Cambridge IGCSE® Combined and Co-ordinated Sciences Physics Workbook (Cambridge International IGCSE) 1316631060, 9781316631065

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Cambridge IGCSE Combined and Co-ordinated Sciences

B13 Variation and selection

157

..

266

Bl3.0l Variation

157

CS.01 What is an acid?

Bl3.02 Selection

160

CS.02 Acid and alkali solutions

270

CS.03 Metal oxides and non-metal oxides

271

CS.04 Acid reactions in everyday life

273

CS.OS Alkalis and bases

275

CS.06 Characteristic reactions of acids

276

CS.07 Acids and alkalis in chemical analysis

279

CS.08 Salts

280

CS.09 Preparing soluble salts

281

CS.10 Choosing a method of salt preparation

283

B14 Organisms and their environment

167

Bl4.0l Ecology

167

Bl4.02 Energy flow

168

Bl4.03 The carbon cycle

170

Bl4.04 Human influences on ecosystems

171

Chemistry Cl Planet Earth

'■

CS Acids, bases and salts

177

Cl.01 The atmosphere

177

Cl.02 Water treatment

182

Cl.03 The Earth's crust

184

C2 The nature of matter

187

C2.0l The states of matter

CG Quantitative chemistry

266

288

C6.0l Chemical analysis and formulae

288

C6.02 The mole and chemical formulae

295

C6.03 The mole and chemical equations

297

C6.04 Calculations involving gases

299

188

C6.05 Moles and solution chemistry

300

C2.02 Separating and purifying substances

193

C2.03 Atoms and molecules

198

C7 How far? How fast?

306

C2.04 The structure of the atom

203

C7.0l Energy changes in chemical reactions

306

C2.05 Electron arrangements in atoms

207

C7.02 Rates of reaction

311

C3 Elements and compounds

214

C7.03 Catalysts

316

C7.04 Reversible reactions

320

C3.0l The Periodic Table - classifying the elements

215

C3.02 Trends in groups

219

CB Patterns and properties of metals

C3.03 Trends across a period C3.04 Chemical bonding in elements and compounds

222

224

C3.05 The chemical formulae of elements and compounds

232

C3.06 Metals, alloys and crystals

235

C4 Chemical reactions

244

328

C8.0l The alkali metals

328

C8.02 Aluminium

331

C8.03 The transition elements

332

C8.04 The reactivity of metals

334

C9 Industrial inorganic chemistry

343

C9.0l The extraction of metals by carbon reduction

344

C9.02 The extraction of metals by electrolysis

348

C9.03 Ammonia and fertilisers

350

C9.04 Sulfur and sulfuric acid

352

C9.05 The chlor-alkali industry

353

C4.0l Chemical reactions and equations

244

C4.02 Equations for chemical reactions

246

C4.03 Types of chemical reaction

248

C4.04 A closer look at reactions, particularly redox reactions

252

C9.06 Limestone

354

C4.05 Electrolysis

254

C9.07 Recycling metals

355

Contents

Cl0 Organic chemistry

360

P3.03 Mass, weight and gravity

433 435

Cl0.01 The unique properties of carbon

360

P3.04 Force, mass and acceleration

Cl0.02 Alkanes

362

Cl0.03 Alkenes

364

P4 Turning effects of forces

Cl0.04 Hydrocarbon structure

366

Cl0.05 Chemical reactions of the alkanes

366

Cl0.06 Chemical reactions of the alkenes

367

Cl0.07 Alcohols

367

Cl0.08 The reactions of ethanol

370

Cll Petrochemicals and polymers

373

Cll.Dl Petroleum

373

Cll.02 Alternative fuels and energy sources

379

Cll.03 Addition polymerisation

380

Cll.04 Condensation polymerisation

382

C12 Chemical analysis and investigation

388

Cl2.0l Chemical analysis

388

Cl2.02 Inorganic analysis

389

Cl2.03 Organic analysis

394

Cl2.04 Experimental design and investigation

395

Cl2.05 Practical skills

398

Physics

441

P4.0l Keeping upright

441

P4.02 The moment of a force

441

P4.03 Calculating moments

444

P4.04 Stability and centre of mass

446

PS Forces and matter

451

P5.0l Forces acting on solids

451

P5.02 Stretching springs

452

P5.03 Hooke's law

454

P5.04 Pressure

455

PG Energy transformations and energy transfers

462

P6.0l Energy for life

462

P6.02 Forms of energy

463

P6.03 Energy conversions

465

P6.04 Conservation of energy

466

P6.05 Energy calculations

469

P7 Energy resources

476

P7.0l The energy we use

476

P7.02 Energy from the Sun

480

Pl Making measurements

403

Pl.01 How measurement improves

403

PS Work and power

484

Pl.02 Measuring length

404

P8.0l Doing work

484

Pl.03 Density

406

P8.02 Calculating work done

485

f 1.04 Measuring time

409

P8.03 Power

488

P2 Describing motion

414

P8.04 Calculating power

489

I 2.01 Understanding speed

414

P9 The kinetic model of matter

494

I 2.02 Distance-time graphs

419

P9.0l States of matter

494

I 2.03 Understanding acceleration

419

P9.02 The kinetic model of matter

496

I i2.04 Calculating speed and acceleration

422

P9.03 Forces and the kinetic theory

499

P3 Forces and motion

430

P9.04 Gases and the kinetic theory

501

I .01 Roller-coaster forces

430

PIO Thermal properties of matter

,, .02 We have lift-off

430

Pl0.01 Thermal expansion

506 506

■

Cambridge IGCSE Combined and Co-ordinated Sciences

509

P18 Electrical quantities

Pl0.03 Designing a thermometer

5ll

Pl8.0l Current in electric circuits

596

Pl8.02 Electrical resistance

600

Pll Thermal (heat) energy transfers

I

516

Pll.01 Conduction

516

Pll.02 Convection

519

Pll.03 Radiation

521

Pll.04 Some consequences of thermal (heat) energy transfer

523

P12 Sound

530

Pl2.0l Making sounds

530

Pl2.02 At the speed of sound

532

Pl2.03 Seeing sounds

534

Pl2.04 How sounds travel

536

P13 Light

Ill

•

Pl0.02 Temperature and temperature scales

541

Pl3.0l How far to the Moon?

541

Pl3.02 Reflecting light

542

Pl3.03 Refraction of light

546

Pl3.04 Total internal reflection

550

Pl3.05 Lenses

552

P14 Properties of waves

561

Pl4.0l All at sea!

561

Pl4.02 Describing waves

562

Pl4.03 Speed, frequency and wavelength

566

Pl4.04 Explaining wave phenomena

567

P15 Spectra

575

Pl5.0l Infrared, ultraviolet

575

Pl5.02 Electromagnetic waves

57 7

P16 Magnetism

581

Pl6.0l Permanent magnets

581

Pl6.02 Magnetic fields

583

P17 Electric charge

589

P17.0l A bright spark

589

Pl7.02 Charging and discharging

590

Pl7.03 Explaining static electricity

591

596

Pl8.03 More about electrical resistance

602

Pl8.04 Electricity and energy

604

P19 Electric circuits

609

Pl9.0l An international language

609

Pl9.02 Circuit components

609

Pl9.03 Combinations of resistors

613

Pl9.04 Electrical safety

616

P20 Electromagnetic forces

621

P20.0l Electricity meets magnetism

621

P20.02 The magnetic effect of a current

622

P20.03 Force on a current-carrying conductor

625

P21 Electromagnetic induction

630

P21.0l Generating electricity

630

P21.02 Power lines and transformers

633

P22 Atomic physics

641

P22.0l Atomic structure

641

P22.02 Radioactivity all around

645

P22.03 The microscopic picture

647

P22.04 Radioactive decay

651

P22.05 Using radioisotopes

653

Glossary

660

Index

663

CD-Rom Revision checklists Multiple-·choice tests Glossary (matches the coursebook) Notes on activities for teachers/technicians Self-assessment checklists Activities Answers to end-of-chapter questions Answers to questions Study and revision skills Helps notes and terms and conditions

Thanks to the following for permission to reproduce images:

Cover image: Pery Burge/Science Photo Library Biology

Bl unit opener, Bl.OS JOHN DURHAM/SPL; Bl.01, Bl.02, 4.01, BS unit opener, BS.07 Eleanor Jones; Bl.03, B8.03 BIOPHOTO ASSOCIATES/SPL; Bl.04, B2 unit opener, B2.0l, BS.01-5.04, B9.0l, Bl0.03, Bl3 unit opener, Bl3.0l, Bl3.05a, Bl4 unit opener, Bl4.02, Bl4.03 Geoff Jones; B3 unit opener, B3.03 Top-Pies TBK/Alamy Stock Photo; B3.0l MARTYN F. CHILLMAID/SPL; B3.02. B3.04, B3.05 ANDREW LAMBERT PHOTOGRAPHY/SPL; B4 unit opener, B4.04 Nigel Cattlin/Alamy Stock Photo; B4.02, B6 unit opener, 6.03 DR KEITH WHEELER/SPL; B4.03, B6.0l, Bl2.0l POWER AND SYRED/SPL; BS.OS Alex Segre/Alamy Stock Photo; BS.06 Images of Africa Photobank/Alamy Stock Photo; B6.02, Bll unit opener, Bll.01 STEVE GSCHMEISSNER/SPL; B7 unit opener, B7.02 PHOTOTAKE lnc./Alamy Stock Photo; B7.0l PROF. P. MOTTA/DEPT. OF ANATOMY/UNIVERSITY "LA SAPIENZA", ROME/SPL; B8 unit opener, B8.02 Tom Merton/Caiaimage/Getty Images; B8.0l PETER MENZEL/ SPL; B8.04 CORBIN O'GRADY STUDIO/SPL; B9 unit opener Science Photo Library - KTSDESIGN/Getty Images; BlO unit opener, Bl0.05 Pictox/Alamy Stock Photo; Bl0.01 SCIENCE PICTURES LIMITED/SPL; Bl0.02 IRENE WINDRIDGE/SPL; Bl0.04 Mediscan/Alamy Stock Photo; Bl0.06 DAVID M. PHILLIPS/SPL; Bl2 unit opener, B12.05, B13.02a imageBROKER/Alamy Stock Photo; B12.02 CNRI/SPL; B12.03 LEONARD LESSIN/FBPA/SPL; Bl2.04, Bl4.04 blickwinkel/Alamy Stock Photo; Bl3.02b Sam Sangster/Alamy Stock Photo; Bl3.03 Mary Evans Picture Library/Alamy Stock Photo; Bl3.04 PAT & TOM LEESON/SPL; Bl3.05b Terry Mathews/Alamy Stock Photo; Bl4.0l Richard Wareham Fotografie/Alamy Stock Photo; Bl4.05 Robert Brook/Alamy Stock Photo Chemistry

Cl unit opener, Cl.01 ESA/KEVIN A HORGAN/SPL; Cl.02, fig. C5.02b Leslie Garland Picture Library; Cl.03 joebelanger/iStock/Getty Images Plus/Getty Images; C2 unit opener, C2.08 PEKKA PARVIAINEN/SPL; C2.02, C2.03, C2.04, C2.06, C2.07, C3.03, C3.04, C3.07b, C4.0l, C4.05-7, C4.08a(i),a(ii),b, CS unit opener, Fig CS.02, Fig C5.6b, Fig C5.09b, C7.06, C7.10, Cl0.03, Cl2 unit opener, Cl2.02a,b, Cl2.03 ANDREW LAMBERT PHOTOGRAPHY/SPL; C2.05 Courtesy of IBM Archives; C2.0l, C4 unit opener, C4.03 CHARLES D. WINTERS/ SPL; C3 unit opener, C3.08 KENNETH LIBBRECHT/SPL; C3.0l, C3.05, C8.07, C8.09, Cl0.01, Cl2.0l Richard Harwood; C3.02 Kerstin Waurick/iStock/Getty Images Plus/Getty Images; C3.06, C3.07a, C4.02 MARTYN F. CHILLMAID/SPL; C4.04a,b, C4.09, CS.03 TREVOR CLIFFORD PHOTOGRAPHY/SPL CS.01 DAVID MUNNS/SPL CS.04 EUROPEAN SPACE AGENCY/AEOS MEDIALAB/SPL CS.OS Jeremy Pardoe/Alamy Stock Photo; CS.06, C9.09a MARTIN BOND/SPL; C5.07a, CS.08, C7.04, C7.07, (7.09, C9.04, Cl0.02 MARTYN F. CHILLMAID/SPL; C5.07b, C7 unit opener, C7.05, C8.0l, C8.10a,b, Cll.06b CHARLES D. WINTERS/SPL; CS (tip) ARNOLD FISHER/ SPL; C6 unit opener zlikovec/Getty Images; C6.0l CHRISTIAN DARKIN/SPL; C7.0l SCOTT CAMAZINE/K. VISSCHER/SPL; C7.02 TEK IMAGE/SPL; C7.03 Classic Image/Alamy Stock Photo; C7.08 ASTRID & HANNS­ FRIEDER MICHLER/SPL; C8 unit opener, C8.04 Art Directors & TRIP/Alamy Stock Photo; C8.02 JAMES KING­ HOLMES/SPL; C8.03 Chris Mellor/Lonely Planet Images/Getty Images; C8.05 J.C.HURNI, PUBLIPHOTO DIFFUSION/SPL; C8.06 Print Collector/Hulton Archive/Getty Images; C8.08 (all) VvoeVale/iStock/Getty Images Plus/Getty Images; C9 unit opener, C9.0l ROSENFELD IMAGES LTD/SPL; C9.02 NOAA/SPL; C9.03 BEN JOHNSON/SPL; C9.05, fig. C9.13a DIRK WIERSMA/SPL; C9.06 MAXIMILIAN STOCK LTD/SPL; Cl0 PASIEKA/ Getty Images; Cl0.04 DAVID R. FRAZIER/SPL; Cll unit opener shotbydave/Getty Images; Cll.01 SPUTNIK/ SPL; Cll.02, Cll.03 PAUL RAPSON/SPL; Cll.04 ROGER HARRIS/SPL; Cll.05 LEONARD LESSIN/SPL; Cll.06 David Talbot

■

Cambridge IGCSE Combined and Co-ordinated Sciences

Physics

Pl unit opener, Pl.01 GoGo Images Corporation/Alamy Stock Photo; P2 unit opener, P2.03 Gavin Quirke/

Lonely Planet Images/Getty Images; P2.0l TRL LTD./SPL; P2.02, Pl3.09 Cambridge University Press/Nigel

Luckhurst; P3 unit opener, P3.04 ANDREW WHEELER/SPL; P3.0l Chad Slattery/The Image Bank/Getty

Images; P3.02 Getty Images; P3.03 ERICH SCHREMPP/SPL; P4 unit opener Peter Cade/Getty Images; P4.0l Will Steeley/Alamy Stock Photo; PS unit opener, PS.02 ALEXIS ROSENFELD/SPL; PS.01 GUSTOIMAGES/SPL;

P6 unit opener, P6.04, PlS.02 NASA/SPL; P6.0l Jeff Rotman/Nature Picture Library; P6.02 Visions of America,

LLC/Alamy Stock Photo; P6.03, PlO unit opener, PlO.0la,b, Pl0.03, Pl0.04, Pl3.02, fig. Pl3.02a, Pl3.05, Pl3.06, Pl3.07, Pl3.08, Pl4.03b, fig.Pl4.07a, Pl4.04a, b, Pl8 unit opener, fig.Pl8.0l, Pl8.0la, Pl8.02, Pl9.02a, fig.Pl9.03a, fig. Pl9.04a, Pl9.03, Pl9.04, P22.05 ANDREW LAMBERT PHOTOGRAPHY/SPL; P6.05 Bernhard Lang/Photographer's Choice/Getty Images; P7 unit opener P7.03 Kelly Cheng Travel Photography/ Moment/ Getty Images; P7.0l Jim Wileman/Alamy Stock Photo; P7.02 SEY LLOU/ AFP/Getty Images; P7.04 Steve Allen/

Stockbyte/Getty Images; P7.05 Mint Images-Frans Lanting/Mint Images/Getty Images; P8 unit opener, P8.0l ACE STOCK LIMITED/Alamy Stock Photo; P9 unit opener Charity Burggraaf/Getty Images; P9.0l Agencja Fotograficzna Caro/Ala my Stock Photo; Pl0.02 MATT MEADOWS/SPL; Pll unit opener, Pll.03 EDWARD

KINSMAN/SPL; Pll.01 ShaniMiller/Getty Images; Pll.02, Pl2.04, Pl9.04 sciencephotos/Alamy Stock Photo; Pl2 unit opener PASIEKA/Getty Images; Pl2.0l ©Bernard Richardson, Cardiff University; Pl2.02a Mode/ Richard Gleed/Alamy Stock Photo; Pl2.02b Doug Taylor/Alamy Stock Photo; Pl2.03 David Redfern/Redferns/ Getty Images; Pl3 unit opener, Pl3.06, P22 unit opener, P22.08 TEK IMAGE/SPL; Pl3.0l ROYAL GREENWICH

••

OBSERVATORY/SPL; Pl3.03 HANK MORGAN/SPL; Pl3.04 James Balog/Aurora/Getty Images; Fig. Pl3.07a,

Pl4.03a, P20.0l, P22.03 SPL; Pl4 unit opener, Fig. Pl4.08a BERENICE ABBOTT/SPL; Pl4.0l Thomas Kitchin & Victoria Hurst/First Light/Getty Images; Pl4.02 Rick Strange/Alamy Stock Photo; Pl4.05 JOHN FOSTER/

SPL; PlS unit opener, PlS.03 TONY MCCONNELL/SPL; PlS.01 DAVID PARKER/SPL; PlS.04 DAVID R. FRAZIER/ SPL; Pl6 unit opener Sylvie Saivin/ EyeEm/Getty Images; Pl6.0l CORDELIA MOLLOY/SPL; Pl6.02 JEREMY WALKER/SPL; Pl7 unit opener JKboy Jatenipat.Getty Images; Pl9 unit opener, Pl9.0l ROSENFELD IMAGES LTD/SPL; Pl9.02 David J. Green - electrical/Alamy Stock Photo; P20 Monty Rakusen/Getty Images; P21 unit opener, P21.0l ED MICHAELS/SPL; P21.02 standby/Getty Images; P22.0l IBM/SPL; P22.02 PUBLIC HEALTH

ENGLAND/SPL; P22.04 PASCAL G9ETGHELUCK/SPL; Fig. P22.12a Leslie Garland Picture Library/Alamy Stock Photo; P22.06 Crown Copyright - Public Health England; P22.07 Mark Kostich/ VETTA/Getty Images SPL = Science Photo Library

All biology artworks are by Geoff Jones.

This book has been written to help you obtain the knowledge and skills required for your Cambridge IGCSE" Combined Science 0653 or Cambridge IGCSE" Co-ordinated Sciences (Double Award) 0654 course. We hope that you enjoy using it.

All the Biology topics come first, then Chemistry and then Physics. However, you almost certainly won't follow this sequence in your lessons. You will probably find that you study Biology, Chemistry and Physics alongside each other, so you will use different parts of the book in different lessons.

Core and Supplement

Your teacher will tell you whether you are studying:

• Cambridge IGCSE Combined Science 0653 or Cambridge IGCSE Co-ordinated Sciences (Double Award) 0654 • only the Core part of the syllabus, or the Supplement as well.

Cambridge !GCSE Combined Science 0653 is a single award syllabus. This means that your final papers are the equivalent of one IGCSE subject. Cambridge IGCSE Co-ordinated Sciences 0654 is a double award syllabus. In this case, your final papers are the equivalent of two !GCSE subjects.

If you study the Core only, you will be entered for Papers 1 (Multiple Choice (Core)) and 3 (Theory (Core)) and either Paper 5 (Practical Test) or 6 (Alternative to Practical). If you also study the Supplement, you may be entered for Papers 2 (Multiple Choice (Extended)) and 4 (Theory (Extended)), and either Paper 5 (Practical Test) or 6 (Alternative to Practical).

There are sidebars in the margins of the coursebook to show which material relates to each syllabus and paper. If there is no sidebar, it means that everyone will study this material. Use this table to ensure that you study the right material for your syllabus and paper:

You will study the material: Without a sidebar

You will study the material:

You will study the material:

Without a sidebar

Without a sidebar

With a double black sidebar

With a double blue sidebar

With a double blue sidebar

With a single blue sidebar

everything.

You will study

This includes the material:

Without a sidebar

With a single blue sidebar

With a double blue sidebar With a single black sidebar

With a double black sidebar

■

Cambridge IGCSE Combined and Co-ordinated Sciences

Questions Each chapter has several sets of questions within it. Most of these require quite short answers and simply test if you have understood what you have just read or what you have just been taught. At the end of each chapter, there are some longer questions testing a range of material from the chapter. Some of these are past questions from Cambridge exam papers, or similar in style to Cambridge questions. We would like to thank Cambridge International Examinations for permission to reproduce exam questions.

Activities Each chapter contains activities. These will help you to develop the practical skills you will need in your course. There are further activities on the CD-ROM. These are marked with this symbol: • There are two possible papers aimed at testing your practical skills, called Paper 5 and Paper 6 (Practical Test and Alternative to Practical, respectively). Your teacher will tell you which of these you will be entered for. You should try to do the activities in this coursebook no matter which of these papers you are entered for.

Summary At the end of each chapter, there is a short list of the main points covered in the chapter. Remember, though, that these are only very short summaries and you will need to know more detail than this for your course.

CD-ROM There is a CD-ROM in the back of the book. You can use the revision checklists on the CD-ROM to check off how far you have got with learning and understanding each idea. The CD-ROM also contains a set of interactive multiple-choice questions which test whether you know and understand the material from each chapter. You will find some self-assessment checklists on the CD-ROM too, which you can print off and use to assess yourself each time you observe and draw a specimen, construct a results chart, draw a graph from a set of results or plan an experiment. These are all very important skills, and by using these checklists you should be able to improve your performance until you can do them almost perfectly every time. There are some suggestions on the CD-ROM about how you can do well in your course by studying and revising carefully.

Workbooks There are three workbooks to go with this coursebook...: one for each science. If you have the workbooks, you will find them really helpful in developing your skills, such as handling information and solving problems, as well as some of the practical skills.

This chapter covers

sections set out the key topics within each unit, and help with navigation through the chapter.

This chapter covers:

■ ■ ■ ■ ■

the human nervous system

neurones and how they work the difference between voluntary and involuntary actions reflex actions the structure and function of the eye

■ the hormone adrenaline

Key terms

boxes contain clear definitions of important scientific terms in each chapter. ")

■ ■ ■ ■

the hormones insulin and glucagon how humans maintain a constant internal body temperature how plants respond to stimuli the role of auxin in shoot growth.

Worked examples

are featured throughout to provide step-by-step guidance for answering questions. ") WORKED EXAMPLE C4.0l

A solution is made up of two parts: the solute: the solid that dissolves the solvent: the liquid in which it dissolves.

What is the balanced equation for the reaction between magnesium and oxygen?

Step 1: Make sure you know what the reactants and

products are. For example, magnesium burns in air (oxygen) to form magnesium oxide.

Step 2: From this you can write out the word equation: Step 3: Write out the equation using the formulae of

Tip boxes contain advice for students to avoid common

misconceptions and provide support for answering questions.

)

TIP

Remember that ice is not always at 0 °C- it may be colder than that. When you take ice from a freezer, it may be as cold as -20 °C.

magnesium+ oxygen ➔ magnesium oxide the elements and compounds: Mg+02 ➔ MgO

Remember that oxygen exists as diatomic molecules. This equation is not balanced: there are two oxygen atoms on the left, but only one on the right.

Step 4: Balance the equation:

2Mg+02 ➔ 2Mg0

■

Cambridge I GCSE Combined and Co-ordinated Sciences Activity sections th ro u ghout each chapter p rovide guida nce for condu cti ng pra ctical investigations.

}

ACTIVITY C7.05

®

Questions 11 a re featu red throughout each cha pter to assess students' knowledge and u n dersta nding of science. QUEST I O N S

B2.01

The factors affecting reaction rate

B2.02

Skills:

B2.03

AO3.l Demonstrate knowledge of how to safely use techniques, apparatus and materials (including following a sequence of instructions where appropriate) AO3.2 Plan experiments and i nvestigations

AO3.4 I nterpret and evaluate experimental observations and data

•

List three exa m ples of diffusion in livi ng orga n isms.

You will need to think a bout you r knowledge of pa rticle th eory to a n swer this q u estion. a

b

AO3.3 M a ke and record observations, measurements and estimates

What effect does an i ncrease i n tempe rature have on the kinetic energy of molecules of a gas or a solute?

Predict a n d expla i n how an increase i n temperature will affect the rate of diffusion of a solute. Check the introd uction and the cover flap for i nfo rmation on how to use the side bars in the margi ns.

AO3.5 Eval uate methods and suggest possible improvements

ffi

Defi ne diffusion.

Wear eye protection. Sulfuric acid is corrosive.

You must plan an investigation to d iscover how one chosen factor affects the rate of a chemical reaction. 1

}

Mg + H 2SO4 ➔ M gSO4 + H2

Meas u re 10 cm3 of 2 mol/dm 3 sulfu ric acid i nto a boi l i n g tu be.

2 Add a 5 cm stri p of magnesi u m ri bbon and sta rt a stopclock.

3 When th e reaction stops, record the time taken. 4 List the factors that could speed up or slow down this reaction.

5 Choose o n e of these factors a n d plan a n i nvestigatio n t o discover how i t affects t h e rate.

6 You r i nvestigation sho uld prod uce sufficient results to ena b le you to d raw a gra p h.

A worksheet is included on the CD-ROM. The Notes on activities for teachers/technicians contain details of how this experiment can be used as an assessment of skills AO3.2 and AO3.5.

You should know:

■

how diffusion resu lts from the ra ndom movement of particles

■ the factors that affect the rate of diffusion

■

why d iffusion is i mportant to cells and livi ng orga nisms

At the end of each cha pter, a Summary is incl uded to recap the key topics.

}

■ ■ ■

the i m portance of water as a solvent

a bout osmosis, which is a special kind of diffusion, i nvolving water molecu les

how osmosis affects a n i m a l cells and

plant cells.

How to use this book I 1 11 1 wing the summa ry, th ere will be selection of exam-style End of chapter questions to help students to pre p a re for the type of , I l l! " lions on the IGCSE Combined or I GCSE Co-ordi nated Sciences exams.

End-of-chapter questions .1

When a force m oves, it does work. Copy a nd co m plete the fo llowing sentences, writi ng more or less in the spaces. a

b

When it m oves, a bigger force does . . . . . . . . . . . . . . . . . work than a smaller force.

The greater the d ista nce moved by the force, the . . . . . . . . . . . . . . . . . work it does.

Power tells us a bout how q u ickly work is done. Copy and complete the fol lowi ng sentences,

writi ng work or energy in the spaces. a

b

Power is the rate at w h ich . . . . . . . . . . . . . . . . . is tra nsferred.

b

[ 1]

[l]

Power is the rate at wh ich . . . . . . . . . . . . . . . . . is done.

[l] [l]

Write this equation i n words.

[2] [3]

We can calculate work done using this equation: W = F x d. a

}

Copy a n d co mplete the table to show the u n its of each q u a ntity in the equation. Qua ntity

w

I U n it

■

F 4

d

Omar a nd Ahmed a re lifting weights in the gym . Each lifts a weight of 200 N . O m a r lifts the

weight to a h eight of 2.0 m , wh ereas A h m ed l ifts it to a h eight of 2.1 m. Who does m o re work i n lifting the weight? Expla i n how you know.

M i llie and Lily a re identica l twins who e njoy swi m m i ng. Their a rms an d legs provide

the force needed to move them through the water. Mi llie can swi m 25 m i n 50 s. Lily can swim 100 m i n 250 s.

a

b

Ca lcu late the swi m m i ng speed of each twi n .

Which twi n has the greater powe r when swi m m i ng? Explain how you can tell.

Write a word equation showing h ow work done a n d energy transferred a re related.

[2]

[2] [2]

[2]

I

(his chapter covers:

the characteristics of livi ng thi ngs the structure of animal cells and plant cel ls the functions of the different pa rts of cel ls h ow to calcu late magnification.

1.01 Characteristics of living things l \lology is the study of living things, which are often , llled organisms. Living organisms have seven features 1 >1 characteristics which make them different from ,l>jects that are not alive (Figure B1.01). The definitions

movement: a n action by an organism causing a cha nge of position or place

respiration: the chemical reactions in cells that break down nutrient molecu les and release energy

sensitivity: the abi lity to detect and respond to cha nges in the envi ron ment

of these characteristics are shown in the key terms box. You should learn these definitions now, but you will find out much more about each of them later in this book.

growth: a permanent increase i n size

reproduction: the processes that m a ke m ore of the same kind of organism excretion: removal from organisms of toxic materials and su bstances in excess of req u i rements

nutrition: taking in of materials for energy, growth and development

Ca m bridge IGCSE Com bined a nd Co-ordi nated Sciences Growth All o rga nisms begin sma ll and get la rger, by the growth of their cells and by adding new cells to their bodies.

Excretion All orga n isms produce u nwanted or toxic waste produ cts as a resu lt of their meta bolic reactions, and these m ust be rem oved from the body.

Movement All organisms a re a ble to m ove to some extent. M ost a ni ma ls can move their whole body fro m place to p lace, and plants can slowly m ove parts of themselves.

Reproduction Organ is ms a re able to m a ke n ew orga n is ms o f th e sa m e species as themselves.

Figu re B1.01 Cha racteristi cs of livin g orga nisms.

movement: a n action by a n organism or part of a n organ ism causi ng a change of position or place respiration: the chemical reactions in cells that brea k down nutrient molecules and release energy for metabol ism

sensitivity: the abi lity to d etect or sense stimuli i n t h e i nterna l or external environment a n d to make appropriate responses

growth: a permanent increase in size and dry mass by a n increase in cell number o r cell size or both

I n a d d ition to these seven c h a racte ristics, living o rgan isms h ave a n other fea t u re i n co m m on: w h e n w e stu d y liv in g

Sensiti'(,ity All orga nisms pick u p i nfo rmation about ch a nges i n their enviro n ment, and react to the cha nges.

Nutrition Organisms take su bstances from their environ ment and use them to provide energy or materials to m a ke new cells.

Respiration All orga nisms break down glucose and other su bsta nces i nside their cells, to release en ergy that they can use.

reproduction: the processes that make more of the same ki nd of organism

excretion: removal from organisms of the waste prod ucts of meta bolism (chemical reactions in cells including respiration), toxic materials and su bstances in excess of requirements nutrition: ta king in of materials for energy, growth a n d development; plants requ i re light, carbon dioxide, water and ions; a nimals need orga nic com pounds and ions a nd usua lly need water

o rga nisms u n de r a m i c roscope, we can see that they a re a l l m a d e of ce lls.

Bl: Cells

.02 Cells

II 1 1 I /J n i s m s a re m a d e of ce lls. Cells a re very 1 1 1, i ll, o la rge o rga n isms conta i n m i llions of cells. ,1 11 1 H orga n isms a re u n ice l l u l a r, w h ich means that I I 1 1 1y ,,r made of j ust a si ngle cell. Bacteria and yeast a re

cell membrane

, 1 1 1 1 p les of si ngle-celled o rga n is m s .

M roscopes

1 1 1 , I ' 1 cells c lea rly, you need to use a mi crosco pe ( 1 1)\1 1 1 Bl.02). The ki n d of m i c roscope used in a

1 l tn I l a b o ratory is c a l led a light m icroscope beca use I I 1 1 1 1 1 'S li ght t h rough the piece of a n i m a l o r plant 1 1 1 1 , 1 1 loo ki n g at. It uses glass lenses to magn ify a n d

I , 1 1 1 /'1 L h e i m a ge. A very good light m icroscope ca n 1 1 1i 11:1 1 ify a b o ut 1500 t i m es, so t h a t a l l the struct u res i n 1 11 1 1 1 1 1 Bl.03 a n d Bl.04 c a n b e seen.

I 'l 1 1 1 i c m i c rogra phs of pla nt and a n i m a l cells a re shown i n l 1 1 1, 1p,( s B1.01 a n d Bl.02. A m i c rogra ph is a pictu re m a d e

1 1 l l tp, 1 1 l 1 11 I,

m i c roscope. A p hoto m i c rogra ph is a pictu re m a d e light m i crosco pe.

1 1 1 ,1 1 eve n sma ller t h i n gs i n s i d e a cell, a n electron 1 1 111 1 c co pe is used. T h is uses a bea m of electro ns

cytoplasm

n uclear envelope

Figu re B1.03 A typical a n i m a l cell - a liver ce ll - as seen

using a l ight microscope.

i n stea d of light a n d can magn ify up to 500 000 t i m es . Th is m e a n s that a lot more d et a i l ca n be seen i n s i d e

a c e l l . W e c a n see m a ny stru ctu res more clea rly, a n d a lso some struct u res that cou ld n ot b e seen a t a l l with a light m i c roscope. Pictures m a d e using an electron m icroscope a re cal led electron m i crographs.

1 1 11 1 human eye can not see 1 1 1t> 1,L cells.

A 1 1 nd lens magn ifies , 11,out x 1 0. Cells can 1111 ,n be seen as dots.

The light microscope magn ifies up to x 1500. With a light microscope you ca n see some structu res inside a cell, such as a n ucleus.

I I) 1 1 1 B1.02 Eq u i pment used fo r looking a t biological m ateria l.

= = = = = An electron m icroscope magnifies up to x 10 mi llion. With a n electron m ic roscope much more d eta il can be seen.

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Cam bridge IGCSE Combined and Co-ordinated Sciences

n ucleus

nuclear envelope

cytoplasm

/

---1,-tt-- la rge vacuole conta i ning cell sap

mem brane a round vacuole

I■

starch gra i n inside ch loroplast

Figu re B1.04 A typica l pla nt cell - a pa lisade ce ll - as seen

using a light m icrosco pe.

cytoplasm

I m a ge B1.02 Ce l ls fro m the tra chea (windpi pe) of a m a m mal, seen through a light m icroscope (x 300).

ACTIVITY B1 .01

Skill:

Making drawings of biological specimens

A03.3 Observing, measuring and recording

Scientists need to be a ble to look closely at specimens either with the naked eye or using a microscope - and note significant features in them. It is also im portant to be able to make scientific d rawings. These need to be simple but clear. I n this Activity, you will be provided with a specimen of a n a nimal t o d raw.

I mage B1.01 Ma ny p la nt cel ls co ntai n green stru ctu res,

c a lled ch lo ro plasts. Even if it d oes not have ch loroplasts,

you ca n sti ll identify a pla nt cell beca use it has a cell wall

a round it (x 2000).

H ere a re some points to bear i n mind when you d raw: ■ M a ke good use of the space on you r sheet of pa per. You r d rawing should be la rge, b u t do leave space aro u nd i t so that you have room for la bels.

B1: Cells

1 lwc1y use a sharp H B (medi u m hard) pencil and have a ,, ,n(i eraser with you. I f ( p all li nes si ngle and clear. I l! , 1 1 't use shading u n less it is a bsolutely necessary. I >1 in'L use colours. i . 1kc time to get the outl i n e of your d rawi ng correct fi rst, l l()wing the right proportions. l

, , 1 1 some poi nts to bear in mind when you , •I .i ci iagra m: l J•,t • ruler to draw each l a bel line. M, 1k sure the end of the label line actually touches 1 I i • tructure being labelled. W1 1 I the la bels horizontally. I , t p the la bels well away from the edges of , I l l Ir d rawing.

The following a re two very i m portant things to n otice:

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You must use the same u nits for all the measu rements. Usually, milli metres a re the best u nits to use. You should not include a ny units with the fi nal answer. Magnification does not have a un it. However, you must i nclude the 'times' sign. If you read it out loud, you would say 'times five'.

Questions Al M easu re the length of the lowest 'tail' (it is rea l ly ca lled an a ppendage) on the centipede below. Write your a n swer i n m illi metres.

AC TIVITY B1.02

I ulating magnification 11111:

Observing, measuring and recording t 1 1 1 gs and photogra phs of biological specimens a re , , illy made at a different size from the actual o bject. 1, 1 1 1. ignification of a diagram or photogra ph is h ow , i , 1 1 lc1rger it is than the rea l thi ng: size in d rawing or photograp h .. . 1 1 1 g n 1f1 cat1on = _______;:::...._....:...._.....:::..__:___ size of the rea l object

, , ,m 1 p le, measure the length of the spider's body i n 1 1 Igra m. You should find that it i s 4 0 m m long.

A2 The real length of the a p pend age was 10 m m . U s e this, and your a nswer t o question Al, to ca lcu late the magnification of the d rawing of the centi pede.

QU ESTIONS

B1.01

B1.02

How many times can a good light m icroscope magnify?

If an o bject was 1 m m across, how big wou ld it look i f it were magnified ten times?

Cell structure Cell membrane

, •. 1 1 pider was 8 mm long. So we can ca lculate the , 1 1 1 1 lion like this: length i n d rawi ng magn ification = ------­ length of rea l spider =

40 m m 8 mm

=xS

W hatever sort of a n i m a l or p la nt they come from , a l l cells have a cell membrane (so m eti mes c a lled the cell su rface m e m b ra n e) a ro u n d the outside. Inside the cell m e mbrane is a jelly-like su bsta nce c a l led cytoplasm, i n which a re fou n d m a ny s m a l l structure s c a l led o rganelles. T h e m ost obvious of these o rga n e lles i s u s u a lly the nucleus. In a plant cell, the n u cleus is very d ifficult to see, beca u se it is right a g a i nst the cell wall.

The cell m e m b ra n e is a very thin layer of p rotei n a n d fat. It is very i m porta nt to the cel l beca use it contro ls w h at goes in a n d out of it. It is partially permeable, w h i c h means that it will let some su bsta n ces through but n ot others.

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I

Cambridge IGCSE Combined and Co-ordinated Sciences

Cell wall

All p la nt cells a re s u rro u n d e d by a cell wall m a d e m a i n ly o f cellulose. P a p e r, w h i c h is m a d e fro m ce l l w a l ls, is a ls o m a d e of c el l u lose. A n i m a l cells

n eve r h ave c e l l w a l ls made of cellu lose. Cellu lose b e l o n gs to a gro u p of s u bsta nces c a l l e d polysaccha rid es, w hi ch a re d escri b e d i n C h a pter B2. Cellu lose fo r m s fi b res that criss-cross over one a n oth e r

t o fo rm a very s t ro n g cove ri n g t o t h e c e l l ( I m age B1.03). This h e lps to p rotect and s u pport t h e cell. I f t h e c e l l a bsorbs a l o t of w a t e r a n d swe lls, t h e ce l l w a l l sto p s it fro m b u rsti ng.

Beca u se of t h e s p a ces between fi b res, even very la rge

mo lecu les a re a b le to go t h ro u gh the cellu lose cell wall. It is the refore s a i d to be fu lly perm ea b le .

Cytoplasm

Cyto p l a s m is a clear j e l ly. It i s nea rly a l l water; a b o u t 70% is water in m a n y cel ls. M a ny su bsta nces a re d isso lved in it,

especi a l ly p rotei n s . M a ny d iffere nt m etabolic reactions (th e c h e m ica l reactions of l ife) take p l a ce i n the cytoplasm.

Vacuoles

A vacuole is a space in a cell, su rro u n d e d by a m e m b ra n e a n d conta i n i n g a solution. Plant cells have very large vacuoles, which cont a i n a solution of sugars and oth e r substa nces, cal led cell sap. A fu l l vac u o le p resses out.wards o n the rest of the cell, and h e l ps to kee p it in s ha pe. A n i m a l cells have m u c h s m a ller m e m b ra n e-bo u n d spaces, ca lled

vesicles, which m ay conta i n n utrients o r water.

Chloroplasts

C h loroplasts a re n ever fo u n d i n a n i m a l ce lls, bu t most

of the ce lls i n the green pa rts of pla nts have t h e m . They co nta i n a gre e n colou ring or pigment ca lled ch lorophyll. Ch loro p hyll a bsorbs e n e rgy fro m s u n light, and this e n e rgy is then u sed fo r m a ki n g food fo r the pla nt by photosynthesis (Cha pte r B4).

Ch loro plasts often co nta i n sta rch gra i ns, which have b e e n m a d e by photosynthesis. A n i m a l c e l l s never co nta i n sta rch gra i n s . S o m e a n i m a l cells, h oweve r, do have gra n u les (ti ny grai ns) of a n oth er s u bsta nce s i m i l a r to starch, ca lled glycoge n. These gra n u les a re fou n d i n the cytoplasm, not i ns i d e ch loroplasts.

Nucleus

The n u cleus is w h e re the g e n etic i n fo r m ation is sto red . This h e l ps the cell to m a ke the right s o rts of p roteins. Th e i nfo rmation is kept o n the ch ro mosomes, wh ich a re

i n h e rited fro m t h e o rga n ism's parents. T he c h ro m osomes a re made of DNA.

C h ro m osomes a re very l o n g, but so t h i n that they can not easily be seen even using the electron m i croscope.

H owever, when t h e cell is d ividing, t h ey beco m e short a n d thi c k a n d ca n be seen with a goo d light m i c roscope.

Ta b le B1.01 co m pa res so m e featu res of plant cells and a n i m a l ce lls.

Plant cells

have a cel l u lose cell wall

outs i d e the cell m e m b ra n e have a cel l m e m b ra n e have cytoplasm have a n u cleus

often have ch loroplasts conta i n i n g ch lorophyll

often have l a rge vacuoles conta i n i ng ce l l s a p

often have sta rch gra i ns I mage B1.03 Cellu lose fibres from a plant cell wall. This

picture was taken using a n electron m icroscope (x 50 000).

\\

a re often regu l a r in s h a p e

I A n i m a l cells

h ave n o ce l l wall

h ave a cel l m e m b ra n e h ave cyto p la s m h ave a n u cleus

h ave no ch loro p l a sts

h ave o n ly s m a l l vacuoles n eve r h ave sta rc h

gra i ns; so m eti m es h ave glycogen gra n u les

a re often i r regu l a r i n s h a pe

Ta ble B1.01 A co m parison of plant a n d animal cells.

Bl: Cells

ACTIVITY 81.03

•

Using a m icroscope

Practise using a microscope to look at very