. • Sedimentary rock derives from fragments of rock called sediment. In this case, rocks are subjected to the action of water, wind and glaciers—in other words, erosion. They are fragmented, transported, and then deposited. Over time, the fragments are compacted and cemented, becoming sedimentary rock. They sometimes contain fossils. • Metamorphic rock is rock that has undergone a transformation. This transformation occurs deep in the Earth’s crust, caused by heat and pressure.

The word “igneous” comes from the Latin igneus, meaning fire. The word “metamorphic” comes from the Greek words meta (change) and morphos (form). The word “metamorphosis” has the same origin.

Weathering and erosion

Weathering and erosion

Sedimentary rock

Sediment

Igneous rock

Compaction and cementing

Ground level

Cry

sta

He

at a

Cooling

nd

lliza tion

pre

Weathering and erosion

ssu

re

Heat and pressure

Melting Magma

Metamorphic rock

Figure 15 The cycle of rock formation

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Igneous Rock Magma Liquid rock in the Earth’s crust. When it reaches the surface, it is called lava.

Igneous (or magmatic) rock is formed from partially melted rock, or magma. When the magma cools, it solidifies and creates igneous rock. There are three types of igneous rock: • Intrusive (or plutonic) igneous rock derives from the slow cooling of magma within the Earth’s crust. The rock has very large crystals that are easily visible to the naked eye. Examples: granite, diorite and gabbro [see Figure 16a)]. • Extrusive (or volcanic) igneous rock is formed when a volcano spews lava that cools in contact with the air or water. The crystals have no time to develop because they cool so rapidly. That is why this rock is made of microscopic crystals. Examples: obsidian, rhyolite, andesite and basalt [see Figure 16b)]. • Porphyritic rock has undergone two cooling phases. The crystals in it therefore vary in size. The first cooling phase is slow and occurs deep within the Earth’s crust. It causes the formation of large crystals. The second cooling phase is quicker. It indicates that the rock has been brought back up to the surface, pushed by magma. The large crystals of the first phase are then fixed in a mass of smaller crystals. Examples: certain types of granite [see Figure 16c)].

a) An intrusive igneous rock: gabbro

b) An extrusive igneous rock: basalt

c) A porphyritic rock: granite Figure 16 Some types of igneous rock

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Sedimentary Rock Do you know where the sand and pebbles you find on beaches come from? They have broken apart from larger rocks, sometimes kilometres away. It probably happened several hundred years ago.

Pebble A rock worn and polished by the friction of the water, and deposited on the shore by waves.

Various factors act on the Earth’s crust. Freezing and the action of glaciers and waves remove pieces of rock from the crust. These rock fragments (or sediment) are then carried and polished by water, wind and landslides. They are then deposited in successive layers at the bottom of oceans and lakes. Over time, this sediment is compacted and cemented to become sedimentary rock (see Figure 17).

a) Limestone

b) Sandstone

c) Conglomerate

Figure 17 Some types of sedimentary rock

Fossils are sometimes found in sedimentary rock. Fossils are the remnants of primitive marine or terrestrial life forms (see Figure 18). Over the years, the soft parts of these primitive organisms decompose. They are replaced by minerals, which cause the rock to preserve their form. The hard parts of the animal or plant (such as the shell, bones or teeth) sometimes remain intact.

Fossil An imprint or remnant of an animal or plant preserved in the Earth’s crust.

Figure 18

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Metamorphic Rock Sometimes, already-formed igneous, sedimentary and even metamorphic rock undergoes changes in structure. In the depths of the Earth’s crust, they are transformed by the action of pressure and heat. They fold and buckle as if they were made of modelling clay. During these transformations, the minerals are rearranged. They settle in bands or sheets, or change in texture. The resulting rock is said to be metamorphic (see Figure 19). For example, through metamorphism argillaceous shale turns into slate, sandstone into quartzite, limestone into marble, and granite into gneiss (see Figure 20).

a) Slate

b) Quartzite

c) Marble

Figure 19 Some types of metamorphic rock

Heat and pressure

Heat and pressure a) Granite

b) The transformation process

c) Gneiss

Figure 20 The transformation of granite into gneiss is a slow process caused by heat and pressure.

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Table 5 outlines the process of formation of the three types of rock. Table 5 Types of rock and their formation and composition

Igneous rock

How are they formed?

What are they made of?

How are their components distributed?

Sedimentary rock

Metamorphic rock

Through the cooling and solidification of magma

Through the erosion and transportation of fragments that are subsequently deposited, compacted and cemented

From already-formed rocks that change under the action of pressure and heat

From minerals, such as feldspar and quartz

From mineral grains, inorganic debris and fossils

From various minerals

The grains are often disrupted

They form a sequence of layers corresponding to the layers of accumulated sediment.

– In light and dark bands (for example, gneiss) – In rigid sheets (for example, mica schiste, slate)

Types of Soil Land and soil are two different things. Soil is the surface layer of matter that, among other things, enables plants to grow. Soil is created from the mixture of certain components of the lithosphere, hydrosphere and atmosphere. Soil is a vital element because it fulfils the needs of plants. Without it, life as we know it on the Earth would be impossible. Soil is essential to human survival as well. Without soil, there would be no harvests or animal farming.

The Formation of Soil The formation of soil is a very ancient process. Soil derives from an intact rock called bedrock. Two processes cause it to be formed: the alteration of the bedrock and the influx of organic material from living things.

Bedrock A thick layer of rock lying under the soil.

The alteration corresponds to the crumbling of the rock through erosion. It is caused by, among other things, water infiltrating the fissures of the bedrock. Every time the temperature drops below zero, this water freezes. Since ice’s volume is greater than the volume of the same mass of liquid water, the ice exerts pressure on the fissure walls, causing them to break. The acids contained in the water also contribute to the bedrock’s disintegration. The influx of organic matter is due to the accumulation of different kinds of debris. Some debris comes from plants: leaves, fruit, pieces of bark, dead roots, etc. Other debris is of animal origin: feathers, hair, excrement, carcasses, etc. As it decomposes, the debris forms humus. Last, but not least, countless micro-organisms are added to the mix.

Acid A substance with a pH value of less than 7. Vinegar and lemons are acidic substances with a sour taste.

Humus Partially decomposed organic matter. It can be of animal or plant origin.

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In part, therefore, soil results from the transformation of the bedrock into fragments of different sizes. The presence of a certain quantity of humus and micro-organisms is also necessary for its formation (see Figure 21).

Decomposing organic matter

Degradation of the bedrock Figure 21 The formation

of soil

Bedrock

Soil Profile The deeper you dig in the soil, the bigger the elements you will find. You will probably notice, too, different layers of composition and structure. These are the soil’s horizons. The soil profile is generally formed from three horizons:

Leaching A process by which a substance is dissolved and then carried off by water.

• Horizon A (or litter) is found on the surface. It is here that plant and animal matter is transformed into humus. The thickness of horizon A and the organic matter’s speed of decomposition affect the amount of humus. This horizon changes significantly when water infiltrates it. Horizon A is therefore low in minerals because rain carries them to horizon B. This is called leaching. • Horizon B is the area where minerals that are leached from the surface layer accumulate. There is little organic matter here, but many minerals. The rock in this layer is less fragmented than that of horizon A. • Horizon C (or subsoil) provides the raw material for the upper layers. It is here that the partially degraded bedrock, and the various minerals that compose it, are found.

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Soil Texture and Structure The texture of the soil depends on the size of the particles that compose it. The particles’ size can vary from gravel to microscopic bits of clay. Soil is generally a mixture of three particle types: sand, silt and clay.

Silt Fine particles of soil carried by water and wind.

The most fertile soils are argilloarenaceous silts, which are made up of clay and sand. These are also called light sandy loam. They contain enough fine particles to retain water and allow minerals to adhere. These soils are approximately made up of:

Micrometre (μm) A unit of measurement in the International System of Units (SI) equivalent to one millionth (10-6) of a metre.

– one-third sand (particles of over 50 μm or micrometres)

– one-third silt (particles of 2 to 50 μm)

– one-third clay (particles of less than 2 μm)

The structure of the soil is an indication of how the elements are arranged. They can be deposited loosely or packed tightly. Soil porosity designates the percentage of free space in a given volume of soil. Porosity is directly related to soil structure. It determines how easily water and air circulate in the soil. This physical characteristic is a factor in the development of animal and plant life. Some soils possess very large pores (or spaces). These allow gases and water to circulate freely. Other soils have finer pores that, like sponges, retain a portion of the water.

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Soil Inhabitants The soil houses an unbelievable quantity and variety of living organisms (see Figure 22). These living organisms determine the properties of the soil in which they are found. Earthworms, for instance, aerate the soil when they dig. Moreover, they secrete a viscous substance (mucus) that holds soil particles together. Bacteria transform atmospheric nitrogen, enabling plants to easily assimilate it. Plant roots extract water and minerals dissolved in the soil. In turn, they hold the soil in place, mitigating the effects of erosion.

Ground mushroom

Carpenter ant

Sawyer beetle

Rove beetle

Millipede Slug

Snail

Nematode Centipede

Pseudoscorpion Pill bug

Figure 22 The soil houses a whole community of organisms: bacteria, fungi, invertebrates (insects, worms, etc.), seeds and roots of all kinds.

Cicada nymph

Mite Earthworm

Springtail Soil protozoa

Wireworm

Relief: The Evolution of the Landscape Despite its apparent stability, the Earth is a world in perpetual motion. It is controlled by powerful forces. These forces come from extreme differences in temperature, which create convection, and from the great pressure that prevails beneath its surface. These phenomena cause the Earth’s crust to fold over, rise up and fracture. They give the lithosphere its relief: mountains, valleys, plains and more. The Earth’s relief is constantly changing because of underground forces. They are not the only forces at work. Winds, water and glaciers combine to alter the landscape as well. Erosion does its work on rocks and the Earth’s relief. It rounds the summits of mountains. It digs valleys and fills them up and carries debris far from its source. Humans also contribute to the transformation of relief. They construct roads, dig mines and build cities and towns. We will explain these phenomena in more detail in the following section.

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A landscape in Torres del Paine National Park in Chile

Memory Check* 1. Explain why the lithosphere is indispensable to life. Give at least two reasons. 2. What is the difference between a rock and a mineral? 3. a) How is igneous rock formed? b) How is sedimentary rock formed? c) How is metamorphic rock formed? 4. In your opinion, is the rock described below igneous, sedimentary or metamorphic? a) A rock in which minerals are deposited in layers b) A rock formed of very large crystals easily visible to the naked eye c) A rock containing organic debris d) A rock formed of crystals of varying sizes. The larger crystals appear frozen in a mass of smaller crystals. 5. How do geologists distinguish land from soil?

6. Using a diagram, explain how the freeze-thaw cycle accelerates the crumbling of rock. 7. The soil is formed from three layers called horizon A, horizon B and horizon C. Indicate which horizon corresponds to each of the following descriptions. a) This horizon is also called litter. b) In this horizon, the bedrock is found. c) Here, there is an accumulation of dissolved and deposited minerals. 8. The texture of the soil depends on the particles that compose it. Rank the following types of soil according to the size of their particles. a) Sand b) Gravel c) Silt d) Clay 9. Name two major forces capable of altering the Earth’s relief. * Question 9 allows you to check your knowledge of concepts that were covered in the units of Textbook A.

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S ECTION 2 Geological Phenomena The Earth in Motion

Volcanoes

Earthquakes

SECTION

SECTION

p. 325

Orogenesis

p. 328

The Continents Divide

p. 313

Plate Tectonics

p. 316

Convection

p. 317

How the Plates Move

p. 318

Biological Erosion

p. 330

p. 330

Mechanical Erosion

p. 330

Aging Mountains

p. 331

Chemical Erosion

p. 330

Acid Rain

p. 333 Convection in Daily Life

p. 335

Sea Breeze

p. 337

Land Breeze

p. 337

The Structure of a Volcano

p. 322

Volcanic Eruptions

p. 323

The Causes of Earthquakes

p. 326

Vulnerable Zones

p. 327

Categories of Erosion

2

Geological Phenomena SECTION

p. 322

1

General Characteristics of the Earth

The Earth and Space

p. 313

Erosion

p. 329

3

Astronomical Phenomena The Water Cycle p. 332

Convection Cells p. 334 The Coriolis Effect Winds

p. 335

p. 334 The Characteristics of Wind p. 336 Smog and Temperature Inversion p. 338

Natural Energy Sources

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312 The Earth and Space

p. 340

Are Energy Sources Limitless? p. 342

Overview

Alfred Wegener was born in 1880 in Berlin, Germany. In 1910, he developed the theory of continental drift. He advanced the bold idea that there was once a supercontinent: Pangaea. Two hundred million years ago, this continent fragmented to produce the continents we know today. However, it was only in the 1960s that the scientific community accepted his idea.

SCIENCE

But there is another source of energy that the entire planet has at its disposal: the Sun. It warms the air, the water and the ground during the day, and this heat dissipates during the night. These fluctuations of energy give rise to many other phenomena: erosion, the water cycle, winds and sea currents. These phenomena also contribute to the alteration of the Earth’s relief.

HISTORY OF

Where do mountains come from? How are immense rocks and steep cliffs formed? What force wakes volcanoes and makes the ground tremble beneath our feet? Under the thin layer of its crust, the Earth conceals powerful internal forces. These forces lift, fold and fracture the Earth’s crust. This crust is continually being transformed. The Earth has its own source of energy: its internal core. The core’s heat is at the root of numerous phenomena: mountain formation, earthquakes, volcanoes and tsunamis.

The Earth in Motion On a human scale, transformations to the Earth’s crust are extremely slow. This is why they went unnoticed for so long. On a geological scale, however, the Earth is a very active planet.

The Continents Divide At first glance, the ground you walk on appears completely immobile. It was long believed that the continents, mountains and oceans had not changed since the planet’s birth. However, in the early 20th century, Alfred Lothar Wegener, a German meteorologist and physicist, began studying certain curious indicators, which suggested the continents were moving. Wegener carefully studied a number of geographical maps. Something intrigued him: South America and West Africa seemed to fit almost perfectly into each other (see Figure 23). In fact, all of the continents seemed able to be assembled like the pieces of a jigsaw puzzle. Did this mean they had once been joined together?

Africa South America

Figure 23 Africa and South America

seem able to fit into each other.

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Wegener was also interested in the rock composition of certain mountain chains. Among them were the Appalachians, the Caledonides and the Mauritanides (see Figure 24). The Appalachians span Southern Québec and the northeastern United States. The Caledonides are in the British Isles and Scandinavia. The Mauritanides are in northwest Africa. Wegener remarked that these three mountain chains had the same age and rock composition. Could they once have been part of the same mountain chain?

Greenland

North America The Caledonides Europe

The Appalachians

Atl

n cea O c anti

Africa

The Mauritanides

Figure 24 The Appalachians, Mauritanides and Caledonides are the same age and have the same rock composition. On this map, the continents have been squeezed together to illustrate how these rock formations might have been part of a single mountain chain in the Pangaean era.

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314 The Earth and Space

Wegener also examined fossils. These gave him another clue. Mesosaurus was a small reptile that lived in fresh water 260 million years ago. Fossils of Mesosaurus have been found in both South Africa and Brazil. Today, these two regions are separated by 3000 km of ocean. However, Mesosaurus was unable to swim from one continent to the next because it was unable to live in salt water. It was not the only prehistoric creature to attract Wegener’s attention. Lystrosaurus was a small land reptile that lived 240 million years ago. It appears to have migrated from South America to Africa. But it could not swim. How could it have made it to the other side of the ocean? (See Figure 25 on the following page.)

Arctic Ocean

North America

Europe

Asia

Atlantic Ocean Africa

Pacific Ocean Equator

Pacific Ocean Indian Ocean

South America

Oceania

Mesosaurus Lystrosaurus Antarctic Ocean 1

Antarctica

3 000 km

Figure 25 Fossils of Mesosaurus and Lystrosaurus have been found

on both sides of the Atlantic Ocean.

Wegener pondered the indicators he had gathered. He put forward the idea that the continents had once formed a single immense continent, Pangaea. This continent existed approximately 220 million years ago. It was set in a single ocean, Panthalassa (see Figure 26). Then, this supercontinent broke apart. It was split into large pieces that then drifted to their present sites. These pieces formed the continents and oceans we know today. Wegener called this phenomenon continental drift. Unfortunately, Wegener never managed to demonstrate what forces caused the continents to shift. As a result, the scientific community at the time refused to adopt his ideas.

Europe North America

Pangaea A word of Greek origin meaning “all worlds.” The name given by Wegener to an immense continent formed of all land masses.

Panthalassa A word of Greek origin meaning “all seas.” The name given by Wegener to the single ocean surrounding Pangaea.

Asia

India

Panthalassa Africa South America Australia Antarctica

Figure 26 Wegener’s

supercontinent, Pangaea, and its single ocean, Panthalassa. SECTION 2

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315

Plate Tectonics In the 1960s, sonar was invented. With it, the ocean depths could be mapped for the very first time. The device helped geologists make several important discoveries, including the continental plates and oceanic ridges. Continental shelves are the underwater extensions of the continents. Their contours fit into each other even better than those of the continents. Oceanic ridges are long chains of underwater mountains. The Mid-Atlantic Ridge, for instance, seems almost to separate the Atlantic Ocean into two equal parts (see Figure 27).

Asia Europe

North America Continental shelf

Africa

South America

Mid-Atlantic Ridge Oceania

Antarctica Figure 27 A map of underwater relief

Around the same time, scientists also discovered the existence of the asthenosphere, or upper portion of the Earth’s mantle (see page 290). This discovery revealed that the continents float on a layer of partially melted rock. From this point on, it was possible to imagine them in motion.

John Tuzo Wilson ENCYCLOPEDIA

316 The Earth and Space

John Tuzo Wilson (1908–1992) was a Canadian geophysicist. In 1965, he modified the theory of continental drift in light of these new discoveries. He suggested that the Earth’s crust is divided into vast rigid plates. These plates include both the continents and underwater relief. Furthermore, these plates move. The oceanic ridges, in fact, are borders between two plates that are moving apart. Along the fissure created by this distancing (divergence zone), magma rises to the surface and rapidly solidifies. That is why the ridges are

very young mountain chains whose rocks are volcanic in origin. Wilson named his theory plate tectonics (see Figure 28 below, and Figure 31 on the following page).

Eurasian Plate

Eurasian Plate

North American Plate Philippine Sea Plate

Indian-Australian Plate

Cocos Plate

Juan de Fuca Plate

Pacific Plate

Nazca Plate

Antarctic Plate

African Plate South American Plate

Scotia Plate

Figure 28 According to the theory of plate tectonics, the Earth’s crust is divided into

seven large plates and a handful of secondary plates. You can see them in the diagram, along with the direction of their movements. The continents are the uplifted portions of six of these plates.

Divergence Convergence Slip Plate movement

Convection: The Plates’ Driving Force Scientists use convection to explain the plates’ movement. There are convection currents in magma, beneath the Earth’s crust. The magma is carried by these currents. In fact, magma behaves like a soup simmering on a stove (see Figure 29). It receives heat from the Earth’s core. The hottest rock rises, travelling from the lower mantle to the upper mantle. It then moves horizontally, pushed by the arrival of newer, hotter rock. While making this horizontal movement, the liquid rock carries the plate above it. This is how the enormous plates move under the Earth’s crust (see Figure 30 on the following page).

Convection current A movement that occurs in a liquid or gas when a temperature difference exists within the substance.

Figure 29 The

movements of convection can be observed in liquid heated on a stove. SECTION 2

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317

Lithosphere

Figure 30 A convection current constitutes a complete cycle. During this cycle, the magma heats up, rises, cools, then sinks again. The movement pushes the plate above the magma.

Asthenosphere

How the Plates Move The plates are therefore in motion, powered by the convection currents of magma. The plates move at a rate of 1 to 20 cm a year. North America and Europe, for instance, are moving apart at a rate of 2 cm a year. This may seem slow to you, but think of what this movement could do over millions of years. The plates may end up moving several thousand kilometres. Slowly but surely, the plates approach each other, draw apart or slide against each other (see Figure 31). These movements put enormous pressure on the Earth’s crust. When the pressure becomes too strong, the crust folds, fractures and heaves. In other words, mountains form, earthquakes occur and volcanoes erupt. Most of these geological phenomena occur at the edges of the plates.

a) Two plates move apart: this is a divergence zone (or rift).

b) Two plates move toward each other: this is a convergence zone (or subduction zone).

Figure 31 The three types of movements involving two plates

ENCYCLOPEDIA

318 The Earth and Space

c) Two plates slide against each other: this is a slip zone (or transform fault).

When two plates move apart, a fault appears in the crust. Magma can infiltrate this fault and form new crust (see Figure 32). This is what occurs along the length of the oceanic ridges.

Fault A fissure in the Earth’s crust.

Lithosphere

NEWS FLASH…

Figure 32 The distancing

of two plates creates a fault into which magma can infiltrate.

Asthenosphere

But the Earth is round and entirely covered with crust. In other words, if new crust is formed in one place, it must disappear from another. This disappearance occurs when two plates collide.

Drill holes are used to collect mineral substances, such as oil. These drill holes are several hundred metres deep. The deepest offshore drill hole lies in the Pacific Ocean. It reaches a depth of 2.1 km. On land, the deepest drill hole is in Russia. Its depth is approximately 12.3 km. At this depth, the temperature rises to 200ºC. It is measured with probes set into the drill rods.

Take, for instance, the South American Plate. It is being pushed toward the Pacific Ocean because the Mid-Atlantic Ridge is growing. In the Pacific Ocean is the Nazca Plate. It is pushed toward the American continent by the East Pacific Ridge (see Figure 33). The result? The Nazca Plate—which is thinner—slides slowly beneath the South American Plate. As it sinks into the mantle, the Nazca Plate melts and is transformed into magma. A portion of the Earth’s crust is therefore disappearing, to be recycled in the mantle.

Andes

Pacific Ocean

Nazca Plate

South America

South American Plate

Figure 33 The Nazca

Plate is sinking slowly beneath the South American Plate.

SECTION 2

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Trench

HISTORY

A large and very deep cavity.

OF SCIENCE After studying economics, history and physics, Jacques Piccard (born 1922) collaborated with his father, engineer Auguste Piccard, to build a bathyscaphe, a submersible able to descend to great depths. In January 1960, he and American naval officer Don Walsh reached a depth of 10.9 km in the Marianas Trench near Japan. They discovered the flora and fauna of the ocean trenches, which are very different from those that develop in the light of the sun.

When one plate sinks beneath another plate, an oceanic trench is formed. The deepest is the Marianas Trench in the Pacific Ocean. It is so deep that the whole of Mount Everest would fit inside (see Figure 34).

Height of Mount Everest

11 000 m

8850 m

Depth of the Marianas Trench Figure 34 The Marianas Ocean Trench

Sometimes two colliding plates are both too thick for one to sink below the other. This is the case with collisions between two continental plates. The Earth’s crust folds and mountains surge up from the ground. The Himalayan mountain chain resulted from the collision of the Indian-Australian Plate and the Eurasian Plate (see Figure 28 on page 317). The Himalayas are still being formed because the forces that caused this collision are still active (see Figure 35).

Figure 35 The Himalayas are a mountain chain that is still being formed. Mount Everest, at 8850 m, is considered the Earth’s highest peak.

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320 The Earth and Space

Scientists predict that in 30 million years, Los Angeles and San Francisco will be at the same latitude. They also predict that the Mediterranean will gradually close up. They believe Turkey will be pushed west by Arabia, while the latter will fuse with central Europe. Moreover, Australia might collide with the Sunda Islands (see Figure 36 on the following page).

3 ● 1 ●

5 ●

4 ●

2 ●

6 ●

1 North America ● 2 South America ● 3 Europe ● 4 Africa ● 5 Asia ● 6 Oceania ● 7 Antarctica ●

7 ● Figure 36 According to scientists, the continents might look like this in 30 million years.

Memory Check* 1. Alfred Wegener put forward the idea that the continents were shifting. Explain how the following elements caused him to reach this conclusion: a) Examining various geographical maps b) Observing the age and rock composition of certain mountain chains c) Studying certain fossils 2. Why didn’t the scientific community accept Wegener’s ideas? 3. a) What is a supercontinent? b) Describe Wegener’s supercontinent. 4. The invention of sonar enabled the underwater depths to be mapped. a) Name two discoveries made in the 1960s that had to do with underwater relief. b) How did John Tuzo Wilson explain the formation of the oceanic ridges?

5. a) What is the asthenosphere? b) How did the discovery of the asthenosphere give credibility to Wilson’s theory of plate tectonics? 6. What is the difference between continental drift and plate tectonics? 7. a) According to scientists, what phenomenon makes the tectonic plates move? b) How fast do the plates move? 8. a) What are the three types of plate movements? b) What type of movement causes new crust to form on the Earth’s surface? Describe this process. c) What type of movement causes some of the Earth’s crust to disappear? Describe this process. * These questions allow you to check your knowledge of concepts covered in the units of Textbook A.

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Volcanoes: The Wrath of Vulcan Eruption The surface runoff of volcanic matter (lava, ash, carbon dioxide, etc.) from the depths.

Extinct volcano A volcano that is no longer active.

Volcanoes are both fascinating and terrifying. A volcano is probably one of the most spectacular manifestations of the Earth’s internal dynamics. During a volcanic eruption, the heat emitted is intense. The Sun disappears temporarily, masked by clouds and suffocating ash. Rivers of lava threaten neighbouring populations (see Figure 37). Fortunately, most volcanoes on the Earth are extinct or dormant. But sometimes the Earth’s crust breaks. Openings form, allowing lava, smoke and ash to escape. A volcano awakens and becomes active. All over the world, teams of scientists are now at work attempting to predict volcanic eruptions. Their goal is to warn nearby populations in time.

The Structure of a Volcano The word “volcano” comes from Vulcan. In Roman mythology, Vulcan was the god of fire and metalworking. He is also said to be the god of blacksmiths. His name means “imperious and ardent will.”

There are various types of volcanoes, but most have certain points in common. Figure 38 shows the main parts of a typical volcano. Volcanic activity often depends on the geography of the volcano and its surroundings, as well as the type of lava expelled. Eruptions can be unleashed from the crater or from a fissure somewhere else. The eruption does not always take place at the peak of the volcanic cone. It can occur on the volcano’s flanks or even some distance from the cone.

Lava flow

Volcanic projections

Crater Main volcanic cone

Main chimney

Magma chamber (reservoir)

Figure 37 The 1986 eruption of

Mount Augustine in Alaska

ENCYCLOPEDIA

322 The Earth and Space

Figure 38 The structure of a volcano

Secondary volcanic cone Secondary chimneys

Volcanic Eruptions There is a relationship between volcanoes and tectonic plates. The collisions between the plates involve enormous quantities of energy. These events often shake the Earth’s crust. They can lead to the formation of “mountains of fire” in places where the crust is weak.

Continental plate

HISTORY Volcanologists are scientists who study the formation and activity of volcanoes. Volcanologists Katia (1947–1991) and Maurice Krafft (1946–1991) worked in close proximity to erupting volcanoes. In doing so, they produced impressive photos and films of volcanic activity. They also saved many lives by helping to evacuate communities from dangerous areas. Unfortunately, their fascination with volcanoes also caused their deaths during an eruption on the Japanese island of Shimabara in 1991.

SCIENCE

A chain of volcanoes

The magma that gushes from an erupting volcano. Lava appears in the form of rivers of melted matter.

OF

Take the example of an oceanic plate that sinks under a continental plate (see Figure 39). As the oceanic plate penetrates the mantle, it melts and is transformed into magma. The magma strives to rise to the surface. It makes its way through faults in the crust. Sometimes, lava that has cooled after an ancient eruption acts as a cork, blocking the volcano’s crater. Then, melted rock and gases from the Earth’s interior accumulate in the magma chamber. The pressure rises. When the pressure becomes too strong, it pops the cork. At this moment, the accumulated energy rises to the surface with great force. This produces violent explosions, accompanied by projections of lava, rock, ash and carbon dioxide.

Lava

Oceanic plate Magma

Melting crust

Figure 39 Areas in which an oceanic plate sinks under a continental plate are conducive

to volcano formation.

SECTION 2

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323

Other volcanoes form in places where two tectonic plates move apart. They are not as violent as those described above. In such cases, lava and gases exit the crater and meet no resistance. They then pour out slowly (see Figure 32 on page 319).

Geyser A jet of heated water and water vapour that gushes from a fissure in the ground.

Volcanoes are not only agents of destruction. They also help to transform the landscape and fertilize the soil. Moreover, electricity can now be produced by tapping magma’s energy. In Iceland, magma heats underground bodies of water. The water rises to the surface in the form of geysers (see Figure 40). This water is used for heating and other daily needs. Iceland, in fact, is an uplifted portion of the Mid-Atlantic Ridge.

a) Water heated by magma boils and bubbles.

b) A jet of water gushes at regular intervals.

Figure 40 Two geysers in Iceland

Memory Check* 1. How does the collision between an oceanic plate and a continental plate create a volcano? 2. Explain how two plates moving apart create a volcano. 3. What is the difference between magma and lava? * These questions allow you to check your knowledge of concepts covered in the units of Textbook A.

ENCYCLOPEDIA

324 The Earth and Space

Earthquakes: When the Earth Trembles Earthquakes, tremors or seisms. Each of these terms describes the same phenomenon: the movement of the Earth’s crust. This movement is often caused by contact between two tectonic plates. At the moment of contact, the friction between the plates produces shock waves of varying intensity. These shock waves, also called seismic waves, can flatten entire towns in a matter of seconds (see Figure 41).

Seismic waves Waves that spread through the ground in every direction from an earthquake’s point of origin.

NEWS FLASH…

a) Following the 1995 earthquake, residents of Dinar, Turkey, take in the extent of the disaster.

In Québec, it is not the contact of two plates that causes most earthquakes. Here, they are commonly provoked by fractures— many of which result from meteoroid impacts. Ever since the melting of the glaciers, approximately 10 000 years ago, the continent has been gradually rising. Each rise produces earthquakes in the weakest—or most heavily fractured—zones. The Charlevoix region is particularly vulnerable to this type of earthquake.

b) Collapse of a highway in Kobe, Japan, after the earthquake in 1995 Figure 41 An earthquake can cause enormous damage in only

a few seconds. SECTION 2

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325

The Causes of Earthquakes Seismologists Scientists who study earthquakes and the propagation of waves in the Earth’s crust.

The movements of the tectonic plates can trigger earthquakes. Seismologists have classified these movements into three categories. First, two tectonic plates can collide. Then, the plates can move apart. Finally, they can slide against each other (see Table 6). Table 6 Tectonic plates and earthquakes

Tectonic plate movement

NEWS FLASH… On December 26, 2004, an underwater earthquake of a magnitude of 9.0 on the Richter scale occurred. It created a tsunami 10 m high. The tsunami hit Indonesia, Sri Lanka, India and Thailand most heavily. The scale of human loss was catastrophic: over 230 000 victims. It is one of the five most powerful earthquakes ever recorded. The earthquake is thought to have originated on the border of the Indian-Australian and Pacific plates. The upper plate was shoved 20 m higher, the height of a six-storey building. It was this movement that gave the tsunami its energy.

Illustration

Characteristics of earthquakes triggered by this movement

Two tectonic plates collide

– Pressure can make the Earth’s crust fold (formation of mountains). – One of the plates can sink beneath the other (formation of oceanic trenches). – Major earthquake zone.

Two tectonic plates move apart

– Magma escapes through the fault between the plates. – Zone of relatively superficial earthquakes that cause little damage.

Two tectonic plates slide against each other

– The plates move along a fault. – Zone of serious earthquakes due to the friction of the plates.

Three-quarters of the Earth’s surface is covered with water. Most earthquakes, therefore, occur under water. At such moments, enormous waves called tidal waves are often formed. These waves are also called tsunamis, a Japanese word meaning “harbour wave.” These waves travel very quickly. When they reach the continental shelf, they become higher and higher. When they hit the coastline, they can be up to 30 m high.

ENCYCLOPEDIA

326 The Earth and Space

Vulnerable Zones

NEWS FLASH…

Certain regions of the globe are more vulnerable to earthquakes than others. These regions are located along the edges of the tectonic plates, in zones of major volcanic activity. These zones are the Pacific Ring of Fire, the MidAtlantic Ridge, the Mediterranean perimeter and the Great Rift Valley in Africa. The Ring of Fire is a series of volcanoes that circle the Pacific Ocean. These volcanoes are found near the oceanic trenches (see Figures 42 and 43).

In the 1960s, many countries obtained seismographs. These devices enabled them to precisely locate the borders of the tectonic plates, where most earthquakes occur.

LEGEND Edge of tectonic plate Principal volcanic eruptions of the 20th century

Eurasian Plate

R

G IN

O F

North American Plate

F I R E

Juan de Fuca plate Philippine Sea Plate

Pacific Plate

Cocos Plate

Caribbean Plate

PACIFIC OCEAN

Nazca Plate

W

Indian-Australian Plate

Juan de Fuca Plate Scale at the equator

Antarctic Plate

Figure 42 This map shows the volcanoes of the Pacific Ring of Fire.

PACIFIC OCEAN

North American Plate UNITED STATES

Memory Check*

San Andreas Fault

Pacific Plate

1. What is the relationship between plate tectonics and earthquakes? 2. What happens when an earthquake occurs under water? 3. A map of the major volcanoes looks a lot like a map of the major earthquakes. a) Name at least three zones these two maps have in common. b) How can you explain the similarities between the location of the volcanoes and that of the earthquakes? c) What are the characteristics of earthquakes triggered by the three types of tectonic plate movements? * These questions allow you to check your knowledge of concepts covered in the units of Textbook A.

MEXICO

Scale

LEGEND Edge of tectonic plate

Figure 43 Certain cities lie very close

to a fault. They are therefore more vulnerable to earthquakes. San Francisco, Los Angeles and San Diego were built along the San Andreas Fault in California. SECTION 2

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Orogenesis: Mountain Formation We know today that most of the so-called younger mountainous regions are found in zones where tectonic plates collide. By learning more about plate behaviour, we can better understand the process of mountain formation. This process is called orogenesis. When two continental plates collide, the Earth’s crust warps (see Figure 44). It folds over and lifts. In doing so, it creates mountain chains, such as the Himalayas or the Alps. A mountain is a landform with steep slopes and an altitude of at least 600 m. The highest summit on the Earth is 8850 m high. That is Mount Everest in the Himalayas. Mountains are easy targets for wind, water, ice and several other erosion factors. These factors are continually acting on mountains, and each transforms them in its own way.

Figure 44 When two continental

R IDGE

plates collide, the Earth’s crust folds, creating a mountain chain.

N

O

RT

H

AT L

AN

T IC

Mount Royal, Mont St. Bruno and Mont St. Hilaire are some of the Monteregian Hills. The Monteregians are not volcanoes. They were formed following an intrusion of magma in the upper portion of the Earth’s crust. Erosion gradually wore away the soil around and above the solidified magma.

Memory Check* 1. What is the difference between a hill and a mountain? 2. What is the difference between a mountain and a volcano? 3. What is the relationship between plate tectonics and mountain formation? * These questions allow you to check your knowledge of concepts covered in the units of Textbook A.

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328 The Earth and Space

HISTORY OF

Erosion

No matter how hard they are, rocks don’t last forever. Under the effects of wind, water, and ice, they wear down and break up. Erosion weakens and weathers rocks. Rock fragments can remain in place or be transported by glaciers, wind and streams. They are then deposited in the form of sediment. Erosion results in a flattening of landforms. Erosion invariably tends to make mountains lower and fill in valleys. Figure 45 illustrates the three stages of erosion: 1. Weathering. Runoff and the freeze-thaw cycle fragment surface rocks. 2. Transportation. Rock fragments are carried by runoff water and wind. Erosion is compounded by the abrasive power of fragments transported by the water.

James Hutton (1726–1797), a physician and agricultural chemist, is considered the father of geology. Geology is a science that studies the Earth, its transformations and its composition. Hutton observed changes in the landscape—the erosion of riverbanks, for instance, and the crumbling of cliffs. He deduced that it took millions of years to produce the Earth’s present landforms. His contemporaries, however, contested his research because they estimated that the Earth was only 6000 years old.

SCIENCE

When you walk outside, you might be forgiven for thinking that the landscapes around you never alter. But if you took a walk every 5000 years, you would notice enormous changes. The movement of tectonic plates is at the root of many of these changes. However, there is another force at work transforming the Earth’s landscape: erosion.

3. Sedimentation. At the end of their journey, the fragments suspended in water or transported by glaciers or wind accumulate and are compacted at the bottom of the ocean. They also accumulate in valleys and plains.

2. Transportation 1. Weathering

3. Sedimentation

Figure 45 The three

stages of erosion

Weathering comes about in different ways. The main agents of the fragmentation of surface materials are water, wind and the freeze-thaw cycle. Water can act in its liquid form or as ice or water vapour. Erosion is a natural phenomenon, but certain factors can slow down its actions. For instance, plant roots hold soil in place. In that way, they protect it from the degradation caused by runoff water and winds. Cutting trees on mountainsides should be avoided because they retain soil and prevent landslides.

SECTION 2

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Categories of Erosion Rocks that compose the Earth’s surface are subject to various factors. Wildlife, plant life and the climate are a few of the factors of erosion.

Biological Erosion This type of erosion is caused by living organisms, such as animals and plants. When they decompose, living organisms release acidic substances that attack rocks. Tree roots infiltrate the fissures of rocks, ultimately breaking them (see Figure 46).

Figure 46 Tree roots can cause

biological erosion.

Mechanical Erosion This type of erosion is caused by variations in temperature and pressure, or by wind and water (see Figure 47). This is a physical process that fragments rock, but does not change its chemical composition.

Chemical Erosion

Figure 47 Niagara Falls spans the

Sometimes rain becomes acidic because of pollutants in the air. When this acid rain falls, it chemically changes certain minerals in the soil (such as limestone), a process that gradually destroys rocks (see Figure 48).

border between Canada and the United States. Every year, they recede by 3 m because the water wears down the rock.

Figure 48 Acid rain alters the

surface of public monuments. ENCYCLOPEDIA

330 The Earth and Space

Aging Mountains Contrary to what might be believed, mountains age. Of course, their aging process is different from that of a human being. Yet both mountains and humans have one thing in common: their appearance depends on their age. A young mountain has a high and pointed peak. An old mountain has a rounded shape (see Figure 49). The youngest mountain chains are the Alps, the Himalayas, the Rockies, the Caucasus Mountains and the Andes. These are mountains with very sharp relief, with steep slopes and pointed summits. Most of them are still growing because the shift of the tectonic plates that formed them is ongoing. The Laurentians, the Appalachians and the Australian Cordillera are old mountain chains. They are more rounded and flattened because they have endured erosion’s effects for a longer time. In fact, hundreds of millions of years ago, the Laurentians were as high as the Himalayas.

a) The Laurentians

b) The Rockies

Figure 49 The Laurentians, at left, are a group of very old mountains: their peaks are rounded and

relatively short. The Rockies, at right, are much younger. Their peaks are pointed and very high.

Memory Check 1. a) What would the Earth’s landforms look like if they were completely eroded? b) Will the day ever come when all landforms are completely eroded? 2. Name the three categories of erosion, then describe them. 3. What are the principal factors that affect erosion?

4. Is it possible to slow down erosion? If so, how? 5. a) Why are the Himalayas getting higher and higher? b) Why are the Laurentians getting lower and lower?

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The Water Cycle Precipitation

HISTORY

The various forms that water takes to return to the ground: rain, snow, hail, ice pellets, freezing rain and sleet.

OF SCIENCE Luke Howard (1722–1864) was a British pharmacist with a passion for meteorology. Howard kept a journal in which he wrote detailed descriptions of the weather. His notes provide a precious window on the weather of his era, long before the existence of weather reports. His journal contains descriptions of the shapes of clouds, and estimates of their altitude. Howard gave the clouds Latin names like cirrus, stratus, cumulus and nimbus. These names are still used today.

Take a look at a globe. The first thing you’ll notice is that the dominant colour is blue. In fact, 75 percent of the Earth’s surface is covered with water. Every day, a vast number of water molecules evaporate with the action of the Sun’s rays. However, the total quantity of water on the Earth and in the atmosphere remains constant. This is because water is constantly being recycled. All the water that evaporates ultimately falls to the ground in the form of precipitation. Water always returns to its point of departure because of its successive changes of state. This is what we call the water cycle (see Figure 50). Water follows a cycle: there is therefore no beginning or end. Water travels constantly between the oceans, the atmosphere and solid ground. This continual circulation of water is divided into four main stages: 1. Evaporation transforms the water of the oceans and other bodies of water into water vapour. In this way, water passes to the gaseous state. Living things, through respiration and transpiration, also produce water vapour. This phenomenon is also called evapotranspiration. All of this water vapour ends up in the atmosphere. 2. When the water vapour crosses a colder zone, it turns liquid again. This is condensation, or cloud formation. Clouds are made of groups of water droplets. These droplets have condensed on flecks of dust in the atmosphere. 3. The minuscule droplets of water that form clouds gradually enlarge. Ultimately, they become too heavy to remain in the atmosphere. They then fall to the ground in the form of precipitation. 4. Then, the water returns to waterways via runoff over the Earth’s surface. The water can also seep to underground reservoirs by infiltration.

Condensation

Precipitation

Evapotranspiration Evaporation

Figure 50 Water is continually being

transformed. It travels from the Earth’s surface to the atmosphere in an endless cycle: the water cycle. ENCYCLOPEDIA

332 The Earth and Space

Infiltration Runoff

Acid Rain Indirectly, the water cycle purifies the air. How? Most of the water that is evaporated comes from the oceans, which are salty. However, rainwater is not salty: it is fresh. The evaporation-condensation process therefore separates pure water from the substances dissolved in it. In its natural state, rainwater is slightly acidic because of the carbon dioxide (CO2) in the air. However, this acidity has sharply increased over the 20th century. This is due to the countless human activities that have disrupted the natural water cycle. Various pollutants from industry can be introduced into the water cycle at any stage. These pollutants change the pH value of water (see The Material World on page 186). Molecules of sulphur dioxide (SO2) and various nitrous oxides (NOX) escape from factories. Sulphur dioxide mixes with water vapour contained in the air. A chemical reaction occurs that produces sulphuric acid (H2SO4). This is why water becomes more acidic. Eventually, it falls to the ground again in the form of acid rain (see Figure 51). Acid rain is highly toxic to ecosystems. It also damages construction materials and is often the cause of changes to the exteriors of buildings and monuments.

Polluting gases

Winds

Acid rain

Figure 51 Once acid rain falls, polluting gases become part of the water cycle.

Memory Check 1. Describe the journey of a water molecule. Begin your account with the moment the molecule leaves the ocean via evaporation. End your account with the moment the molecule returns to the ocean. 2. How do the activities of living things affect the water cycle? 3. How does the water cycle purify water? 4. Explain how rain can become acidic. 5. What are the consequences of the acidification of rain?

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In Greek mythology, Aeolus was the god of the winds. The adjective “aeolian” is derived from his name.

Prevailing wind The wind that blows most frequently in a given region of the globe.

Winds: Aeolus’ Choice The you the you

air that surrounds us is in constant motion. On a hot summer’s day, can recognize a wind by the coolness it brings. Sometimes, in winter, wind cuts right through you because of the intense cold it makes feel.

Prevailing winds are not distributed evenly over the Earth’s surface. Two factors explain their particular distribution: the unequal warming of the atmosphere (convection cells) and the rotation of the Earth (the Coriolis effect) [see the following page].

Convection Cells NEWS FLASH… Cyclones are violent winds that blow in a circular pattern around a centre called an eye. Most cyclones are born over warm seas. They are called hurricanes in the Caribbean Sea and Gulf of Mexico, and typhoons in the western Pacific. To distinguish cyclones, each is given a name. There are six different lists of male and female names. Every year, a different list is used. When a cyclone causes major damage, its name is withdrawn and replaced with another. The year 2005 saw a record 26 cyclones. When the list ran out, the letters of the Greek alphabet were used to name the last five cyclones.

Air is heated unequally over the Earth’s surface. This determines the general circulation of air masses (see Figure 52). Take, for instance, the equatorial region. Here, the Sun’s rays directly hit the ground. The ground absorbs solar energy. This energy is then released from the ground in the form of heat. The surrounding air warms, increases in volume and lightens. It rises in altitude. This creates a low-pressure area (or depression) at ground level. Air that is cooler and therefore heavier has a tendency to move in and replace the air in the low-pressure area. Thus, the hot air mass and the cold air mass are constantly in motion. The looping movements of these air masses are called convection cells. They are a way of explaining global atmospheric circulation.

60° N

30° N

30° S

60° S

Figure 52 There are six convection cells on the Earth’s surface.

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334 The Earth and Space

Convection in Daily Life Convection plays a role in several phenomena. Scientists, for instance, believe that convection currents in magma help move the tectonic plates (see page 317). On a smaller scale, convection is used in household heating systems (see Figure 53). It is also used in ovens and stoves. Household heating systems are installed in basements mainly because of convection. Warm air rises and heats the rest of the house.

The Coriolis Effect When studying prevailing winds, we must also consider the rotation of the Earth. The Earth turns on its axis like a top, from west to east. This rotation diverts the air masses in the atmosphere to the right (in the Northern Hemisphere) or to the left (in the Southern Hemisphere). This is called the Coriolis effect. Gaspard Coriolis was a French mathematician and physicist. In 1835, he showed that the air’s motion changed direction because of the rotation of the Earth. This movement produces the following winds: • The trade winds, which blow from east to west between the equator and the tropics • The prevailing west wind which blows from west to east in the middle latitudes • The polar east wind which is diverted to the west in the polar regions (see Figure 54) North Pole

Figure 53 A convection current

created by a home heating system

Polar east winds 60° N

Prevailing west winds 30° N Equator

Doldrums

Northeast trade winds Equatorial doldrums Southeast trade winds Prevailing west winds

South Pole

30° S

60° S Polar east winds

Figure 54 The Earth’s rotation diverts atmospheric currents, which gives rise

to prevailing winds.

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The Characteristics of Wind Did you know that winds of all kinds blow in the four corners of the planet? Some of them are gentle, others are hot or cold. Still more are dry or wet. Some are famous for carrying dust. These winds have names like trade wind, chinook, mistral, nor’wester, sirocco and zephyr. In general, wind can be characterized by two elements: direction and speed. The direction of the wind is determined with a weather vane (see Figure 55). Weather vanes point in the direction the wind is coming from (its origin). When they point south, this indicates that the wind is coming from the south and heading north. For a weather vane to work properly, its back half must be larger than its front half. A weather vane is not always arrow-shaped. It is often equipped with a compass rose, which indicates the cardinal points. Wind speed is measured with an anemometer (see Figure 56). It is expressed in kilometres/hour. Wind speed can also be estimated with the Beaufort scale by interpreting the wind’s effect on certain elements in the environment. Figure 55 Weather vane and compass rose

indicating the wind’s direction

Figure 56 Anemometer indicating

wind speed

An instrument exists that indicates both wind force and direction: a wind sock (see Figure 57). They are often found on the edges of fields or near airport landing strips.

A wind sock measures both the wind’s force and its direction.

Figure 57

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336 The Earth and Space

Sea Breeze Have you ever noticed that there is nearly always a gentle breeze blowing at the seaside? This breeze is created by the temperature difference between the air above the water and the air above the land. On a hot, sunny day, the sand warms faster than the water. The air over the sand is therefore warmer than the air over the sea. This hot air rises in altitude. It is replaced with cool air that was previously massed over the sea. Now it is the cool air’s turn to be warmed. This movement of air masses produces a breeze that blows from the sea to the land. Since winds are named after their point of origin, it is called a sea breeze.

NEWS FLASH… Sailors used the principle of breezes to sail out to sea. Crews often left before sunrise, taking advantage of the land breeze that pushed them from the shore. Later on in the day, the sea breeze helped them return home.

Land Breeze Similarly, the ground cools faster than the water when the sun disappears. Thus, at night, the air above the sand is cooler than the air above the sea, producing a wind that blows from the land to the sea. This is what is called a land breeze. Figure 58 compares the two breezes.

Sea breeze is a wind that blows from the sea to the land during the day.

Land breeze is a wind that blows from the land to the sea during the night.

Figure 58 Sea breezes and land

breezes blow in different directions.

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Smog and Temperature Inversion The word “smog” is an amalgamation of the words smoke and fog.

Normally, the higher you rise in the troposphere, the cooler the air gets. But this is not the case when a cool air mass settles under a warm air mass. Cool air, which is heavier, stays close to the ground. The warm air above prevents it from rising and dispersing. All of the air therefore becomes stable: it does not move, which is unusual. We are witnessing temperature inversion at low altitude (see Figure 59). In industrial zones, this phenomenon can be dangerous. Certain atmospheric pollutants can remain imprisoned in the cold air mass above ground. These substances can be harmful for the environment and living things (see Figure 60 on the following page).

high pressure (cold air)

inversion layer of warm air stagnant smog layer

air cooled by the ocean ocean Figure 59 Temperature inversion

When there is a temperature inversion, atmospheric pollutants remain near the ground. They contaminate the air we breathe. Sometimes they mingle with water vapour. Then they form a cloud of polluted fog called smog. In general, the Earth warms during the day. The cold air mass and its pollutants ultimately dissipate. But if the temperature inversion persists, the fog created by dust particles imprisoned in the cold air mass can thicken. This can cause serious long-term pollution problems.

ENCYCLOPEDIA

338 The Earth and Space

Figure 60 The city of Montréal under

clear skies (above) and covered with smog (at right)

Memory Check 1. What are the two main factors that explain the distribution of prevailing winds on our planet? 2. Draw a diagram of an atmospheric convection cell. 3. What direction does the prevailing wind take in Québec? 4. Airplane pilots must take the Coriolis effect into account. In your opinion, what wind direction would facilitate an airplane flight between Canada and France at its departure (Montréal–Paris) and then on the return flight home (Paris–Montréal)? Why? 5. a) What instrument determines wind direction?

b) What instrument measures wind speed? c) What does a wind sock do? 6. Land warms more quickly than water. It also cools more quickly than water. a) Explain how these two phenomena give rise to sea breezes and land breezes in coastal regions. b) How do sailors use sea breezes and land breezes to sail? 7. Describe the weather conditions necessary for smog formation.

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Natural Energy Sources NEWS FLASH… An automobile’s brakes use friction force to transform kinetic energy into thermal energy. When a driver puts on the brakes, they become hot. If the driver uses the brakes excessively, they can become as red as the heating element on a stove. This is the reason why cooling systems for automobile brakes are essential.

Balancing Rock, on Long Island near Tiverton, Nova Scotia, is a spectacular example of potential energy stored in a rock.

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340 The Earth and Space

Energy is manifested naturally in our environment. But humans can also transform energy artificially. Energy is different from matter because it has no mass and occupies no volume. It is studied through its effects on matter. Energy can take different forms. They include: • Kinetic energy • Chemical energy • Potential energy • Nuclear or atomic energy • Thermal energy • Radiant energy In their quest for comfort, humans have attempted to reproduce these natural forms of energy. Table 7 describes each of these energy forms. It also gives examples of their natural and artificial sources.

Table 7 Forms of energy and their natural and artificial sources

Energy form Potential energy

The energy stored in an object because of its position above the Earth’s surface.

Natural sources – As long as a rock on a mountain peak does not move, it possesses potential energy. – When the wind blows it over and it rolls down the slope, the rock releases kinetic energy. – The higher the slope, the greater the quantity of kinetic energy released. Artificial sources – Elevators – The energy accumulated in a compressed spring

Kinetic (energy of movement)

The energy of an object in motion.

Thermal (or heat) energy

The energy generated by the movement (or agitation) of particles that compose matter (see The Material World, page 177). – The more intense the particles’ agitation, the greater the thermal energy. – The weaker the particles’ agitation, the colder the object.

Natural sources – Geysers and natural hot springs

Energy stored in matter. – This energy is released when products react with each other. Bonds between the atoms break and new substances are formed.

Natural sources In cellular respiration, the cells of living organisms transform sugars and use the energy released in the process.

Chemical energy

Artificial sources In northern countries, heating systems produce heat in winter.

HISTORY Henri Becquerel (1852–1908) discovered radioactivity by chance in March 1896. Marie Curie (1867–1934) and her husband, Pierre Curie, followed up on Becquerel’s work. She discovered that radium and polonium were radioactive. Henri Becquerel, Pierre Curie and Marie Curie shared the Nobel Prize in Physics in 1903. Marie Curie was the first woman to win the Nobel Prize. She received a second one for her work in chemistry in 1911.

SCIENCE

Examples

OF

Description

Artificial sources – Fireworks – Automobile airbags Nuclear energy (or atomic energy)

The powerful energy released when atoms split or fuse. – This energy is stored in the nuclei of atoms.

Natural sources Nuclear energy is produced in the Sun’s core by the fusion of hydrogen nuclei. Other stars produce nuclear energy in similar ways. Artificial sources – Innovations in nuclear medicine – Atomic bomb

Radiant energy

Energy transmitted by electromagnetic waves (see page 350). – It can be absorbed and reflected by objects. – One form of this energy (visible light) enables us to see objects.

Natural sources – Sunlight – Animals as small as fireflies manufacture light. Artificial sources – Electricity and light bulbs – Microwave ovens – Mobile phones

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Are Energy Sources Limitless? Energy sources are raw materials or natural phenomena. They are classified according to whether they are renewable or nonrenewable. Nonrenewable energy sources, such as gas and coal, do not regenerate when they are used. Renewable energy sources, such as sun or wind, cannot run out. They will be there as long as there is a sun.

Sun, wind 2.3%

In managing energy resources, humans are faced with a major problem. Nonrenewable energy sources are diminishing, while their consumption is rising. Some scientists predict that by 2010, demand for oil will exceed the oil industry’s capacity to supply it. In a hundred years, we will have managed to exhaust the oil that nature has taken 100 million years to produce. The development and use of renewable energy must therefore be encouraged. Tables 8 and 9 present the different sources of renewable and nonrenewable energy.

Atomic 4.5% Water 5.8% Biomass 10.2% Natural gas 19.3%

Oil 31.8%

Coal 26.1% Energy consumption according to source

Table 8 Nonrenewable energy sources

Energy source and description Fossil fuels (coal, oil, natural gas)

Form of energy

Advantages

Thermal energy

Simple facilities

– This kind of energy is relatively polluting (pollution varies according to the fuel used). – It causes acid rain. – It releases greenhouse gases and thus contributes to global warming. – It uses resources that have taken millions of years to form.

Nuclear energy

– Production of large amounts of energy. – This kind of energy does not pollute the atmosphere. – This kind of energy has several applications.

– It generates waste that remains radioactive for thousands of years. – It enables highly destructive weapons to be designed.

– Reserves are difficult to get at. – Reserves are distributed unequally over the Earth’s surface. Uranium (among others) – Uranium is found in many rocks, but in small quantities. – Mining is difficult and very expensive.

ENCYCLOPEDIA

Disadvantages

342 The Earth and Space

Table 9 Renewable energy sources

Energy source and description

Form of energy

Advantages

Disadvantages

Water – Pressure created by a waterfall

Hydraulic energy

– Low-polluting energy – Low operating costs – Highly reliable source of energy – Facilities are long lasting.

– Large-scale facilities – High cost of facilities – Facilities require large areas to be flooded (loss of habitat). – Construction of facilities compromises biodiversity and local populations.

Wind – Wind force

Wind energy

– This kind of energy has little impact on the environment. – Wind turbines can be dismantled and the landscape restored to its former condition. – Wind turbines can be installed in the sea and on land.

– There are few regions where winds are sufficiently strong and regular. – This energy source is irregular because the wind does not always blow. – Wind turbines are vulnerable to bad weather and can malfunction. – Back-up energy sources must be available. – Wind turbines’ high masts mar the landscape. – Wind turbines can have negative health effects.

Geothermal – Extraction of the ground’s internal heat – Geysers and hot springs

Geothermal energy

– This kind of energy does not contribute to the production of greenhouse gases. – Low operating costs – This kind of energy provides hot air in winter and cool air in summer (heat pump).

– This kind of energy can only be used only in certain areas. – High cost of facilities – This kind of energy is not easily transported.

Tidal – Movement of the tides

Tidal energy

– Energy always available – This kind of energy conserves resources. – Low operating costs

– Construction of facilities requires large areas to be flooded (loss of habitat). – Facilities work only part of the day.

Solar – Radiant energy from the sun – Artificial light

Solar energy

– Using this kind of energy allows nonrenewable forms of energy to be conserved. – Nonpolluting energy – Low operating costs – Small facilities can power a pool, boat, etc.

– This source of energy is irregular because it is not always sunny. – Back-up energy sources must be available. – Low energy output – High production costs

Biomass (wood, manure, agricultural waste, biogas) – Waste reclamation

Thermal energy

– Infinitely renewable energy – This kind of energy produces few greenhouse gases. – Reclamation of forest, agricultural and municipal waste

Burning of wood can have a more negative effect on the environment than expected.

Memory Check* 1. Indicate whether each of the following objects is a potential, kinetic, thermal, chemical, nuclear or radiant energy source. a) Batteries to power a radio b) An atomic bomb c) An apple in an apple tree d) A hockey puck sliding across the ice

e) An apple being eaten f) A radiator to warm your feet 2. Why are fossil fuels considered nonrenewable energy sources? 3. Wind turbines and solar panels provide renewable energy. Why aren’t there more of them around? * These questions allow you to check your knowledge of concepts covered in the units of Textbook A.

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S ECTION 3 Astronomical Phenomena Light

p. 345

The Properties of Light

p. 346

The Electromagnetic Spectrum p. 350

Don’t Wear a Black T-Shirt

p. 348

The Secrets of White Light

p. 348

The Terrestrial Planets

p. 354

The Gas Giants

p. 355

The Law of Universal Gravitation p. 351 The Sun SECTION

1

General Characteristics of the Earth SECTION

The Earth and Space

2

Geological Phenomena SECTION

p. 352

The Waltz of the Planets The Birth of the Solar System

p. 353

p. 352

3

Astronomical Phenomena

Pluto, the Dwarf Planet p. 356

Natural Satellites

p. 357

Comets

p. 357

The Rotation of the Earth

p. 359

The Revolution of the Earth p. 360 The Earth

p. 359

Polar Auroras

p. 363

Meteoroid and Asteroid Showers p. 365

Meteoroids

p. 364

The Effects of Meteoroid and Asteroid Showers p. 365

The Phases of the Moon The Moon

ENCYCLOPEDIA

Shooting Stars

p. 366

Solar Eclipses

p. 370

Lunar Eclipses

p. 371

p. 369

p. 368 Eclipses

344 The Earth and Space

Why Is It Hot at the Equator and Cold at the Poles? p. 362

p. 370

Overview

At our solar system’s centre, there is an enormous ball of gas: the Sun. This star gives off a vast amount of energy in the form of radiation of all kinds. One of the forms of radiation lets you see the objects around you: it is sunlight. Sunlight is essential to life on Earth. It is absorbed by plants and enables them to manufacture food via photosynthesis (see The Living World on page 284). The succession of day and night determines humans’ and animals’ sleeping patterns. Variations in day length govern a number of phenomena, including migration and reproduction in certain animals. The largest source of natural light is the Sun. However, the Earth only absorbs approximately half the solar light it receives. The rest is dispersed into space or reflected off the Earth’s surface (see Figure 61).

Radiation absorbed by

Solar radiation that enters the Earth’s atmosphere (100%)

Human beings are able to manufacture a light brighter than the Sun: laser light. A laser emits enough energy to pierce metal. If its power is reduced, it can be used in medicine—to correct myopia, for instance. In commerce, lasers are used to read bar codes; in electronics, to read compact discs. In 1960, American engineer and physicist Theodore H. Maiman (born in 1927) manufactured the first laser. Maiman’s device emitted a beam using pulses produced by tubes, such as those in a camera’s flash. These pulses passed through a precious stone, a ruby. The entire device was no longer than a D alkaline battery.

SCIENCE

Light

HISTORY OF

Do you sometimes get the feeling that the Sun is crossing the sky during the day? Do you think, at night, that the stars are moving? Your senses can trick you into thinking that the Earth is immobile and that it is the sky that is turning. Humans, however, live on a planet, the Earth, that is making its way through the Universe like an immense spaceship.

Radiation reflected by

Air (6%) Air (16%) Clouds (20%)

Clouds (4%) Ground (4%) Ground (50%) Figure 61 Of all the solar

radiation entering the atmosphere, only half reaches the ground and is absorbed there. SECTION 3

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345

The Properties of Light Light is a form of energy. It can be of natural or artificial origin. The sun is the main source of natural light. Humans are capable of creating artificial sources of light—electric light bulbs, for instance. Most of the objects surrounding us are not sources of light. They do, however, have the capacity to reflect or absorb the light they receive. An object that absorbs light stores energy. It can give off this energy in another form. Light energy can be transformed into thermal energy (heat), mechanical energy (movement), electrical energy or chemical energy (see Table 7 on page 341, and The Technological World on page 398). The amount of energy that can be absorbed by an object depends on the intensity of the light and the nature of the object. The greater the light’s intensity, the more energy the object’s surface will absorb. On a hot summer’s day, for instance, in full sun, the metal balconies of some buildings can become extremely hot to the touch. However, as soon as clouds cut off the sun’s light, they begin to cool. In a movie theatre, when a tall person sits in front of you, part of the screen is hidden. This is because light travels in a straight line from its source (see Figure 62). When light encounters an obstacle, three things can happen: it can be stopped by the obstacle, go through it almost completely, or go through only partially.

Figure 62 Objects and people project shadows because light travels in a straight

line. Light cannot bypass objects it encounters.

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346 The Earth and Space

This is what happens in each case: • The obstacle is opaque, meaning nothing can be seen through it (for example, a person, a mirror, brick). In this case, light does not pass through at all: it is blocked by the obstacle. A shadow is formed behind this obstacle. • The obstacle is transparent, meaning it can be seen through (for example, glass, air, water). In this case, light goes through the obstacle almost completely. • The obstacle is translucent, meaning that light passes through it but what is on the other side cannot be seen (for example, wax paper, thin cloth). In this case, light goes through the obstacle only partially. A certain amount is absorbed (see Figure 63). Opaque

arent

Trans l

p Trans

ucen

t

Figure 63 Surfaces

absorb and reflect light in different ways.

Table 10 describes what happens to light when it hits different surfaces. Table 10 How light behaves when it hits different surfaces

Type of surface Opaque Rough and dark, e.g. a black wall

Absorption

Reflection

These surfaces absorb most of the light. They give off absorbed light in another form of energy, e.g. heat.

These surfaces reflect a small amount of the light in multiple directions (dispersion of light).

These surfaces absorb a small amount of the light.

These surfaces reflect most of the light.

Transparent

Light goes through these surfaces almost completely.

These surfaces reflect a small amount of the light.

Translucent

Light goes through these surfaces only partially. A certain amount is absorbed.

These surfaces reflect some of the light.

Smooth or pale, e.g. a white wall or mirror

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Don’t Wear a Black T-Shirt What happens when light hits an opaque obstacle? All opaque objects reflect some of the light that hits them. They absorb the rest. Dark-coloured objects reflect little light. They absorb most of it. They usually give off the absorbed energy in the form of heat. We call this phenomenon the black body effect. It explains why, in summer, you feel hotter when you wear dark clothes. You will also notice that asphalt becomes very hot in full sun. This phenomenon also explains why dark objects are difficult to see at night. Light-coloured objects reflect most of the light that hits them. They absorb little light and therefore transform little of it into heat (see Figure 64).

Figure 64 Dark colours tend

to absorb light. Light colours reflect light. The photograph shows a Madagascar lemur.

The Secrets of White Light Sunlight is white. Artificial white light also exists. Many people believe that white light is colourless and that something must be added to it to colour it. What do you think? Do you think that shining a beam of white light through a red filter will colour it red? Well, you’re wrong! In 1666, Isaac Newton showed that white light was in fact a mixture of different colours. Newton shone a beam of white light through a triangular glass prism. He then observed that the white light separated into several coloured beams on the other side (see Figure 65 on the following page). He deduced that the white light’s colour resulted from a mixture of all of the other colours (see Figure 67 on the following page).

ENCYCLOPEDIA

348 The Earth and Space

Triangular prism

White light

Figure 65 Newton used a triangular prism to separate white light into different

colours. In doing so, he demonstrated that the sum of all these colours produces white light.

Take the example of the red filter. In reality, this filter is not adding the colour red to the white light. Instead, it is blocking all of the other colours and only letting red pass. You might say that instead of adding red to the white light, the filter is removing all of the other colours. The series of colours contained in white light is called the visible spectrum of colours. In the visible spectrum, the colours go from red to orange to yellow to green to blue to indigo and then to violet.

Figure 66 The rainbow is a

perfect example of the sun’s visible spectrum of colours.

As you can see, these are the colours of the rainbow (see Figure 66). Red

Yellow

Magenta White

Green

Cyan

Blue

Figure 67 The more

colours are added, the paler the light. When all colours are present, the light is white.

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The Electromagnetic Spectrum White light is not the only radiation emitted by the sun. It was not until the late 19th century that scientists discovered this phenomenon. They called the range of the sun’s energy radiation the electromagnetic spectrum Table 11 Radiation emitted by the sun (see Figure 68). In this spectrum, Form of energy Characteristics the human eye perceives only the Radio waves Electromagnetic radiation with a very long wavelength. These waves are also part called visible light. But certain produced by clouds of gas and relatively cold celestial objects. insects can see ultraviolet rays and Microwaves Radiation with a long wavelength. certain snakes can see infrared rays. Table 11 presents each of the Infrared rays Electromagnetic radiation with a wavelength slightly longer than that of visible light. Humans perceive this radiation as heat. different kinds of radiation emitted by the sun. Visible light The part of the spectrum that humans can see. Ultraviolet rays

Electromagnetic radiation with a wavelength slightly shorter than that of visible light. Ultraviolet (UV) rays can cause skin cancer.

X-rays

Radiation with a short wavelength. These rays are produced by hot gases from clouds and stars, and around black holes.

Gamma rays

Radiation with a very short wavelength. These rays are also emitted by the more energized celestial objects in the Universe.

Radio waves

Microwaves

Infrared rays

Visible light

Ultraviolet rays

X-rays

Gamma rays

Figure 68 The electromagnetic spectrum

Memory Check 1. Why do we say that sunlight is indispensable to life on Earth? 2. Two people are arguing. One insists that if it is cold in winter, it is because the sun’s rays are weaker in winter than in summer. The other claims that it is because the sun’s rays are reflected by snow rather than being absorbed by the ground. What is your opinion? 3. What is the difference between light absorption and light reflection?

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350 The Earth and Space

4. What is a shadow? Using a diagram, explain your answer. 5. How would you go about demonstrating that the colour of white light is really a mixture of several colours? 6. a) What is the electromagnetic spectrum? b) What is invisible light? c) Give two examples of invisible light.

The Law of Universal Gravitation

Isaac Newton (1642–1727) was a Britsh mathematician, physicist, astronomer and philosopher. He wondered about the way objects fall to the ground, and about the movement of the Moon. He demonstrated that gravitational force is responsible for both phenomena.

SCIENCE

On the Earth, gravity corresponds to an object’s weight. Weight is the force of attraction that the Earth exerts on an object. But be careful: weight and mass must not be confused. Weight is a force that acts on a body. Mass is the quantity of matter contained in a body (see The Material World, page 178).

HISTORY OF

If you hold an object in your hand and drop it, it falls to the ground. Isaac Newton was able to explain why this was so (see Figure 69). In 1687, Newton discovered that an invisible force attracts objects toward the centre of the Earth. He developed the law of universal gravitation. According to this law, all objects in the Universe are mutually attracted to each other. The intensity of this attraction depends on the mass of these objects and the distance that separates them. Every object with a mass—be it ever so small—is subject to gravity.

Gravity is manifested in various ways. It is what keeps the Earth in orbit around the Sun and it is what keeps our feet planted on the ground. It is also what assembles the stars into galaxies. The gravity on the surface of a planet (or natural satellite like the Moon) depends on the planet’s mass and its radius. On the surface of the Moon, for instance, gravity is six times weaker than it is on the Earth. This explains why astronauts can jump like kangaroos when they walk on the Moon. Their weight is actually six times lower than it is on the Earth, even though their mass has not changed.

NEWS FLASH…

Figure 69 The Earth is attracted

to the Moon, just as the Moon is attracted to the Earth.

Memory Check 1. Gravity depends on two factors. What are they? 2. The Earth is attracted by the Moon. True or false? Explain your answer.

All objects are attracted toward the ground. This attraction is caused by the gravitational force of the Earth. The Greek philosopher Aristotle (384–322 BCE) believed that heavy objects fell faster than light ones. Scientists held this opinion until Galileo (1564–1642), another philosopher, decided to put the notion to the test. It is said that he dropped three balls—made from lead, wood and paper, respectively—from the top of the Tower of Pisa. The three balls hit the ground at the same time. In effect, gravitational force is the same for all objects, regardless of their weight. They are therefore pulled toward Earth at the same speed.

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The Birth of the Solar System Asteroid A small celestial object. Its diameter is only a few hundred kilometres.

Galaxy

HISTORY

A grouping of stars and other celestial bodies. The Sun is part of a galaxy called the Milky Way.

OF SCIENCE At the beginning of the 20th century, the American astronomer Henrietta Leavitt (1868–1921) studied variable stars. These stars sometimes seemed brighter than at other times. Through her research, Leavitt was able to measure the distances between these stars and the Earth. Because the variable stars she was studying were in another galaxy, astronomers were able to start drawing a threedimensional map of the Universe.

Approximately 5 billion years ago, our solar system did not exist. In its place, there was an immense cloud of dust and gas (see Figure 70). Following the explosion of a nearby star, the cloud began to flatten and spin. Some of the debris released from the explosion clustered in a central mass. Gradually, this mass accumulated enough heat to become a star. Our Sun was born. Other debris assembled to form the planets of our present solar system. At the same time, still more debris formed comets, asteroids and the planets’ natural satellites.

Figure 70 Prior to its birth

approximately 5 billion years ago, our solar system was an immense cloud of dust and gas.

The Sun The Sun is the closest star to the Earth. It is an enormous ball of gas made up primarily of hydrogen (H) and Helium (He). Its temperature is extremely high: 5770°C on the surface and 15 000 000°C at the centre. Its enormous mass is 333 000 times greater than that of the Earth. Its surface gravity is 28 times greater than that of the Earth. But despite all this, the Sun is an ordinary star— very similar to the other stars in our galaxy (see Figure 71).

Figure 71 The Sun

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352 The Earth and Space

The Sun behaves like an immense nuclear reactor. Its centre gives off a huge amount of energy and the temperature there can reach 15 000 000°C. It is estimated that the Sun has already used up roughly half of its energy reserves. In other words, in about 5 billion years, the Sun’s hydrogen reserves will begin to run out. The Sun’s diameter will then increase until it swallows the Earth. The temperature of our planet will rise to 2000°C and all life forms will disappear. Then, little by little, the Sun will cool and die.

Nuclear reactor A system in which nuclear fusion or fission reactions occur. Fusion of hydrogen atoms is the Sun’s main source of energy.

NEWS FLASH…

The Waltz of the Planets

In December 1995, NASA launched the observation probe Soho, which is now in orbit around the Sun. For the next few years, Soho will transmit information—for example, on gas and plasma eruptions on the Sun’s surface, and on solar winds—via radio antenna. These phenomena trigger magnetic storms in the Earth’s upper atmosphere. The storms disrupt cell phone communication and satellite transmission of TV programs, among other things.

Our solar system is primarily made up of the Sun and the eight planets that gravitate around it. Natural satellites, comets and asteroids are also part of our solar system. Because of gravity, the eight planets follow paths in the form of an ellipse (a slightly flattened circle) around the Sun. These paths are called orbits. The asteroid belt between Mars and Jupiter separates the solar system into two parts (see Figure 72). The first part is located between the Sun and the asteroid belt. It holds the dense, solid planets: Mercury, Venus, Earth and Mars. These are called the terrestrial planets. The second part is located between the asteroid belt and the outer limits of the solar system. It holds the giant, gaseous planets: Jupiter, Saturn, Uranus and Neptune.

Venus’ orbit Asteroid belt Pluto’s orbit

Neptune’s orbit Earth’s orbit

Mercury’s orbit

Uranus’ orbit

Jupiter’s orbit

Saturn’s orbit Mars’ orbit

Figure 72 The orbits of the eight planets in our solar system, plus the dwarf planet Pluto

and the asteroid belt between Jupiter and Mars.

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The Terrestrial Planets The word “terrestrial” comes from the Latin terrestris, meaning “of earth.” Like the Earth, the terrestrial planets are made of rock, not gas, as the giant planets are.

The four planets closest to the Sun are Mercury, Venus, Earth and Mars. These are the terrestrial planets. They resemble each other because they are small, dense and made mainly of rock (see Table 12). Table 12 The four terrestrial planets

Planet Mercury

NEWS FLASH… Galileo built his telescope in 1609. He was the first to use it to observe the sky. As a result, he discovered many fascinating phenomena: Saturn’s rings, Jupiter’s satellites, the phases of Venus, sunspots, and more. His observation of the phases of Venus supported his belief that it was the Earth that travelled around the Sun, and not the reverse. Using accurate tools helps us draw better conclusions. Every time the precision of a scientific instrument is improved, new discoveries are sure to follow. In other words, technology contributes to the development of scientific knowledge.

Venus

Earth

Characteristics This is the only planet without an atmosphere. It is too small and too hot to retain one. This probably explains why it is riddled with craters produced by meteoroids. On Mercury, meteoroids are not destroyed by the atmosphere’s friction before reaching the surface.

It has a thick atmosphere composed of carbon dioxide that creates an enormous greenhouse effect. The heat can reach 477°C.

This is the largest of the terrestrial planets. The Earth is surrounded by a thin layer of gas dotted with white clouds. It is solid, but 75 percent of its surface is covered with water. It is the only planet that has water on its surface. It is also the only known planet with life forms. According to one theory, the Earth was continually bombarded with meteoroids after its formation. One major collision caused it to lose an enormous mass of debris. This was then assembled to form the Earth’s only satellite: the Moon.

Mars

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This is called the red planet because of the rust that covers it. Its temperature is low (–63°C, on average), and 95 percent of its atmosphere is carbon dioxide. It is believed that Mars was once a site of major volcanic activity, and that water once existed on its surface. It may once have experienced conditions favourable to life (the latest explorations have been unable to confirm this).

The Gas Giants The gas giants are very different from the terrestrial planets. These giant planets are Jupiter, Saturn, Uranus and Neptune. Like the Sun, their atmosphere is mainly composed of hydrogen and helium. Surprisingly, none of these planets possesses a solid surface. Since they have no ground, no spacecraft can land on them (see Table 13).

Table 13 The four giant planets

Planet Jupiter

Characteristics This is the largest planet in our solar system. Its diameter is nearly 11 times that of the Earth. It is composed mainly of hydrogen. Its surface is covered with coloured, constantly changing gaseous bands.

Saturn

It is surrounded by immense rings of rock and ice. Since Saturn is less dense than water, it would float if it were dropped in an enormous ocean. It, too, is very colourful.

Uranus

The blue-green colour of this planet results from the gas composition of its atmosphere. It is made up of hydrogen, helium and methane. Uranus also has thin carbon-based rings. This planet is invisible to the naked eye. It is the first to have been discovered with a telescope.

Neptune

This is often said to be Uranus’ twin. It possesses an atmosphere rich in methane, however, which makes it look like a huge blue sphere. The German Johann Galle discovered Neptune in 1846.

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Sun

Jupiter Saturn Mercury Earth Venus

Uranus Mars

Neptune Pluto

This diagram shows the size of the solar system’s eight planets, and the dwarf planet Pluto, in relation to the Sun. Distances between them are not to scale. The rings of the giant planets are not shown.

Pluto, the Dwarf Planet In 2006, Pluto was reclassified from planet to dwarf planet. Until then it had been considered as the farthest planet in the solar system and the last to be discovered (see Figure 73). Because of its distance, almost 6 billion kilometres from the Sun, very little is known about this dwarf planet. It is thought to be composed of a mixture of rock, ice and solidified gases. It is smaller than the Moon, and very cold (–223°C).

Figure 73 The distant dwarf

planet Pluto as photographed by the American Hubble Space Telescope.

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356 The Earth and Space

Table 14 presents some of the characteristics of the solar system’s eight planets.

Table 14 The planets of the solar system

Planet

Distance from the Sun (millions of km)

Diameter at the equator (km)

Duration of revolution (around the Sun)

Duration of rotation (on its axis)

Average surface temperature (°C)

Number of satellites*

59 days

127

0

243 days

462

0

57.9

4 878

Venus

108.2

12 102

224.7 days

Earth

149.6

12 756

365.3 days

23.9 hours

15

1

Mars

227.9

6 794

687 days

24.6 hours

–63

2

Jupiter

778.4

142 984

11.86 years

9.9 hours

–148

63

29.46 years

10.6 hours

–178

46

Mercury

88 days

Saturn

1 427.

120 536

Uranus

2 871.

51 118

84 years

17 hours

–216

27

Neptune

4 498.

49 532

165 years

16 hours

–214

13

* Number of satellites known as of September 1, 2005

Natural Satellites: Companions of the Planets A natural satellite (also called a moon) is a celestial body that revolves around a planet. Mercury and Venus are the only planets without them. Jupiter is the planet with the most. Jupiter has the biggest satellites, including Ganymede, which is bigger than Mercury.

Comets A comet is a ball of snow, ice, rock and dust (see Figure 74 on the next page). Most comets seem to reside in a zone beyond Neptune’s orbit. Every comet follows its own orbit around the Sun. However, certain comets have an elongated oval-shaped orbit that periodically brings them very close to the Sun. When a comet nears the Sun, the snow it contains sublimates (changes directly from the solid state to the gaseous state), and the gases disperse around the nucleus. Moreover, this releases dust that escapes from the comet’s nucleus. It is these phenomena that cause the comet’s tail to form. The tail is blown by the solar wind. It always extends away from the Sun, no matter where the comet is located.

Solar wind A current of particles emitted by the Sun. It is composed primarily of protons and electrons.

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A comet produces a new tail every time it passes near the Sun. Since comets lose a little of their mass with each trip, they do not last forever. After approximately 1000 journeys—or about 100 000 years—there is no ice left to evaporate. The comet is nothing more than a large rock.

Tail (approx. 10 million km)

When comets pass near the Sun, they leave a great deal of debris behind. The Earth sometimes passes into a zone containing comet debris. When it comes in contact with the Earth’s atmosphere, the debris burns and breaks up. At this point, from the Earth, we see shooting stars in the sky. When there are several, this is called a meteoroid shower (see page 366).

Nucleus

Head (approx. 100 000 km) Figure 74 Diagram of a comet

Memory Check 1. a) What is the estimated age of the solar system? b) Is the Sun the same age as the Earth? c) Explain how a cloud of dust and gas gave birth to the solar system. 2. What chemical element is the principal constituent of the Sun? 3. Name the four terrestrial planets. 4. a) Name the four giant planets. b) Why do we call these planets gas giants? 5. When was Pluto’s status changed from planet to dwarf planet? 6. Name the planets that match each of the following descriptions: a) This one is the largest terrestrial planet. b) This one would float if it were dropped into an enormous ocean. c) This one’s day is longer than its year. d) This one has no atmosphere. e) This one has the most natural satellites. f) This one is the largest planet in the solar system. 7. How are comets’ tails formed? 8. What is the origin of meteoroid showers?

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358 The Earth and Space

The Earth It was long thought that the Earth was stationary and that it was the Sun that turned around it. We now know that it is the Earth that turns around the Sun. We also know that the Sun is the centre of the solar system. The Earth’s movement around the Sun is called the revolution of the Earth. This movement is the source of many phenomena, including the changing seasons. But the Earth also turns on its axis. This is known as the rotation of the Earth. Rotation is what gives us the cycle of day and night.

The Rotation of the Earth: Day Turns to Night You have probably already noticed that, on any given day, the Sun appears to be crossing the sky. In the morning, the Sun appears in the east. At noon, it is in the south. In the evening, it sets in the west. This illusion was the basis of the old theory that the Earth was the centre of the Universe. In reality, it is the rotation of the Earth on its axis that explains why the Sun rises, climbs higher in the sky and descends on the horizon (see Figure 75).

Nor

Horizon The imaginary circular line where the sky and the land (or sea) appear to join.

th P

Sou th

ole

Pole

Figure 75 The cycle of day and night is produced by the rotation

of the Earth on its axis.

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Latitude A way of indicating the distance between a point on the surface of the Earth and the equator. Latitude is measured in degrees (o). Latitudes are imaginary lines dividing the Earth and running parallel to the equator.

The Earth turns on a tilted axis. This imaginary axis runs through the two poles. The rotation occurs from west to east over a period of 24 hours (or, more precisely, 23 hours, 56 minutes and 4 seconds). The speed of the rotation is approximately 1700 km/hr at the equator. Because of the Earth’s spherical shape, this speed varies according to latitude. This rotation movement causes the cycle of day and night. Since the Earth is round and opaque, the Sun can only illuminate one side of it at a time. The globe’s two hemispheres do not face the Sun at the same time (see Figure 76). When America is plunged into darkness, it is day in Australia, and vice versa.

Figure 76 The phases of the Earth

can be seen from space.

The Revolution of the Earth: A Change of Seasons Like all the planets in the solar system, the Earth turns around the Sun. This trajectory is called an orbit. Despite its great speed (approximately 29.75 km/s), it takes the Earth 365 and a quarter days to revolve around the Sun. This period is called a revolution or solar year. The solar year is slightly longer than the civil year (the one shown on the calendar). What was to be done with the handful of leftover hours and minutes each year? A solution was devised: every four years, a day is added to the calendar—the 29th of February. This creates a leap year of 366 days. Because the Earth’s axis is tilted, our planet is in different positions during the year, in relation to the Sun (see Figure 77 on the following page). This is what divides the year into four seasons. At one point in the orbit, one hemisphere is slightly tilted toward the Sun. Six months later, it is the other hemisphere that tilts toward our star. ENCYCLOPEDIA

360 The Earth and Space

A Winter solstice (December 22) The longest night of the year in the Northern Hemisphere. The days begin to lengthen the next day. B Spring equinox (March 21) The day is as long as the night.

N

S N

S

Sun N

S

N

D Fall equinox (September 23) The day is as long as the night.

S

C Summer solstice (June 21) The shortest night of the year in the Northern Hemisphere. The days begin to shorten the next day.

Figure 77 The cycle of the seasons is caused by the Earth’s revolution around

the Sun and by the tilting of the Earth’s axis.

The Sun’s apparent path in the sky reaches its farthest position north on the celestial equator on or around June 21. This is the summer solstice in the Northern Hemisphere. Summer begins. It is the longest day and the shortest night. The radiant energy reaching the ground is at a maximum.

The word “solstice” comes from the Latin words sol (Sun) and stit (standing), and means “the Sun stands.”

The Sun’s apparent path reaches its farthest position south on the celestial equator on or around December 22. This is the winter solstice in the Northern Hemisphere. Winter begins. It is the shortest day and the longest night. The radiant energy reaching the ground is at a minimum. When the Earth is between the two solstices, it is spring or fall. During these seasons, day and night have almost the same duration all over the planet. The equinoxes occur on March 21 and September 23. In the Northern Hemisphere, they mark the beginning of spring and fall, respectively.

The word “equinox” comes from the Latin words aequi (equal) and nox (night), and indicates that “the day is equal to the night.”

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HISTORY

OF SCIENCE French physicist Léon Foucault devised an experiment to demonstrate that the Earth turned on its axis. To show this, he used the pendulum that now bears his name. A pendulum can be made out of a ball suspended from a thread. When the ball is pushed, it makes a steady back-and-forth movement. If you used a pendulum in a car, it would still oscillate the same way, no matter which direction you were driving in. In 1851, in Paris, Foucault installed an immense 67-m-long pendulum from the dome of the Pantheon. With every movement, the pendulum left a mark in a pile of sand. Significantly, the marks were never in the same place. They shifted 3 to 4 mm every time. Since a pendulum always swings along the same axis, this meant that it was the Earth that was turning!

Why Is It Hot at the Equator and Cold at the Poles? The heat produced on the ground by sunlight is more concentrated when the Sun’s rays touch the Earth’s surface on the perpendicular. The rays then form a right angle with the Earth’s surface. This is the case in the equatorial regions. In the polar regions, the Sun’s rays hit the Earth on the diagonal. The heat produced by sunlight is therefore less concentrated (see Figure 78). It is in January that the Earth passes closest to the Sun. In July, the Earth is farther from the Sun. However, in July it is hotter in the Northern Hemisphere. Why is this so? You saw that the Earth’s axis is tilted as it follows its orbit around the Sun. In summer, the Northern Hemisphere is tilted toward the Sun. The Northern Hemisphere therefore receives the Sun’s rays more directly than the Southern Hemisphere. This is why it is hotter in Québec in summer, even though the Earth is closer to the Sun in winter.

a) The Sun’s rays at the equator

b) The Sun’s rays in Québec

Figure 78 In both cases, the same amount of solar radiation is hitting the ground.

However, diagonal rays cover a larger surface.

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Polar Auroras Long ago, people believed that the polar auroras were portents of misfortune and disaster. Today, we know that this phenomenon is caused by the solar wind. When the solar wind particles arrive near the Earth, they are diverted toward the poles. This is why the auroras are observed primarily in polar regions. There are two types of polar aurora: the aurora borealis appears in the Northern Hemisphere (see Figure 79), while the aurora australis occurs in the Southern Hemisphere. The arrival of solar wind particles stimulates the particles in the Earth’s atmosphere. This is what triggers the spectacular light show of the polar auroras. The phenomenon can take various forms. It is observed mainly as a green glow shimmering over the horizon. Sometimes the glow intensifies to form a large, luminous arc, with rays that appear to flicker. Sometimes these luminous rays form a corona of light.

Figure 79 An aurora borealis in the

starry skies above the popular Mont-Mégantic Observatory

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Meteoroids Meteoroids are solid debris originating from the solar system. The debris enters into violent contact with the atmosphere, or the surface of celestial bodies in its path. Once they enter the Earth's atmosphere, they become meteors. Every year, over 3000 meteors hit the Earth. Some of these rocks are too large to burn up completely on contact with the atmosphere. Most of them fall into the oceans and are never recovered. There are always a few, however, that hit solid ground. Once on the ground, they are classified as meteorites. While passing through the Earth’s atmosphere, meteoroids undergo the following transformations: 1. Their surfaces are heated. 2. Their surfaces are partially melted (because of friction with the air). 3. They become luminous (the larger the meteoroid, the brighter it becomes). 4. They solidify as they slow down. Debris entering the Earth’s atmosphere varies greatly in size, ranging from a grain of dust to a block of stone weighing a tonne or more. When debris penetrates the atmosphere, what happens next depends on its speed, size and the material it is made of. • The smallest debris burns up as soon as it enters the atmosphere’s upper layers. It breaks up and forms shooting stars. • The largest and fastest debris reaches the Earth’s surface. It sometimes leaves remnants on the ground. To reach the Earth’s surface, meteoroids must pass through each layer of the atmosphere. It is therefore a rare occurrence (see Figure 80).

Figure 80 Most meteoroids break up on contact with the atmosphere. Only a few

are large enough to reach the ground and form a crater.

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364 The Earth and Space

Meteoroid and Asteroid Showers In the solar system, meteoroid and asteroid impacts can be seen on the surfaces of all the terrestrial planets. They are also visible on the planets’ natural satellites, including the Moon. The Earth is not immune. The force of each collision depends on the size of the meteoroids and asteroids involved. It creates shock waves around the point of impact, often leaving a crater (see Figure 81). However, most of the Earth’s craters have been caused by tectonic plate movement and erosion.

The Effects of Meteoroid and Asteroid Showers From the Earth’s earliest days, meteoroid and asteroid showers have been leaving organic molecules on the ground. These molecules may be the source of the first traces of life. Meteoroids have created only minor disruptions, while asteroids, which are much larger, may well have destroyed existing life forms or altered their evolution. Approximately 65 million years ago, an asteroid collided with the Earth. Scientists believe this event had something to do with the massive extinction of living species that occurred around the same time. Among these species were the dinosaurs (see Figure 82). The impact took place in Yucatán, in Mexico. A large asteroid (approximately 10 km wide) hit the coast. Immediately, rivers of lava must have gushed from the crater. Tonnes of dust, moreover, would have formed an immense black cloud throughout the Earth’s atmosphere. Daylight probably disappeared for months, or even years. Acid rain would have soaked the ground, leading to the disappearance of countless living species. The dinosaurs are thought not to have survived this disaster, nor did most living species. The dinosaurs’ disappearance did, however, pave the way for other animal species, such as mammals, to develop. Mammals took over the habitats left vacant by the dinosaurs.

Figure 81 The Manicouagan crater in

Northern Québec is one of the largest in the world. It is approximately 100 km in diameter, and scientists believe the asteroid that created it was at least 5 km wide. The impact is closely associated with the history of hydroelectricity in Québec, because the crater now constitutes the reservoir of the Daniel-Johnson Dam.

Figure 82 The impact that caused

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Figure 83 Meteoroid shower

Shooting Stars On a cloudless night, you can often see streaks of shining light in the sky (see Figure 83). These are called shooting stars. Despite their name, they are not stars, but meteoroids or debris. They leave brilliant but short-lived trails in the sky. These trails are produced by debris that lights up the air when it enters the Earth’s atmosphere at great speed. This debris comes from comets. When they pass near the Sun, comets leave a trail of dust and rocky debris behind them. This dust and debris are transformed into meteoroid showers when the Earth passes through the comets’ orbit. The Earth encounters a number of such clouds of debris every year. These meteoroid showers can be seen at very precise periods in the year. The showers are named after the constellations they seem to be coming from (see Table 15 on the following page). The Perseids, for instance, are easily visible around August 12 if the sky is clear. At this time, it is not unusual to see up to 100 shooting stars in an hour.

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366 The Earth and Space

Table 15 Principal meteoroid showers throughout the year

Name

Period

Average number of shooting stars an hour

Constellation

Quadrantids

January 1 to 6

40

Boötes

Lyrids

April 19 to 24

15

Lyre

Aquarids

May 1 to 8

20

Aquarius

Perseids

July 25 to August 18

50

Perseus

Orionids

October 16 to 27

25

Orion

Leonids

November 15 to 20

15

Leo

Geminids

December 7 to 15

50

Gemini

Memory Check 1. What is the difference between the rotation and the revolution of the Earth? 2. Answer the following questions using a lamp to represent the Sun and a ball to represent the Earth. a) Explain the cycle of day and night. b) Explain the apparent movement of the Sun in the sky. c) Explain the cycle of the seasons. d) If the Earth was not tilted on its axis, what would be the consequences? 3. Using a lamp to represent the Sun, explain how perpendicular rays heat the ground more than diagonal rays. 4. a) What is the solar wind? b) What is the relationship between the solar wind and the polar auroras? 5. Explain the following terms: comet, asteroid, meteoroid and shooting star. 6. Why is the Earth’s surface not covered with craters, like the Moon’s? Give at least two reasons. 7. “The dinosaurs’ disappearance allowed humans to appear.” What do you think of this statement?

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The Moon The Moon is approximately 384 400 km from the Earth (see Figure 84). From an astronomical point of view, this is very close. From time immemorial, the Moon has been a source of fascination for humans. It is the subject of countless myths and legends. Long ago, certain peoples based their calendars on the Moon. Even today, many societies attribute great importance to the lunar cycle.

Figure 84 The Moon

always shows us the same side.

The Moon gives off no light. It seems luminous because it is reflecting the Sun’s rays. In daytime, the Moon is often difficult to see because the Sun is shining too strongly. When we look at it night after night, it seems to be in continuous transformation because of its phases (see Figure 85). But one thing does not change: the Moon always shows us the same side. In fact, the Moon takes exactly the same time to rotate as it does to revolve around the Earth. The other side, the one the Earth never sees, is called the dark side of the Moon.

Last quarter

New moon

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368 The Earth and Space

Full moon

The Phases of the Moon When observed from the Earth night after night, the Moon changes in appearance. At times, it is completely round. At other times, only a small crescent can be seen. These are called the lunar phases. These variations result from the play of light orchestrated by the different positions of the Sun, the Earth and the Moon. You cannot see the Moon when it is situated between the Earth and the Sun. This is the period of the new moon. The Moon is actually still there, but its illuminated half is turned to the Sun. The part of the Moon turned toward the Earth is not illuminated and is therefore invisible (see Figure 87 on page 370). After two or three days, the Moon appears in the form of a thin luminous crescent. This crescent grows and, after a week, the Moon has half of its face illuminated. This is the Moon’s first quarter. When the Moon has completed half its circuit around the Earth, it is opposite the Sun in a line with the Earth. Its face is completely round and the illuminated part is visible all night. This is the full moon. After this, the last quarter of the Moon is observed. This phase then gradually disappears, becoming a new moon once more. There are approximately 29.5 days between two new moons. This is the lunation or lunar month. So, the Moon waxes for two weeks, passing from the new moon to the full moon. It then wanes over the two weeks that follow. First quarter

New moon

Figure 85

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Eclipses When you look at the Sun and the Moon in the sky, they sometimes appear to be the same size. In reality, the Moon is approximately 400 times smaller than the Sun. But since it is also 400 times closer to the Earth, the two celestial bodies seem to have the same dimensions. Sometimes, the Earth, the Moon and the Sun are perfectly aligned in space. An impressive phenomenon can then be observed: an eclipse. There are solar eclipses and lunar eclipses.

Solar Eclipses Solar eclipses occur when the Moon has just moved to a place that is exactly between the Earth and the Sun. The Moon therefore covers the solar disk: it is as dark as night in daytime. Eclipses can be total, partial or annular. A total eclipse occurs when the Moon covers a surface that is slightly larger than the solar disk. At this point, a black disk with a luminous contour can be seen: the solar corona. The shadow projected by the Moon covers a small surface of the Earth called the umbra. Only people within this small region can experience the total eclipse. People in regions situated in the penumbra experience a partial eclipse (see Figure 87). Eclipses of the Sun last a maximum of seven minutes, and a number of them can be seen every year. An annular eclipse occurs when the Moon is too far from the Earth to completely hide the Sun. A thin ring of sunlight remains visible (see Figure 86).

Figure 86 An annular eclipse of the Sun

Penumbra

Umbra

Sun

Planet

Figure 87 The umbra is the region in which an object completely hides a light source.

The penumbra is the region in which an object partially hides a light source.

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370 The Earth and Space

Lunar Eclipses

Galileo was the first person to observe the heavens with the help of a telescope. It was in 1609 but, long before this, humans had been observing the sky with the naked eye. In those days, nobody knew how dangerous it was to look directly at the Sun without a filter. You probably already know that you must never look directly at a solar eclipse, partial or total. It should always be observed with a filter, especially if you are using a telescope or night glass. When there is an eclipse, the luminosity is weaker. We can see the Sun easily without squinting. However, ultraviolet rays can still burn the eye’s retina and cause permanent damage to the cornea.

SCIENCE

During a total lunar eclipse, the Moon is entirely in the Earth’s umbra. This type of eclipse can last for over an hour. During partial lunar eclipses, only part of the lunar disk is in the Earth’s shadow. Lunar eclipses last an average of three hours. They occur at least twice a year.

HISTORY OF

Lunar eclipses occur when the Earth is exactly between the Sun and the Moon (see Figure 88). The Moon is then masked by the shadow of the Earth. In other words, it is in the umbra. It is easier to see a lunar eclipse than a solar eclipse. In fact, every person in the hemisphere opposite the Sun—in other words, on the side of the Earth that is night at the time of eclipse—can see it happen if the sky is clear.

Figure 88 A lunar eclipse

Memory Check 1. Use a lamp to represent the Sun, a ball for the Earth and a smaller ball for the Moon. Simulate and explain the following phenomena: a) The phases of the Moon b) The dark side of the Moon c) A solar eclipse d) A lunar eclipse 2. If you lived on the Moon, could you sometimes see an eclipse of the Earth? 3. Explain the difference between the umbra and the penumbra.

SECTION 3

Astronomical Phenomena

371

THE TECHNOLOGICAL WORLD From the Wheel to the Rocket Long ago, people travelled on foot or by horse. Now, there are cars, airplanes, trains and countless other means of transportation. The same thing has happened in our homes. We have replaced candles with light bulbs. People have toasters, microwave ovens, dishwashers and more. Many of these inventions add to our comfort and make our lives easier. Often, they have been thought up by engineers. These people’s work consists of designing, analyzing and improving systems and processes. You too can understand how the objects around us work. You can even create new ones. In “The Technological World,” you will explore how technical objects work. The Design Process

p. 376

Specifications

p. 378

Technical Diagrams

p. 382

The Manufacturing Process Sheet

p. 385

Raw Material, Material and Equipment

p. 386

Systems

p. 389

Basic Mechanical Functions

p. 392

Energy Transformation

p. 395

Types of Motion

p. 406

Effects of a Force

p. 410

Simple Machines

p. 412

The Transmission of Motion

p. 419

The Transformation of Motion

p. 423

SECTION 1 Engineering

The Technological World

p. 374

SECTION 2 Technological Systems

p. 388

SECTION 3 Forces and Motion

372

p. 404

Here is what you will discover reading “The Technological World”: • First, in Section 1, “Engineering,” you will learn about the work of an engineer. You will explore the various tools this person uses to complete a project. You will see that verbal and written communication are very important because an engineer’s work is often carried out within a team. You will discover that engineers must prepare various diagrams and documents. • Then, in Section 2, “Technological Systems,” you will study what a system is and what its components are. You will see that each system fulfils a specific function. You will explore various examples of technological systems. • Finally, in Section 3, “Forces and Motion,” you will discover the types of motion and their origins. You will also see that there are mechanisms that enable motion to be transmitted or transformed.

373

SECTION 1 Engineering The Design Process

Specifications

p. 376

p. 378

Design

p. 376

Production

p. 376

Marketing

p. 377

Contents of the Specifications

p. 379

Perspectives Considered in the Specifications p. 379

SECTION 1 Engineering

The Technological World

SECTION 2 Technological Systems

SECTION 3 Forces and Motion

Technical Diagrams

p. 382

The Design Plan

p. 382

The Technical Drawing

p. 383

Standard Symbols

p. 384

Raw Material

p. 386

Material

p. 387

Equipment

p. 387

The Manufacturing Process Sheet p. 385

Raw Material, Material and Equipment p. 386

ENCYCLOPEDIA

374 The Technological World

The Physical Perspective

p. 380

The Technical Perspective

p. 380

The Economic Perspective

p. 380

The Industrial Perspective

p. 380

The Human Perspective

p. 380

The Environmental Perspective p. 380

OVERVIEW In this section, we will try to understand the stages of the engineering process. An example is the best way to do this. An examination of the Bike Home project will make our subject more concrete.

HISTORY OF

Before 1949, snowed-in roads were rarely ploughed in Québec. Joseph-Armand Bombardier (1907–1964), a Québec manufacturer and mechanical engineer, sought a means of making winter transportation easier. In 1935, after several trials, he created a prototype that could transport several people on snow-covered roads. He called the invention the snowmobile. However, Bombardier hoped to build a smaller vehicle that would carry only one person. In 1959, he built the first modern snowmobile.

SCIENCE

Bike Home is a company that sells bicycles. Penelope runs the company. She has noticed that the public’s demand for electric bicycles is growing. She would like to develop a bicycle with an electric motor to meet her customers’ demands. Unfortunately, Penelope has no specialist in small electric motors on her team. She therefore decides to approach the Edison Motors company. She asks them to design an electric motor adapted to a bicycle (see Figure 1).

Figure 1 Bike Home and Edison Motors sign a partnership agreement.

Engineers’ work is primarily teamwork. A number of people are brought together to form what is called a project team. Each person participates according to their skills. Sometimes, certain people or companies collaborate only at a particular stage. In our example, Penelope, her team and the people at Edison Motors will work together to design an electric bicycle.

SECTION 1

Engineering

375

HISTORY

OF SCIENCE In 1896, Guglielmo Marconi, an Italian physicist, patented the first wireless communication system. A few years later, in 1901, Marconi sent the first wireless transatlantic message. The message was transmitted from Cornwall, England, to the Canadian province of Newfoundland and Labrador, a distance of 3380 km. In this way, Marconi demonstrated that wave propagation is not affected by the curvature of the Earth.

The Design Process In industry, the design process consists of three phases: design, production and marketing (see Figure 2 on the following page). Each of these phases is essential. Together, they ensure that the object produced meets a need, is built according to standards and is distributed at the right time to the people who need it.

Design Design encompasses all stages that must be completed before manufacturing an object. Any project in the field of technology begins with the identification of a need and a target market. Let’s say the employees in an office are bothered by the noise from the air-conditioning system. The management looks for a way to reduce the noise. They hire an engineer to solve the problem. First, the engineer must fully understand the problem presented to her. She must then verify if the problem has already been solved by someone else. To do so, she will examine products that are already on the market. This stage is called the market study. If none of the products on the market are suitable, the engineer will ask herself if she can modify or improve an existing product. If not, she must design a new solution herself. Once she has the idea, she must carry it out. The steps that our engineer must now take are writing a set of specifications, preparing a design plan and technical drawing, and then manufacturing a prototype. These stages will be described in detail later on. Our engineer must then test the prototype—in other words, verify that it meets the requirements of the specifications. The design plan and technical drawing must also be verified and corrected as needed. Finally, when the prototype is satisfactory, our engineer should think about making a patent application.

Production

Manufacturing process sheet A document that describes all the operations relating to the manufacture of a product, the order in which they must be carried out, and the time to be allocated to each stage.

Flow-process grid A document that describes the stages of assembly involved in creating a finished product.

ENCYCLOPEDIA

376 The Technological World

The moment has come to manufacture the product. The steps to follow are: • Preparing a manufacturing file (including a manufacturing process sheet and flow-process grid) • Manufacturing (including parts manufacturing, assembly, packaging, various quality controls and compliance with standards) • Writing and publishing an instruction manual (for customers) and a maintenance manual (for companies providing after-sales service) Engineers are involved mainly in the first of these three stages. We will explain more about it in the following pages.

Marketing

DESIGN

Marketing introduces the manufactured object to people who might need it. It also gets the object distributed to those who are ready to buy it. It involves organizing the product’s commercial development (setting the sales price, doing promotion, setting up delivery, etc.).

Analyze the technological problem

Has the problem already been solved?

YES

Present the existing solution

NO

Write a set of specifications

We must also ensure the product’s maintenance throughout its useful life, in other words, train people to repair it, set up service outlets, produce spare parts, etc.

Prepare a design plan Make a technical drawing Manufacture a prototype

Last but not least, we have to think about disposing of the product or recycling it when it ceases to be used. In other words, we must make sure the product meets environmental standards when it is put in the garbage, or make provisions for its recovery if it can be recycled. Engineers are not involved in the marketing stage. However, they must be aware of the processes involved and take them into account when they design an object.

Identify a need

Test the prototype: Does it meet specifications?

NO

YES

Apply for a patent

PRODUCTION

Prepare a manufacturing process sheet Prepare a flow-process grid Manufacture the product Write an instruction manual and maintenance manual

MARKETING

Market the product Maintain the product

Figure 2 Diagram of the

technological procedure

Discard or recycle the product

Memory Check 1. The design process consists of three phases. To which phases does each of the following activities correspond? a) Distributing a product to the people who need it. b) Complying with standards in the manufacturing of a product. c) Ensuring that the product meets a need.

2. Engineers must be aware of every stage of the design process. However, they are not involved in all of these stages. Which of the stages described in Figure 2 require the involvement of engineers?

SECTION 1

Engineering

377

Specifications

Design An activity that involves developing a project for the purpose of creating a product. The person or people responsible for design are not necessarily those who originally had the idea.

Manufacturing

HISTORY

All operations resulting in the construction of an object conceived of by designers.

Let’s return to the example of Bike Home. Penelope and her team are not the ones who will be manufacturing the motor of the future electric bicycle. Rather, this mandate will be given to the Edison Motors company, which will design and manufacture a motor for the Bike Home company. Penelope’s team must specify the characteristics of the motor that is to be installed on their future bicycle. They must do so in a written document that will be submitted to Edison Motors. In our example, one company will design and manufacture the electric motor. However, design and manufacturing are often undertaken by two different companies. This written document is called a set of specifications (see Figure 3). These specifications define and specify the company’s requirements. They describe the characteristics of the desired product. The specifications must be produced at the very beginning of a project. In their specifications, Penelope’s team must express their needs as clearly as possible. They can state, for instance, that the motor must weigh 15 kg or less.

OF SCIENCE Born in 1452, Leonardo da Vinci is well known for his numerous works of art. But he also boasted many achievements as a scientist, engineer and inventor. In these capacities, he designed a number of machines. He drew the prototype of a diving suit, for instance, and several flying machines. Though the machines did not work, they were based on accurate— and, for the era, highly advanced—aerodynamic observations.

[Ville de Montréal, Service des infrastructures, transport et environnement, Wastewater Treatment Plant, Contract 1558-AE, Preliminary Treatment Building, Replacement of Inflow Lines from Sludge Pumps to Cyclones, Specifications, April 2006] Figure 3 Example of a set of specifications used in engineering

ENCYCLOPEDIA

378 The Technological World

Contents of the Specifications When preparing specifications, the function of the object must first be defined. What will it be used for? Then, the object must be described as accurately as possible by answering the following questions: • What are the requirements for manufacturing, use and maintenance? • What standards must the object meet? • What are the object’s characteristics? • What are the manufacturing costs? • What is the completion deadline for each stage? • What is the project’s feasibility?

Perspectives Considered in the Specifications Every technical object has a useful life. This life begins when the object is manufactured and ends when it ceases to be used. It must then be discarded. When Bike Home builds an electric bicycle, they must not only think about the requirements associated with its construction, they must also consider everything that can happen in a bicycle’s useful life.

Standards A set of rules established by specialists. They are assembled in a document produced by a national or international organization. In technology, standards are designed to guarantee that the manufactured product meets acceptable levels of performance and quality.

Feasibility A feasibility study serves to determine if a project is viable. It must take into account timetables, technical knowledge, the political and financial situation, etc.

The specifications must take into account every aspect of the situation. The object to be designed must be imagined from different perspectives. Think about the person using it, for instance. On this level, an electric bicycle must be comfortable, easy to use, pleasant to ride, etc. Bike Home might therefore require that the motor not be noisy. The object’s resistance must also be considered. Since a bicycle is designed for outdoor use, it must be resistant to rain. On this level, Bike Home must therefore require that the motor be watertight. Figure 4 illustrates six perspectives to consider in developing specifications. Four concern manufacturing and two relate to use. The elements each perspective must take into account are described on the next page. You will also find an example of a set of specifications in Figure 5 on page 381.

USE

MANUFACTURING Physical perspective Technical perspective Economic perspective

Object to be designed (nature and function)

Human perspective Environmental perspective

Industrial perspective Figure 4 Six perspectives to consider when writing a specifications sheet

SECTION 1

Engineering

379

The Physical Perspective

Rust A brownish-red compound resulting from a chemical reaction between oxygen in the air and material containing iron. Rust is produced in a moist environment.

NEWS FLASH … To receive a patent, an invention must meet three conditions. First the invented object must be new; in other words, no other similar object must exist in the world. Second, it must be useful; in other words, it must have a use. Third, it must constitute an inventive contribution; in other words, it must be original for any person fully acquainted with the technique involved. The Canadian Intellectual Property Office (CIPO) is responsible for patent-related matters. The organization has set up a bank of over 30 million patents, 2.5 million of which are Canadian. For example, in Stanstead, Québec, Marc Campagna designed a non-polluting engine in his chemical laboratory.

The physical perspective concerns all the natural elements (air, water, earth) that might have an effect on an object or its use. The person or company designing the object must be informed of these natural elements because they must ensure that the product will stand up to these elements. Since a bicycle is used outside, for instance, it will sometimes be exposed to rain. It must therefore be constructed out of material that is resistant to rust. A coat of protective paint might do the trick.

The Technical Perspective The technical perspective includes factors that affect the operation of the object to be designed. For instance, Bike Home must specify the maximum speed the bicycle will attain. The company must also indicate how long the motor can run before the batteries have to be recharged.

The Economic Perspective The specifications must detail all costs the designer has to take into account. These include production costs, selling price and all maintenance costs.

The Industrial Perspective The person or company designing the product must take into account the place where it is to be manufactured. They must consider the production facilities, the tools, the work force and the completion deadline. The manufacture of certain products, for instance, requires qualified workers. If a company does not have this work force, they cannot meet their manufacturing objectives.

The Human Perspective The human perspective takes into account the people who will use, maintain and repair the product. The person or company should therefore design and manufacture an object that people will like and that is easy to maintain. Aesthetics, safety and comfort are also concerns.

The Environmental Perspective The person or company designing the product must consider its effects on the environment. Today, for instance, manufacturers are attempting to produce automobiles that pollute less. The product’s recycling potential at the end of its useful life is also a concern.

ENCYCLOPEDIA

380 The Technological World

Specifications Nature and Purpose of the Object An electric motor for a bicycle that will enable a cyclist to move either by pedalling or by using a motor.

Construction From a physical perspective, the motor must be: – coated with material that is resistant and adapted to the climate – watertight From a technical perspective, the motor must enable the bicycle: – to be driven 30 km before recharging – to be driven at a maximum speed of 35 km/hr From an economic perspective, the motor’s manufacturing costs must not: – exceed $100 From an industrial perspective, the motor must: – be able to be repaired at Edison Motors and Bike Home facilities – operate with technology that is fully understood by the facilities’ personnel

Economic and industrial perspectives are not considered in the specifications in this textbook because they do not really apply to an in-class manufacturing context.

Use From a human perspective, the motor must be: – quiet (maximum 50 decibels) – light (maximum 15 kg) – easy to use – easy to maintain – safe to use From an environmental perspective, the motor must not: – contain any substance that is harmful to the environment

Figure 5 Here are the

specifications prepared by Bike Home for Edison Motors.

Memory Check 1. What purpose do specifications serve? 2. Explain what the expression “useful life” means. 3. Imagine that you work in the aerospace field. You are a part of a team designing a vehicle to be used by a team of astronauts to explore the planet

Mars. From each of the six perspectives, give an example of what specifications for manufacturing this vehicle might contain.

SECTION 1

Engineering

381

Technical Diagrams

Prototype One of the first copies of an object or system. It can serve as a model for testing or large-scale production.

Technical diagrams are used in the design phase. These diagrams explain the functioning and essential elements of the object that is going to be built. Diagrams are a quick and simple way of representing an object. This form of representation is mainly used in the stages leading up to the creation of a prototype. There are several types of technological diagrams. We will study the design plan and the technical drawing here.

The Design Plan The design plan describes in a simplified fashion the elements that make up an object or device and explains how they work. It is prepared at the beginning of the design phase. This diagram specifies only the operating principles and objectives of the object or device. Figure 6 shows a doorknob. Figure 7 shows you the doorknob’s design plan.

Standard symbol A symbol recognized by all people who work in technology.

The design plan must indicate: • the useful force developed by the object (this is also called the force of action) and the direction in which this force is applied • the main components • the motion involved, using standard symbols (see page 384)

Door latch 1 Rotational motion: turning the knob

to release the latch

Set screw

2 Alternating motion: pulling or pushing the knob Figure 6 Door knob

ENCYCLOPEDIA

382 The Technological World

Figure 7 Design plan for a door knob

The Technical Drawing The design plan is the inspiration for the technical drawing. The technical drawing shows the exact configuration of the object (see Figure 8). Following this diagram, we can manufacture the object. The technical drawing includes: • parts directly involved in the object’s function • other parts • links between the parts (see pages 392 and 393), using standard symbols (see page 384)

Side view

Front view

H4

A

A

A

Symbol

D1 D2 D3

H2

A

A

Size

D1

Knob diameter

6.6 cm

D2

Knob face diameter

5.5 cm

D3

Spindle diameter

1.1 cm

H1

Cylinder depth

1.2 cm

H2

Distance of screw hole

2.0 cm

H3

Spindle socket depth

2.5 cm

H4

Knob depth

5.1 cm

R

Radius of curvature of knob

12.8 cm

A-A

Central axis

Cross section H1

Description

R

H3

Figure 8 Technical drawing of a door knob

SECTION 1

Engineering

383

Standard Symbols In Figure 9, you can see some of the standard symbols regularly used in preparing technical diagrams. With these symbols, you can quickly describe motion and links. They also illustrate the mechanisms of motion transmission and transformation at work in an object or device. We will cover the concepts represented by these symbols in Section 3, “Forces and Motion” (see page 404). Motion Rectilinear motion (in one direction)

Alternating motion (rectilinear in two directions)

Circular motion (in one direction)

Links Free-moving part

Circular motion with symbol showing on part

Threads Complete link

Screw

Gears Gear (or pinion)

Oscillatory motion (circular in two directions)

Nut

Screw-and-nut system

Belts, pulleys, chains and sprockets Bevel gear

Rack and pinion

Belt and pulleys

Chain and sprockets

Figure 9 Some standard symbols

Memory Check 1. Explain the difference between a design plan and a technical drawing. 2. Why are standard symbols used in a technical diagram?

ENCYCLOPEDIA

384 The Technological World

The Manufacturing Process Sheet Let’s return to the example of Bike Home. This company has asked Edison Motors to manufacture an electric motor for a bicycle. Edison Motors has now finished the plans for the motor. It can therefore enter the production phase. The people who designed the motor must pass on a lot of important information to the manufacturing specialists. To do this, they give them a document describing every stage in the manufacturing of the motor’s parts. This document is called a manufacturing process sheet. The people also give them a document that describes each stage in the assembly process. This document is called a flow-process grid. These two documents are a little like recipes. The person manufacturing the parts follows to the letter the steps described in the manufacturing process sheet (see Figure 10) and the flow-process grid. When writing process sheets like these, you must always assume that the person using them knows nothing about the project. It is therefore very important to describe each step clearly. The manufacturing process sheet lists all material and tools to be used. It indicates the order in which each operation must be performed. It also specifies how much time they will take. Furthermore, it states the number of workers needed for each stage. When all of the parts are ready, they must be assembled. Then the flow-process grid lays out the stages of assembly of the final product. MANUFACTURING PROCESS OF SPRINGS No

MANUFACTURING PROCESS SHEET

40

COMPONENT: Spring

PHASE, SUB-PHASE OR OPERATION Insert the spring wire into the hole in the metal rod.

SHEET: 2 to 4 VISUAL

MACHINE-TOOL, EQUIPMENT – Metal rod

MANUFACTURING PROCESS OF SPRINGS No 62

ASSEMBLY: Spring DRAWING XXX:

SHEET: 1 to 4 REFERENCE: 1

NUMBER: 1

MATERIAL: STEEL

PROCESS SHEET No 1

No

PHASE, SUB-PHASE OR OPERATION

10

Fasten a variable speed drill to a fixture held with a machine vise.

It is important that speed be adjustable because winding must be done at low speed.

20

30

Tighten a metal rod in the drill mandrel. A small 1.5-mm hole must be drilled into one end of the rod beforehand.

Cut spring wire to desired length.

VISUAL

SHEET: 3 to 4 VISUAL

MANUFACTURING PROCESS OF SPRINGS

MACHINE-TOOL, EQUIPMENT

No

PHASE, SUB-PHASE OR OPERATION

– Combination pliers – Metal rod

66

Cut the ends of the spring.

– Mounted drill – Mandrel key – Metal rod

– Wire cutters.

MACHINE-TOOL, EQUIPMENT – Wire cutters

Cut the spring in two if needed.

50

Using needle-nose pliers, bend the spring wire to prevent it from slipping out.

– Needle-nose pliers – Metal rod

70

63

When the spring is released, its diameter will have nearly doubled.

60

WINDING

61

Using combination pliers, maintain tension on the spring wire and start the drill at a very low speed. Two people are recommended for this operation: – One to control the speed – One to control the tension and evenness of the spring. The pliers’ tension can be replaced with a weight suspended from a pulley threaded with the wire.

– Metal rod – Combination pliers or 200 g weight

Try to keep coils tight while winding. A moment’s distraction can create a defect in the spring. If this occurs, continue winding; unwanted portions of the spring can be removed later.

– Combination pliers – Metal rod – Safety glasses

62

64

Cut the first coil to release the spring.

65

Pull the cut coil out.

– Wire cutters

FORMING HOOKS

71

Insert the two needle-nose pliers under the first coil and twist the coil segment that will form the hook upward at a right angle.

72

Repeat operation 71 for the other hook.

Fixture

Hole

SHEET: 4 to 4 VISUAL

NOTE Use caution during this operation. Releasing the spring abruptly can hurt you.

MACHINE-TOOL, EQUIPMENT

– Drill – Wooden fixture – Plumbing collar – Machine vise

PHASE, SUB-PHASE OR OPERATION After winding: – Hold the spring firmly as shown in the photo. – Maintain tension with pliers. – Release grip. – Release tension on wire.

– 2 needle-nose pliers

Light pressure to the right

Figure 10 Example of a manufacturing process sheet: manufacturing a spring

Memory Check 1. When preparing a manufacturing process sheet, why should you suppose that the person using it knows nothing about the project? 2. Imagine you are assembling the parts of a bookshelf. In your hands, you have a sheet

showing a list of parts, a list of tools you need and the complete assembly procedure. What should be added to this sheet to make it a real manufacturing process sheet?

SECTION 1

Engineering

385

Raw Material, Material and Equipment: Three Names for Three Different Things Do you know the difference between raw material, material and equipment? These terms can be a little confusing, but it is important to understand what each one means.

Raw Material A raw material is a substance of natural origin that undergoes a transformation. Trees, for instance, are raw material. We chop them down to make planks or paper. Iron is a raw material used to produce steel. We use steel in applications, such as beam and rail construction. Bauxite is the raw material that provides aluminum. We use raw material in virtually every sector of industry and line of business. Once transformed, raw material becomes a finished product (see Figure 11).

b) Steel rails (material) a) Iron (raw material)

c) Trees (raw material) d) Lumber (material) Figure 11 Some types of raw material and the material made from them

ENCYCLOPEDIA

386 The Technological World

Material Raw material is transformed into material. The material is then used to manufacture machines, objects or other items. In industry, material is a basic commodity. Figure 12 shows you some of the major categories of material.

Metals (e.g. aluminum)

Ceramics

Stone and concrete

Composite material (e.g. fibreglass)

Polymers (e.g. plastic)

Textiles

Glass Figure 12 Some of the major

Equipment

categories of material

A piece of equipment is an object, instrument, tool or machine. It is used to extract or transform raw material, or to manufacture products (see Figure 13).

Scale

Burner

Pair of scissors

Figure 13 These objects

are considered to be equipment.

Memory Check 1. What is the difference between raw material, material and equipment? 2. For each of the following examples, indicate whether they are raw material, material or equipment. a) Sheep’s wool c) A level e) A brick b) Paper d) Oil f) A pencil

SECTION 1

Engineering

387

S ECTION 2 Technological Systems Systems SECTION

SECTION

2

Technological Systems SECTION

Components of a System

p. 390

Links

p. 392

1

Engineering

The Technological World

p. 389

Basic Mechanical Functions

p. 392

3

Forces and Motion Energy Transformation

p. 395

Analyzing Links

p. 394

The Steam Locomotive

p. 401

Guiding Control p. 394

The Role of Energy

p. 395

Forms of Energy

p. 396

Mechanisms That Transform Energy

p. 398

The Production of Hydroelectricity p. 402

Efficient vs. Inefficient Energy Transformation p. 402

OVERVIEW We saw in the previous section that there are many different types of engineering projects. Moreover, increased knowledge of material properties, as well as the development of new material, adds to the variety of technical objects engineers can create. Technical objects perform a function. This requires an interaction between each of the object’s components and between the object and its environment. When a technical object transforms matter or energy, it is considered to be a technological system. For instance, an electric motor for a bicycle transforms electrical energy into kinetic energy capable of moving a bicycle forward. A technological system is therefore an assemblage of the following elements: inputs (energy or initial matter), a transformation process and outputs (energy or resulting matter). Such a system is designed to accomplish a specific function. Very often, there are also control mechanisms that verify that this function is properly carried out. ENCYCLOPEDIA

388 The Technological World

Systems A bicycle is a system. A system is made up of several subsystems. Every subsystem has its own function, and the various subsystems interact. Furthermore, each subsystem includes several parts called components. The primary function of a bicycle is to support a person’s weight and enable that person to move. Figure 14 shows the various subsystems of a bicycle and their functions.

System: Bicycle

Subsystem: Braking Function: Ensures that the bicycle can be stopped

Subsystem: Lighting Function: Provides front and back lights powered by an independent current source

Subsystem: Frame Function: Connects the other subsystems to each other and holds the back wheel

Subsystem: Seat Function: Enables the cyclist to sit

Subsystem: Wheel Function: Absorbs shocks from the ground and enables the bicycle to move

Subsystem: Transmission Function: Enables force to be transmitted to the back wheel and allows changes of speed

Subsystem: Steering Function: Holds the front wheel in place and allows the bicycle to be steered

Figure 14 Subsystems of a bicycle and their functions

SECTION 2

Technological Systems

389

Components of a System Machines (or technological systems) are generally used to accomplish a task. Normally, a force is required to make a machine work. In a technological system, the force applied constitutes one of the inputs. Inputs are everything that enters a system. Everything that exits a system is an output. Inputs can be transformed by the system, or not. The task the machine performs constitutes a transformation process. The result of this process is an output. Take an apple peeler, for instance. This machine is a technological system. Figure 15 and Table 1 (on the following page) describe this system and its inputs and outputs. The function of the peeler is to peel apples. The unpeeled apple and the force required to peel the apple are the system’s two inputs. The peeled apple and peels are the system’s two outputs. The machine applies a force to the apple. But the person using the peeler also exerts a force: they must put the apple in place. They must also verify that the apple is properly installed in the machine before activating it. This verification stage is also one of the system’s inputs. In this case, verification is done by the user. However, there are also systems in which verification and controls are programmed and are done automatically. This is the case with dishwashers and washing machines (see Figure 16).

Figure 15 Technological system:

apple peeler

Figure 16 On a dishwasher’s control

panel, a red light indicates which stage is under way. This signal is a system output because it gives information to the person using the machine.

ENCYCLOPEDIA

390 The Technological World

Table 1 Inputs and outputs of two systems

Apple peeler

Inputs

Outputs

Dishwasher

Initial material

Apples

Dirty dishes Water Dishwasher detergent

Verification and control mechanisms

Manual adjustment of the apple

Selection of an automatic wash cycle

Energy source

Muscle force

Electricity

End material

Peeled apples

Clean dishes Red light

Information given to the person using the machine Waste and residue Drawbacks

Apple peels

Waste water Noise of the system operating

Table 1 shows the inputs and outputs of the two systems illustrated in Figures 15 and 16. The apple peeler is an example of a technological system with a specific function: peeling apples. As you have seen, there are inputs and outputs in this system, as well as components. In a system, the mechanisms of motion transformation and transmission, as well as the simple machines, can vary. But they are always part of the system’s components. To summarize, everything that plays a role in a technical object’s functioning constitutes a component. If one of the components is missing, the system cannot operate properly.

Memory Check 1. There are a number of technological systems all around you. Think about an electric kettle and answer the following questions: a) What is the function of this technological system? b) What are the inputs? c) What are the outputs? d) What type of energy is required to make the system work? e) What, if any, are the system’s verification and control mechanisms? 2. In each case, state whether these technological systems transform matter or energy. a) A car motor b) An electric mixer c) A table lamp d) A toaster

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Basic Mechanical Functions Nail

Screw

The concept of function is fundamental in technology. Function is the role played by an object, system, subsystem or part. There are mechanical functions we call basic mechanical functions. These functions are at the root of most technical objects. The most frequently used are the link and guiding control.

Weld

Nut

Links

Figure 17 Some examples of

fasteners

The link is fulfilled by a fastening unit that connects two parts. Figure 17 shows you some fasteners.

Fastener An element of a system with a specific function.

There can be a link between two parts alone or between several parts. The link is always: • direct or indirect • removable or nonremovable • rigid or elastic • complete or partial Table 2 describes the eight possible types of links. Table 2 Types of links and their characteristics

Type of link Direct link

Characteristics

Example

This link connects parts without using an intermediary. The connected parts must have complementary shapes.

Blocks in a building set that fit together

Indirect link

This link includes one or more fasteners. Something is added—another part, for instance—to connect the two components.

A knob attached with a screw to a door

Removable The connected parts can be separated at will without damaging link the fastener or link surfaces.

A pen and its cap

ENCYCLOPEDIA

392 The Technological World

Table 2 Types of links and their characteristics (continued)

Type of link Nonremova ble link

Characteristics

Example

The connected parts cannot be separated without damaging one or more of them, or the fastener.

Boat made of matchsticks glued together

Rigid link

Unlike the elastic link, this link does not allow the position of the assembled elements to be changed.

Table with four legs

Elastic link

The fastening device can be flattened or stretched to allow the parts to change position. These links usually use springs or rubber blocks.

Suspension attached to a bicycle

Complete link

This link does not allow the parts to move independently of each other. Unlike the partial link, if one of the parts moves, it will cause the other to make the same motion.

Handle attached to the head of a hammer

Partial link

In this link, one of the parts (the door) can move in certain directions without the other (the door frame) moving.

Door attached to a door frame SECTION 2

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Types of Motion In your class and on the street, there are people and objects that move. Have you ever tried to count the number of different kinds of motion you can observe in a day? Believe it or not, all these examples can be classified into only four types. Scientists believe all motion is a combination of the following four simple types: 1 Rectilinear motion ● 2 Alternating motion ● 3 Circular motion ● 4 Oscillatory motion ● Figure 22 describes these types of simple motion and gives an example of each.

1 A skateboard is an example of rectilinear motion. A

rectilinear motion describes a straight line.

regularly in one direction and then the other. A trumpet’s piston valves, for instance, produce an alternating motion.

3 When you go around the Ferris wheel, carousel or other

4 A swing executes a circular motion in one direction and

similar ride in an amusement park, you experience a circular motion. A circular motion describes a curve or circle.

then the other. It describes an oscillatory motion, which is a back-and-forth motion around a central point.

Figure 22 The four types of simple motion

ENCYCLOPEDIA

2 An alternating motion is a rectilinear motion executed

406 The Technological World

Memory Check

Every day, we use several forms of energy to fulfil our needs. To heat our homes, for instance, we use thermal energy drawn from electricity, fuel oil, natural gas, wood, and so on. To power our cars, we use the chemical energy supplied by gas, diesel or ethanol. To light our homes, we use the radiant energy of a lamp, candle or match. There are many forms of energy. It is also possible to change from one form to another, in other words, to transform energy or convert it.

For a long time, people believed that light came from the eyes and illuminated objects, enabling us to see them. It was only in 1000 CE that an Arab scientist, Alhazen (965–1039), found an explanation for the provenance of radiant energy. He discovered that light came from a source—the sun, for instance, or a candle. He also studied lenses and mirrors. His research helped scientists develop optical instruments, the microscope and the telescope.

SCIENCE

Energy Transformation

HISTORY OF

1. Name two technical objects whose function is to assemble two parts. 2. Describe the four characteristics of the links produced in each of the following cases: a) An ice cream container and its lid b) A photo stuck to a bulletin board with a thumbtack c) A sticker pasted in an album 3. Name two technical objects whose function is to guide a part. 4. What is the difference between guiding rotation and guiding translation? Give an example of each.

The Role of Energy We often use the word “energy” in our everyday conversation. You can say that a person in bursting with energy, for instance, or has no energy left. However, this word has a specific meaning in technology. In technology, we define energy as a system’s capacity to perform work— for instance, making objects move (for the definition of work, see page 417). There are sources of energy all around you. The sun’s rays, which illuminate and warm the Earth, are a form of energy. Electricity, which runs our home appliances, is also a form of energy.

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Forms of Energy Here are 10 different forms of energy. Potential energy

Mechanical energy

This is the energy an object possesses because of its position above a surface. A ball you hold in your hand has potential energy. If you let it fall, its potential energy will transform into kinetic energy and it will fall to the ground. Potential energy is a specific form of mechanical energy.

Energy resulting from the sum of potential energy and kinetic energy.

Elastic energy This is the energy an object possesses when its shape is changed through stretching or compression. A stretched elastic or compressed spring are two examples of objects that store elastic energy. When a force ceases to be applied to them, these objects assume their original shapes. Elastic energy is a specific form of potential energy.

Kinetic energy This is the energy of objects in motion. A moving bicycle or car possesses kinetic energy. The same applies to a tossed ball. Kinetic energy is a specific form of mechanical energy.

Radiant energy This is a form of energy that enables you to see objects. When it hits your eyes, it triggers the production of specific signals. These signals travel from your eyes to your brain. They tell you about what you are seeing. Radiant energy is a specific form of electromagnetic energy (see The Earth and Space on page 350).

Electrical energy This form of energy makes machines like televisions and computers work. It is also used to power lighting systems and certain heating systems.

ENCYCLOPEDIA

396 The Technological World

Magnetic energy This is the form of energy that magnets possess due to their positions relative to each other. When you put two magnets of the same poles together (two south poles or two north poles), they push away from each other. If you place two magnets of different poles near each other, they are drawn together. Magnetic energy is a form of potential energy because it depends on the position of the object.

Chemical reaction A reaction that occurs when the bonds between atoms break and new molecules are formed.

Thermal energy

This is the form of energy released during a chemical reaction. The chemical energy in gas turns car engines. Your body uses the chemical energy contained in food. This enables you to do things, like move.

Nuclear energy This is the form of energy possessed by the nuclei of atoms. Special techniques are required to release the nuclear energy contained in radioactive substances, such as uranium.

The nuclear physicist Enrico Fermi (1901–1954) and his colleagues developed what they called an “atomic pile”— the first nuclear reactor. On December 2, 1942, the physicist and his team succeeded in making it work. Unfortunately, one of its first applications was the manufacture of the first atomic bomb. Though nuclear energy possesses immense destructive power, it is also an energy source used in many countries to produce electricity.

SCIENCE

Chemical energy

HISTORY OF

This form of energy is present in all objects. When an object contains a lot of thermal energy, it is hot to the touch. If it contains very little thermal energy, it is cold to the touch (see The Material World on page 181).

Acoustic energy This is the energy produced when matter vibrates. This energy makes the ossicles (small bones) of your ears move. These movements are transmitted to nerve cells and then to the brain. The brain tells you about what you are hearing.

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Mechanisms That Transform Energy It is impossible to create or destroy energy. Energy can only be transformed—in other words, change from one form to another. We therefore speak of the transformation, or conversion, of energy (see The Material World on page 194). There are different ways of making energy change from one form to another. Energy can sometimes be transformed directly. Table 5 shows this type of transformation. Often, however, the desired form of energy cannot be obtained directly. Intermediate forms must then be used. On pages 401 and 402, we will see two examples of intermediate transformations.

NEWS FLASH … The Earth acts as an enormous magnet. This magnetic energy, called the Earth’s magnetic field, helps many migratory animals find their way. Currently, scientists are studying the ways in which animals use the Earth’s magnetic energy. Through their research, they have found a connection between this energy and minute particles of iron found in or near the brains of animals that undertake long migrations.

Table 5 Direct transformations of energy

Initial form of energy Thermal

Form of energy obtained Kinetic

Electromagnetic

Electrical

The electromagnetic energy of the sun is captured by solar panels and transformed into electrical current.

Kinetic

Electrical

Tidal power plants use the kinetic energy of the tides to turn turbines and produce electricity.

Description The sun warms the air. Because hot air is lighter, it rises above cold air. These air currents create winds.

Wind turbines are giant windmills. The wind’s kinetic energy turns their blades and produces electricity.

ENCYCLOPEDIA

398 The Technological World

Illustration

Table 5 Direct transformations of energy (continued)

Initial form of energy Chemical

Form of energy obtained Kinetic

Description

Illustration

Your muscles convert the chemical energy in the food you eat to muscle (or kinetic) energy. This enables you to move.

Motors use the chemical energy in gas. They transform it into kinetic energy, which makes cars run.

Electrical

Chemical

When electrical energy is produced, it is possible to store it in batteries. During this operation, electrical energy is transformed into chemical energy.

Kinetic

A mixer uses electrical energy to execute a circular motion, which mixes food.

Thermal

Our home heating systems are powered with electrical energy. They transform this energy into heat (or thermal energy) to keep us warm in winter.

Radiant

Light bulbs transform electrical energy into radiant energy to give us light.

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Table 5 Direct transformations of energy (continued)

Initial form of energy Electrical (continued)

ENCYCLOPEDIA

Description A radio station or television transforms electrical energy into acoustic energy.

Kinetic

When a roller coaster’s cars begin their descent, their potential energy is transformed into kinetic energy.

Electrical

Water accumulates in reservoirs located upstream from (in front of) hydroelectric dams. When it is released, its potential energy is transformed into kinetic energy. Turbines transform this energy into electricity (see Figure 20, page 402).

Elastic

Kinetic

When a stretched elastic is released, it quickly snaps back into shape.

Nuclear

Thermal

Nuclear plants use the energy contained in the nuclei of atoms to heat water. The steam obtained can then be used to produce electricity.

Potential

400 The Technological World

Form of energy obtained Acoustic

Illustration

The Steam Locomotive

Steam Locomotive Boiler

Water Steam pipe

Cylinder Piston

Firebox

Piston rod Connecting rod

Figure 19

Transformations of energy in a steam locomotive

Crankpin Driving wheel

The steam locomotive is a kind of machine powered by steam that was used in the past. This locomotive is a system that performs several intermediate energy transformations (see Figure 19). It all starts with coal, a source of chemical energy. When coal is burned, its chemical energy transforms into thermal energy. This thermal energy heats water and produces steam. The steam activates the pistons, which, by generating kinetic energy, make the wheels turn. The pistons also activate a generator, which produces electricity for heating and lighting. Excess electrical energy is stored in batteries in the form of chemical energy. This chemical energy is saved for future conversion into light and heat. SECTION 2

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401

The Production of Hydroelectricity Water from streams and rivers can be held back by a dam. During this time, the dam is storing potential energy. When the water is released, it discharges kinetic energy. The movement of the water drives turbines that produce electricity. This electricity is transmitted to homes and factories (see Figure 20).

Spillway

Dam Potential energy

Transmission lines

Water reservoir

Penstock

Electrical energy

Generator Turbine

Kinetic energy

Figure 20 Energy transformations occur when hydroelectricity is produced.

The Mercier Dam on Baskatong Lake in the Laurentians

The hydroelectric plant converts the kinetic energy of water into electrical energy.

Efficient vs. Inefficient Energy Transformation When energy changes from one form to another, it is never entirely transformed. To determine the efficiency of an energy system, we calculate the percentage of energy that is actually transformed into the desired form. If a system manages to transform most of the energy, we say that it is energy efficient. If not, we say that it is energy inefficient. Energy that has not taken the desired form has not disappeared. It has simply taken another form. In reality, we cannot destroy or create energy. In many cases, energy dissipates in the form of heat. This is the case, for instance, with electrical light bulbs, which get hot when they are on.

ENCYCLOPEDIA

402 The Technological World

You saw in Table 5 (see page 398) that the radiant energy of the sun can be transformed into electrical energy. Figure 21 shows the energy efficiency of a solar panel. At present, solar panels have an efficiency of approximately 14 percent. This means that 14 percent of all the light radiation hitting the panels is absorbed and transformed into electricity. A portion of the rest of the radiation is transformed into heat. Another portion undergoes no transformation at all. In other words, the light rays are reflected and return to the atmosphere. This is one of the reasons why we use solar panels so rarely: a great many panels must be installed to obtain a small quantity of electrical energy.

Energy given off in the form of heat

Reflected energy

Absorbed energy

Figure 21 Energy efficiency of a solar panel

Memory Check 1. What does the word “energy” mean in technology? 2. We studied 10 different forms of energy: potential, elastic, kinetic, radiant, electrical, magnetic, thermal, chemical, nuclear and acoustic. For each of these forms of energy, give an example of a technological system that uses it or transforms it. 3. What does the sentence “It is impossible to create or destroy energy” mean? 4. The combustion engine’s function is to transform the chemical energy of gas into kinetic energy capable of making a car run. Why does an engine like this have a cooling system?

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S ECTION 3 Forces and Motion Types of Motion

Effects of a Force

SECTION

p. 406

p. 410

1

SECTION

2

Technological Systems SECTION

p. 407

What Slows Motion?

p. 407 The Lever

Types of Force

p. 410

The Five Simple Machines

p. 413

How Do Simple Machines Make Our Lives Easier? p. 417

Engineering

The Technological World

What Triggers Motion?

Simple Machines

p. 412

Mechanical Systems

p. 418

Chain and Sprocket

p. 420

Belt and Pulley

p. 420

Gears

p. 421

Friction Wheels

p. 422

The Pulley

p. 422

3

Forces and Motion

The Transmission of Motion p. 419

Connecting Rod and Crank p. 424

The Transformation of Motion p. 423

ENCYCLOPEDIA

404 The Technological World

Cam and Follower

p. 424

Rack and Pinion

p. 425

Screw and Nut

p. 425

p. 413

The Inclined Plane p. 414 The Pulley

p. 415

The Wedge

p. 416

The Wheel and Axle

p. 416

Overview In the previous section, we began our analysis of technological systems by studying their components, functions and control mechanisms. We will now continue our examination by taking a closer look at the motion of mechanical systems. We will see that this motion is created by forces. A force can set a part in motion or change its motion. However, a badly directed or overly intense force can lead to distortion or breakage. Usually, if one sets just one part in motion first, one can obtain the required result. In fact, a technological system is a set of individual machines capable of transferring motion from one part to another in such a way that the system functions well together. We will see that there are mechanisms capable of transferring motion, while others actually transform it.

NEWS FLASH … In an acrobatic show, we see a technological system in full swing. The movements of circus artists and trapezes are a set of forces and motions. Imagine the strength it takes to move the body of an acrobat, swinging from the hands of the carrier to the second trapeze. Months of training are required to achieve the right balance of force and motion. This training helps trapeze artists safely reach heights of perfection.

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Types of Motion In your class and on the street, there are people and objects that move. Have you ever tried to count the number of different kinds of motion you can observe in a day? Believe it or not, all these examples can be classified into only four types. Scientists believe all motion is a combination of the following four simple types: 1 Rectilinear motion ● 2 Alternating motion ● 3 Circular motion ● 4 Oscillatory motion ● Figure 22 describes these types of simple motion and gives an example of each.

1 A skateboard is an example of rectilinear motion. A

rectilinear motion describes a straight line.

regularly in one direction and then the other. A trumpet’s piston valves, for instance, produce an alternating motion.

3 When you go around the Ferris wheel, carousel or other

4 A swing executes a circular motion in one direction and

similar ride in an amusement park, you experience a circular motion. A circular motion describes a curve or circle.

then the other. It describes an oscillatory motion, which is a back-and-forth motion around a central point.

Figure 22 The four types of simple motion

ENCYCLOPEDIA

2 An alternating motion is a rectilinear motion executed

406 The Technological World

Observe living creatures or objects that move. You might notice that they are not performing only one of the four types of simple motion. This is due to the fact that types of motion can be combined. This is the case in mechanical systems. They work because of the different motions of their parts. They rarely rely on only one type of motion. Each motion has a specific function.

What Triggers Motion? To ride somewhere on his bicycle, the boy in Figure 23 must make an effort. He has to pedal. He therefore exerts a force to move forward. You might say that a motion cannot be triggered on its own. A force is required to provoke it. When you let go of an object above the ground, it falls. What provokes this motion? It is a type of force called gravitational force. You know that distances are measured in metres or kilometres. Forces, however, are measured in newtons. The name was adopted in honour of scholar and mathematician Isaac Newton. He formulated the law of universal gravitation (see The Earth and Space on page 351). Force is measured with a device called a dynamometer (see the Skills Handbook on page 458).

Gravitational force The force that pulls objects toward the centre of the Earth. The greater the mass of an object, the more strongly it is pulled.

What Slows Motion? Let’s return to the example of the boy riding his bicycle. Suppose he pedals a few times and then stops pedalling. The bicycle will continue to move forward for a certain time, then stop. Why does the bicycle stop? Because of the friction of the air, the moving parts of the bicycle and the tires’ contact with the ground. The asphalt of the road comes in contact with the rubber of the tires, and this friction slows the bicycle. Friction is therefore a force that opposes motion (see Figure 23).

Friction The force that slows down two bodies in contact.

Force exerted to move forward

Figure 23 Friction force (yellow

Friction force

arrow) slows the wheels of the bicycle. SECTION 3

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407

The type of ground surface is an important factor in a bicycle’s motion. More specifically, the ground’s characteristics have an effect on friction. Have you ever tried to ride a bicycle on grass or sand? It is much harder to pedal on these surfaces than it is on asphalt. This is because the friction force is greater. More force must therefore be applied to overcome the friction force (see Figure 24).

Figure 24 The friction force (yellow arrow) affecting a bicycle is much greater on grass than it is on asphalt.

Aerodynamic profile A shape designed to offer the least possible resistance to the air. Designers try to give this type of profile to cars and airplanes.

Imagine a car driving on the road. The contact between the tires and the pavement causes friction and slows the car. But the resistance of the air also causes friction. The more square the design of a car, the greater the resistance caused by the air (see Figure 25). This is why people are employed to give our cars aerodynamic profiles, which reduce their resistance to the air.

Figure 25 A bus is subject to greater

air resistance than a car with an aerodynamic profile. ENCYCLOPEDIA

408 The Technological World

Friction is not always something to avoid. Bicycles and cars use friction to brake. For instance, when you press on the brake levers of a bicycle, the brake pads (pieces of rubber) are pressed on to the wheel and slow the bicycle by friction. Figure 26 shows a bicycle’s braking mechanism.

HISTORY OF

SCIENCE

An air-cushion vehicle is a boat whose flat bottom is suspended on a cushion of air. It was designed to reduce water friction on the hull and, consequently, move the boat faster. Any hulled boat sinks in the water and must fight against the water’s friction force. As a result, its engine burns a large amount of energy. In 1953, British engineer Christopher Cockerell (1910–1999) invented an air-cushion system to replace rigid hulls. In 1959, after numerous trials, Cockerell built the first air-cushion vehicle, which he called a hovercraft. Figure 26 Friction causes a bicycle to brake.

Memory Check 1. Name the four types of simple motion. Give an example of each. 2. What must be done to trigger a movement? 3. a) What is the unit of measurement of force? b) What instrument is force measured with? 4. Imagine you are pushing a toy car along the ground. Even though you push it hard, the car always ends up stopping. Explain why. 5. Why is it harder to pedal a bicycle on grass than it is on asphalt? 6. a) Explain how a bird’s shape helps it fly through the air. b) Explain how a fish’s shape helps it swim through the water. c) Explain how an earthworm’s shape helps it move through the earth. 7. When a space shuttle lands, it deploys a series of parachutes. Explain how the parachutes help the shuttle brake.

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Effects of a Force A force is a mechanical action that sets an object in motion. A force can also change the speed or trajectory of an object already in motion. Furthermore, a force can deform an object.

Types of Force When we exert a force on an object, we can put it in motion or change its motion. We can also distort it or break it. The friction force exerted by asphalt on a car’s tires, for instance, is a shearing force because the car’s motion and the friction force are exerted in opposite directions. On the other hand, the friction force exerted by air resistance is a compression force: if the car body and windshield were less resistant, they might well be crushed. Table 6 describes the different types of force that can be exerted on objects. Table 6 The most common types of force

Type of force

Description

Flexion force

When a gymnast presses or pulls on the bar, her weight applies a flexion force. The bar is likely to bend under the effect of this force.

Tension force

When you pull an object in one direction to move it, that is tension. A person pulling a rope, for instance, exerts tension on it.

Compression force

Compression is the opposite of tension. It is a force applied to compress an object. When you squeeze a sponge, for instance, you exert compression force.

ENCYCLOPEDIA

410 The Technological World

Diagram

Example

Table 6 The most common types of force (continued)

Type of force

Description

Torsion force

When you screw on or unscrew a lid, you apply a torsion force. The two objects, lid and jar, turn in opposite directions.

Shearing force

If you pull the corners of a metal sheet in opposite directions, it is likely to break. It will shear, or tear.

Diagram

Example

Memory Check 1. Name the five most common types of force. Give an example of each. 2. Which types of force are used in the following situations? a) I take a tissue from a box of tissues.

b) c) d) e)

I I I I

sit on a chair. wring out a wet towel. tear a sheet of paper. press a button on my calculator.

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Simple Machines Simple machines are found in many objects that you encounter in your everyday life. They enable you to lift objects or they make it easier to move them around. Figure 28 shows the five types of simple machines. 1 The lever ● 2 The inclined plane ● 3 The pulley ● 4 The wedge ● 5 The wheel and axle ●

Figure 27 A simple machine

1 The lever ●

4 The ●

2 The inclined plane ●

wedge

Figure 28 These five types of simple machines can help us lift or carry loads, large and small.

ENCYCLOPEDIA

412 The Technological World

3 The pulley ●

5 The wheel and axle ●

The Five Simple Machines Simple machines perform three main functions: 1 They transmit forces ● 2 They change the direction of a force ● 3 They modify the intensity (size) of a force ●

The Lever

1 Bottle-opener ●

2 Hammer ●

3 Screwdriver ●

Figure 29 These three objects can be used as levers.

Load

E

Load arm

Force (or effort)

Lever arm

Archimedes (287–212 BCE) was a Greek scholar and mathematician. He studied how forces were used in simple machines like the pulley and the lever. The famous saying, “Give me a place to stand and I will move the Earth,” is often attributed to him. By using the lever principle, he designed the catapult. With this war machine, enormous rocks could be thrown at specific targets.

SCIENCE

L

HISTORY OF

A number of objects operate on the lever principle (see Figure 29). In a lever, a movable bar rests on a supporting point called a fulcrum (see Figure 30). At one end of the movable bar is the load. This is what must be lifted or moved. A force is applied to the other end of the movable bar. A lever, then, has three components: the fulcrum, the load and the force. The portion of the bar between the fulcrum and the force is the lever arm. The portion of the bar between the fulcrum and the load is called the load arm.

F Fulcrum (supporting point) Figure 30 Diagram of a lever

The lever in Figure 30 is only one of several types of levers that exist. In fact, the positions of the lever’s components can be changed. By switching the positions of the fulcrum, load and force, we obtain the three types of levers (see Figure 31 on the following page).

SECTION 3

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413

E E

F L

F E

L F

L L

L E

F

First-class lever. In this type of lever, the fulcrum lies between the force and the load. An example is a pair of scissors. First-class levers are used in work that requires force and precision.

L Load

E Force or effort

F

E

E

F

L

F

Second-class lever. This type of lever always exerts a greater force on the load than the force supplied. The load is located between the force and the fulcrum. A wheelbarrow is an example of this type of lever.

Third-class lever. The force is exerted between the fulcrum and the load. With this type of lever, a greater force must be exerted on the lever than that which the lever exerts on the load. However, it can move the load very quickly. This is exactly what a hockey player does when hitting a puck.

Fulcrum

Figure 31 The three types of levers

The Inclined Plane An inclined plane has a slope. This slope reduces the force that must be exerted to lift a load or object. In fact, the inclined plane enables the force to be exerted in a different direction. Instead of lifting the object, you push it. This requires less force. The same thing occurs when you climb a hill. When the slope is gradual, it is easy to climb. However, the distance covered to reach a given height is greater. When the slope is steep, more force must be supplied to climb it, but the distance covered to attain the same height is shorter (see Figure 32).

d

a) Gradual slope

Height

an

Dist

e

st Di

c an

v co

Height

e er

ered

ov ce c

b) Steep slope

Figure 32 The angle of a slope is a factor in the distance that must be covered to reach a given height.

ENCYCLOPEDIA

414 The Technological World

The Pulley The pulley is another simple machine that helps us lift loads. A pulley is composed of a wheel fitted with a cord or chain. The cord or chain is inserted in the groove in the wheel. There are two types of pulleys: the fixed pulley and the movable pulley (also called a loose pulley) (see Figure 33). A fixed pulley does not reduce the force required to perform a task. It only enables the direction of the force to be changed. For instance, when you pull down the cord of a Venetian blind, the blind rises. Only the direction of the force has changed. The force exerted by your arm is equal to the force applied on the blind (see Figure 34). Figure 34 A Venetian blind is

fitted with a fixed pulley.

a) Fixed pulley

b) Movable pulley

Figure 33 The two types of pulleys

Groove (of a pulley) The narrow, hollowed-out part of the pulley through which the cord or chain passes.

To reduce the force required to perform a task, a movable pulley is used. One end of the cord is attached to the ceiling. The load is attached directly to the pulley. The load and pulley therefore follow the same movement. The force is exerted upward, in the same direction as the load and pulley. However, this force is half the force that would have been necessary without the pulley. This is because the cord attached to the ceiling supports half the load. It is possible to combine several movable pulleys. If you do so, the force required to move a load will be reduced even further. A fixed pulley, moreover, can be combined with a movable pulley. This system is called a hoist. It offers the advantages of both types of pulleys: the force is exerted downward and is only half the force that would be necessary without the two pulleys (see Figure 35). The pumps we use to bring oil to the surface are fitted with hoists (see Figure 36).

Figure 35 A hoist is a system

combining fixed and movable pulleys.

Figure 36 This pump jack comprises

several pulleys and a lever. These machines raise and lower pump valves to cause oil to rise to the surface.

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415

HISTORY

OF SCIENCE

The Wedge

The invention of the wheel, like those of writing, metal work, agriculture and animal husbandry, was a major innovation in human history. The first wheel made its appearance in Mesopotamia sometime in the 4th millennium BCE. Potters built wheels to streamline the production of clay objects. At the time, people got around mainly on foot and, more rarely, by raft and dugout. It dawned on them that they could adapt the wheel to rudimentary carts. This new use of the wheel revolutionized the transportation of people and goods. Today, the wheel plays an important role in most means of transportation. It is also an essential component in the design of a number of simple machines, such as the pulley, the winch, the crane and gears.

A wedge is generally a triangular prism. It is used to exert a force on an object. For instance, a wedge can be used to pry two objects apart. To do this, the thinner end of the wedge is inserted between the two objects. A force is then exerted to separate them. An axe is an example of a wedge (see Figure 37). Wedges help us grasp objects that must be lifted. By sliding a wedge under an object, we free up a space for our fingers. The longer the wedge and the more gradual the slope, the less force must be supplied. However, the wedge must be pushed over a greater distance.

a) Axe

b) Nail point

c) Wedge under a piece of furniture

Figure 37 Some examples of wedges

The Wheel and Axle The simple machine composed of a wheel and axle is widely used in our dayto-day lives. You could, for instance, drag a box directly along the ground. But it would be much easier if you put it in a wagon and pulled it. Bicycle and automobile wheels, winches and windmills are examples of machines using the wheel-and-axle principle (see Figure 38).

Axle A long rod whose ends enter one or more wheels. Figure 38 The winch

is an application of a simple machine composed of a wheel and axle. ENCYCLOPEDIA

416 The Technological World

How Do Simple Machines Make Life Easier? Thanks to simple machines, we require less force to perform work. To make things clearer, we will examine the concept of work in greater detail. In science and technology, the word “work” has a particular meaning. Work is the result obtained when a force is exerted on an object and it is moved a certain distance. Suppose that your knapsack is on the ground. If you take it and put it on your desk, you could say that you have performed work on your bag. You have pulled your bag upward and the bag has also moved upward. The simple machines we have discussed do the same thing. They too can accomplish work.

Figure 39 Levers at work

Figure 39 shows an example of work performed by a lever. Each man is performing work because he is applying a force to a lever. The energy of the men is transferred to the tree. The lever moves in the direction of the force. The lever, too, performs work. It applies a force on the load and shifts it upward. Thus, objects and machines, like people, perform work. In science and technology, the definition of work is as follows: work = force applied × distance

Bear in mind that work is the result obtained. Work is always the same, whether you use a simple machine or not. You can raise a load to a height of 2 m, for instance, by carrying it there with your hands. In this case, your arms are supplying all of the force required. You can also move this load with the help of an inclined plane. This time, the force exerted by your arms is weaker, but the distance to be covered is longer. In each case, the result is the same. The work is therefore the same. SECTION 3

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417

Let’s return to the pulley example. Figure 33 on page 415 shows a fixed pulley and a movable pulley. Each movable pulley halves the force required to lift a load. Let’s see what happens, using an example. We want to lift a load. With a movable pulley, the force exerted to lift this load is 3 newtons instead of 6 newtons. However, to lift the load, you have to pull the cord 4 m instead of 2 m. Force multiplied by distance (in one case, 3 N x 4 m, and in the other, 6 N x 2 m) gives the same quantity of work: 12 joules.

Mechanical Systems: Simple Machines Combined

Mechanical advantage The relationship between the force required to move a load without a device, and the force needed to move the load using a machine or mechanical system.

Two or more simple machines can be combined. By doing this, we obtain a mechanical system. Mechanical systems perform work, as simple machines do. They often provide an even greater mechanical advantage. In other words, they can move loads even more easily than a simple machine alone. Figure 40 shows an example of a mechanical system.

Figure 40 This ride is a mechanical system. It is formed of several simple machines

combined.

Memory Check 1. Name the five simple machines. Give an example of each. 2. Archimedes was a Greek scholar who lived in the 3rd century BCE. He once said, “Give me a place to stand and I will move the Earth.” What do you think he meant? 3. Take a look at Figure 27 on page 412. What simple machine is being used to draw water? 4. a) Describe what a hoist is.

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418 The Technological World

b) How is a hoist used? 5. How is the word “work” defined in science and technology? 6. How does a simple machine reduce the force required to accomplish work? Answer using an example. 7. a) What is a mechanical system? b) What is mechanical advantage?

The Transmission of Motion Simple machines can be combined to form mechanical systems. These systems transmit motion from one object to another with the help of various mechanisms (see Figure 41). These mechanisms transmit the four types of motion: rectilinear, alternating, circular and oscillatory (see Figure 22 on page 406).

Chain

Sprocket

Friction wheel

Belt

Figure 41 These objects can be

assembled in various ways to obtain motion transmission mechanisms.

Of the various motion transmission mechanisms, these five are the most common: 1 Chain and ●

sprocket

2 Belt and ●

pulley

3 Gears ●

4 Friction wheels ●

5 Pulley ●

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419

Chain and Sprocket When you ride a bicycle, the motion of your legs must be transmitted to the wheels. You apply a force to the pedals, which are attached to the centre of a toothed wheel, or sprocket. This force triggers a circular motion of the sprocket. This circular motion is then transmitted to the bicycle’s back wheel. A smaller sprocket attached to the back wheel performs the transmission. A chain connects the two sprockets. In a mechanism like this, the two sprockets turn in the same direction. The chain is the means by which the pedals’ motion is transmitted to the back wheel (see Figure 42).

Figure 42 On a bicycle, the chain and sprockets transmit the motion of the cyclist’s feet

to the back wheel.

Belt and Pulley A belt operates along the same principle as a chain. But instead of turning on a sprocket, a belt is inserted in the groove of a pulley. Motion is transmitted from one pulley to the next in the same way. When a pulley is turned, the belt follows the motion and turns the second pulley. The second pulley turns in the same direction as the first (see Figure 43).

Figure 43 A clothesline works using a belt-and-pulley mechanism.

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420 The Technological World

Gears Toothed wheels are also used in another well-known motion transmission mechanism: gears. A gear set consists of at least two toothed wheels that turn as they press against each other. Two gears in a set turn in opposite directions to each other. In a gear pair, the gears are not necessarily the same size. When the gears are different sizes, the small gear turns faster than the large one. The small gear can therefore execute several revolutions, while the large one makes only one. A clock is a mechanism comprising gear sets of different-sized gears (see Figure 44). Gears move the hands so that they always show the correct time. In fact, this mechanism guarantees that the minute hand turns 60 times while the hour hand turns once.

Figure 44 Motion transmission

in the gear mechanism of a clock

There are gear systems made of spur gears, as shown in Figure 44. Figure 45 shows a gear set composed of bevel gears. This type of gear causes a rotation motion to be transmitted to another plane. The motion, therefore, makes a 90° turn.

Figure 45 The hand drill: a gear set fitted with bevel gears. A hand drill is used to drill holes manually.

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Friction Wheels Friction wheels are similar to gears. The difference is that they have no teeth. Because these wheels are touching, the circular motion of one turns the other through friction. Like gears, friction wheels turn in opposite directions to each other (see Figure 46).

The Pulley A pulley is a mechanism that transmits rectilinear motion. As we have already seen, it is a simple machine (see page 415). If the cord of a pulley is pulled in a rectilinear manner, the load rises, also following a rectilinear trajectory. Lifting devices, such as cranes, operate like this (see Figure 47).

Figure 46 A printing press uses

a series of rolls that operate as friction wheels.

Figure 47 A crane moves heavy objects along a rectilinear trajectory.

Memory Check 1. a) What type of motion does a sprocket transmit? b) What type of motion does a pulley transmit? 2. Name the motion transmission mechanism that: a) Uses two sprockets that turn in the same direction b) Transmits a rotation motion to another plane c) Makes a clothesline work d) Uses two toothed wheels turning in opposite directions e) Changes the direction of a force

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422 The Technological World

The Transformation of Motion We explained at the beginning of this section that there were four types of motion: rectilinear, alternating, circular and oscillatory (see page 406). Certain mechanisms make it possible to change from one type of motion to another. These mechanisms transform motion. Of the various motion transformation mechanisms, these four are the most commonly used:

● Connecting rod and crank

2 Cam and follower ●

3 Rack and pinion ●

4 Screw and nut ●

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423

Connecting Rod and Crank A connecting rod and crank transform circular motion into alternating motion.

Sparkplug Piston

Connecting rod

Crankshaft

Crank Figure 48 Components of a combustion

engine

In a combustion engine, a piston compresses a mixture of air and gas in a cylinder. A sparkplug then produces a spark that causes the mixture to explode. The explosion pushes the piston, which moves the connecting rod down. The subsequent motion of the crank turns the crankshaft, which moves the other connecting rod up. This compresses the air and gas drawn into the other cylinder, where a spark will cause an explosion.

Cam and Follower

Cam

A cam and follower transform a circular motion into an alternating motion. A cam is a wheel that is not quite circular. Rather, it is egg-shaped. The follower is a rod that is pressed against the cam. The follower slides on the turning cam. When the follower is on the pointed part of the cam, it moves farther away. It gets closer again when it slides on the rest of the cam. The follower therefore has an alternating motion. This mechanism is used in car motors and steam machines, among other things. Figure 49 shows a system composed of a cam and follower.

Follower Figure 49 On a sewing machine, a cam and follower cause

the needle to make an up-and-down motion.

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424 The Technological World

Rack and Pinion A rack and pinion are often used to transform motion. This mechanism changes circular motion into rectilinear motion. It is composed of a toothed wheel (the pinion) that turns on a toothed bar (the rack). Figure 50 shows an example of this mechanism. A rack is used in an automobile’s steering system. Study Figure 51. The pinion is attached to a rod. Since the rod is connected to the steering wheel, the pinion executes the same circular motion as the steering wheel. The teeth of the pinion enter the spaces between the teeth of the rack. When the pinion turns, the toothed bar moves left or right. In doing so, it transmits its motion to the axle, which changes the direction of the car’s front wheels.

Figure 50 This lever corkscrew is a

system comprising two pinions and a rack.

Pinion

Rack

Figure 51 The steering rack of an automobile

Screw and Nut The screw-and-nut mechanism transforms circular motion into rectilinear motion. When the screw (or bolt) turns, the nut moves along the screw in either direction (see Figure 52).

Figure 52 A C-clamp works with a

screw-and-nut system. This mechanism exerts a lot of force.

Memory Check 1. Name the motion transformation mechanism that: a) Is composed of a toothed wheel and toothed bar b) Has an egg-shaped wheel 2. Indicate whether each of the following examples is a motion transmission mechanism or a motion transformation mechanism:

a) b) c) d)

A video cassette A lever corkscrew A clothesline A vise

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TOPIC 1

How to Work Safely . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428 General Safety Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428 Laboratory Safety Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . 428 Electrical Safety Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 429

TOPIC 2

How to Apply the Experimental Method . . . . . . 430 Scientific Method and Problem Solving . . . . . . . . . . . . . . . . . . . 430 The Experimental Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 430

TOPIC 3

How to Apply the Design Process . . . . . . . . . . . . . . 433 Building Technical Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433 Analyzing Technical Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434

TOPIC 4

How to Conduct a Research Project . . . . . . . . . . . 436 Research Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436 Internet Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437

TOPIC 5

How to Communicate Effectively . . . . . . . . . . . . . . . 438 Oral Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 438 Communication Using Visual Aids . . . . . . . . . . . . . . . . . . . . . . . 439

TOPIC 6

How to Present Scientific Results . . . . . . . . . . . . 440 The Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 440 The Cartesian Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441 The Bar Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442 The Histogram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443 The Line Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444 The Pie Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445

426

TOPIC 7

How to Draw Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . 446 Graphic Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 448 Geometry Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 449

TOPIC 8

How to Build a Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450

TOPIC 9

How to Scale Down an Object . . . . . . . . . . . . . . . . . . 451

TOPIC 10

How to Use Observation Instruments . . . . . . . 452 The Magnifying Glass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452 The Light Microscope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453 The Binocular Microscope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 455

TOPIC 11

How to Use Measuring Instruments . . . . . . . . . . 457 The Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457 The Dynamometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 458 The Graduated Cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 459 The Thermometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 460

TOPIC 12

How to Use Technological Instruments . . . . . . . 461 The Back Saw and Mitre Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461 The Hand Drill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461 The Drill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 462 The Riveter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 462 The Crescent Wrench . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463 The Glue Gun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463

427 427

TOPIC

1

How to Work Safely It is important to follow certain safety precautions when conducting an experiment. Begin by reading the safety instructions on this page. Your teacher will explain the specific safety procedures that should be followed at your school.

General Safety Instructions 1

Let your teacher know at the beginning of the year if you have any allergies or health problems that could affect your work in class. Tell your teacher if you wear contact lenses or a hearing aid.

2

Listen carefully to the instructions that your teacher gives at the beginning of a laboratory period.

3

If you have developed your own procedure for an experiment, ask your teacher to approve it before you begin.

4

Handle all equipment with care.

5

Protect your textbooks and notebooks from splashes and spills.

6

Advise your teacher immediately of any injury or broken equipment, even if it seems minor.

5

Always keep your workspace clean and organized to avoid accidents.

6

Never chew gum, do not eat and do not drink in the laboratory.

7

If you have long hair, tie it back.

8

Never taste substances in the laboratory. Never smell substances directly. Use the technique illustrated in Figure 1 if you do need to smell a substance.

9

Make sure you know the location of the nearest fire extinguisher, fire blanket, emergency shower, first-aid kit, eyewash and fire alarm. Learn how to use each of them.

Laboratory Safety Instructions 1

Look over the WHMIS symbols of safety and hazardous materials listed in Table 1 on the next page.

2

Make sure you understand the safety instructions before you begin an experiment.

3

Wear a lab coat or apron when using messy or corrosive products.

4

Never leave an experiment unattended.

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428 Topic 1

Figure 1 This picture shows the proper way to smell a

substance in a laboratory: do not place the substance directly under your nose; hold it slightly away from you; use your hand to direct the vapours toward your nostrils.

WHMIS Hazard Symbols

Safety Symbols

WHMIS is an acronym for Workplace Hazardous Materials Information System. WHMIS hazard symbols are used throughout Canada to identify hazardous substances. These substances are found in the workplace, in schools and so on. They include household products and solvents. You are probably already familiar with some of these symbols. Study the symbols in Table 1 so that you can recognize them and take the necessary precautions when handling hazardous substances.

Here is a list of the safety symbols that are used in your textbook (see Table 2). Make sure you know what they mean before you begin an activity or experiment. Table 2 Safety symbols

Eye protection: wear safety glasses

Hair protection: tie back long hair

Skin protection: wear gloves

Table 1 WHMIS hazard symbols

Clothing protection: wear a lab coat or an apron

Compressed gas

Beware of hot objects: wear heat-resistant mitts

Flammable and combustible material

Beware of harmful fumes: work under a fume hood

Oxidizing material

Beware of pointed or sharp objects

Material causing immediate and serious toxic effects Material causing other toxic effects

Biohazardous infectious material

Corrosive material

Electrical Safety Instructions 1

Do not touch any electrical equipment if your feet are bare, if your hands are wet or while standing on a wet floor.

2

Do not leave electrical cords lying on the ground.

3

If you need to step away from your set-up, shut off and unplug any heat-producing apparatus (e.g. a hot plate). Electrical equipment should not be plugged in when not in use.

4

If you need to change a light bulb in a piece of equipment, be sure to unplug the equipment first.

5

Never touch fallen electrical wires that you find lying on the ground. If you do, you might be electrocuted.

Dangerously reactive material

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429

TOPIC

2

How to Apply the Experimental Method The Scientific Method and Problem Solving The objective of science is to describe, explain and predict phenomena. To solve a problem, scientists use a method that guides their thought processes and experiments; it is called the scientific method. Scientists’ primary concern is to establish relationships between the problem that they need to solve and existing phenomena. In other words, they must determine whether a theory that is already accepted by the scientific community can explain the problem that they are studying. If not, they must suggest changes to existing theories or develop new ones. When scientists develop a new theory, they often need to deduce connections between the problem that they need to solve and other phenomena, in order to arrive at a temporary explanation. This is called hypothetical

An example of an observation: I observe that asphalt gets very hot on sunny days.

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430 Topic 2

deduction. Sometimes they need to predict what is going to happen. This is called hypothetical prediction. In each case, scientists must verify their explanations and predictions using experiments. This is the experimental method, which is part of the scientific method. In class, you will apply accepted theories to problems that you need to solve. You too will learn to use the scientific method to guide your thought processes and experiments.

The Experimental Method The experimental method consists of five steps. However, you might want to change the order provided here. Also, you might not need to do each step every time you want to solve a problem. You can always backtrack and make changes as you go along.

I observe

I define the variables

You are interested in a phenomenon or are required to solve a problem.

You conduct an experiment to answer a question. In order for your results to be valid, it is important to specify the factors that you will be controlling.

You make observations using your five senses. You can also use instruments, such as the microscope or the telescope, to extend your senses. Observations may or may not involve measurements. Observations that involve measurements are called quantitative observations. Observations that do not involve measurements are called qualitative observations. For example, “I saw the snow melt” is a qualitative observation. However, “I saw that the snow had melted completely after one hour” is a quantitative observation. Quantitative observation An observation involving quantities that can be expressed in numbers.

Qualitative observation

Examples of variables: • “I must use two articles of clothing of different colours: one light and one dark.” (The variable is the colour of the clothing.) • “I must expose these two articles of clothing to the same light source, for the same amount of time.” (The variable is the length of exposure to the light source.)

I experiment You must determine the steps of your experiment. This work plan is called the experimental procedure. Your procedure must be clear enough for another person to reproduce the same experiment (see Figure 2).

An observation that involves quality, shape or properties and cannot be expressed in numbers.

Experimental procedure A description of the steps and conditions of an experiment.

I develop a research question (or questions) Your observations will often give rise to questions. Sometimes, you might want to deduce an explanation before carrying out your experimental investigation. You might also predict the answer to your question. This prediction is hypothetical, uncertain and temporary. It must be confirmed or disproved by your experimental investigation. Example of a question: “Does dark clothing become hotter in the sun than light clothing?” Example of a hypothetical prediction: “I think that dark clothing will become hotter than light clothing.”

You must: 1

Choose the equipment and materials that you will need

2

Prepare a procedure that clearly numbers each step; this procedure must take laboratory safety instructions into account

3

Use all of the equipment in your list

4

Respect and monitor all of the variables that you have selected

5

Conduct your experiment and follow all the applicable safety rules

6

Record all the information you collected

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431

Procedure EQUIP MENT AN D 1. Place a piece of white MATERIAL cardboard under a lamp, • a piece of white cardboard 30 cm away from the (30 cm x 22 cm) light bulb. • a piece of black cardboard 2. Place a piece of black (30 cm x 22 cm) cardboard under another lamp, • two thermometers 30 cm away from the light bulb. • two table lamps with 3. Record the initial temperature of the two thermometers. 4. Slide a thermometer under each piece of cardboard. 5. Turn on the lamps. 6. Wait 20 minutes. 7. Record the final temperatures of the two thermometers. 8. Put away the equipment.

(“I develop a research question” section). You must also be able to draw all possible conclusions from your experiment. If you made a prediction, determine whether it is consistent with your results. It is important to analyze the results objectively, even when you are disappointed with them and they are not what you expected. You can discuss the results and conclusions with your classmates. You can also present the entire procedure in an oral or written lab report. Make any changes that you think are necessary to improve your procedure for next time. You can also make changes if you ask yourself other questions after the experiment.

An example of how to present results: Temperature change under the pieces of cardboard

Figure 2 Example of an experimental procedure, list of

Thermometer under white cardboard

Thermometer under black cardboard

Initial temperature (°C)

22

22

Final temperature (°C)

26

31

Temperature change (°C)

+4

+9

material and experimental set-up

I analyze my results and present them You must organize, analyze and present your results in an appropriate manner (see Topic 5). These results consist of all of your observations. The values that you have calculated based on your observations are also part of your results. You must analyze your results to answer the initial question or questions SKILLS HANDBOOK

432 Topic 2

An example of how to interpret results: This experiment has shown that a piece of black cardboard becomes hotter than a piece of white cardboard when exposed to light. As a result, I conclude that the hypothetical deduction is correct that dark clothing becomes hotter in the sun than light clothing. The proof is that the temperature under the black cardboard increased by 9°C, whereas the temperature under the white cardboard increased by only 4°C. An example of another question: “What would happen if I exposed the pieces of cardboard to light for a longer period of time?”

TOPIC

3

How to Apply the Design Process Various approaches can be used to solve a technological problem. Together, these approaches are referred to as the “design process.” This procedure can involve building or analyzing technical objects.

that you choose for building your rain catcher must take into account what you have available (equipment, budget, time and so on). This analysis will help you to plan your work effectively.

3. Make a list of available resources. To build your technical object, make a list of the necessary equipment and material. For your rain catcher, take a look at what you have at home or in your garage. You might find objects or material that your family no longer needs and that you can reuse.

4. Draw a design plan.

Building Technical Objects The construction of a technical object involves nine steps. The process is not linear. You can change the order of the steps and backtrack as needed.

1. Determine a design idea. This is the step where you determine the existence of a need to be filled. For example, you realize that rainwater could be used to meet household water needs. However, there is no apparatus available to collect rainwater. You therefore decide to build a rain catcher. Brainstorming can help you develop a design idea. Make a list of all of your ideas.

2. Analyze each scenario. Analyze each of the ideas from your brainstorming session and choose one. For example, the scenario

Before building a prototype, engineers draw a design plan. You will need to do the same to demonstrate your solution for the rain catcher. You could begin by drawing a sketch and then a design plan, and, lastly, modifying your plan based on improvements that you want to make to your object. The design plan explains how a prototype works.

5. Prepare a technical drawing. A technical drawing shows the structure of the object and contains the information required to build it. The technical drawing should be prepared during the first stages of the design phase. Put as much detail as you can into the technical drawing of your rain catcher. In addition, show where all of the pieces of your prototype come from.

Prototype One of the first copies of an object or system. It can serve as a model for testing or large-scale production.

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433

6. Prepare a manufacturing process sheet. Think about the different steps that you will need to follow to build your prototype. The manufacturing process sheet helps you to organize your ideas. It provides a detailed list of the tools and material that you must use. It also describes the order of the steps for building your prototype. Determine, in order, the steps that you must follow to build your rain catcher. Once you begin building your object, you can modify your manufacturing process sheet. Make changes based on the reality of the situation and the difficulties that you encounter along the way.

7. Build your technical object.

Analyzing Technical Objects By analyzing a technical object, you will be able to answer these three questions: • What is the purpose of the technical object? • How does it work? • How is it made?

1. What is the purpose of the technical object? During this first step, you must identify the function of the object, that is, its role. Let us consider the example of a binder clip (see Figure 3). You use it to hold together sheets of paper. The function of the binder clip as a technical object is therefore to hold together several sheets of paper.

You have now reached the construction phase. Follow the technical drawing and manufacturing process sheet that you prepared for your rain catcher. If you make changes, be sure to make note of them and explain your reasons. Next, test your prototype.

8. Market your technical object. This is the step where you showcase the value of your product. Design and prepare packaging if necessary. Prepare operating instructions and a maintenance guide. This step is essential for marketing and selling a product.

9. Review your design process. You can review your design process at any time. Suggest improvements to your prototype if necessary. Make note of these on your technical drawing. Take these notes into account when preparing your manufacturing process sheet. Figure 3 A binder clip

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434 Topic 3

2. How does the technical object work?

3. How is the technical object made?

When you explain how an object works, you must describe:

You must analyze the size and shape of the parts of your object. You must also explain your choice of material. Often, you will present your analysis in the form of a technical drawing (see Figure 5).

• the role of each component of the object • the scientific principles that explain how the object works • the forces applied to the parts of the object In the case of the binder clip, a lever system opens the clip. When you apply force with your fingers, you relax the pressure of the jaws on the sheets of paper. When you stop applying the force, the jaws once again exert enough pressure to hold the papers together. Figure 4 illustrates the axis of rotation, the lever arms and the points of application of the force.

Look more closely at your binder clip. You will notice that it is made from a strong, sturdy metal. You will also see that the shape of the clip allows you to exert pressure with your fingers. In addition, there is a link between the part where you apply pressure and the part that holds together the sheets of paper. The hard steel clip acts as a link that facilitates the return motion.

ø3

24

49

31

24 Axis of rotation Movement Position after movement Hard steel clip Jaws Steel lever Lever arm of the applied force

Lever arm of the reaction force Point of application of the applied force Point of application of the reaction force

Figure 4 Design plan for a binder clip

The dimensions shown are in millimetres.

69

Figure 5 Technical drawing of a binder clip

When you examine technical objects, you are developing analytical skills. You will learn to look at everyday objects from a different perspective. This will help you to improve these objects or to draw on them for inspiration in developing new technological designs. SKILLS HANDBOOK

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How to Conduct a Research Project Research Project

12

If necessary, consult experts in the field.

Research helps you to gather information about various topics. You can use your research results to solve scientific or technological problems. When you do research, you usually present the information that you have gathered in written, visual or oral format, or a combination of the three. Here are a few tips for conducting research and organizing and presenting information.

I do research 1

Make sure you understand the objective of the research that you will be conducting.

2

Define your topic by asking yourself one or more questions before you begin. Your research must help you answer these questions.

3

Prepare a work schedule.

4

Begin by looking for general information in on-line or hard copy encyclopedias.

5

Go to the library and borrow books on your topic.

6

Look for information on the Internet using keywords.

7

Choose relevant and credible documents and websites (see “Determining the reliability of a website or web page” on the next page).

I organize my information You must organize the information that you have gathered, in order to communicate it. To do this, carefully reread your notes and organize them by topic.

I present the information In the previous step, you organized your information. Next, you will present your results in writing or some other format. To do this you must: 1

Prepare an outline that is as detailed as possible

2

Write a draft of your text (introduction, development and conclusion)

8

Select the extracts that you need by skimming though the information.

3

Divide your text into paragraphs (one idea in each paragraph) and include subtitles

9

Prepare note cards summarizing what you have learned.

4

Check your spelling and sentence structure

10

Write down your references on note cards so that you will be able to cite them later in a bibliography.

5

Prepare a final copy

6

Prepare a table of contents using your outline as a guide

7

Prepare a bibliography using your notes

11

Make changes to your original questions as required.

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Internet Research Research tools When doing Internet research, you can use a number of strategies. For example, if you want to look up information about a given topic, use tools, such as search directories or search engines. Keywords are extremely important in conducting research effectively.

Choosing keywords Use precise words to limit your search results. Try using the “advanced search” option of your search engine. Symbols will also help limit your results. A few common symbols are explained below.

Means “AND.” You will obtain fewer search results. For example, pie + sugar – Means “NOT.” The search engine finds pages that contain the first word and that do not contain the second. For example, pie - sugar “ ” The search engine will find only those pages containing the exact expression. For example, “sugar pie” +

Determining the reliability of a website or web page As you conduct a search on the Internet, keep in mind that the information you find is not always reliable. Would you ever think of asking unreliable people for information? Of course not! On the Internet, you must consider the reliability of your source of information.

2

Is the Internet address short, simple and easy to identify? Addresses ending in “org,” “gouv.qc.ca,” “gc.ca” or “edu” are generally considered reliable.

3

Is the content of the site clear and accessible?

4

Does the information appear to be accurate and objective?

5

Is the information clearly structured?

6

Is the site well written?

7

Does the site contain advertising? If so, that might mean that the organization or person presenting the information on the site does not have financial means to have the information verified by experts.

8

Are references cited?

9

Does the site show the dates when it was created and updated?

Here are some questions to help you determine the reliability of a website: 1

Is the person or organization that created the site clearly identified? SKILLS HANDBOOK

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TOPIC

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How to Communicate Effectively Communication forms the basis of your discussions with other people. It allows you to convey ideas as well as the results of your research or experiments. It also allows you to learn what your classmates have to say. In this topic, we will focus on: • oral communication (in a presentation)

what questions the audience will ask, and prepare your answers. 4

Prepare numbered index cards. Write down only the major points (keywords, expressions).

5

Make sure you respect the time allotted for your presentation.

6

Bring all of the necessary equipment to school the day before the presentation.

• communication using visual aids (a poster)

Oral Communication This section outlines certain rules for ensuring effective oral communication.

Presentation 1

Get rid of the butterflies in your stomach (take a deep breath, pause between sentences).

2

Be clear and concise.

3

Speak loudly enough so that the students sitting at the back of the class can hear you.

4

Do not speak too fast, and pronounce your words properly.

5

Use expression in your voice.

6

Do not move around too much. Avoid language tics (“um,” “like” and so on), as well as repetitive movements.

7

Look at your entire audience, not just the adults or your friends.

8

Express yourself using your whole body (hand movements, facial expressions, voice), but do not exaggerate.

9

Face the audience.

Preparation 1

Structure your presentation as follows: a) Prepare an introduction. • Begin by attracting the audience’s attention. For example, tell a story, share an insight or ask a question. • State your topic and the objective of the presentation. • Give an outline of the presentation. b) Develop your topic by following your outline and by establishing relationships between the various parts of your presentation. c) In your conclusion, summarize the main points of your presentation. d) Allow time for questions from the audience, or ask questions yourself.

2

3

In order to sound natural, do not memorize your text. Rehearse your presentation by practising it a few times or by recording yourself. Try to foresee

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Concise An adjective describing a text or speech that expresses many ideas using few words.

More tips 1

Explain difficult words in relation to your topic.

2

Support your statements using clear visual elements (see below).

3

Interact with your audience (ask questions, distribute handouts and so on).

4

Speak slowly when explaining difficult concepts.

5

Use humour or present your ideas in an original way, but do not stray from your topic.

Communication Using Visual Aids You can use visual aids when you give a presentation. They can help you capture the audience’s attention and explain difficult concepts. Visual aids are also useful if you do not have enough space to write on the board. You can also use them to provide additional information while respecting the time limit. Also, if you are shy, visual aids help to focus the audience’s attention away from you. Visual aids can take different

forms: posters, displays, slides, transparencies, computer presentations and so on. Follow these rules when using visual aids: 1

Avoid putting too much information on your poster. Write down the main ideas and keywords, and avoid using long sentences.

2

Make sure that the entire audience can see the information. All photocopies (especially reductions) must be clear and legible.

3

Limit the number and size of your posters.

4

During your presentation, use all of the visual media that you have prepared.

5

Write your text in bright colours that contrast with the background.

6

Remove items as you finish with them so that the audience will focus on the rest of your presentation.

7

Number the visual aids based on the order in which you will be presenting them, and give each one a title.

8

Practise at least once with all of your visual media.

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TOPIC

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How to Present Scientific Results Scientific information is often presented in tables and graphs because it is easier to read and interpret in this format. Scientists prepare tables and graphs when they want to present their results to other scientists. In this topic, you will learn how to make tables, Cartesian planes, bar graphs, histograms, line graphs and pie charts.

Table 3 provides an example. It contains information that Melanie collected in Sept-Îles during the week beginning Sunday, July 9. Melanie wrote the following observations in her notebook:

The Table An important part of science involves gathering information and analyzing it. In a table, data can be presented in columns and rows, making it easier to analyze. This format can help you interpret how a situation changes and draw conclusions from it. The table is also a basic tool for recording information that you can later represent in a Cartesian plane, graph or histogram.

Sunday: 23°C, wind from th e southeast Monday: 18°C, wind from th e east Tuesday: 10 °C, wind from th e northeast Wednesday: 8°C, wind fro m the north Thursday: 9°C, no wind Friday: 18°C, wind from the southeast Saturday: 19°C, wind from the southeast

Follow these steps when you make a table: 1

Determine the number of categories of information. This number will tell you how many columns you need.

2

Divide the space into as many columns as you have categories of information.

3

4

5

Write the name of the category at the top of each column. Write the unit of measure in parentheses if necessary.

Table 3 Weather observations in Sept-Îles for the week

of July 9 to 15

Day

Temperature (°C) Wind direction

Sunday (July 9)

23

southeast

Fill in your table using the information that you have gathered.

Monday (July 10)

18

east

Tuesday (July 11)

10

northeast

Provide a title for your table. Number it if you need to make several tables.

Wednesday (July 12)

8

north

Thursday (July 13)

9

no wind

Friday (July 14)

18

southeast

Saturday (July 15)

19

southeast

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In order to plot a graph in a Cartesian plane, you must be familiar with certain terms. Figure 6 shows what these terms mean. The information used to plot the graph in this Cartesian plane is found in Table 4.

The Cartesian Plane A Cartesian plane shows the variation or distribution of a variable in relation to one or more other variables. In a Cartesian plane, you can represent results from an experiment, an investigation, research and so on. This allows you to:

Cartesian plane

• observe trends in the variation or distribution of results

A graph with two perpendicular axes in which coordinates represent information.

• establish relationships between the different variables

Variable A quantity that can have different values.

Table 4 Average water consumption as a function of the time that a garden hose is left running

Time (min)

2

4

6

8

10

12

14

16

18

20

40

60

80

100

120

140

160

180

Name of variable y A value of the ordinate or of the variable y

Quantity of water (L)

140

Axis of ordinates or y-axis

120 100 80

Graph or curve A coordinate (x, y)

60 A value of the abscissa or of the variable x

40 20 0

2

4

6

8

10 12 14 16 18 20

Time (min) Axis of abscissas or x-axis

Name of variable x

Average water consumption as a function of the time that a garden hose is left running a) A Cartesian plane

Title

b) A graph in a Cartesian plane

Figure 6 The parts of a Cartesian plane

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The Bar Graph A bar graph is used to compare the number of elements in each category of a set. For example, it can be used to represent the number of students on each school team. The bars can be horizontal or vertical.

5

The height of each bar should correspond to the number of elements in the category.

6

Indicate the names of the variables. Write any units of measure in parentheses, beside the name of the variables.

7

Provide a title for your graph. Number it if you need to make several graphs.

Follow these steps to prepare a vertical-bar graph: 1

Draw the axis of abscissas or x-axis and the axis of ordinates or y-axis on a piece of graph paper.

2

For the x-axis, choose a scale that allows you to represent all of the categories. On the x-axis, draw as many bars of equal width as you have categories. Do not leave any space between the bars, unlike the bar graph, where you left a space between each bar.

3

Write the name of each category.

4

For the y-axis, choose a scale that allows you to represent all of the elements in the largest category. Write your scale on the y-axis.

The bar graph in Figure 7 was prepared from the information found in Table 5.

Abscissa A value of the variable represented on the horizontal axis or x-axis. This variable is also called “variable x.”

Ordinate A value of the variable represented on the vertical axis or y-axis. This variable is also called “variable y.”

Table 5 The number of

students on school teams

Team Basketball

Number of students 34

Volleyball

23

Swimming

48

Diving

12

Badminton

24

Soccer

68

Number of students

70 60 50 40 30 20 10 0 Basketball

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Swimming

Diving

Badminton

Team

Number of students on school teams

Figure 7 A bar graph

442 Topic 6

Volleyball

Soccer

The Histogram

7

A histogram is a graph depicting the number of elements in each category of a continuous variable (see Figure 8).

Provide a title for your graph. Number it if you need to make several graphs.

The histogram in Figure 8 was prepared from the information found in Table 6.

Follow these steps to prepare a histogram: 1

Draw the x-axis and the y-axis on a piece of graph paper.

2

For the x-axis, choose a scale that allows you to represent all of the categories. On the x-axis, draw as many bars of equal width as you have categories. Do not leave any space between the bars, unlike the bar graph, where you left a space between each bar.

3 4

5

6

Table 6 The distribution of

people visiting a medical clinic, grouped by age

Age (years) Under 10

Number of people 1 375

10 to 19

875

Write the name of each category.

Continuous variable

20 to 29

720

For the y-axis, choose a scale that allows you to represent all of the elements in the largest category. Write your scale on the y-axis.

A variable that can have any value in a given interval, for example, students’ heights.

30 to 39

814

40 to 49

925

50 to 59

1 210

60 to 69

1 530

70 to 79

1 470

80 to 89

652

90 and over

125

The height of each bar should correspond to the number of elements in the category. Indicate the names of the variables. Write any units of measure in parentheses, beside the name of the variables.

1 800 1 600 Number of people

1 400 1 200 1 000 800 600 400 200 0 Under 10

10 to 19

20 to 29

30 to 39

40 to 49

50 to 59

60 to 69

70 to 79

80 to 89

90 and over

Age (years) The distribution of people visiting a medical clinic, grouped by age Figure 8 A histogram

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The Line Graph

6

A line graph (also called a broken-line graph) is used to represent a continuous variable that changes as a function of another variable.

Indicate the names of the variables. Write any units of measure beside the name of the variables.

7

Provide a title for your graph. Number it if you need to make several graphs.

1

Draw the x-axis and the y-axis on a piece of graph paper.

2

For the x-axis, choose a scale that allows you to represent all of the values of the continuous variable. Write your scale on the x-axis.

3

For the y-axis, choose a scale that allows you to represent all of the values of the other variable. Write your scale on the y-axis.

4

Plot points representing each coordinate.

5

Join the points (see Figure 9). If there are many points and they are spread out, draw a line so that there are roughly an equal number of points on each side. This is called a line of best fit (see Figure 10).

The line graph in Figure 9 was prepared from the information found in Table 7.

25 Temperature (°C)

Follow these steps to prepare a line graph:

20 15 10 5 0 0

2

4

6

8

Time

Temperature as a function of time on June 12, in Montréal Figure 9 A line graph

Table 7 Temperature as a function of

time on June 12, in Montréal

Hours past midnight Temperature (°C) 0 (midnight on (h) June 12) 16 3

12

6

10

9

18

12

22

15

23

18

19

21

17

24 (midnight on June 13)

15

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444 Topic 6

10 12 14 16 18 20 22 24

Figure 10 A line of best fit

Table 8 How students get to school

The Pie Chart Pie charts can be used to divide a group into subgroups based on a specific criterion. Each subgroup is designated by a sector. The greater the number of elements that the sector represents, the larger the angle of the sector. Follow these steps to prepare a pie chart: 1

Calculate the percentage of the number of elements in each category with respect to the total number of elements. Use the following formula: Percentage 

Number of elements in the category Total number of elements

Method

9 (9  15  3  3)

 100% 

9 30

Angle (in degrees)

9

30

108

Bus

15

50

180

Car

3

10

36

Other

3

10

36

7

Make each sector a different colour.

8

Make a legend for your pie chart. The legend should show the colour of each subgroup. Beside the chart, you can make a list of the colours and what they mean (see chart in Figure 11a). You can also identify each sector with a line (see chart in Figure 11b).

9

Give your pie chart a title.

 100%

 100%  30%

Percentage (%)

Walking

Sample calculation (based on information in Table 8): Percentage 

Number of students

Therefore, 30% of the students walk to school. 2

Calculate the angle of each sector. Use the following formula:

Angle 

Percentage 100

Walking (30%) Bus (50%)

 360°

Car (10%)

Sample calculation (based on information found in Table 8): Angle 

30 100

Other (10%)

 360°  108° a) How students get to school

3

Using a compass, draw a large circle on a sheet of paper.

4

Mark the centre of the circle with a small cross.

5

Draw a radius joining the centre of the circle to a point on the circumference directly above the centre.

Car (10%)

6

Then, using your first radius as a starting point, draw other radii clockwise. Use the angles that you calculated in Step 2, which are indicated in Table 8.

Walking (30%)

Other (10%)

Bus (50%)

b) How students get to school Figure 11 Pie charts

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How to Draw Diagrams It can be difficult to describe technical objects using words. This is why it is helpful to complement your description with a diagram (see Figure 12).

Top view

70.7 m

Orthogonal projections are often used to represent objects in three dimensions. Each image of an orthogonal projection corresponds to an angle of view of 90° in relation to the other images (see Figure 13a). The three diagrams of an airplane shown in Figure 13b) are orthogonal projections.

22.2 m

12 mm

Side view

19.4 m

165 mm

25.6 m 68.6 m

Figure 12 A technical object and its technical drawing

Front view

Top view

View from left side

64.4 m

11.0 m

Front view

b) Three orthogonal projections of an airplane a) Orthogonal projections provide three angles of view that are at 90° angles to each other.

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Figure 13 Representing an object using orthogonal

projections

Follow these steps to draw a diagram: 1

Carefully observe the object that you want to draw.

2

Determine what is important to represent in your diagram.

3

Limit yourself to the useful elements of the object.

4

If necessary, draw the object as seen from different angles.

Leah’s room 2.8

0.9

Closet Door

5

If you need to show the inside of the object, draw a cross-section. To do this, imagine that you have cut the object in half and draw what you would see (see Figure 17 on the next page).

6

Write notes on your diagram. Provide useful information, such as the names of the parts of the object, dimensions, different viewpoints and so on.

7

Provide a title for your diagram.

The technical drawing shown in Figure 14 was prepared to help Leah furnish her bedroom. Notice that only the useful details have been included. Diagrams can also represent phenomena or explain how equipment operates. In this case, it is absolutely essential to limit the diagram to the most important details. For example, the diagram in Figure 15 shows a food web in a marsh.

Bedroom 3.5

3.0

Window

Window Frog

0.6

1.2

0.7

1.2

4.3 The dimensions shown are in metres.

Wading bird

Waterbug

Mosquito larva

Figure 14 Technical drawing of Leah’s room

l To draw a diagram, you wil ent ipm need the following equ and material: • a blank sheet of paper • a pencil or mechanical pencil • an eraser • a geometry set, including a compass, ruler, set squares and a protractor

Catfish

Rotifers

Water fleas

Algae

Figure 15 Diagram of a food web in a marsh

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447

Graphic Symbols Remember that, in order to draw a clear diagram, you must limit yourself to essential information. You must also follow certain conventions that make it easier to draw the diagram and to read it. There are many different symbols used to represent the various elements of a technical drawing. Figure 16 illustrates a few of them.

The dark line represents visible edges and contours.

The symbol ø represents the diameter of a circle. This circle was drawn using a compass opened to half the diameter of the circle, or 13 mm.

Ø 26

The symbol R represents the radius of a curve. For example, in Figure 18, the radius corresponds to the opening of the compass that was used to draw the curve. The radius is equal to half of the diameter.

The thin broken line represents hidden edges and contours. R 15

The mixed broken line represents axes. dimension line 29

dimension extension line figure

Figure 16

The thin solid line represents extension lines and dimension lines. The dimension figure gives the actual length of the object.

Sketch

Technical drawing

Figure 18 Drawing a curve

Lines used in technical drawings

Cross-sections are represented by hatched lines surrounded by a solid line. Cross-sections allow you to see the inside of an object. Figure 17 provides two examples of cross-sections. The first shows a piece of wood with two holes running through it. The second shows two pieces of metal attached by a nut and bolt.

Figure 19 shows how you can use a technical drawing to represent a block of wood that has a hole drilled into it. The diameter is 60 mm.

Ø 60 The thin mixed broken line shows the axis. The thin freehand line shows the boundaries of the cross-section.

Dimension line 200

The thin broken line shows a hidden contour.

The length is 200 mm.

Sketch

Technical drawing

An extension line Sketch

Technical drawing

Figure 17 Two examples of cross-sections

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The dark line shows the contours of the piece.

100

Unit of measure

200 The dimensions are in millimetres.

The hatched lines show a crosssection.

Figure 19 Vocabulary used in technical drawings

Geometry Instruments

Set squares

The main tools used by a draftsperson are geometry instruments and computers. You are probably already familiar with a compass and a protractor. This page summarizes what you can do with them.

You can use set squares to draw 30°, 45°, 60° and 90° angles. You can also use them to draw straight parallel lines (see Figure 21). 90°

The compass A compass is used to draw circles and arcs. 30°

90°

60°

The protractor

45°

45°

A protractor is used to measure and draw angles (see Figure 20).

This angle measures 40°.

Figure 20 A protractor

Two straight parallel lines

Figure 21 Different types of set squares

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TOPIC

8

How to Build a Model A model is a simplified representation of a concept or phenomenon. We build models for various reasons; this is why there are different kinds of models (regular models, scale models, mathematical formulas and so on). Here are a few reasons for making models: • Some objects are too expensive to use at the experimental level (for example, airplanes). • Some experiments are impossible to carry out (for example, volcanic eruptions). • Some structures, such as atoms, are too small for us to see; that is why we have an atomic model. • Models can provide accurate information for some activities; for instance, a mathematical formula is used to calculate the heart rate that we should maintain during physical activity. • Some models allow us to make predictions before a phenomenon actually occurs (for example, weather forecasts). When building a model, take into account only those properties that you want to analyze. Suppose that you want to verify buoyancy conditions before building a boat. You can make a hull using modelling clay, as shown in Figure 22. It is not necessary to build a scale model of the boat to study the conditions in which it will float.

Sometimes, the model must be a construction of an object on a reduced scale, that is, a scale model. For example, we can build a scale model to study the resistance of a bridge (see Figure 23). We can then place this scale model in a tank of water to study the effects of currents and waves.

Figure 23 Scale model of a bridge

A model can also be a mathematical formula. Consider the example of a person who is doing physical activity. To train efficiently, this person must know his or her maximum heart rate. This information can be obtained using this mathematical formula: Maximum heart rate = 220 – age

Therefore, if you are 14 years old, your maximum heart rate when you exercise is 206 beats a minute: Maximum heart rate = 220 – 14 = 206

Figure 22

An experiment on buoyancy

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450 Topic 8

Remember, however, that this model is only an approximation. Therefore, the maximum heart rate of two people of the same age is not always identical, but the differences are generally small. By contrast, an athlete who is training for the Olympics would benefit from a more accurate model.

TOPIC

9

How to Scale Down an Object The Ariane 5 rocket is approximately 45 m tall (see Figure 24). If you have to build a reducedscale model that is 18 cm tall, what scale should you use?

When you build a reduced-scale model, you must always use the same ratio between the dimensions of the original object and the dimensions of the corresponding part in the reduced-scale model. In other words, for the Ariane 5 rocket, you must follow the “45 m to 0.18 m (18 cm)” ratio for all parts of your model. 45 m = 0.18 m (18 cm)

Consider the following example. If a part of the original rocket is 1 m long, then what size should this part be in your reduced-scale model? In other words, by what number do we need to divide 45 m to obtain 1 m? The answer is 45. You must therefore divide the height of the original rocket and the height of your model by 45. This will give you the scale of your model.

45 m = 0.18 m (18 cm) ÷ 45

÷ 45 1 m = 0.004 m (4 mm) Scale of the model

Figure 24 On the left, the Ariane 5 rocket. On the right,

a reduced-scale model of the rocket.

Next, how can you determine the length of the rocket tank in your model? The original tank measures 8 m. To obtain the length of the tank in your model, you must multiply each number in the scale by 8. Therefore, the tank in your model will be 3.2 cm long.

1 m = 0.004 m (4 mm) x8 Ratio The quotient of the two lengths being compared.

x8 8 m = 0.032 m (3.2 cm)

Length of the tank in the rocket

Length of the tank in the model

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TOPIC

10

How to Use Observation Instruments Observation instruments are used to extend your senses. They help distinguish important elements that can help you solve scientific and technological problems. In this topic, you will learn how to use three instruments: a magnifying glass, a light microscope and a binocular microscope.

The Magnifying Glass Properties •

A magnifying glass is a biconvex lens. In this type of lens, the edges are thinner than the centre. The lens can be glass or plastic (see Figure 25).

•

The more domed the lens, the greater the magnification.

•

A magnifying glass can magnify an image from 2 to 20 times.

Figure 25 A biconvex lens has thin

edges and a thick centre.

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How to use a magnifying glass A magnifying glass can be used to closely examine items, such as a stamp, a rock sample or an insect. Follow these instructions when using a magnifying glass: 1

Place the magnifying glass as close as possible to your eye.

2

Bring the studied object closer to the magnifying glass until you obtain a clear image.

The Light Microscope Parts The microscope is used to magnify objects that are too small to be seen with the naked eye. To use a microscope, you must be familiar with its parts and their functions (see Figure 26).

A Eyepiece

I Pointer

J Arm

nosepiece D Objective

lenses E Stage

B Body The body is made up of the eyepiece and the objective lenses. C Revolving nosepiece This revolving disk holds the objective lenses. It rotates so that you can use different lenses. D Objective lenses The objective lenses magnify your specimen. Each objective lens has a different power of magnification. A light microscope usually has four lenses that magnify the object 4 , 10 , 40 and 100 . Magnification can be calculated by multiplying the number on the eyepiece (for example, 10 ) by the number on the lens (for example, 4 ). In this example, an object will appear 40 times larger under the microscope than to the naked eye. E Stage The stage holds the slide. An opening in the centre of the stage allows light to pass through the slide.

B Body

C Revolving

A Eyepiece The eyepiece is the part that you look through. In most microscopes, the eyepiece magnifies the object 10 times (10 ).

K Coarse-focus

knob

F Stage clips G Condenser L Fine-focus knob

F Stage clips The stage clips hold the slide in place on the stage. G Condenser The condenser directs the light toward the specimen. It includes the diaphragm, which controls the amount of light that reaches the specimen. H Light source The light source illuminates the specimen. I Pointer The pointer is the line that you see when you look through the eyepiece. You can use the pointer to identify a specific area in the field of vision. J Arm The arm connects the base to the body.

H Light source

K Coarse-focus knob This knob brings the image into rough focus. M Base

L Fine-focus knob This smaller knob brings the image into sharp focus. It is used after the coarse-focus knob. M Base

The base supports the microscope. Figure 26 The various parts of a microscope

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How to use a light microscope

1

Always carry a microscope with both hands, and keep it upright. Firmly hold the arm with one hand and the base with the other hand (see Figure 27).

2

Plug in the microscope, and make sure the light is working.

3

Check whether the lenses are clean by looking through the eyepiece. If necessary, clean the lenses and the light source with lens paper.

4

Using the coarse-focus knob, lower the stage as far as you can.

5

Place a slide on the stage. Secure it in place using the stage clips.

6

Check the opening of the diaphragm, and adjust it if necessary.

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7

Using the nosepiece, rotate the smallest objective lens into place.

8

Slowly raise the stage using the coarse-focus knob. The objective lens should not touch the slide.

9

Then lower the stage until you obtain the clearest image possible (it might still be a bit blurry).

10

Do not touch the coarse-focus knob after this point.

11

Use the fine-focus knob to obtain a sharp image.

12

Using the movable stage, centre the object before using the next objective lens.

13

Sketch what you see through the microscope.

14

To increase magnification, use the next objective lens. Then bring the object into focus using the fine-focus knob, but do not lower the stage.

15

Once you have finished studying the specimen, lower the stage and rotate back into place the objective lens with the smallest magnitude. Remove the slide, too.

16

Unplug the microscope by pulling on the plug and not the cord.

17

Clean the equipment (lenses, objective lenses, slides and so on), and put it away.

Figure 27 How to carry

a microscope

The Binocular Microscope Parts The binocular microscope is useful to magnify objects that are visible to the naked eye (see Figure 28). The image you see is three-dimensional because you are viewing it with both eyes, through two eyepieces. A binocular microscope can magnify an object up to 50 times. You can calculate the magnification by multiplying the number on the eyepiece (for example, 10X) by the number on the objective lens (for example, 5X). In this example, the magnification is 50X.

F Eyepieces ●

A Focus knob ● G Optical ●

tubes A Focus knob ● H Head ●

This knob raises and lowers the head of the binocular microscope. B Lamp ● The lamp must be on when you use the microscope. C Arm ●

B Lamp ●

I Objective ●

lens

The arm connects the head to the base. D Switch ●

C Arm ●

The switch turns the power on and off. E Base ● The base supports the stage plate.

J Stage plate ●

F Eyepieces ● You look through the eyepieces. G Optical tubes ●

K Stage clips ●

The optical tubes provide an initial magnification. H Head ● The head connects the optical tubes to the objective lens. I Objective lens ● The objective lens magnifies the specimen. J Stage plate ●

D Switch ● E Base ● Figure 28 Parts of the binocular microscope

The stage plate holds the specimen. K Stage clips ● The stage clips hold the slide in place.

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How to use the binocular microscope 1

Always carry the binocular microscope with both hands and keep it upright. Firmly hold the arm with one hand and the base with the other hand.

2

Plug in the microscope, turn on the switch, and make sure the lamp is working.

3

Check whether the lenses are clean by looking through the eyepieces. If necessary, clean the lenses and the lamp with lens paper.

4

Choose the stage plate on which you will place your specimen. Use a light stage plate with a dark specimen and a dark stage plate with a light specimen. Place your specimen on the stage plate that you have selected.

5

Adjust the lamp so that your specimen is well lit.

6

Pivot the eyepieces to adjust them to your eyes.

7

Bring the specimen into focus to obtain a clear image. Begin by looking through the fixed eyepiece and turning the focus knob.

8

Using both eyes, focus on the specimen to obtain a three-dimensional image. Then turn the adjustable eyepiece until you see a single, clear threedimensional image.

9

Unplug the microscope by pulling on the plug and not on the cord.

10

Clean the equipment (lenses, objective lens, slide and so on) and put it away.

A starfish

A portion of a starfish, magnified 32X

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TOPIC

11

How to Use Measuring Instruments Measuring instruments are used to gather information about various objects. However, you must use them properly in order to obtain accurate measurements. In this topic, you will learn how to use a scale, a dynamometer, a graduated cylinder and a thermometer.

2

a) Place an object on the platform. b) Move the 100-g sliding mass as far to the right as possible without letting the pointer fall below the 0 mark. c) Move the 10-g sliding mass as far to the right as possible without letting the pointer fall below the 0 mark.

The Scale The laboratory scale is an instrument that measures the mass of an object, usually in grams (see Figure 29). Follow these instructions when using a triplebeam scale: 1

Begin by calibrating the scale as follows: a) Place the scale on a flat, steady surface. b) Set the sliding masses of the three beams at 0. c) Make sure the pointer is pointing to 0. d) If necessary, turn the adjustment knob to bring the pointer to 0.

To weigh an object, proceed as follows:

d) Use a pen or spatula to move the 1-g sliding mass until the pointer is in line with the 0 mark. e) Record the mass by adding the values from each scale. The above steps apply to the mass of a solid object. To determine the mass of a liquid or a substance that you cannot place on the scale platform, you will need to make two measurements. 1

Weigh a clean, empty container.

2

Weigh the container together with the substance whose mass you want to determine.

3

Calculate the mass of the substance using the following formula:

Mass of substance

=

mass of full container

–

mass of empty container

Base Sliding masses Platform

Adjustment knob

Beams

Graduated scales

Pointer

Figure 29 Parts of a triple-beam balance

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The Dynamometer Follow these steps to measure the magnitude or intensity of a force using a dynamometer (see Figure 30): 1

Calibrate the dynamometer as follows: a) Suspend the dynamometer. b) Make sure the marker is aligned with the 0 mark. c) Use the adjustment knob if necessary.

2

Measure the force: a) Suspend from the hook the object for which the force is to be measured. b) Read the force (in newtons) based on the position of the marker with respect to the graduations of the dynamometer.

Adjustment knob

Marker

Graduations

Figure 30 Components of a dynamometer

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The Graduated Cylinder When you measure the volume of an object or liquid, you are determining the space that it occupies. When the object is a solid, such as a rock, its volume is usually measured in cubic centimetres (cm3). The volume of a liquid, such as the quantity of milk in a glass, is usually measured in litres (L) or millilitres (mL). Note, however, that 1 mL = 1 cm3. The volume of liquid is usually measured with a graduated cylinder. To read the measurement accurately, your eyes must be at the level of the meniscus (see Figure 31).

Graduated cylinder Line of sight

Measuring the volume of a solid by displacement You can measure the volume of an irregular solid (such as a pebble) by using a graduated cylinder. Follow these steps: 1

Record the volume of the liquid alone. In the example shown in Figure 32, the volume of the liquid is 50 mL.

2

Tilt the cylinder and let the pebble slide down along the side. Take another reading of the volume. In Figure 32, adding the pebble increased the volume to 62 mL.

3

The difference between these two measurements gives you the volume of your solid. In this case, the pebble occupies a volume of 12 mL (62  50 = 12 mL) or 12 cm3. Meniscus The curve formed by a liquid when it touches the sides of a container.

Meniscus

Liquid

Figure 31 A reading taken with eyes at the level of the

meniscus

Measuring the volume of a liquid Follow these steps to measure the volume of a liquid: 1

Pour the liquid that you want to measure into a graduated cylinder.

2

Place the graduated cylinder on a flat, steady surface, such as a table.

3

Your eyes should be at the level of the column of liquid.

4

Take your measurements from the centre of the meniscus (the lowest point).

a) Initial water level

b) The addition of the pebble

c) Water level after the pebble is added to the cylinder

Figure 32 The volume of the pebble is equal to the difference

between the levels of the liquid before and after the pebble is immersed in the liquid. SKILLS HANDBOOK

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The overflow-can method

The Thermometer

Another way to measure the volume of an irregular solid is to use the overflow-can method (see Figure 33). It provides a more accurate measurement than with a graduated cylinder. Follow these steps:

Temperature is measured with a thermometer (see Figure 34). A hot substance has a high temperature, whereas a cold substance has a low temperature. Your school laboratory is probably equipped with alcohol thermometers.

Place the overflow can on a level surface and remove your finger from the spout.

3

Place a graduated cylinder beneath the spout to catch the displaced water.

4

Gently place into the overflow can the object for which the volume is to be measured. Be sure not to touch the water.

5

Use the graduated cylinder to catch the water displaced by the object.

6

Measure the volume of water in the graduated cylinder. The quantity of water displaced by the object corresponds to its volume.

100°C: boiling point of water

37°C: average human body temperature

➞

2

➞

Fill the overflow can and cover the spout with your finger.

➞

1

0°C: freezing point of water

Figure 34 A thermometer

Follow these precautions when using a thermometer:

Figure 33 Measuring volume using an overflow can

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1

Handle the thermometer with care. Because it is made of glass, it can break easily. If it contains mercury, do not discard the mercury into the sink or the trash because this metal is toxic. Do not hold the thermometer by the bulb.

2

Never use a thermometer to stir a substance.

3

Never allow the thermometer to touch the sides of the container.

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How to Use Technological Instruments During activities in your science and technology class, you will need to use certain tools. The instructions on the next two pages will help you become familiar with these tools and teach you how to use them properly: • back saw and mitre box • hand drill • drill • riveter • crescent wrench • glue gun

The Hand Drill

Drill bits

Always wear safety goggles when you handle tools.

The Back Saw and Mitre Box With a back saw and mitre box, you can make 45° and 90° cuts into pieces of wood. These are the angles that you will need to cut if you want to make baseboards (strips of wood running along the bottom of a wall) or frames. Be careful with sharp objects.

Crank Chuck Figure 35 Parts of

a hand drill

Locking ring

A hand drill is operated using a crank (see Figure 35). It can be used to drill holes from 1/32 of an inch to 1/4 of an inch (from 0.8 mm to 6 mm) in wood, metal and plastic. Follow these instructions when using a hand drill:

Follow these instructions when using a back saw and mitre box: 1

Mark your cutting point using a pencil.

2

Place the piece of wood in the far corner of the mitre box.

3

Align your cutting point with the slots so that you are cutting into the scrap.

4

Place the saw in the slots.

5

Make small cuts using a forward motion, and then continue with a back-and-forth motion.

1

Choose a drill bit.

2

Place the drill bit in the chuck.

3

Turn the locking ring to lock the drill bit into place.

Cutting point

Use a centre punch to start your hole.

Scrap

Place the drill bit in this hole.

Centre punch

4

5

The point where a piece of wood is to be cut.

A piece of wood to be discarded.

A pointed metal rod used to mark the centre of a hole to be drilled.

6

Turn the crank.

7

To avoid breaking the bit, apply pressure only when the hand drill is moving up or down. SKILLS HANDBOOK

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The Drill A drill is used to make holes in wood, metal and plastic (see Figure 36). Follow these steps when using a drill: 1

Make sure the drill is unplugged.

2

Choose a drill bit.

3

Place the bit in the chuck.

4

Turn the locking ring to lock the drill bit into place.

5

Use a centre punch to start the hole.

6

Place the drill bit in this hole.

7

Plug in the drill and press the trigger.

Chuck

Trigger

Locking ring

Figure 36

Drill bits

Parts of a drill

The Riveter The riveter is used to join two pieces of metal without welding them (see Figure 37). Follow these steps when using a riveter: 1

Use a vise or C-clamp to hold together the pieces that you want to rivet.

2

Pierce a hole in the pieces of metal. The diameter of the holes should be slightly larger than the diameter of the rivet (for example, 4.5 mm for a 4.4-mm rivet).

3

Place the mandrel of the rivet in the head of the riveter. Squeeze the handles slightly so that the rivet does not fall.

4

Place the rivet in the hole.

5

Squeeze the handles until the rivet breaks.

6

Release the handles and discard the mandrel.

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To rivet To join two sheets of material (metal, plastic and so on) using one or more rivets.

Handles

Head

Figure 37 Parts of a riveter

Mandrel

Rivet

The Crescent Wrench A crescent wrench is used to tighten and loosen nuts and bolts (see Figure 38). Follow these steps when using this tool: 1

Place the nut or bolt between the jaws of the wrench.

2

Turn the thumbwheel to tighten the jaws around the nut or the bolt.

3

Fixed jaw Thumbwheel

Handle

Nut Adjustable jaw

Turn the wrench clockwise to tighten the nut or bolt. Turn it counter-clockwise to loosen it.

Bolt

Figure 38 Parts of a crescent wrench

The Glue Gun With a glue gun, you can glue surfaces together quickly and firmly (see Figure 39). It is handy for gluing pieces that are difficult to keep in place. It can be used for metal, wood, ceramic, porcelain, cardboard, leather, polystyrene and fabric. Follow these steps when using a glue gun: 1

Place a glue stick in the glue gun.

2

Plug in the glue gun, and let it warm up for five minutes. Caution: the tip of the gun and the glue can get extremely hot.

3

Squeeze the trigger to apply glue to the surfaces you want to attach.

4

Put the pieces together.

5

Hold the pieces in place until the glue hardens.

Glue stick

Tip

Trigger

Figure 39 Parts of a glue gun

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Glossary and Index A Abscissa: A value of the variable represented on the horizontal axis or x-axis. This variable is also called “variable x.” 441–444 Abyss: A place where the ocean is extremely deep. An abyss is also called an “oceanic trench.” 292 Acid: A substance with a pH value of less than 7. Vinegar and lemons are acidic substances with a sour taste. 183, 307 sulphuric, 333 Acidification (of precipitation): When the pH of precipitation falls below 5 or 6, making it acidic. 333 Acidity and alkalinity, 183 indicator, 185, 186, 188 pH, 186 Adaptation: A physical or behavioural modification that helps a species survive in its habitat. 225 behavioural, 225 of insects, physical, 7, 8, 9 successful, 215 of trees to winter, 35 Adolescence, 99, 271 energy requirements during, 109 growth during, 109 and puberty, 99 Aerodynamic profile: A shape designed to offer the least possible resistance to the air. Designers try to give this type of profile to cars and airplanes. 408 Agriculture, 130, 136 Air: The mix of gases surrounding the terrestrial globe. Air is composed mostly of nitrogen and oxygen. 293 components of, 293 fresh, 293 humidity of, 58 mass of warm, 58 movement of, 55 in soil, 128 stability of, 338 Air draught: The vertical distance of a boat above the waterline. 86 Alkalinity: The quality of a substance with a pH over 7. 183–184 See Base. Allergies (food), 115 Aluminum, 291 Amphibians, 10

464 Glossary and Index

Anatomy: The study of the structure and organization of humans, plants or animals. 219 Angiosperms, 243 Animals forest, 28 shelters of, 11 threats to, 28, 40 Anthropods, 7, 10 Archimedes’ Principle, 79 Asexual reproduction: A method of reproducing without fertilization: an individual organism produces other identical organisms. 240, 241 Asteroid: A small celestial body. Its diameter is only a few hundred kilometres. 352 Asteroid belt, 353 Asthenosphere: The layer on which the tectonic plates float. This layer is made of partially melted rock. 290, 316 Atmosphere: The envelope of gas that surrounds the Earth. 51, 55, 292 movements of the, 55, 56 simulator of the, 56 Atom: The smallest particle of matter. 203–204, 209–211 Atomic energy. See Nuclear power. Atomic number, 207 Aurora borealis: Luminous phenomenon appearing in the sky in the northern hemisphere. 295, 363 Axis of abscissas or x-axis, 441–444 of the Earth, 362 of ordinates or y-axis, 441–444 of rotation, 435 Axle: A long rod whose ends enter one or more wheels. 412, 416

B Back saw, 461 Bar graphs, 442 Bar magnet: A bar-shaped magnet. There are also horseshoe-shaped magnets, circular magnets and others. 30 poles of a, 30 Base: A substance with a pH value over 7. Bicarbonate of soda (or baking soda) is an example of a base and has a bitter taste. 107, 183, 187 Basic mechanical function(s), 69 of guiding control, 396

of linking, 396 Bedrock: A thick layer of rock lying under the soil. 307, 308 Bees, 8, 9 Belts, 384, 419, 420 Bicycle, 44, 63 parts of a brakes, 68 chain, 69, 87 chainrings, 68, 69 derailleur, 68, 69 handlebars, 68 lever, 68 pedal, 69, 87 rims, 68 seat, 68 spokes, 68 sprockets, 68, 69, 87 wheel, 68, 87 propulsion system of a, 69 inputs, 69 links, 69 outputs, 69 workings, 74 Binocular microscope, 455–456 Biomass, 343 Biosphere, 291, 292 Biotechnology, 113 canning, 113 pasteurization, 113 Bird feeders, 31, 32 characteristics, 31, 32 construction, 31, 32 food, 31, 32 setting up a, 31, 32 species of birds for a, 31 Birth, 100 Black body effect, 348 Boats buoyancy, 85 direction of, 87 hull, 81, 87 keel, 81 mast, 83 righting a capsized, 85–87 stability of, 81 and water’s friction, 83 and the wind, 81, 82 Boiling point, 188, 460 Breeze, land, 337 sea, 337 Broken-line graph, 444 Buccal apparatus of insects, 8 Buoyancy: The capacity of an object to float. Buoyancy results from the effect of two forces: the object’s weight

(downward force) and the buoyancy force of the water on the object (upward force). 77, 85 mass ratio, 77, 87 volume

C Cadence: In cycling, the number of pedal revolutions a minute. 71, 87 Calcium, 299 Cam and follower, 423, 424 Canada’s Food Guide, 105, 122 beverages, 106 eating well, 106 food groups, 105 food labels, 106 foods, 106 oils and fats, 106 physical activity, 106 pyramids of, 106 servings, 106 Carbon monoxide, 159 Carnivore: Feeds on animals. 19, 232, 233 Cartesian plane: A graph with two perpendicular axes in which coordinates represent information. 441 Cataract: An eye disease that causes the crystalline lens to become completely or partially opaque. This prevents light from passing through it. 296 Cell: The basic unit of living organisms. 109, 110, 111 animal, 96, 277–279 genetic material of the, 97 of the human digestive system, 110, 111, 112 membrane, 112 nucleus, 97 olfactory receptor, 159, 160 plant, 96, 277–279 reproductive, 122 sex, 96 Cellular respiration: Producing energy by consuming organic nutrients along with oxygen. Cellular respiration releases carbon dioxide and water. 109, 110, 111, 284–285

Centre punch: A pointed metal rod used to mark the centre of a hole to be drilled. 461 Centrifugation: A process that separates the components of a mixture by rapid rotation. 148 Chains, 384, 419, 420 Change, physical or behavioural, 183, 215, 225 Characteristic property: A property that helps identify a substance or object, determine its use and predict its effect on the environment. 175, 188 Characteristics of living organisms: What differentiates organisms formed of one or many cells. These cells are able to control chemical reactions that are useful for survival and reproduction. 277 Chemical changes: A result of new substances taking on their own properties. 193, 194 Chemical energy: Energy released when matter is transformed. 340, 341, 346, 397 Chemical formulas atoms, 210 elements, 210 molecules, 210 Chemical reaction: A reaction that occurs when the bonds between atoms break and new molecules are formed. 397 Chlorofluorocarbons (CFCs), 296 Chromatography, 39, 40 Chromosome: A structure that contains the DNA of a cell. Chromosomes contain all the genes required to produce an organism. In plants and animals, the chromosomes are found in the nucleus. 97, 236–237 Climate, 52 adaptations of trees to, 35 Climate change drought, 72 flooding, 72 Cloning, 98 Cohesion: The force that keeps a substance’s particles together. 59 Cologne, 165 Comet: A celestial body made up of ice and rock. It revolves around the Sun in a long, narrow orbit and is followed by a bright tail. 357 Communication oral, 438–439

using visual aids, 439 Compass (geometry), 445, 449 Compass (orientation), 29 magnet of a, 30 workings of a, 29, 30 Compost: A mixture of organic and mineral substances resembling black earth. Compost results from the decomposition of plant and animal residues. 134, 190 Compression force, 410 Concise: An adjective describing a text or speech that expresses many ideas using few words. 438 Condensation: The passing of water from a gaseous state to a liquid state. Dew, frost and rain are examples. 53, 54, 87, 89, 332 Condoms, 122, 272, 273 Conduction, 135 Conifers, 34, 243, 247 Connecting rod and crank, 423, 424 Conservation of matter: A law of chemistry and physics whereby the mass of a substance does not change after it undergoes a transformation. 194 Consumers, 19, 232, 233 carnivores, 19, 232, 233 herbivores, 19, 232, 233 omnivores, 19, 232, 233 Continental drift, 315 Continental shelves, 316 Continuous variable: A variable that can have any value in a given interval, for example, students’ heights. 443 Contraception: Methods of preventing fertilization of an ovum by a spermatozoon or, if fertilization has taken place, implantation of the fertilized egg. 116, 120, 121, 122, 272–273 Convection cell: The looping movements of the hot air mass and the cold air mass that are contained in the atmosphere. 334 Convection current: A movement that occurs in a liquid or gas when a temperature difference exists within the substance. 317, 318 Coriolis effect, 335 Corrosion: A chemical reaction causing the progressive destruction of an object. For example, in the presence of air or water, oxygen and iron react together to produce rust. 89 Crescent wrench, 463

Glossary and Index

465

Cutting point: The point where a piece of wood is to be cut. 461 Cycle of day and night, 359 of life. See Life cycle. menstrual, 261 of the seasons, 361 of trees, annual, 35 of water. See Water cycle.

D Decantation: A method whereby a heterogeneous mixture that has layers can be separated into distinct substances. 150, 199 Deciduous trees, 34 Decomposers, 233 Deforestation, 24 Dehydrator, 113 Derailleur, 68, 69 Design: An activity that involves developing a project for the purpose of creating a product. The person or people responsible for design are not necessarily those who originally had the idea. 376, 378 Design plan: A type of technical drawing that represents how an object or system works. 88, 113, 376, 382, 433 Design process, 88, 125, 162, 164, 166, 167, 376, 433, 434 Desertification, 44 Development, stages of human, 122 adolescence, 122 adulthood, 122 childhood, 122 infancy, 122 Diffusion: The movement of particles when they shift from a region where they are concentrated to a region where they are less concentrated. 111, 112, 122, 282 Digestion, 107, 109, 110, 122 Digestive system (human), 109, 110, 112, 115, 122 Dissolution: Uniform mixing of two or more substances. 197 solute, 197 solvent, 197 Distillate, 163, 164, 201 Distillation, 150, 162, 163, 200 homogeneous mixture, 201 residue, 201

466 Glossary and Index

Diurnal: Active during the day. 11 DNA, 97 human, 98, 122 Drainage: The removal of excess water from soil. 132, 133 Draught: The vertical distance of a boat below the waterline. 86 Drill, 462 Drinking water (or potable water): Water that poses no health risk to people. Standards guarantee its quality. 60, 62, 300, 301 Drought, 72 Dynamometer: A device used to measure applied force. 79, 407, 458

E Earth, 353, 354 age of, 95 crust, 290 internal layers of, 290 internal structure, 290 mantle, 290 black, 134, 190 nucleus of, 290 types of soil on, 307 Earthquake: A sudden vibration of the Earth’s crust. It is usually caused by two tectonic plates rubbing together or by the movement of magma beneath a volcano. 325–327 Eating well, 106 Eclipse: The passing of one celestial body in front of another, making it temporarily invisible. 370 lunar, 371 solar, 370 Ecological niches: The combination of all the conditions that promote the development and survival of a species. 15, 28, 232, 234 Ecosystem(s), 2, 5, 10, 22, 28 forest, 22 in miniature, 4 maple forest, 28 Eggs, 16, 255 Electrical energy: Energy produced by electric current. 346, 396 Electrons, 204 Element: All of the atoms that have the same number of protons. 204–207 Embryo, 242, 250–251, 262, 263 Energy: What is used to produce work. For example, food provides humans with the energy to stay active. In the

International System of Units, energy is measured in joules. 71, 346, 395 acoustic, 397 elastic, 396 forms of, 341, 395, 396 kinetic (or movement), 340, 341, 396 magnetic, 397 natural, 340 nonrenewable, 342 potential, 340, 341, 396 radiant, 396 renewable, 342, 343 solar, 350 sources, 395 transformation, 395, 398, 401 Energy efficiency, 402 Energy resources, 342 Engineers, 375 Environment, 44 consequences of our actions on, 48 Epiphytic plant: A plant that grows on another plant without harming it. 229 Erosion: The wearing away of rocks and soil by water, wind and certain human activities. 310, 329, 330, 365 agents of fragmentation of surface materials, 329 biological, 329 chemical, 330 factors, 330 mechanical, 330 sedimentation, 329 stages, 329 transportation, 329 Eruption: The surface runoff of volcanic matter (lava, ash, carbon dioxide, etc.) from the depths. 322, 323 Essential oil: An oil obtained through the distillation of a plant’s aromatic substances. 143, 150 Estrogen, 258 Evaporation: The process by which water passes from a liquid state to a gaseous state. 49, 87, 89, 332 Evapotranspiration, 332 Evolution: The sum of all transformations undergone by a life form over the course of generations. 96, 215, 235 and dinosaurs, 95 and humans, 95 and natural selection, 235 of species, 97 Experimental procedure: A description of the steps and conditions of an experiment, 431

Extinct volcano: A volcano that is no longer active. 322 Eyes of insects, 9

F Family tree, 217 Fastener: An element of a system with a specific function. 392 Fastening unit, 392 Fault: A fissure in the Earth’s crust. 319 Feasiblity: A feasibility study serves to determine if a project is viable. It must take into account timetables, technical knowledge, the political and financial situation, etc. 379 Fertilization: The union of a male cell (spermatozoon) and a female cell (ovum or ovule) to form a new individual. 245, 252 external, 253 internal, 254 Filter, 199 Filtrate, 199 Filtration: A method that allows separation of different substances of a heterogeneous mixture. 199 Flooding, 44, 49, 72 Flow-process grid, 376, 385 Flowers, 150 extraction of the essence of, 150, 167, 168 pistil, 231 pollen, 231 stamen, 231 tree, 34 Food chains, 232 in a semi-aquatic terrarium, 21 Foods, 115 Force: A pushing or pulling action on an object. Force is needed to twist a spring out of shape or to throw a ball. You apply force whenever you push or pull on an object. The unit used to measure force is the newton (N). 79, 408, 435, 458 compression, 410 shearing, 411 Forest(s), 22 advantages of, 24 boreal or taiga, 26 fires, 40 living organisms of the, 28 Mediterranean, 27 orientation in the, 29 temperate, 26

threats to, 24, 40 tree savannahs, 27 tropical and subtropical, 26 uses for, 24 of the world, 25–27 Fossil: An imprint or remnant of an animal or plant preserved in the Earth’s crust. 305 Fossil ancestors: Long-dead organisms for which whole or partial body imprints have been found. 219, 305 Freezing point, 52, 460 Friction: The force that slows down two bodies in contact. 407, 408 Friction (atmospheric): Resistance to movement caused by air molecules. 295. Fungi: Organisms, such as yeasts and moulds, that feed on organic matter (and are therefore incapable of photosynthesis) and reproduce by means of spores. 218

G Galaxy: A grouping of stars and other celestial bodies. The Sun is part of a galaxy called the Milky Way. 352 Galileo, 371 Gamete: The male reproductive cell (spermatozoon) or female reproductive cell (ovum) that can unite with another, similar cell from the opposite sex, through the process of fertilization. 96, 245 of trees, 35 Gas carbon dioxide, 73, 293, 333 deadly, 159 greenhouse, 342, 343 propane, 160 Gastrula, 263 Gear shift: The part of a bicycle that makes the chain slide from one sprocket to another, or from one chainring to another. 68, 69 Gears, 384, 419, 421 Gene: A DNA segment that determines a specific genetic trait. 97, 122, 236–237 Genus, 218 Geologist: A person who studies the nature and history of the Earth’s crust. They study the composition and structure of the Earth. They also

analyze rocks, minerals, and plant and animal fossils. 290 Germination of seeds, 35 Geyser: A jet of heated water and water vapour that gushes from a fissure in the ground. 324 Glacier: An accumulation of snow transformed into ice that slowly descends into a valley. 299 Global warming, 44, 51, 52 Glucose, 136 Glue gun, 463 Graduated cylinder, 459–460 Graphs. See Bar graph, Broken-line graph, Pie chart, and Line graph. Gravitational force: The force that pulls objects toward the centre of the Earth. The greater the mass of an object, the more strongly it is pulled. 407 Gravity: The force applied by one object on another. The amount of force depends on the mass of the objects and the distance between them. 351 Great Rift Valley in Africa, 327 Greenhouse effect: When heat is trapped in the atmosphere between the surface of the Earth and the clouds. This natural phenomenon is amplified by the presence of polluting gases in the atmosphere. 73, 354 Groove (of a pulley): The narrow, hollowed-out part of the pulley through which the cord or chain passes. 384, 412, 415, 419, 420, 422 Groundwater, 60 Guiding control: The mechanism that makes a component follow a specific movement. rotation, 394 translation, 394 Gymnosperms, 243

H Habitat: The environment in which a specific species lives. 215, 224 of forest animals, 28 natural, 232 peat bogs, 228 of small animals in a semi-aquatic terrarium, 11, 13, 15 Hand drill, 461 Heart rate, 70 maximum, 71, 87

Glossary and Index

467

Heat, 306 energy. See Thermal energy. Hectare: A unit of measurement equivalent to 10 000 m2. 26 Herbarium: A collection of dried, flattened and classified plants that can be preserved and studied. 33, 35 Herbivore: Feeds on plants. 19, 232, 233 Histogram, 443 Hoist, 415 Horizon: The imaginary circular line where the sky and the land (or sea) appear to join. 359 Horizons A, B and C, 308 Hull: The exterior surface of a boat and its framework. Fixtures, such as the mast, keel and rudder, are attached to it. 81 Humidity, 49, 58 of soil, 128 Humus: Partially decomposed organic matter. It can be of animal or plant origin. 134, 307, 308 mineral salts contained in, 134 Hurricane, 49 Hydroelectric dams, 400 Hydroelecticity production, 402 Hydrogen, 204 Hydrosphere: All of the bodies of water on the Earth’s surface (solid, liquid and gas). 292, 298 Hypothalamus: This area located at the base of the brain is responsible for several functions, such as hunger, thirst and emotions. 160

I Ice, 80 Identification key, 6 for insects, 6 for invertebrates, 6 Inclined plane, 412, 414 Infiltration, 332 Input: An element that enters a system (living or nonliving) and affects how it works or lives. 69, 109, 390 Insects, 4, 6 behavioral adaptations, 15, 20 body of, 7, 8, 9, 15 characteristics of, 7, 15 ecological niche of, 15 fossilized, 6 life cycle of, 15, 16 metamorphosis, 16

468 Glossary and Index

moulting, 16 names of, 15 physical adaptations, 7, 8, 9, 15, 20 in a terrarium, 4, 10, 15 Instruments geometry, 449 measuring, 457–460 observation, 452–456 Interrelation: A close relationship between two elements in an environment. These elements can be living or nonliving. 19 of living organisms in a semi-aquatic terrarium, 19, 20 in the forest, 28 non-living organisms in a semiaquatic terrarium, 19 Invention, 75 and need, 88 Invertebrates, 6, 7, 250 arthropods, 7, 10 Iron, 291

J-K Jupiter, 353, 355 Keel: The flat, heavy structure attached to the bottom of a sailboat. 81 Kinesiologist: A person who specializes in promoting healthy lifestyles and preventing health problems. For example, this expert will prescribe physical activities to improve and maintain health and physical performance. 71

L Laboratory, safety in, 428–429 Larva: In certain animals, such as amphibians and insects, the stage of development prior to becoming an adult. 16, 253 Latitude: A way of indicating the distance between a point on the surface of the Earth and the equator. Latitude is measured in degrees (°). Latitudes are imaginary lines dividing the Earth and running parallel to the equator. 360 Lava: The magma that gushes from an erupting volcano. Lava appears in the form of rivers of melted matter. 323

Law of Universal Gravitation, 351 Layer(s) of the atmosphere, 294, 295, 364 ozone, 296 Leaching: A process by which a substance is dissolved and then carried off by water. 308 Leaf (leaves) colour, 38 green pigment, 38 needles (as a form of leaf), 34 parts of the, 34 blade, 34 lobes, 34, 220 petioles, 220 scales, 34 sinus, 34 twig, 34 veins, 220 photosynthesis, 36 of trees, 34 Lever, 65–68, 412, 435 components of a, 413 effort (force exerted), 66 first-class, 414 fulcrum, 66, 413, 414 load arm, 66, 87 load of a, 66, 87 mechanical advantage, 65 second-class, 66, 414 simulator of a, 66 third-class, 414 Life cycle: The stages of development of a species, from conception to death. 16, 17, 34, 99, 100 of small animals in a semi-aquatic terrarium, 11, 13–15 Light: The part of electromagnetic radiation that is visible to our eyes. 136, 345–350 as an energy form, 346 and opaque, transparent or translucent obstacles, 347 reaction to different surfaces, 347 solar, 345 visible, 350 white, 348 Ligneous: A ligneous substance is compact and fibrous. This substance forms the root, stem and branches of certain plants, including trees and bushes. 34 Line graph, 20, 444 Link: The mechanism that holds two components of an object together. 69, 384 complete, 392, 393

direct, 393 elastic, 393 indirect, 393 nonremovable, 393 partial, 393 removable, 392 rigid, 393 Lithosphere: The rigid structure that comprises the Earth’s crust and part of the upper mantle. The thickness of the lithosphere ranges from 70 km (beneath the oceans) to 150 km (beneath the continents). 292, 302 Living organisms, adapted to a semi-aquatic terrarium, 10, 11, 15, 17, 18 classes of, 222 of the forest, 28 invertebrates, 222, microscopic, 18 multicellular, 18 in the soil, 128 unicellular, 18 vertebrates, 222 Lunar phases, 369

M Maceration, 162 Machine, simple. See Simple machine. Magma: Liquid rock in the Earth’s crust. When it reaches the surface, it is called lava. 303, 304, 317, 324 Magnetic declination, 30 Magnetic field (of the Earth), 290 Magnifying glass, 452 Mammal(s), 95 first transgenic, 98 Manufacturing: All operations resulting in the construction of an object conceived by designers. 376, 378 Manufacturing process sheet: A document that describes all the operations relating to the manufacture of a product, the order in which they must be carried out, and the time to be allocated to each stage. 88, 113, 376, 385, 434 Marketing, 376 Mars, 353, 354 Mass: An indication of the amount of matter in a substance. 175, 351 of air cold, 334 warm, 58, 334

International System of Units (SI), 178 kilogram, 179 scale, 179 of water, 52 Material: A substance used in the construction of an object. 113, 168, 386, 387 Mechanical advantage: The relationship between the force required to move a load without a device, and the force needed to move the load using a machine or mechanical system. 418 Mechanical energy: Energy resulting from the sum of potential energy and kinetic energy. 346, 396 Mechanisms, 384 control, 388 motion transformation, 423 motion transmission, 419, 420 Melting point, 188 Meniscus: The curve formed by a liquid when it touches the sides of a container. 459 Mercury, 353, 354 Metamorphosis: A change in the form, nature or structure of an animal. It is such a dramatic transformation that the animal is no longer recognizable as the same creature. 16 complete of insects, 16 incomplete of insects, 16 Meteoroid: A fragment of rock or ice that comes from space. A meteoroid, whose size can vary from a grain of dust to a stone block of a tonne or more, can hit the Earth at very high speed. 292, 295, 364, 365 meteoroid impacts, 365 meteoroid showers, 366 Meteoroid impacts. See Meteoroid Method experimental, 430–432 scientific, 430 Micrometer (μm): A unit of measurement in the International System of Units (SI) equivalent to a millionth (10-6) of a metre. 309 Micro-organism, 116, 118, 277 Microscope, 453–454 Microwaves: Invisible waves ranging in length from 1 mm to dozens of centimeters. 350 Milky Way, 352

Mineral(s), 128, 138, 139, 140, 168, 302, 305, 306 industrial, 140, 168 metallic, 140, 168 Mineral salts: Salts present in the ground, and in water and organic matter. 134, 298, 299 Mines, 139 Mitre box, 461 Mixture(s): A substance that contains at least two types of particles. There are homogeneous mixtures and heterogeneous mixtures. 195 appearance of, 145, 151 artificial, 151, 162, 168 components of, 149, 151, 168 composition of, 145 gaseous, 144 heterogeneous, 146, 147, 148, 168, 195, 196 liquid, 144 natural, 142, 162, 168 preparing, 144 properties of, 151 separating, 149, 151 solid, 144 types of, 149 uses of, 151 Model: A physical object or theory used to predict the outcome of a design. 450 Molecule: The joining of two or more atoms. For example, a water molecule is composed of two hydrogen atoms and one oxygen atom, called H2O. 203, 209-210 Monerans: Unicellular organisms, such as Escherichia coli, that lack a nucleus. This kingdom is now divided into Bacteria and Archaeans. 116, 122, 218 Moon, 365, 368 Moulds, 218 Moult: A phenomenon during which some animals renew their carapace, their external skeleton, their horns, their plumage, their fur and so on. The moult can occur at different points in the life cycle, depending on the animal. 16 Mountain chains, 317, 331 and precipitation, 58 Mountains, aging process of, 331 Motion: The movement of a body. of air, 87 alternating, 406, 419, 423, 424 atmospheric, 55, 56 circular, 406, 419, 423, 424

Glossary and Index

469

oscillatory, 406, 419, 423 rectilinear, 406, 419, 423 transformation, 384, 423 transmission, 419, 420 types of, 406–409, 419, 423 Mucous membranes: The layer of cells lining the inner walls of the digestive and respiratory tracts. These cells secrete mucus, which lubricates the wall and keeps it moist. 296

N Natural disasters, 46 Natural satellite: A celestial body that revolves around a planet. 357 Needles (as a form of leaf), 34 Neptune, 353, 355 Neutrons, 204 Newtons, 407, 458 Nitrogen, 136, 293 Nitrous oxides, 333 Nocturnal: Active at night. 11 Nonrenewable resource: A natural resource available in limited quantities. It is only restored over a long period of time or not at all, for example, petroleum. 342 North geographic, 30 magnetic, 30 Nose, 154, 160 nasal cavities, 160 organ, 154 sense of smell, 154 Nuclear power (or atomic energy): Energy produced by reactions that take place in the nucleus of an atom. 340, 341, 342, 397 Nuclear reactor: A system in which nuclear fusion or fission reactions occur. Fusion of hydrogen atoms is the Sun’s main source of energy. 353 Nutrients: The particles from which cells are nourished. They are derived from digested food. 280 Nutrition, 104, 109 chemical and physical changes involved in, 107, 108, 109, 110, 122

O Odours, 156, 157, 159 perception of, 160

470 Glossary and Index

Orbit: The path followed by one celestial body as it revolves around another. 353, 357, 360 Ordinate: A value of the variable represented on the vertical axis or yaxis. This variable is also called “variable y.” 442 Ore: A substance taken from the subsoil or underlying rock that has a high enough concentration of saleable mineral products that it can be mined and processed for profit. 138 Organic matter, 128 Orogenesis: The movements of the Earth’s crust that form mountains. 328 Osmosis: The passage of water across a membrane that allows only certain substances to pass from an environment with a lower concentration of solute to an environment with a higher concentration.111, 112, 122, 282–283 Output: An element produced by and exiting from a living or nonliving system. 69, 390 Overflow can, 79, 460 Oxygen, 293 Ozone, 293

P Pacific Ring of Fire, 327 Pangaea: A word of Greek origin meaning “all worlds.” The name given by Wegener to an immense continent formed of all land masses. 315 Panthalassa: A word of Greek origin meaning “all seas.” The name given by Wegener to the single ocean surrounding Pangaea. 315 Paper filter, 199 graph, 442–444 litmus, 186 universal indicator, 188 Pasteurization: A process that uses heat to kill harmful bacteria sometimes found in liquids such as milk. 113, 114 Patent, 380 applying for a, 377 Pebble: A rock worn and polished by the friction of the water, and deposited on the shore by waves. 305 Perennial: A plant that lives longer than two years. 34

Perfume(s), 124, 125, 142, 147, 168, 169 and alcohol, 142, 165 and aromatic plants, 126 birth of a, 164 change in the scent of, 165 creation of, 125, 161 creators of, 154, 161 families of, 158, 161 and flowers, 126 harmony of, 165 marketing of, 125, 169 nose, 154 production of, 125, 142, 167, 169 Period of revolution: The time it takes a celestial body to complete one orbit. 360 Periodic table: A table that represents all natural and artificial elements known to date. 205–207 Permafrost: The part of the ground that stays frozen all year long in colder regions. 131 Petroleum: A liquid fossil fuel formed by the decomposition of plants and animals that have been dead for millions of years. This process requires very specific conditions. 198, 201, 342 pH, 17, 20, 186–188 and electrical conductivity, 135 meter, 17, 188 of rain, 330, 333 of soil, 128, 131, 135, 141, 168 Photoperiod: The length of the period of daylight in relation to the period of darkness. The photoperiod varies according to latitude and season. It regulates the activity period of living organisms. 28 Photosynthesis: A process that allows plants to produce their own food using solar energy, water and carbon dioxide. 36, 37, 284, 345 Physical changes: A change in the state of matter. In physical changes, the particles of the substance remain the same. 191 Physical characteristics of a semiaquatic terrarium, 13 absorption of odours, 13 animal camouflage, 13 circulation of air and water, 13 growth of plants, 13 soil composition, 13 Pie chart, 445

Pigment: A substance that is present in various tissues or organs and gives them their colouring. 38 Pituitary gland: A gland located at the base of the brain. In humans, it is about the size of a pea. 258 Placenta, 263 Planet: A celestial body that orbits around a star. A planet does not produce light. 353–357 giant, 355 terrestrial, 354 Plant(s), 36, 126, 141 circulation of water in, 36, 37 growth of, 36, 37 perfumed oils contained in, 150 and photosynthesis, 36, 37, 136, 141 transpiration of, 36, 37 Plate tectonics, 290, 316, 317 Pluto, 353, 356 Poles of a bar magnet, 30 Pollution, atmospheric, 338 Population: A group of individuals belonging to the same species that occupies a given territory. 234 Porosity: The percentage of free space in a given volume of soil. 128, 129 Potable water. See Drinking water. Potassium, 136, 299 Power plants tidal, 398 nuclear, 400 Precipitation: The different forms that water takes to return to the ground: rain, snow, hail, sleet or freezing rain. 54, 55, 57, 332 effect of a mountain range on, 58 lowering the pH of, 330, 333, 334 Pregnancy: The period, from fertilization to birth, during which a woman carries her baby. 120, 262–268 amniotic sac, 263 embryo, 262, 263 embryoblast, 262 gastrula, 267 placenta, 267 trimesters of, 264–266 umbilical cord, 263 Pressure: The force exerted on a surface. For example, when you press down on your pencil as you write, you are applying pressure to the paper. 182, 306 Prevailing wind: The wind that blows most frequently in a given region of the globe. 334, 335

Procedures for separating mixtures, 149, 150, 151, 152, 153, 162, 163, 168 Producers, 19, 233, 376 Property: Information used to describe a substance. 175, 188, 346 Propulsion system, 69, 74 Protist: Unicellular organisms with a nucleus. Some, such as algae, can perform photosynthesis and others, such as amoebae, feed on organic matter. 218 Protons, 204 Prototype: One of the first copies of an object or a system. It can serve as a model for testing or large-scale production. 376, 382, 433 Protractor, 449 Puberty: A stage of sexual development in which a series of changes prepares the human body for reproduction. 99 adolescence and, 99, 122 physical and psychological changes at, 99 Pulley, 384, 412, 419, 420, 422 fixed, 415 movable, 415 Pure substance: A substance that contains only one type of particle. 142, 195

Q Qualitative observation: An observation that involves quality, shape or properties and cannot be expressed in numbers. 431 Quantitative observation: An observation involving quantities that can be expressed in numbers. 431

R Rack and pinion, 423, 425 Radiant energy: Energy from a light source, such as the Sun. 340, 341 Radio waves, 350 Rain, 61 acid, 330, 333 Rainbow, 349 Ratio: The quotient of the two lengths being compared. 451 mass , 77 volume

Raw material: Material that is taken from nature and transformed, either by hand or industrially. 386 Rays gamma, 350 infrared, 350 solar radiation (or Sun’s rays), 362, 368 Reflection and absorption of light, 347 Relief: The shape of the Earth’s surface. 310 Renewable resource: A natural resource that originates mainly from animals and plants. If well managed, it is inexhaustible. A forest is an example of a renewable resource. 342 Report, lab, 432 research, 21 Reproduction: A fundamental activity that allows individuals to produce other individuals of their species. 215, 237, 240, 241, 242, 243, 247–258 Reproductive organ: Any one of an individual’s structures that is involved in reproduction. 244, 256 human, 99, 122 of trees, 35 Reptiles, 10 Research project, 436 Internet, 437 Residues, 199 Revolution: The motion of one celestial body around another. 359 of the Earth, 359, 360 Ridges, 316 of East Pacific, 319 Mid-Atlantic, 319, 324, 327 Rivet: To join two sheets of material (metal, plastic and so on) using one or more rivets. 462 Riveter, 462 Rocks, 128, 302 formation of, 137 igneous, 137, 168, 303, 304 extrusive (or volcanic) igneous, 304 intrusive (or plutonic) igneous, 304 metamorphic, 137, 168, 303, 306 porphyritic, 304 process of formation of, 307 properties of, 137 sedimentary, 137, 168 types of, 137, 138

Glossary and Index

471

Room temperature: The temperature of the surrounding air. In a room, this temperature is approximately 20°C. 176 Rotation, 394 of the Earth, 359 Rotation period: The time it takes a celestial body to make one revolution on its axis. 360 Rust: A brownish-red compound resulting from a chemical reaction between oxygen in the air and material containing iron. Rust is produced in a moist environment. 380 Runoff, 332

S Safety electrical, 429 general, 428 in laboratory, 428–429 Saliva, 107, 108, 110, 122 acidic or basic, 108 Sap, 36 Saturn, 353, 355 Scale, 457 Scale (weighing), 442, 450 Scale model, 450–451 Scavenger: An animal that feeds on the bodies of already dead animals. 232–233 Scents, family of, 157 production of, 166 Scientific theory: A collection of ideas and knowledge used to explain a phenomenon. This phenomenon must be observed by numerous scientists over the course of many experiments to become a theory. 430 Scrap: A piece of wood to be discarded. 461 Screw and nut, 423, 425 Seasons, 360–362 Sedimentation, 329 Sediments: Material deposited in layers. It comes from soil erosion or deposits of organic matter. 303 Seed(s), 245–246 cotyledon, 242 dispersion of, 35 embryo, 242 seedcoat, 242 tree, 35

472 Glossary and Index

Seismic waves: Waves that spread through the ground in every direction from an earthquake’s point of origin. 325 Seismologists: Scientists who study earthquakes and the propagation of waves in the Earth’s crust. 326 Semi-aquatic ecosystem: A container space made up of a shoreline, a shallow body of water and all the living organisms that inhabit this environment. 5, 10 animals adapted to a, 10 amphibians, 10, arthropods, 10 identification of, 15 mollusks, 10 reptiles, 10 worms, 10 Sense of smell, 154, 160 delicate, 156 efficacy of, 159 Separation of mixtures, 149, 151, 168, 198 Set squares, 449 Sex hormones, 258 estrogen, 258 progesterone, 258 testosterone, 258 Sexual relations, 119 Sexual reproduction: A method of reproduction that requires fertilization: the joining together of a male gamete and female gamete. 215, 237, 240, 242, 243, 247–258 Sexually transmitted disease (STD): A contagious illness that can be spread through sexual contact, normally from a person that is already infected. We also talk about sexually transmitted infection (STI). 116, 118, 119, 121, 122, 274–275 prevention of, 118, 119, 122 Sexually transmitted infections (STIs), 116 Shearing force, 411 Shelters (of animals), 11 Showers, meteoroid, 366 Silt: Fine particles of soil carried by water and wind. 309 Simple machine: A mechanical system that transfers force directly. The five simple machines are the lever, inclined plane, pulley, wedge, and wheel and axle. 69, 405, 417 main functions of, 413 types of, 412

Smog, 338 Soil, 126, 307 acidic, 128 adapted to trees, 35 alteration of, 307 classification of types of, 128, 130, 131, 168 composition of, 128, 130, 141, 168 air, 128 debris from dead plants and animals, 128 microscopic life forms, 128, 168 particles of rocks and minerals, 128, 141, 168 water, 128 drainage of, 132, 141, 168 horizons of, 308 influx of organic material, 307 inhabitants, 310 mineral, 128, 140 organic, 128 and plant growth, 168 and plants that grow in, 126, 141 properties of, 129, 135, 136 colour, 128, 131 dryness, 128 humidity, 128 pH, 128, 131, 135, 141, 168 porosity, 129, 309 size of particles of which it is composed, 128 structure, 128, 129, 131, 141, 168, 309 texture, 128, 129, 131, 141, 168, 313 types of, 59, 126, 141 uses of, 130, 168 water content, 59 Solar system: The Sun and all the celestial bodies that are subject to its gravitational effect. 352, 353, 357 Solar wind: A current of particles emitted by the Sun. It is composed primarily of protons and electrons. 357 Solar year, 360 Solstice summer, 361 winter, 361 Soluble substance: A substance whose particles have the ability to separate until they are uniformly distributed in another substance. For example, sugar is soluble in water. 196 Solute: The part of a mixture that is dissolved. 196, 197

Solution: A homogeneous mixture containing two or more substances. 148, 196 Solvent: The part of a mixture that dissolves the other substances. 196, 197 Species: A group of similar individuals that can reproduce with each other and whose offspring can also reproduce. 216, 218 evolution of, 95, 97, 122 Homo, 95 Homo sapiens, 94, 95 human, 94, 95 mammals, 95 natural selection of, 122 perpetuation of, 96 reproduction of, 122 Spectrum electromagnetic, of the Sun, 350 visible, of colours, 349 Spores, 242 Sprocket, 384, 419, 420 Stages in human development: The steps in human development from birth to adulthood. 100, 269–271 Standard symbol: A symbol recognized by all people who work in technology. 382, 384 Standards: A set of rules established by specialists. They are assembled in a document produced by a national or international organization. In technology, standards are designed to guarantee that the manufactured product meets acceptable levels or performance and quality. 376, 379 Star: A large celestial body that produces light. Our Sun is a star. 295, 358, 366 Starch, 107, 110 States of matter: The forms of substances: solid, liquid and gas. 176–177 Still, 150 Stone mineral specimen, 140 precious, 140 semi-precious, 140 Studying the market, 161, 169, 376 Subsoil, composition of, 140 Sun, 313, 352 Symbiosis: A mutually beneficial relationship between two living organisms. 229 Symbols chemical, 208

graphic, 448 System: All the components of an object or machine. Their functions are all different, but the goal is the same. 389, 390 human reproductive, 99 mechanical, 418 subsystem, 389 technological, 388, 405

T Target clientele, 161, 167, 376, 432 Taxonomy: The science that classifies all living organisms according to the characteristics they have in common, from the most general (kingdom) to the most specific (species). 215, 217, 218 Technical drawing: A type of drawing that indicates how to construct an object by showing the detail of each component and its links. 88, 113, 376, 383, 433 Technical object, 433, 434 analysis of, 434 construction of, 435 design of a, 376, 378 scaled down, 451 useful life, 379 workings of, 435 Technological diagrams, 382, 383, 446–449 Tectonic plate: A plate-like section of the Earth’s crust that floats in the asthenosphere. 316–321, 323–328, 329, 331, 335 Eurasian Plate, 320 Indian-Australian Plate, 320 movement of, 318 Nazca Plate, 319 see also Plate tectonics Temperature: A measure of the intensity of heat emitted by an object or substance. 49, 55, 57, 175 with altitude, 55 average, 87 average world, 51 in degrees Celsius, 181 thermometer, 181 variations, 87 Temperature inversion, 338 Terrarium: A container in which we reproduce an ecosystem in order to raise small living organisms. 4, 5 semi-aquatic, 10

components of, 19 ecological niche of living organisms in a, 17 insects in a, 4, 10 interrelations of living and nonliving elements in a, 17, 19, 20 microscopic life forms in a, 18 physical characteristics of a, 13, 17, 19 small animals in a, 10, 11, 15, 17 temperature in a, 17, 20 Thermal (or heat) energy: Energy in the form of heat. 340, 341, 342, 343, 346, 397 Thermometer, 460 Trade wind, 335 Transformation, 69 of movement, 69, 384, 423 Translation, 394 Transpiration: The release of water vapour by a living organism. 36, 37, 49 Tree(s), 22 adaptations to winter, 35 advantages of, 24 annual cycle of, 35 branches, 34 characteristics of, 25 climate adaptation, 35 conifers, 34 deciduous, 34 food of, 36 fruits of, 34, 35 function, 35 germination of seeds, 35 identification of, 33, 34 leaves, 34 life cycle of, 34 names of gametes, 35 names of reproductive organs, 35 parasites and other pests, 35 parts of, 34 perennial and ligneous plant, 34 and the photoperiod, 28 sap, 36 soil to which they are adapted, 35 species of, 25 stages of development, 35 stem of, 34, 35 uses of, 24 Trench: A large and very deep cavity. 320 Marianas, 320 oceanic, 292, 320 Troposphere, 56

Glossary and Index

473

Tsunami: An isolated, very high wave caused by seismic or volcanic activity. This wave, also called a tidal wave, washes far inland. 289, 326 Types of soil. See Soil.

U-V Ultraviolet rays (or UV rays): An invisible portion of the Sun’s radiation. The ozone layer prevents UV rays from reaching the Earth’s surface. 295, 296 Umbilical cord, 263 Units of measure, 440, 443–444 Uranus, 353, 355 Values, 441–444 Vapour, water, 73, 87, 293 Variable: A quantity that can have different values. 431–432, 441, 443 x, 441–444 y, 442 Venus, 353, 354 Vertebrates, 250 Volcano: A generally conical structure through which lava and hot gas reach the surface of the Earth’s crust. 322, 323 Volume: The space that an object occupies. 175

474 Glossary and Index

liquid, 180 solid, 180

W Water: At 25°C, water is a clear, colourless liquid with no taste or odour, each molecule of which is formed of two hydrogen atoms and one oxygen atom. The chemical formula of water is H2O. 136, 291, 298, 299 in the atmosphere, 61 buoyancy force, 80 cycle, 48, 62 drinking. See Drinking water. freezing point, 52 fresh, 88, 299, 300 groundwater, 60 infiltration of, 61 movements of, 48 in the ground, 59 physical changes of, 49 condensation, 53, 54 evaporation, 49, 54, 61 transpiration, 49, 61 potable. See Drinking water. rain, 61 runoff, 61 salt, 88

in the soil, 128 vapour, 53 Water cycle: The circulation of water through the atmosphere and the Earth. This circulation is produced mainly through evaporation, condensation and precipitation. 48, 62, 87, 332, 333 Water table: A body of groundwater formed by rainwater infiltration that feeds wells, springs and waterways. 60 Wedge, 412, 416 Weight, 79 of a beaker, 79 dynamometer, 79 of an object, 351 Wheels and axles, 412, 416 friction, 419, 422 WHMIS hazard symbols, 429 Wind, 49, 55, 82, 85, 87, 336, 337 direction of, 336 speed of, 336 Work: The result obtained when a force is exerted on an object and it is moved a certain distance. 417

Y-Z Zygote, 250

Sources LEGEND t: top

b: bottom

c: centre

l: left

r: right

PHOTOS COVER • tl (praying mantis): Stuart Westmorland/Getty Images; tr (highway interchange): PhotoDisc; bl (aurora borealis): CP Photo; br (iceberg): Corbis

ENDPAPERS • Arto Dokouzian and Michel Verreault UNIT 1 • p. 2 tl: Andreas Riedmiller • p. 2 bl: © Theo Allofs/zefa/Corbis • p. 2 br: Steve Vowles/SPL/Publiphoto • p. 4 bl: Réal D. Carbonneau/Images du Québec • p. 4 bc: AP/Wide World Photos • p. 4 br: Jean-Claude Teyssier/Alpha Presse • p. 6 t: © Layne Kennedy/Corbis • p. 6 c (centipede): Dorling Kindersley; (ant): Johner Images/ Getty Images; (woodlouse): Hans Pfletschinger/Alpha Presse; (spider): James Gerholdt/ Getty Images; (daddy-long-legs): Bill Beatty/Visuals Unlimited; (millipede): Colin Keates/ Dorling Kindersley/Getty Images • p. 7: Patrice Halley/Alpha Presse • p. 8 (grasshopper): Jean-Claude Teyssier/Alpha Presse; (mosquito): Jean-Claude Teyssier/Alpha Presse; (butterfly) Jean-Claude Teyssier/Alpha Presse; (fly) Jean-Claude Teyssier/Alpha Presse; (bee): Jean-Claude Teyssier/Alpha Presse • p. 9 l: S. Nishinaga/SPL/Publiphoto • p. 9 r: David Scharf/Getty Images • p. 10: courtesy of the Biodôme de Montréal • p. 11: Janicke Morissette/Le bureau officiel • p. 12: © Pierre Holtz/Reuters/Corbis • p. 14: © Dung Vo Trung/Sygma/Corbis • p. 15: © Ralph A. Clevenger/Corbis • p. 16: Jean-Claude Teyssier/Alpha Presse • p. 17: Jean-Claude Teyssier/Alpha Presse • p. 18: Janicke Morissette/Le bureau officiel • p. 19: © Martin Gilles/BIOS • p. 20 tl: Manfred Danegger/ Alpha Presse • p. 20 b: Jean-Claude Teyssier/Alpha Presse • p. 22 © Eddy Risch/EPA/ Corbis • p. 24 l: AP Photo/Sophia Paris, UN MINUSTAH • p. 24 r: Serge Clément/ Publiphoto • p. 25: Johann Schumacher/Getty Images • p. 26 (tropical forest): Klein/ BIOS; (temperate forest): Charles Martel; (boreal forest): PhotoDisc • p. 27 (tree savannah): © Eddi Boehnke/zefa/Corbis; (Mediterranean forest): Markus Dlouhy/ Imagetrust • p. 28: Marc-Aurèle Fortin, Sous les ormes, 1935 © Fondation Marc-Aurèle Fortin/SODRAC (2013) • p. 29 t: akg-images • p. 29 bl: Adam Hart-Davis/SPL/ Publiphoto • p. 29 br: The Art Archive at Art Resource, NY • p. 31 t: Collection Musée national des beaux-arts du Québec • p. 31 b: Joel Sartore/Getty Images • p. 32 t: Sidamon-Pesson/BIOS • p. 32 b: Janicke Morissette/Le bureau officiel • p. 33: Nuance Photo • p. 34 (maple leaf): PhotoDisc; (pine cones): PhotoDisc. • p. 35 t: Frédéric Back/Archives Radio-Canada • p. 35 b: P. Psaila/SPL/Publiphoto • p. 36 tr: akg-images • p. 36 l: Terre de chez nous • p. 37: Janicke Morissette/Le bureau officiel • p. 38: Corel• p. 39 tl: Janicke Morissette/Le bureau officiel • p. 39 r: Larry MacDougal/Alpha Presse • p. 40 tr: Janicke Morissette/Le bureau officiel • p. 40 l: © Collection/Publiphoto • p. 40 b: PhotoDisc • p. 41 t: © Rex Features (2005) • p. 41 br: Bibliothèque des Arts Décoratifs, Paris, France/Archives Charmet/Bridgeman Art Library • p. 42: Steve Vowles/ SPL/Publiphoto • p. 43: Michael Melford/Getty Images

UNIT 2

• p. 44 tl: Bill Ross/Corbis • p. 45 tl: Esteban Coco/P Photo/EFE • p. 45 cl: Robert McGouey/Search4Stock • p. 45 cr: Bagan Maung/UNEP • p. 46 tl: CP Photo/The Telegram/Joe Gibbons • p. 46 tc: CP Photo/Jacques Boissinot • p. 46 tr: UNEP • p. 47 cr: Steve Wilkings/Corbis • p. 48 tr: Hydro-Québec Archives • p. 48 cl: © Theo Allofs/ Corbis • p. 49 cl: Gay Bumgarner/Getty Images • p. 49 c: Linda Armstrong/ Shutterstock • p. 49 br: AP Photo/David J. Phillip • p. 50 c and cr: Janicke Morissette/ Le bureau officiel • p. 50 cl: Pierre Charbonneau Photographe • p. 51 bl: CP Photo • p. 51 br: AP Photo • p. 52 cl: Theo Allofs/BIOS • p. 53 tl: Igor Karon/iStockphoto • p. 53 cl: William A. Bake/Corbis • p. 53 cr: Ingram Publishing/SuperStock • p. 54 c: Janicke Morissette/Le bureau officiel • p. 54 l: Bruce Dale/Getty Images • p. 55 c: A. T. Willett/Getty Images • p. 56 c: Janicke Morissette/Le bureau officiel • p. 57 t: Yves Marcoux/Publiphoto • p. 57 ct: Duncan McNicol/Getty Images • p. 57 c: John Arnold/ SuperStock • p. 59 tl: Bruce Chambers/Orange County Register/Corbis • p. 60 cr: Janicke Morissette/Le bureau officiel • p. 60 cl: Mark Edwards/Still Pictures/Robert Harding • p. 62 br: AP Photo/Tim Tadder • p. 62 cl: Jörg Böthling/agenda/GA • p. 63 cl: Getty Images • p. 63 c: © MacDuff Everton/Corbis • p. 63 cr: Oldrich Karasek • p. 64 b: © Bill Ross/Corbis • p. 65 c: Pierre Charbonneau Photographe • p. 67 bl: Jose Luis Pelaez, Inc/Corbis • p. 67 cr: © Stockdisc/SuperStock • p. 67 br: Janicke Morissette/Le bureau officiel • p. 70 cl: Kelly Cline/iStockphoto • p. 70 tc: © Tom Stewart/Corbis • p. 71 t: © Joan Glase/SuperStock • p. 71 b: John Kelly/Getty Images • p. 72 l: © Alexander Hubrich/zefa/Corbis • p. 72 c: F. Ardito/UNEP • p. 72 r: © Patrick Bruchet/Paris Match – Gamma/PONOPRESSE • p. 74 r: © Newmann/zefa/Corbis • p. 74 l: Andrée Lavallée-Trân • p. 75 bl: © W.A. Sharman; Milepost 92 _/Corbis • p. 75 bc: © William Manning/Corbis • p. 75 br: P.G. Adam/Publiphoto • p. 76 t: Musée du vélo de Cormatin (France) • p. 76 l: Pierre Rousseau• p. 76 r: © Pierre Perrin/Sygma/Corbis • p. 77 tl: National Archives of Canada: C-008486 • p. 78 t: Janicke Morissette/Le bureau officiel • p. 78 l: © Steve Kaufmann/Corbis • p. 80 tl: © Galen Rowell/Corbis • p. 80 cl: © Garneau/Prevost/SuperStock • p. 80 cr: Janicke Morissette/Le bureau officiel • p. 81 tl: Matt Tilghman/iStockphoto • p. 81 br: The estate of Gerry Roufs • p. 82 bl: rights reserved • p. 82 cr: Janicke Morissette/Le bureau officiel • p. 83 tl: Simon Voorwinde/Shutterstock • p. 83 br: © Erwin Christian Suchard/zefa/Corbis • p. 84 c: Janicke Morissette/Le bureau officiel • p. 85 br: © The Mariners’ Museum/Corbis • p. 86 br: Centre d’archives et de documentation du Musée maritime de Charlevoix • p. 86 tl: Janicke Morissette/Le bureau officiel • p. 86 cl: © Sygma/Corbis • p. 88 r: Janicke Morissette/Le bureau officiel

UNIT 3 • p. 90 tl: © Matthias Kulka/Corbis • p. 90 bl: © Lisa M. McGeady/Corbis • p. 90 br: © Kevin Dodge/Corbis • p. 93: © S. Hammid/zefa/Corbis • p. 94 r: Larry St. Pierre/Shutterstock • p. 95 tr: Polygone Studio • p. 95 b, from l to r: Claire Ting/SPL/ Publiphoto; Jégou/Publiphoto; Jégou/Publiphoto • p. 96 r: F. Leroy/Biocosmos/SPL/ Publiphoto • p. 97 c: Janicke Morissette/Le bureau officiel • p. 97 r: SPL/Publiphoto • p. 98 l: Makoto Iwafuji/Eurelios/SPL/Publiphoto • p. 98 b: © Digital Art/Corbis • p. 99b:

© Lilian Perez/zefa/Corbis • p. 100 (fetus): Dr. G. Moscoso SPL/Publiphoto; (baby): © Whiskey Tango/Corbis; (child): © Royalty-Free/Corbis; (adolescent): © Bohemian Nomad Picturemakers/Corbis; (adult and senior): © Royalty-Free/Corbis • p.101 tl: RoyaltyFree/Getty Images • p. 102 t: © Ariel Skelley/Corbis • p. 103 br: Corel • p. 104 tr: Pierre Charbonneau Photographe • p. 104 cl: © Nathan Benn/Corbis • p. 105 t: © Gabe Palmer/ Corbis • p. 105 r: © PhotoCuisine/Corbis • p. 106: © Envision/Corbis • p. 107 r: Angus Plummer/iStockphoto • p. 108 t: Janicke Morissette/Le bureau officiel • p. 109 b: maXx images • p. 110 t: Jacques Perrault • p. 111 b: Janicke Morissette/Le bureau officiel • p. 112 l: Maximilian Stock Ltd./SPL/Publiphoto • p. 112 br: © Kevin & Betty Collins/ Visuals Unlimited • p. 113 c: rights reserved • p. 114 bl: Janicke Morissette/Le bureau officiel • p. 114 cl: SPL/Publiphoto • p. 115 tc: © Jose Luis Pelaez, Inc./Corbis • p. 116 t, from l to r: James Cavallini/BSIP; CNRI/SPL/Publiphoto; Cath Wadford/SPL/Publiphoto • p. 117 l: O’Neill/Megapress • p. 118 t: VEM/BSIP • p. 119 b: Janicke Morissette/Le bureau officiel • p. 119 r: akg-images • p. 120 l: Charles Gullung/Getty Images • p. 121 r: P. Goetgheluck/SPL/Publiphoto • p. 121 b: © Dennis MacDonald/Alamy • p. 123 tl: © Frank Barylko/DD – Gamma/PONOPRESSE

UNIT 4 • p. 124 tl (roses): © PhotoCuisine/Corbis • p. 124 tl (rose petals): © Owen Franken/Corbis • p. 124 b: akg-images • p. 125 r: Faculté de Pharmacie, Paris, France, Archives Charmet/The Bridgeman Art Library International • p. 126 b (lavender and heliotrope): Frédéric Didillon/BIOS • p. 126 (coleus): Jean-Claude Teyssier/Alpha Presse • p. 127 br: © Royalty-Free/Corbis • p. 128 t, from l to r: Danis Derics/Shutterstock; © Nevada Wier/Corbis; Mauritius/Megapress • p. 129 tl: Janicke Morissette/Le bureau officiel • p. 130 t, from l to r: Wendy Kaveney Photography/Shutterstock; Premium/ FirstLight; © Raymond Gehman/Corbis • p. 132 b: Janicke Morissette/Le bureau officiel • p. 133 b: © Patrice Latron/Corbis • p. 136 tr: © Richard Hamilton Smith/Corbis • p. 136 bl: Stéphanie Colvey • p. 137 tl; Danilo Donadoni/maXx images • p. 137 cr: Markus Dlouhy/Imagetrust • p. 137 br: Lynda Richardson/Alpha Presse • p. 138 tr: Musée minéralogique et minier de Thetford Mines • p. 139 (gold): © Ken Lucas/Visuals Unlimited • p. 139 (copper): © Mark A. Schneider/Visuals Unlimited • p. 140 cr, from l to r: George Diebold Photography/Getty Images; © José Manuel Sanchis Calvete/Corbis; Musée minéralogique et minier de Thetford Mines • p. 140 bl: Jean-Claude Carton/ BIOS • p. 141 r: Janicke Morissette/Le bureau officiel • p. 142 t, from l to r: The National Trust Photolibrary/Alamy; Stéphanie Colvey • p. 143 b: Matt Meadows/Getty Images • p. 144 c: Janicke Morissette/Le bureau officiel • p. 145 tr: © Ariel Skelley/ Corbis • p. 145 b: Paul Poplis/Getty Images • p. 146 t: Philiptchenko/Megapresse • p. 146 br: Janicke Morissette/Le bureau officiel • p. 147 r: Stéphanie Colvey • p. 148 cl: Danijel Micka/iStockphoto • p. 148 br (vinaigrette and grapefruit juice): Stéphanie Colvey • p. 148 (mayonnaise): Suzannah Skelton/iStockphoto • p. 149 r: Janicke Morissette/Le bureau officiel • p. 150 tl: akg-images • p. 150 tr and bl: © Julio Donoso/ Sygma/Corbis • p. 151 tr: Janicke Morissette/Le bureau officiel • p. 151 bl: Pierre Dunnigan • p. 151 bc: Lori Sparkia/Shutterstock • p. 151 br: Bilderberg/Megapresse • p. 152 bl: Merrill Dyck/iStockphoto • p. 152 br: Janicke Morissette/Le bureau officiel • p. 153 cr: Vanessa Vick/Photo Researchers/Publiphoto • p. 153 bl: Brian Yarvin/Getty Images • p. 154 bl: François Gohier/BIOS • p. 154 br: © Charles Gupton/Corbis • p. 155 br: © Wolfgang Kaehler/Corbis • p. 156 tr: © Roy Morsch/Corbis • p. 156 bl: Michael Porsche/Corbis • p. 157 c: Janicke Morissette/Le bureau officiel • p. 158 l: © Barnabas Bosshart/Corbis • p. 158 r (citrus): © Ed Young/Alamy; (jasmine): Frédéric Didillon/ BIOS; (grass): Henri Veiller/Explorer/Gamma-Rapho; (vanilla): Dominique Halleux/ BIOS; (lavender): Klein/BIOS; (oak moss): Frédéric Didillon/BIOS; (leather hides): Warren E. Simpson/Shutterstock • p. 159 t: CC Studio/SPL/Publiphoto • p. 159 bl: © Patrice Latron/Corbis • p. 159 br: Coast Distribution System Canada • p. 160 l: © Royalty-Free/Corbis • p. 161 tl: Nuance Photo • p. 162 br: Janicke Morissette/Le bureau officiel • p. 163 c: Janicke Morissette/Le bureau officiel • p. 164 bl: Janicke Morissette/Le bureau officiel • p. 165 t: © Jean-Pierre Amet/Sygma/Corbis • p. 165 br: Bilderberg/Megapresse • p. 166 tr: Bilderberg/Megapresse • p. 166 b: Gilles Bassignac/ Gamma/PONOPRESSE • p. 167cr: Elena Ray/Shutterstock • p. 169 cl: Royalty-Free/ Alamy; CP Photo

THE MATERIAL WORLD • pp. 170–171: (praying mantis): Stuart Westmorland/ Getty Images; (highway overpass): PhotoDisc; (aurora borealis): CP Photo; (iceberg); Corbis • p. 172 l: Corbis • p. 173 tl: © James Sparshatt/Corbis • p. 173 cr: © PhotoCuisine/Corbis • p. 173 br: © William Taufic/Corbis • p. 174: © Layne Kennedy/Corbis • p. 175 l: Nuance Photo • p. 176 tl and bl: Arto Dokouzian • p. 177 tr: Arto Dokouzian • p. 177 br: Pekka Parviainen/SPL/Publiphoto • p. 179 (automobile, motorcycle, slice of bread): Nuance Photo • p. 179 (standing women, lemon, trombone, pill): PhotoDisc • p. 179 (stamp): Canada Post Corporation, 1999, reproduced with permission • p. 179 bc: Caméléon • p. 180 br: Arto Dokouzian • p. 181 tl: PhotoDisc • p. 181 tc: Search4Stock • p. 181 cl and cr: Nuance Photo • p. 184 tl: Jeremy Burgess/SPL/ Publiphoto • p. 184 cr: Denis Chabot/Québec en images • p. 185 tr: Nuance Photo • p. 185 bl and bc: Arthur Hill/Visuals Unlimited • p. 186 l: akg-images • p. 186 r: Arto Dokouzian • p. 188 tr: Arto Dokouzian • p. 188 cl: Andrew Lambert Photography/SPL/ Publiphoto • p. 189 tr: Nuance Photo • p. 190 t: Raymond Robillard • p. 193 tr: John Weise/iStockphoto • p. 193 c, from l to r: © David Michael Zimmerman/Corbis; Corel Disk; Steve Allen/SPL/Publiphoto; © Kelly-Mooney Photography/Corbis • p. 194 cl: akgimages• p. 194 br: PERES-UNEP • p. 195 tr: Arto Dokouzian • p. 195 br: © The British Museum/HIP TopFoto/PONOPRESSE • p. 196 tl: AP/Wide World Photos • p. 196 tc: Corel Disk •p. 197 br: Koji Sasahara/AP Photo • p. 198 b: Arto Dokouzian • p. 199 tr and br: Arto Dokouzian • p. 200 cl: Beranger/BSIP • p. 200 br: Arto Dokouzian • p. 201 cr: © Greg Smith/Corbis • p. 203 bl: Arto Dokouzian • p. 204 cl: Sheila Terry/ SPL/Publiphoto • p. 205 t: © Bettmann/Corbis • p. 205 br: akg-images • p. 209 br: akg-images • p. 211 t to b: (John Dalton and Joseph John Thomson)/SPL/Publiphoto; (Ernest Rutherford and Niels Bohr) akg-images; (James Chadwick) A.B. Brown/SPL/ Publiphoto

THE

LIVING WORLD • p. 213 tl: Pierre François Beaudry/Images du Québec • p. 213 tc: SPL/Publiphoto • p. 213 tr: Andrew Syred/SPL/Publiphoto • p. 213 cl: Corel Disk • p. 213 cr: W. Ervin/SPL/Publiphoto • p. 214: PhotoDisc • p. 215 (cat, lion, tiger, wolf): PhotoDisc • p. 215 (fox): J. Lepore/Photo Researchers/Publiphoto • p. 215 (dog): © M. Botzek/zefa/Corbis • p. 216 tl: © Craig Tuttle/Corbis • p. 216 tr: © Strauss/Curtis/

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Marigo • p. 223 tr, from t to b: Corel Disk; Cyril Ruoso/BIOS • p. 224 cl: Zoo sauvage de St-Félicien • p. 224 bl, from l to r: Jean-Marie Dubois/Images du Québec; © maXx Images; Visuals Unlimited/Science • p. 225 tl: Heiko Wittenborn • p. 225 bl and br: Royalty-Free/Corbis; Corel Disk • p. 226 l, from t to b: Jean-Claude Teyssier/Alpha Presse; Hanson Carroll; R. Andrew Odum/Getty Images; John Cancalosi/Getty Images; Émile Barbelette/BIOS; Peter Frischmuth/Argus • p. 228 cl: Hans Pfetschinger/Peter Arnold/Alpha Presse • p. 228 c, from t to b: © O. Alamany & E.Vicens/Corbis; © Lynda Richardson/Corbis; Cal Vornberger/Peter Arnold/Alpha Presse; Nigel J. Dennis/NHPA; Corel Disk • p. 229 l, from t to b: © Tom Bean/Corbis; Corel Disk; © Robert Gill; Papilio/Corbis; Corel Disk • p. 230 t, from l to r: Mayet Jean/Bios/Alpha Presse; Andreas Riedmiller; © maXx Images; © Roy Morsch/Corbis • p. 230 cl: L. David Mech (in The Way of the Wolf ) • p. 230 cr: © Tom J. Ulrich/Visuals Unlimited • p. 230 b, from l to r: © Sea World, Inc./Corbis; © Joe MacDonald/Visuals Unlimited; Carl R. Sams II; © Farrell Grehan/Corbis • p. 231 t, from l to r: Pierre François Beaudry/Images du Québec; D. Shaw/SPL/Publiphoto; Montréal Botanical Garden; Corel Disk • p. 232 b, backgrounds from l to r: J. Beauchamp, personal collection; PhotoDisc; Corel Disk • p. 233 r: John Cancalosi/Getty Images • p. 234 tl: © Guy Germain • p. 235 cr and br: akg-images; Rob & Ann Simpson/Visuals Unlimited • pp. 238–239: SIU School of Medecine • p. 240 tl and bl: Nuance Photo • p. 241 tl: © David Muench/Corbis • p. 241tr: JeanClaude Teyssier/Alpha Presse • p. 242 tl: © Royalty-Free/CORBIS • p. 242 b, from l to r: © Ralph A. Clevenger/Corbis; Mary Marin/iStockphoto; J. Burgess/SPL/Publiphoto; John Howard/SPL/Publiphoto; The Picture Store/SPL/Publiphoto • p. 243 tl: Corel Disk • p. 243 tr: Musto/SPL/Publiphoto • p. 243 bl: © Corbis • p. 243 br: N. Cornellier/ Montréal Botanical Garden • p. 244 bc: S. Nishinaga/SPL/Publiphoto • p. 244 br: Steve Hopkin/Ardea London • p. 246 cl: J. Zipp/Photo Researchers/Publiphoto • p. 246 cr: Valan Photos • p. 246 bl: Montréal Botanical Garden • p. 246 br: Jean-Claude Dechevis/ Images du Québec • p. 247 tc: M.F. Merlet/SPL/Publiphoto • p. 247 tr: M. Nimmo/SPL/ Publiphoto • p 248 l: Mary Marin/iStockphoto • p. 248 tr: Eric Walravens • p. 248 br: © Terry W. Eggers/Corbis • p. 250 l: C.V. Angelo/Photo Researchers/Publiphoto • p. 250 r: T. Branch/Photo Researchers/Publiphoto • p. 250 cr: T. Branch/Photo Researchers/Publiphoto • p. 252 t: SIU School of Medecine • p. 252 bl: Jeff Foott/UNEP • p. 252 br: T. Clutter/Photo Researchers/Publiphoto • p. 253 t: Valan Photos • p. 255 c: Michael Durham/Visuals Unlimited • p. 255 br: AP Photo/PA • p. 256 t: Manfred Danegger/NHPA • p. 256 tl: Dr. Gerald Schatten/SPL/Publiphoto • p. 256 cl: Gerard Lacz • p. 257 cl, from t to b: © Roger De La Harpe Gallo Images/Corbis; BIOS • p. 257 r: © Rick Gomez/Corbis • p. 266 tl and b: Dominique Duval/BSIP • p. 270, tr and cr: J. Beauchamp, personal collection • p. 270 cl: R. Henri, personal collection • p. 270 cc: M. Champagne, personal collection • p. 270 bc and br: PhotoDisc • p. 271 br: © Ronnie Kaufmann/Corbis • p. 272 bc; M. Fermariello/SPL/Publiphoto • p. 272 br: © Chor Sokunthea/Reuters/Corbis • p. 273 t, from l to r: C. Molloy/SPL/Publiphoto; (diaphragm and spermicide) G. Parker/SPL/Publiphoto; Saturn Stills/SPL/Publiphoto • p. 273 bl: Astrid & Hanns-Frieder Michler/SPL/Publiphoto • p. 273 bc: Gusto/SPL/ Publiphoto • p. 276 t: Paul Schulte/University of Nevada • p. 276 cl: Marilyn Kazmers/ Getty Images • p. 276 bl: Manfred Kage/Getty Images • p. 277, from a) to f): © Clouds Hill Imaging Ltd./Corbis; © Jim Zuckerman/Corbis; Paul Schulte/University of Nevada; © Lester V. Bergman/Corbis; Clouds Hill Imaging Ltd./Corbis; A. Syred/SPL/Publiphoto • p. 278 cl: St. Mary’s Hospital Medical School/SPL/Publiphoto • p. 279 br: SPL/ Publiphoto • p. 280 bl: © Eleanor Thompson/Corbis • p. 280 bc: Wilkinson/Valan Photos • p. 281: Arto Dokouzian • p. 283: Arto Dokouzian

tr: © Bettmann/Corbis • p. 351 bl: NASA • p. 352 cr: NASA • p. 352 bl: Harvard College Observatory/SPL/Publiphoto • p. 352 bc: GoodShot/SuperStock • p. 354 bl: Gustavo Tomsich/Corbis • p. 354 c, from t to b: D. Van Ravenswaay/SPL/Publiphoto; NASA/SPL/ Publiphoto; Planetary Visions Ltd./SPL/Publiphoto; Space Telescope Science Institute/ NASA/SPL/Publiphoto • p. 355 l, from t to b: NASA/SPL/Publiphoto; Space Telescope Science Institute/NASA/SPL/Publiphoto • p. 356 br: Space Telescope Science Institute/ NASA/SPL/Publiphoto • p. 360 r: SPL/Publiphoto • p. 363 l: Sébastien Gauthier • p. 365 cr: © 1996 NASA/Corbis • p. 366 tr: Tony & Daphne Hallas/SPL/Publiphoto • p. 368 tl: Eckhard Slawik/SPL/Publiphoto • pp. 368–369 b: Eckhard Slawik/SPL/ Publiphoto • p. 370 cr; Dennis di Cicco • p. 371 cl: Eckhard Slawik/SPL/Publiphoto • p. 371 r: SPL/Publiphoto

THE

MAPS AND ILLUSTRATIONS

EARTH AND SPACE • p. 286 cl: CP Photo • p. 287, from t to b: Corel Disk; T. Kinsbergen/SPL/Publiphoto; Weatherstock • p. 288: © Peter Adams/zefa/Corbis • p. 289 bl: akg-images/Bibliothèque Amiens Métropole • p. 291 b, from l to r; Roland Seitre; Corel Disk; Jean-Michel Labat/BIOS; Alexis Rosenfeld/SPL/Publiphoto • p. 293 br: © DiMaggio/Kalish/Corbis • p. 296 c: NASA • p. 297 br; Barry Williams/Getty Images • p. 299 bl: Corel Disk • p. 300 l: J. Beauchamp, personal collection • p. 300 r: Mark Edwards/Still Pictures/Robert Harding • p. 301 c: Andrew Davies/Still Pictures/Robert Harding • p. 302 tl: J. Beauchamp, personal collection • p. 302 b (quartz): Lawrence Lawry/SPL/Publiphoto; (mica, feldspar, granite, hornblende); Musée minérologique et minier de Thetford Mines • p. 304: Arto Dokouzian • p. 305: Arto Dokouzian • p. 306 c: Musée minérologique et minier de Theford Mines • p. 306 bl: Arto Dokouzian • p. 306 br: Musée minérologique et minier de Theford Mines • p. 309 Musée minérologique de Theford Mines • p. 311 tl: © Francesc Muntada/Corbis • p. 312: Weatherstock • p. 313 cl: © Bettmann/Corbis • p. 316 bl: Ontario Science Centre • p. 319 cr: Francoise De Mulder/Roger Viollet/Getty Images • p. 320 b: David Woodfall/Still Pictures/Robert Harding • p. 321 br: Norbert Wu/Getty Images • p. 322 bl: Steve Kaufman • p. 323 br: © MK Krafft – CRI Nancy-Lorraine • p. 324 tl: © Nik Wheeler/ Corbis • p. 324 c: Simon Fraser/SPL/Publiphoto • p. 325 tr: © Tom Wagner/Corbis SABA • p. 325 cl: AP/Wide World Photos • p. 325 br: © Yann Arthus-Bertrand/Corbis • p. 326 bl: AP/Wide World Photos • p. 327 tr: Zephyr/SPL/Publiphoto • p. 329 r: SPL/Publiphoto • p. 330 tr: Martin Guérin/Images du Québec• p. 330 cl: © Steve Vidler/SuperStock • p. 330 br: © Alan Towse; Ecoscene/Corbis • p. 331 cl and cr: P.G. Adam/Publiphoto • p. 332 cl: PhotoDisc • p. 334 bl: © NOAA/Corbis • p. 336 tl: Nuance Photo • p. 336 cr: Markus Dlouhy/Imagetrust • p. 336 bc: © Matthias Kulka/Corbis • p. 337 r: © Neil Rabinowitz/Corbis • p. 339 tl: Roderick Chen/Search4Stock • p. 339 cr: Megapress • p. 340 l: © Erika Koch/zefa/Corbis • p. 340 r: Daryl Benson/Masterfile • p. 341 r: akg-images • p. 344: © Dennis di Cicco/Corbis • p. 345 br: Jochen Tack • p. 348 c: Peter Steyn/Ardea London Ltd. • p. 349 r: Duncan Shaw/SPL/Publiphoto • p. 351

476 Sources

THE

TECHNOLOGICAL WORLD • p. 372: PhotoDisc • p. 373 t: © Georgina Bowater/ Corbis • p. 373: © Jean-Pierre Amet/Sygma/Corbis • p. 373 b: © Tom Grill/Corbis • p. 375 br: Musée Joseph-Armand Bombardier • p. 376 l: S. Terry/SPL/Publiphoto • p. 378 l: Frank Ungrad/Shutterstock • p. 378 r: Nuance Photo • p. 379 br: akg-images • p. 380 bl: © Poulin Pierre Paul/Sygma/Corbis • p. 382 bl: © Jefferson Hayman/Corbis • p. 385: Arto Dokouzian • p. 386 (conifers): PhotoDisc • p. 386 (wood planks): Nuance Photo • p. 386 (iron ore): © James L. Amos/Corbis • p. 386 (steel beams): PhotoDisc • p. 387 (cans): Alcan • p. 387 (plastic bottles): Nuance Photo • p. 387 (helmet): Search4Stock • p. 387 (glass bottle and ceramic bowl): Nuance Photo • p. 387 (stone fireplace): Search4Stock • p. 387 (coat): Nuance Photo • p. 387 c: Arto Dokouzian • p. 388: © Richard Cummins/Corbis • p. 390 cr: Nuance Photo • p. 390 b: Search4Stock • p. 393 t (boat) • p. 394 tl: Kevin Herrin/ iStockphoto • p. 396 bl: Gianni Dagli Orti/The Art Archive at Art Resource, NY • p. 396 r (photos 1 and 2): Nuance Photo • p. 396 r (photo 3): Search4Stock • p. 396 r (photos 4 and 5): Nuance Photo • p. 397 br: E. Wallis/SPL/Publiphoto • p. 398 l: © Chase Swift/ Corbis • p. 401 tl: © Richard Cummins/Corbis • p. 402 l: J. Claude Hurni/Publiphoto • p. 404: PhotoDisc • p. 405 b: David Madison/Getty Images • p. 406 cl: Search4Stock • p. 406 bl: © Adam Woolfitt/Corbis • p. 406 cr: Corel Disk • p. 406 br: Search4Stock • p. 407 cb: Search4Stock • p. 408 tr, bl and br: Search4Stock • p. 408 cl: © Jack Fields/Corbis • p. 409 tl: Search4Stock • p. 410 cr: from t to b: © Duomo/Corbis; © Ronnie Kaufmann/Corbis; Nuance Photo • p. 411 tr: from t to b: Nuance Photo: Quincaillerie Delorimier/Nuance Photo • p. 411 r: Mode Images/FirstLight • p. 412 tl: © Carl & Ann Purcell/Corbis • p. 412 b, from l to r (photos 1 to 4): Search4Stock; (photo 5): PhotoDisc • p. 413 t, from l to r: Search4Stock • p. 414 tl: Janicke Morissette/Le bureau officiel • p. 414 tc: Nuance Photo • p. 414 tr: © Duomo/Corbis • p. 415 cl: Nuance Photo • p. 415 br: Royalty-Free/Corbis • p. 416 cl: © Photo Collection Alexander Alland, Sr. /Corbis • p. 416 c, from l to r: PhotoDisc; Search4Stock; Arto Dokouzian • p. 416 b: Search4Stock • p. 417 cr: Search4Stock • p. 418 c: La Ronde • p. 420 cr: La Ronde • p. 420 b: Nuance Photo • p. 421 tr: PhotoDisc • p. 421 bc: Nuance Photo • p. 422 tl: Nuance Photo • p. 422 cr: Search4Stock • p. 423: © Catherine Karnow/Corbis • p. 425 tr and br: Search4Stock

SKILLS

HANDBOOK • pp. 426–427: Arto Dokouzian and Michel Verreault • p. 428 br: Arto Dokouzian • p. 429 br: Beranger/BSIP • p. 430 b: © Gregg Otto/Visuals Unlimited • p. 432 cl: Arto Dokouzian • p. 433 tl: Janicke Morissette/ Le bureau officiel • p. 434r: Nuance Photo • p. 436 tr: Arto Dokouzian • p. 437 tr: Arto Dokouzian • p. 439 b: Search4Stock • p. 446 cl: Search4Stock • p. 449 cl: Arto Dokouzian • p. 449 bl and r: Nuance Photo • p. 450 bl: Arto Dokouzian • p. 450 tr: © H. J. Martin/Corbis • p. 451 (rocket and model): European Space Agency • p. 452 bl and cr: Arto Dokouzian • p. 452 br: Bilderberg/Megapress • p. 454 tl and br: Janicke Morissette/Le bureau officiel • p. 456 tr: Arto Dokouzian • p. 456 br: Éric Guadagno, Université de Montréal • p. 457: Arto Dokouzian • p. 458 r: Janicke Morissette/Le bureau officiel • p. 459 cl: Janicke Morissette/Le bureau officiel • p. 459 bl: Arto Dokouzian • p. 460 bl and cr: Arto Dokouzian • p. 461 cl and tr: Arto Dokouzian • p. 462 c and br: Arto Dokouzian • p. 463 tr and bl: Arto Dokouzian

Julie Benoît, cartographer: pp. 26–27, 58 b, 73, 131, 139, 298, 313 br, 314, 315 b, 316 c, 321 tl, 327 bl, 327 tl, 365 b • Stéphane Bourelle: pp. 227, 236, 254 b, 255 tl, 258 b, 263 t, 264 b, 265 t, 269 b, 271 t • Pierre-André Bourque: p. 328 br • Collective (AMID Studios, Kevin Cheng, Crowle Art Group, François Escamel, Dave McKay, Mike Opsahl, Dave Maziersky, NSV Productions, Dusan Petricic, Cynthia Watada): pp. 204 r, 208 l, 211 l • Arto Dokouzian: pp. 183 tr, 195 b, 261 tr and c, 291 tr, 293 tr, 295 tr, 298 c, 299 l, 303 c, 342 l, 347c, 358 tl, 359 bl, 361 t, 362 r, 368–369 b, 370 b, 382 r, 383 l, 384 c, 413 bl, 414, 415, 419, 420, 425, 429 cl and cr, 435 bl and br, 446 l, 448 • Robert Dolbec: pp. 335 tr, 375 cl • Michel Grant: p. 439 • Imagineering Scientific and Technical Artworks Inc/Pronk & Associates: pp. 176, 177, 181, 191 tr, 192 l, 196, 197 tr and bl, 241 b, 244 t, 247 b, 249 t, 251 t, 253 b, 268, 294 tl, 306, 308 tr and bc, 310 cr, 315 t, 317 t, 318 b (3 illustrations), 320 t, 326 c (3 illustrations), 332 br, 333c, 334 br, 335 bl, 337 l (2 illustrations), 338 c, 345 cb, 349 t and b, 350 c, 353 b, 356 t, 402 r, 447 l • Bertrand Lachance: pp. 8, 9, 30, 68, 69, 184, 187 b, 220, 221 317 b, 389, 392 tl and r, 393 c, 394 l, 398 r, 399 c, 400 r, 423 (4 illustrations), 453, 455 • Dany Lavoie: pp. 182, 205 c, 216 br, 237 tl • Dave McKay: p. 410 c • Stéphane Morin: pp. 209 l, 210 tl, 213 c, 424, 446 l • Marc Tellier: pp. 7, 13, 16, 58 t, 61, 66, 89, 150, 160 cr, 200, 318 t, 319 t and b, 322 br, 323 l, 328 tl, 329 b, 403 cl • From Omniscience 7, p. 338, Chenelière/McGraw-Hill, © 2001: pp. 290 br, 292 c • From Lucy Daniel, Life Science. Glencoe/McGraw-Hill © 1997, pp. 183 br, 245, 254 tl, 259t, 260 r, 262 c, 273 br (last two illustrations) • From Mader, Inquiry into Life, 8th edition., © The McGraw-Hill Companies Inc.: p. 263 b • From Cecie Starr and Ralph Taggart, Biology: The Unity and Diversity of Life, 6th edition, © Wadsworth Publishing: p. 267 • Jean-François Vachon: pp. 346, 364 b

Index of Cycle One Concepts Encyclopedia

Textbook A Page Where Concept Textbook B Page Where Concept (Year One) Is Introduced (Year Two) Is Introduced (Textbook A)

THE MATERIAL WORLD, p. 172 SECTION 1 The Properties of Matter, p. 174 Non-Characteristic Properties of Matter, p. 175

< o O < O < O o < O O O < O o O < O o < O o

58 (Unit 2) 146, 149 (Unit 4) 153 (Unit 4) 59, 60 (Unit 2) 61 (Unit 2) 148 (Unit 4) 149 (Unit 4) 45 (Unit 1) 59, 60 (Unit 2) 61 (Unit 2) 45, 46, 47 (Unit 1) 59, 60 (Unit 2) 61 (Unit 2) 59, 60 (Unit 2) 61 (Unit 2)

+ O < o O < O < o

59, 60 (Unit 2) 11 (Unit 1) 65, 66 (Unit 2) 143, 149 (Unit 4) 33, 34 (Unit 1) 65 (Unit 2)

O O < o < O + < O < O + + + + < o < O O O < o < O

33, 34 (Unit 1) 59, 60 (Unit 2) 61 (Unit 2) 103, 104 (Unit 3) 158 (Unit 4) 61 (Unit 2) 103, 104 (Unit 3) 158 (Unit 4) 61 (Unit 2) 61 (Unit 2) 158 (Unit 4) 69 (Unit 2) 103, 104 (Unit 3) 117, 122 (Unit 3) 146, 151 (Unit 4) 69 (Unit 2) 103, 104 (Unit 3)

o O o O

Different Degrees of Acidity, p. 187

States of Matter, p. 176

Solids, p. 176 Liquids, p. 176 Gases, p. 177

(Textbook B)

u

128–131, 134–138 (Unit 4)

+ < u

36 (Unit 1) 49, 50, 58 (Unit 2)

u

53 (Unit 2)

u

49, 50, 53, 54, 77–80 (Unit 2)

u

49, 50, 53, 54, 73 (Unit 2) 160 (Unit 4)

+ Particle Theory, p. 177 Mass, p. 178 Volume, p. 180 Temperature, p. 181

The Celsius Scale, p. 181 Temperature and Atmospheric Pressure, p. 182 Temperature and Particle Theory, p. 183

< u + u < u + u + u < u u

58 (Unit 2)

+ < O < u

(Chapter 3, Unit 1) 107–110 (Unit 3)

69 (Unit 2) 103, 104 (Unit 3) 69 (Unit 2) 103, 104 (Unit 3)

u + < O + + < O < u < O < u

< o < O

69 (Unit 2) 103, 104 (Unit 3)

u < O < u

Universal Indicator Paper, p. 188

+ < O

69 (Unit 2) 103, 104 (Unit 3)

The pH Meter, p. 188

+ < O

69 (Unit 2) 103, 104 (Unit 3)

24 (Unit 1) (Chapter 3, Unit 1) 135 (Unit 4) (Chapter 3, Unit 1) 107–110 (Unit 3) 17 (Unit 1) 128, 129, 134, 135 (Unit 4) 131, 136 (Unit 4) 17 (Unit 1) 128, 129, 134, 135 (Unit 4) 131, 136 (Unit 4) 17 (Unit 1) 128, 129 (Unit 4) 134, 135 (Unit 4) 17 (Unit 1)

Measuring Acidity or Alkalinity, p. 185 Litmus Paper, p. 186 pH, p. 186

< < <