Essential Biology for Cambridge IGCSE® [2 ed.] 0198355149, 9780198355144

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Essential Biology for Cambridge IGCSE® [2 ed.]
 0198355149, 9780198355144

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Essential

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Elliot

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Corbis.

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the

Contents

Introduction

Unit

1

1

Characteristics

of

living

Characteristics

1.2

Classication

Features

of

of

Vertebrates

1.5

Invertebrates

1.6

Ferns

1.7

Dichotomous

Starvation

7.5

Digestion

78

7.6

Teeth

80

living

organisms

7.7

Mouth,

7.8

Small

intestine

and

absorption

84

7.9

Large

intestine

and

intestinal

86

Unit

2

2.1

oesophagus

Structure

Different

2.4

Levels

owering

plants

keys

8

Plant

transport

Transport

Water

8.3

Transpiration

94

of

cells

8.4

Translocation

96

Practice

98

types

of

of

cell

organisation

Movement

Osmosis

Active

in

in

and

plant

out

of

cells

and

animal

cells

transport

Transport

24

9.1

Circulation

100

26

9.2

The

102

Chemical

9.3

Heart

9.4

Blood

9.5

Coronary

9.6

Blood

9.7

Blood

9.8

Lymph

heart

and

molecules

106

heart

disease

(CHD)

108

110

32 in

defence

112

and

for

tissue

uid

114

questions

116

10

Diseases

and

immunity

118

38

biological

molecules

questions

10.1

Disease

10.2

Defence

118

10.3

Aspects

10.4

Controlling

40 against

disease

120

Structure

5.2

Factors

and

action

of

enzymes

enzyme

Practice

Plant

and

pH

6.1

Photosynthesis

6.2

What

6.3

Products

of

Unit

11

Gas

spread

122

of

disease

questions

exchange

124

126

in

humans

128

11.1

The

gas

11.2

Gas

exchange

exchange

11.3

Breathing

11.4

Rate

system

128

needed

132

52

photosynthesis?

photosynthesis

photosynthesis

and

Practice

54

54

for

130

50

nutrition

of

46

the

48

questions

is

immunity

action:

temperature

Enzymes

Practice

46

affecting

of

44

Enzymes

Rate

104

42

5.1

6.4

exercise

vessels

38

DNA

Practice

6

100

36

molecules

tests

humans

28

Unit

Biological

in

34

questions

Biological

questions

9

Practice

Unit

92

22

questions

Practice

5.3

90

20

30

5

systems

uptake

18

Osmosis

Unit

90

8.2

3.2

4.3

88

8.1

28

4.2

questions

16

Diffusion

4.1

disease

14

3.1

4

82

12

organelles

Practice

Unit

stomach

10

Unit

3.4

and

18

2.3

3.3

76

8

Cells

Cell

3

74

deciency

6

questions

2.2

Unit

needs

nutrient

2

Unit

Practice

and

4

Practice

and

energy

2

organisms

1.4

Balancing

7.4 classication

organisms

1.1

1.3

and

7.3

Unit

12

of

breathing

134

136

Respiration

138

56 12.1

Aerobic

12.2

Anaerobic

respiration

138

58 respiration

140

60 Practice

production

depth

questions

questions

142

6.5

Glasshouse

62

6.6

Leaves

6.7

Mineral

requirements

66

13.1

Excretion

144

Practice

questions

68

13.2

Kidney

structure

146

13.3

Kidney

function

148

13.4

Kidney

Unit

Unit

7

7.1

Animal

A

13

Excretion

nutrition

balanced

diet

70 dialysis

Sources

of

nutrients

and

kidney

transplants

150

70 Practice

7.2

144

64

questions

152

72

iii

Contents

Unit

14

Coordination

and

control

14.1

Nervous

14.2

Neurones

14.3

Synapses

14.4

Sense

14.5

The

14.6

Hormones

14.7

Controlling

conditions

14.8

Controlling

body

14.9

Tropic

and

and

in

response

humans

reex

arcs

drugs

organs

eye

154

Unit

the

body

Unit

15

18.1

Variation

232

18.2

Mutations

234

158

18.3

Adaptive

236

160

18.4

Natural

162

18.5

Selective

15.2

Heroin

15.3

Alcohol

questions

and

Practice

Smoking

the

and

misuse

of

health

Asexual

16.2

Flower

16.3

Pollination

16.4

Fertilisation

16.5

The

male

16.6

The

female

16.7

Fertilisation

16.8

Pregnancy

and

sexual

reproduction

and

seed

formation

system

Pyramids

19.3

Shortening

19.4

Nutrient

174

19.5

The

176

19.6

Populations,

178

19.7

Human

Methods

reproductive

and

environment

244

ow

244

of

numbers

and

biomass

246

the

food

chain

248

Control

care

of

of

Sexually

system

implantation

nitrogen

250

cycle

252

communities

and

254

populations

Practice

256

questions

258

20

Biotechnology

and

genetic

engineering

260

184

20.1

Microorganisms

186

20.2

Enzymes

188

20.3

Fermenters

264

190

20.4

Genetic

engineering

266

Practice

questions

268

Human

inuences

and

and

biotechnology

biotechnology

260

262

194 21

on

ecosystems

270

196

and

birth

21.1

Food

21.2

Habitat

supply

270

21.3

Pollution

274

21.4

Water

276

21.5

The

21.6

Acid

21.7

Sustainable

21.8

Sewage

21.9

Endangered

destruction

272

200

202

cycle

birth

greenhouse

effect

278

206

fertility

transmitted

pollution

204

control

rain

280

208

infections

(STIs)

questions

resources

282

210

treatment

and

recycling

284

212

Inheritance

species

286

214 21.10

genes

and

Conservation

288

Practice

290

Chromosomes,

17.2

Protein

17.3

Mitosis

17.4

Meiosis

17.5

Inheritance

17.6

Monohybrid

17.7

Codominance

226

17.8

Sex

228

synthesis

and

genes

inheritance

linkage

questions

DNA

214

17.1

Practice

cycles

198

menstrual

Practice

iv

their

ecosystems

192

hormones

The

17

and

Energy

184

reproductive

Ante-natal

16.12

Unit

242

182

structure

16.11

16.14

Organisms

19.2

Unit

16.13

questions

19.1

180

Reproduction

Sex

19

drugs

questions

16.1

16.9

240

166

Unit

16.10

238

breeding

172

sport

Practice

16

features

selection

174

Drugs

Unit

232

170

Drugs

in

selection

168

responses

15.1

15.4

temperature

and

154

164

in

Variation

156

Unit

Practice

18

questions

216

Alternative

218

Glossary

298

220

Index

307

222

224

230

to

practical

paper

292

Introduction

This

book

is

designed

specically

for

Cambridge

®

IGCSE

Biology

involved

in

planning

match

all

to

0610.

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aspects

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of

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teachers

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syllabus.

to Using

this

book

will

ensure

that

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are

for

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beyond

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IGCSE

level

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avoid

pure

to sciences,

in

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below

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are

applied

courses.

sciences

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effective

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make

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learning

book

as

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the

at

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end

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www.oxfordsecondary.com/

essential-biology-answers

1

1

Characteristics

of

living

1.1

and

classication

organisms

Characteristics

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Biology LEARNING

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Describe

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characteristics

of

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organisms.

These

of characteristics

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of

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the

OUTCOMES

are

often

described

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life

processes:

organisms

nutrition,

and

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movement,

growth,

excretion,

sensitivity

reproduction.

Nutrition

Nutrition

needed

is

the

for

growth,

compounds

proteins

energy

nutrition

for

from

complex

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energy

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involves

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ions).

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in

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carbon

these

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simple

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They

sugars

need

proteins.

food

like

energy

ingestion.

then

plants,

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and

The

assimilated

digested

organisms

chemical

nutrients,

needed

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for

respiration

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by

nutrients.

have

food

cells

absorbed

is

is

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to

eat

digested,

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egested

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absorbed

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orga ns,

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carbon

dioxide

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energy

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or

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blood

glucose

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mineral

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areas

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2

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and

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size

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size.

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in

organisms

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metabolism.

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Movement Organisms

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to involves

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other

organisms

next

parent

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to

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generation.

each

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The

animals

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1722

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bases

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closely

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a

once

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has

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is

nam e

it

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acid

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similarities

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species

4.3).

animals.

Each

this:

a

used

be

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proteins

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many

with

more

the

(see

acids.

are

for

least

acids

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there

animals.

organisms.

amino

sequences

different

are

to

sequences

sequences

protein

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likely

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haemoglobin

three

protein.

accurate

of

nam es.

of

can There

TIP

rely

evolutionary

organisms

and

1.2.1.

(yellow)

for

there

related

are

SUMMARY

QUESTIONS

1

complete

they

be.

Copy

and

sentences

using

fertile

the

these

genus

words:

shared

humerus

trivial

1

classication

humerus

radius

binomial

breed

2 ulna

The

system

organisms

of

putting

into

groups

is

called

5

.

The

system

is

4

used

for

naming

Each

organism

organisms.

3 radius

has

two

names.

bat

The (flying)

rst

is

called

the

ulna

name

and

the

name.

second

A

is

species

the

is

a

humerus

very

similar

that

can

group

of

individuals

ulna

together

produce

radius

and

offspring.

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1

classify

living

things

on

the

5

basis

4 2

of

their

features.

3

2

human

a

Explain

the

term

binomial

1 (manipulating)

system

2 3

4

5

b

Find

the

scientic

names

seal

of

(swimming)

Figure

1.2.1

The

variations

on

a

pentadactyl

two

two

limb.

plant

animal

mentioned

and KEY

write

The

binomial

system

uses

two

names

for

each

species:

A

this

topic

alongside

name

species

that

is

breed

and

a

the

group

together

trivial

of

to

Classication

4

The

is

individuals,

produce

important

In

the

living

fertile

in

the

same

habitat

means

of

of

bases

in

18th

century,

Linnaeus

worked

binomial

system

living

offspring.

in

the

study

of

DNA

is

used

as

things.

life

Carl

and

out

of

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work

the

naming

out

and

about

then

evolution. write

sequence

names.

name.

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common

the 3

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2

in

them

and

not

POINTS

their

1

species

species

a

more

accurate

your

a

brief

own

biography

in

words.

classication.

5

1.3

Features

The LEARNING

cells

of

all

State

living



List

the

features

of

cells

structures

in

enzymes

organisms

the

organisms

organisms

are

made

up

of

a

cell

membrane,

OUTCOMES cytoplasm



living

of

features

organisms

into

used

one

to

of

place

the

ve

kingdoms.

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that

you

can

and

Biologists

are

large

cell

see

are

in

the

of

carry

cell.

that

as

out

processes

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of

There

same

are

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synthesis

simple

do

as

to

of

small

and

structure

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all

a

other

eukaryotic.

classify

all

because

kingdoms,

cell

not

cells

example,

kingdom

ve

a

share

For

cytoplasm

respiration.

known

organisms

the

the

bacteria

are

kingdoms.

as

have

cells.

cells

in

protein

such

Bacteria

these

into

structure.

that

present

prokaryotic

features

known

have

1.3.1.

as

and

together

cell

also

in

Figure

nuclei

groups

same

types

known

have

classied

the

stored

involved

main

use

They

ribosomes

are

two

organisms

ve

DNA.

called

that

are

nucleus

and

them

into

bacteria

they

including

have

the

plant

wall

food

kingdom

and

the

animal

kingdom.

cell

reser ve

membrane

Plant

kingdom

plants

are

Plants

are

multicellular

organisms.

The

bodies

of

roots

spread

out

ribosomes

through

flagellum

not

the

compact

soil

to

like

gain

those

water

of

and

animals.

salts

and

Their

their

stems

grow

many

plasmid

leaves

DNA

of

Figure

1.3.1

A

typical

to

roots

absorb

and

light.

stems.

Growth

This

occurs

kingdom

in

special

includes

places

mosses

such

and

as

ferns,

the

tips

which

bacterium.

do

not

reproduce

conifers

out

and

the

using

photosynthesis,

chloroplasts

full

seeds,

owering

of

using

and

plants.

light

to

chlorophyll,

the

All

seed-bearing

plants

make

have

their

cellulose

cell

plants,

such

chlorophyll

own

walls

food.

and

a

as

and

Plant

large

carry

cells

have

sap-lled

vacuole.

Animal

animals

kingdom

have

throughout

their

not

food

have

nervous

Animals

much

the

by

more

body.

eating

cell

walls,

systems

are

also

compact

Animals

plants

do

which

bodies

not

and/or

chloroplasts

multicellular

or

coordinate

than

organisms.

plants.

photosynthesise

other

animals.

large

their

Growth

and

Animal

vacuoles.

All

responses

to

Most

occurs

obtain

cells

animals

stimuli

do

have

and

their

Prokaryote

you

Staphylococcus,

on

the

human

a

type

skin

of

bacterium

can

see

kingdom

in

Figure

are

rod-shaped.

are

a

Bacteria

1.3.1.

Many

exist

have

Some

in

a

simple

bacteria

short

chains

cell

are

of

structure

spherical

cells.

that

and

Most

some

bacteria

found

few

micrometres

in

length

and

can

only

be

seen

with

light

(×4000).

and

electron

microscopes.

(One

micrometre

is

one-thousandth

of

a

millimetre.)

Bacterial

species

There

is

Bacteria

called

from

cells

are

no

are

also

nucleus,

often

animal

mould,

Rhizopus

nigricans,

is

a

and

6

black

structures

contain

spores.

just

a

by

by

loop

additional

(see

page

plant

Some

cell

of

cells

as

of

The

they

have

The

cells

of

some

bacterial

capsules.

DNA

loops

267).

bacteria

walls.

slime

within

DNA

the

structure

do

not

cytoplasm.

inside

of

have

extensions

their

cytoplasm

bacteria

differs

chloroplasts

called

or

agella

fungus.

(singular: The

have

plasmids

mitochondria. Bread

surrounded

surrounded

agellum)

for

moving

through

water

or

other

uids.

tnemelppuS

movement.

tnemelppuS

Protoctists

This

are

in

classied

four

and

some

parasitic

and

are

this

kingdoms.

are

commonly

All

they

vary

in

kingdom

as

is

as

size

from

plenty

do

light

not

cells

they

any

are

of

many

include

‘forests’

to

in

the

are

which

other

unicellular

organisms

which

classied

organisms

can

in

organisms

Plasmodium,

Algae

unicellular

of

nuclei;

protoctists

underwater

so

group

belong

with

including

malaria.

tiny

form

of

diverse

Unicellular

causes

that

a

they

have

protozoans

that

seaweeds

there

contains

protoctists

multicellular .

known

organism

giant

where

kingdom

as

the

is

kelps

parts

of

the

protoctists

which

the

sea

photosynthesise. Paramecium,

a

single-celled

protoctist

(×206).

genetic

Fungi

kingdom

Fungi

are

visible

under

a

light

microscope.

Many

are material

also

visible

to

the

naked

eye.

Most

fungi

are

multicellular

although sur face

yeasts

are

single-celled.

Each

cell

has

a

nucleus

and

a

cell

wall

which coat

is

made

out

chlorophyll

The

main

its

chitin,

and

body

network

food

not

cannot

fungus

branching

of

of

source,

of

cellulose

carry

is

out

called

threads

releasing

in

plants.

Fungi

do

not

proteins

have

photosynthesis.

the

or

as

mycelium.

hyphae

enzymes

It

which

which

consists

grow

digest

of

over

the

a

the

food

surface

outside

Figure

the

fungus.

The

digested

food

is

then

absorbed

by

the

Viruses

Fungi

reproduce

Most

fungi

are

by

making

spores

saprotrophs,

that

which

can

be

means

carried

they

feed

by

the

on

wind.

dead

matter,

but

some

are

are

causes

in

or

of

decaying

1.3.2

Structure

of

a

human

virus.

hyphae.

inuenza

size.

a

extremely

(One

is

small.

about

nanometre

micrometre.)

120

is

Viruses

This

virus

that

nanometres

one-thousandth

are

visible

only

parasites under

an

electron

microscope.

Viruses

are

or

RNA)

of

a

not

cells.

surrounded

few

genes

that

They

by

a

are

particles

protein

code

for

the

made

coat.

The

proteins

up

of

genetic

that

genetic

material

material

form

the

is

coat

(DNA

composed

and

maybe KEY

other

cells

proteins

of

that

another

help

it

organism

reproduce.

(the

host)

Viruses

in

order

are

to

parasites

multiply .

that

Viruses

enter

take

over 1

the

host

cell

and

direct

it

to

make

new

viruses.

Viruses

are

not

POINTS

the

The

cells

have

in

any

in

the

of

the

kingdoms

described

here.

All

the

organisms

do

not

have

of

kingdoms

have

cells.

Viruses

cells

in

a

different

way.

Their

classication

is

based

and

so

material

and

protein

coat

that

they

on

the

type

There

are

Prokaryotes

under

The

plant

species

with

features

kingdom

that

are

animals.

tnemelppuS

Compare

a

Make

a

present

in

all

cells.

and

familiar

Y ou

the

to

should

animal

us.

kingdom

Make

include

a

table

similarities

contain

to

Why

the

table

6

How

are

Plant,

Protoctist

cells

be

without

seen

only

microscope.

organisms

with

as

well

eukaryoltic

structure

of

bacterial

cells

with

the

to

compare

the

features

of

the

as

cells

ve

viruses

not

classied

in

one

of

the

ve

plants

5

Fungi

called

differences.

of

a

nanometres

are

there

in

a

group

many

of

features

cells.

are

made

hyphae.

the

food

up

of

These

supply,

threads

grow

digest

it

plant. and

then

absorb

it.

kingdoms.

kingdoms?

Viruses

an

can

electron

are many

a

many

compare

6

5

can

light

externally

4

have

are

over

3

They

Protoctists

of

2

kingdoms:

QUESTIONS

4

the

ve

Prokaryote,

Fungi.

nuclei.

State

DNA.

have.

3

1

and

of

and

SUMMARY

organisms

cell

are

Animal, genetic

a

classied

2 classied

living

cytoplasm,

membrane

ve

all

classied

tnemelppuS

Viruses

not

be

seen

only

microscope.

cells

but

a

few

under

They

genes

metre? inside

a

protein

coat.

7

1.4

Vertebrates

Animals LEARNING

that

have

vertebrates.



Dene



Describe

the

term

vertebrate

bone

or

some

of

the

ve

vertebrates

external

main

using

visible,

characteristic

Describe

how

vertebrates

All

vertebral

vertebrates

column

cartilage.

They

invertebrates

all

that

have

an

or

backbone

belong

share

to

internal

are

the

common

skeleton

called

phylum

features

made

chordata

with

the

of

either

which

includes

vertebrates.

groups

There

are

ve

main

groups

of

vertebrates:

features sh,



a

OUTCOMES

amphibians,

reptiles,

birds

and

mammals.

these

are

adapted

to

Fish their

environment

Most

sh

as

the

of

time.

Typically,

This

dace

has

ns,

tail

and

a

their



adaptations

for

have

gills.

herring,

sh,

sound

and

eyes

They

Their

shark,

the

can

and

skin

and

a

is

there

out

of

have

lateral

line

and

of

for

for

with

some

for

species,

varying

swimming

detecting

oxygen

from

scales.

such

lengths

and

for

pressure

the

water

Examples

include

cod.

vertebrates

although

are

water

ns

dissolved

covered

classes

limbs,

but

survive

breathe

catsh

other

four

permanently,

that

streamlined

water.

Unlike

some

have

have

ears

evolved

for

into

detecting

legless

forms

streamlined

like shape

in

water

are

They

changes

tuna,

in

skipper,

sh

balance.

using

live

mud

snakes

and

some

lizards.

swimming.

Amphibians

These

vertebrates

amphibians

is

external

inside

a

hatch

into

On

are

have

on

the

body).

adult

water,

amphibians

they

sperm

swimming

in

smooth,

land,

because

female

land,

they

live

and

eggs

can

frogs,

is

which

amphibians

skin.

to

are

Development

tadpoles

they

include

moist

return

toads

external:

gills

using

through

and

to

released

have

breathe

breathe

Although

water

most

breed.

into

the

for

water

fertilised

(not

eggs

breathing.

lungs,

their

Fertilisation

the

but

skin.

when

Examples

of

salamanders.

Reptiles The

bright

thought

for

the

to

red

eyes

startle

frog

to

of

this

tree

predators,

frog

giving

are

time

Reptiles

have

dry,

scaly

skin

to

cut

down

water

loss.

They

can

live

in

escape.

dry

regions

Fertilisation

as

takes

development

shells

air .

they

which

is

not

place

them

lizards,

have

inside

external

stop

Crocodiles,

do

as

the

they

from

to

return

female’s

lay

eggs

drying

snakes,

to

out.

turtles

water

body.

with

breed.

However ,

leathery,

Reptiles

and

to

have

tortoises

waterproof

lungs

are

all

to

breathe

reptiles.

Birds

Birds

of

Birds

with

American

8

crocodile,

Crocodylus

acutus

have

them

feathers

are

have

able

no

different

and

to

teeth

types

y

but

of

their

but

front

some,

different

food.

limbs

like

are

modied

penguins

species

have

and

beaks

as

wings.

ostriches,

adapted

Most

cannot.

to

deal

Fertilisation

is

eggs

which

are

Birds

are

able

to

even

internal

protected

homeothermic

regulate

though

include

and

their

the

hawks,

development

by

eagles,

external

temperature.

temperature

sparrows,

as

the

females

lay

shells.

(warm-blooded).

body

outside

hard

is

This

They

can

changes.

parrots

and

means

keep

that

it

they

are

constant

Examples

of

birds

starlings.

Mammals

Mammals

internal

they

are

young

ones

Like

are

and

born

on

like

is

vertebrates

milk

that

development.

already

from

whales

birds,

internal

the

so

well

mammals

dolphins,

are

temperature.

also

or

All

lungs

bats,

Fertilisation

in

a

mammals

mammals,

for

is

womb

and

suckle

their

even

Grey

Heron,

long

beak

Ardea

for

are

all

maintaining

dolphins,

bears,

a

STUD Y

constant

lemurs

learn

ve

this

DID has

hands

and

feet

adapted

to

living

in

a

and

complete

the

sentences

using

these

ve

classes

wings

breed

scaly

y

sh

moist

fur

land

water

are

different

group

in

groups

called

and

have

skin

have

front

skin

limbs

have

and

or

feathers

of

vertebrate.

Sharks

2

a

the

learn

rare

spend

all

their

hair

that

are

most

and

and

lay

return

their

modied

are

give

and

able

birth

to

to

time

in

species

are

.

of

their

golden

were

an

lmed

Blood.

frogs

were

for

BBC

After

Sir

TV

the

moved

David

series

Life

lming

them

from

to

a

zoo

disease,

to

habitat

and

pollution.

Birds

They

Mammals

in

Panamanian

.

.

.

young

extinction.

.

to

on

form

to

to

water

eggs

with

belong

also

have

advanced KEY

state

you

KNOW?

amphibian

Cold

loss Amphibians

have

these

to pic.

protect

Reptiles

you

of

Mak ing

help

Attenborough’s

the

the

help

words: frogs

to

a

QUESTIONS

development

There

to

featur es

will

YOU

Some

Copy

table

the

threatened

1

with

trees.

Many

SUMMARY

bird

TIP

grou ps.

table

chimpanzee

a

and

mammals.

A



sh.

aquatic

Mak e wolves

cinerea

catching

breathing.

homeothermic,

Leopards,

fur.

develop

Female

glands.

use

hair

young

developed.

mammary

and

have

The

POINTS

.

State

the

features

that

are

exhibited

by

all

vertebrates.

1

Vertebrates

have b

Name

c

Give

the

ve

groups

of

a

are

animals

vertebral

column

that

or

vertebrates. backbone.

an

example

of

each

group.

2 3

T o

which

group

of

vertebrates

does

each

of

the

following

The

into

a

turtle

b

bat

f

hawk

g

shark

c

whale

d

salamander

e

vertebrates

are

divided

belong? ve

groups:

snake sh,

amphibians,

birds

and

reptiles,

mammals.

9

1.5

Invertebrates

Invertebrates LEARNING

are

animals

that

do

not

have

a

vertebral

column

or

OUTCOMES backbone.



Describe

the

external

features Arthropods

of

contains



Describe

of

is

the

largest

of

the

groups

in

the

animal

kingdom

as

it

arthropods

the

insects,

features

segmented

and

myriapods

used

body,

number

an

of

external

species.

skeleton

Each

arthropod

(exoskeleton)

species

and

has

jointed

a

legs.

hard

to

classify

them

exoskeleton

allows

arthropods

to

live

on

dry

land.

When

that they

are

largest

crustaceans, The

arachnids

the

grow

too

big

for

their

exoskeleton,

they

moult

and

grow

a

new

into one.

Some

moult

all

through

their

lives,

others

moult

only

during

the

groups early



Describe

these

their

how

groups

the

are

animals

adapted

stages

of

their

life.

in

Four

to

of

the

different

types

of

arthropod

are:

environment crustaceans,

myriapods,

insects

and

arachnids

Crustaceans

Crustaceans

and

abdomen.

hard

two

ve

and

crabs

of

Woodlouse

detecting

or

slater.

Notice

its

antennae

of

all

are

and

so

the

made

bodies

the

are.

and

crab,

Grapsus

feeding

grapsus.

and

exoskeleton

against

in

They

they

(also

do

crabs,

eyes.

breathe

water.

Some

use

shrimps,

as

They

water

have

a

very

have

between

gills

live

on

slaters)

for

craysh

provides

Crustaceans

using

crabs

known

not

that

predators.

(head-thorax)

land

and

breeding.

and

but

some

return

land

Examples

lobsters.

Notice

centipedes

up

of

many

not

divided

Centipedes

total

number

Centipedes

paralyse

have

slow-moving

two

and

into

have

of

are

millipedes.

separate

one

legs

pair

They

pairs

regions

of

depends

fast-moving

their

herbivores.

the

have

long

segments.

legs

upon

such

on

how

carnivores.

as

each

the

many

They

thorax

segment

segments

have

powerful

prey.

of

legs

You

can

on

each

often

body

nd

segment.

them

They

feeding

in

are

leaf

litter.

defence.

Millipede

moving

10

as

cephalothorax

compound

legs.

live

include

are

can

Millipedes

for

and

of

Woodlice

exceptions

are

that

jaws

claws

pairs

breed.

abdomen.

there

lightfoot

chalky

a

Myriapods

Their

large

a

into

for

stimuli.

bodies

its

have

crustaceans

to

divided

protection

antennae

crustaceans

These

Sally

body

Many

twenty

water

a

effective

pairs

and

Nearly

to

have



with

its

efciently.

many

legs

for

Centipede



a

fast-moving

carnivore.

Insects

Insects

and

On

have

bodies

that

are

divided

into

three

parts:

head,

thorax

abdomen.

the

two

thorax

pairs

of

compound

They

eyes

breathe

called

there

wings.

are

three

They

that

are

through

pairs

have

one

made

holes

in

of

of

legs

pair

of

many

the

and

tiny

sides

many

antennae

of

species

on

individual

the

thorax

the

have

head

and

components.

and

abdomen

spiracles

Monarch

Insects

have

colonised

most

habitats

in

the

world,

although

Notice

are

very

few

species

that

live

in

the

sea.

T wo

reasons

why

they

are

on

that

them

stops

This

is

the

beetles,

bees

is

that

losing

largest

ies,

and

land

group

locusts,

they

too

are

much

within

covered

water,

the

cockroaches,

by

and

a

waterproof

they

arthropods.

dragonies,

can

its

wings

Danaus

for

its

plexippus.

migration

over

so long

successful

buttery,

there

distances.

cuticle

y!

Examples

include

butteries,

moths,

wasps.

Arachnids

These

and

arthropods

have

bodies

divided

into

two

parts,

the

cephalothorax

abdomen.

Arachnids

antennae

They

have

but

paralyse

silken

webs

four

do

their

with

pairs

have

prey

their

of

legs

several

with

and

pairs

poison

spinnerets.

no

of

wings.

simple,

fangs.

They

not

Spiders

Scorpions,

have

no

compound,

are

ticks

able

and

eyes.

to

mites

weave

are

also T arantula

classied

as

arachnids.

paralyse

SUMMARY

QUESTIONS

1

four

a

Name

b

List

c

State

the

groups

key

of

features

ways

in

a

large

spider

with

venom

to

prey.

arthropod.

of

insects. DID

three



its

which

arachnids

look

different

YOU

KNOW?

from There

are

over

a

million

known

insects.

2

3

Distinguish

between

a

centipedes

b

crustaceans

Describe

the

successfully

4

Copy

and

and

the

and

basis

of

visible

features:

altogether ,

of

insects

that

adapt

them

for

of

the

knows.

crustaceans

insects

arachnids

KEY

POINTS

of Arthropods

are

segmented

legs

an

regions

number

of

one

table:

animals

body

no

living

1

pairs

but

arachnids

myriapods

number

the

land.

complete

feature

on

millipedes

features

on

following

pairs

2

of

with

jointed

legs

and

exoskeleton.

Arthropods

different

are

classied

groups

into

including:

antennae crustaceans,

type

of

myriapods,

eyes insects

and

arachnids

wings

11

1.6

Ferns

and

owering

plants

tnemelppuS

Like LEARNING



State

that

owering

making



State

and

plants

the

owering



ferns

non-

reproduce

by

the

between

plants,

ferns

green

in

These

chloroplasts

absorbs

made

spores

Describe

all

and

owering

plants

are

multicellular.

They

are

OUTCOMES

main

features

of

plants

Both

of

differences

dicotyledons

light

of

and

mineral

adapted

monocotyledons

for

tubes.

substances

and

because

many

contain

of

the

their

green

photosynthesis.

cells

contain

pigment

Each

cell

is

chloroplasts.

chlorophyll,

surrounded

by

which

a

cell

wall

cellulose.

ferns

tiny

and

colour

owering

These

salts,

such

to

live

are

and

as

on

plants

called

have

phloem

sugars.

transport

xylem

vessels,

tubes,

Both

ferns

which

and

systems

which

consisting

carry

transport

owering

water

dissolved

plants

are

well

land.

Ferns

Ferns

on

a

are

land.

waxy

them

to

left.

quite

supports

grow

If

fern

Dryopteris

lix-mas

you

will

Ferns

a

look

under

Features

Flowering

by

means

inside

the

Shoots apical

of

and

are

helps

the

at

leaves

that

carried

by

have

true

which

within

the

tree

stem

ferns

and

the

the

of

several

ferns

at

a

in

do

have

a

life

have

Most

of

photograph

some

thick

metres.

not

that

stem

Many

produce

times

of

microscopic

form

loss.

the

for

leaves

that

ferns

rhizome.

certain

to

Their

including

that

called

adapted

water

species

habitats

release

wind

well

leaves.

reduce

ferns

heights

of

make

of

plants,

and

to

different

owering

the

become

roots

those

many

leaves

have

underground

owers

ovary

in

owering

plants

of

of

and

are

which

largest

thick

structures

spores

that

stems,

resembling

live

crown

a

plants

strong

cuticle)

The

conifers

see

These

(the

dry.

of

have

leaves

from

Unlike

The

group

layer

have

the

are

a

Ferns

new

the

seeds.

year

you

spores.

plants.

plants

stems,

make

roots

and

seeds.

The

leaves.

seeds

They

are

reproduce

produced

ower.

roots

bud

The

up

shoot

of

a

is

stem

the

part

bearing

of

the

plant

leaves,

buds

above

and

ground.

owers.

The

The

shoot

apical

is

made

bud

is

leaf

stem

side

buds

side

main

root

Figure

1.6.1

root

root

cap

Structure

of

a

typical

dicotyledonous

plant. Magnolia

12

is

a

dicotyledon.

Maize,

Zea

mays,

is

a

monocotyledon.

part

where

the

stem

grows

new

leaves.

The

stem

supports

the clusters

structures

receive

The

which

stem

food

the

roots

are

anchor

blown

from

shoot,

are

the

by

soil

to

of

in

wind.

Topic

Dicotyledons

of

(see

out

to

of

owering

the

6.6)

also

the

the

not

It

soil

the

up

to

such

found

contain

they

of

flowers

can

owers

the

as

in

leaves

the

a

below

water

it

ground.

from

and

and

roots.

chlorophyll.

prevent

absorb

that

holds

plant,

and

so

place.

plants

do

ground

Roots

leaves

take

from

parts

they

the

Topic

water

since

rmly

(see

air

other

parts

the

spaces

pollination

white

plant

over

and

transport

leaves

usually

the

the

light

and

enables

allows

from

Roots

the

adequate

position

The

of

tnemelppuS

the

Roots

being

mineral

ions

8.2).

and

monocotyledons

leaf

Flowering

plants

dicotyledons

can

and

be

divided

into

two

main

groups:

monocotyledons Figure

1.6.2

Structure

of

a

typical

monocotyledon

Dicotyledons

look

like

Their

leaves

are

parts

of

ower,

often

the

plant

broad

at

with

the

a

bottom

network

of

of

the

opposite

branching

veins.

The

STUD Y

are

in

the

multiples

cotyledons

Grasses

are

of

example

four

(seed

and

for

or

leaves)

cereals,

like

ve

in

the

the

in

a

male

each

parts

ower.

known

as

Dicotyledons

have

two

Be

plant

at

the

bottom

of

page

and

12

of

have

most

long,

monocotyledons

narrow

leaves.

have

Other

parallel

veins.

Grasses

monocotyledons

have

a

variety

ower

inside

are

in

each

of

shapes,

multiples

such

of

as

three.

those

of

palm

trees.

Monocotyledons

The

have

parts

one

of

1

complete

and

the

parallel

sentences

two

using

these

words:

Flowering

plants

multicellular

narrow

network

are

with

plants

veins.

They

often

have

Dicotyledons

wall;

have

that

often

have

have

with

some

inside

a

the

names

of

ve

inside

dicotyledonous

that

grow

key

for

the

ten

plants

Make

a

table

of

differences

between

is

leaves

each

plants

where

you

in

ferns

and

and

have

their

one

seeds

and

seed.

you

have

contain

Monocotyledons

with

parallel

veins.

ve

live.

Dicotyledons

have

two

Construct

and

broad

leaves

identied.

with

3

in

stems

cotyledons dichotomous

cell

cellulose

the

3 plants

a

of

leaves

monocotyledonous

by

chloroplasts.

cotyledon

leaves

cotyledons

are

each

those

cotyledon They



one

2

a

2.1)

(from

owering

and

Monocotyledons

Find

in

POINTS

cell broad

2

(T opic

16).

surrounded

veins.

and

differ ences

cotyledon

1

seed.

plan ts

Note

repro duct ion

the

KEY

QUESTIONS

leaves

differ ences

seed.

SUMMARY

Copy

the

and

leaves

Unit with

the

struct ure

and cereals

of

owe ring

anim als.

learn

monocotyledons.

leaves

awar e

be tw een

cell The

TIP

stamens,

seed.

maize

plant.

page.

owering

plants.

a

network

of

branching

veins.

4

Ferns

to

life

xylem

are

on

plants

land.

and

means

of

well

They

adapted

have

reproduce

by

spores.

13

1.7

Dichotomous

Sorting LEARNING

Construct

and

use

identify

dichotomous

keys

to



Identify

in

a

name

book

of

a

until

plant

you

or

animal

found

the

you

right

a

lot

of

time

and

and

for

through

that

the

would

effort.

features

of start

useful

look

However,

animals

external

animals

could

one.

identify take

and

the

simple pictures

plants

out

OUTCOMES

To •

things

keys

plants

making

a

that

here

are

key

has

it

got

yes

no legs?

has

a

it

got

shell?

snail

has

it

no 6

has

it

earthworm

got

yes legs?

got

yes

no 2

pairs

of

wings?

Figure

1.7.1

Scientists

A

use

key

and

key

has

the

you

answer

to

Use

out

1

2

3

4

Figure

14

1.7.2

Five

invertebrates.

numbered

‘yes’

to

the

means

number

nd

another

above

at

a

a

of

key

‘no’

question

identify

numbered

or

steps

on



this

or

and

an

rst

to

to

2

Has

no

Go

to

4

Has

6

legs

Go

to

3

Has

8

legs

Spider

Has

1

pair

Has

2

pairs

Has

a

Has

no

shell

shell

wings

see

At

things.

or

it

Snail

Earthworm

step

at

the

the

in

Use

branching

the

the

key

branching

beginning

statement.

the

same

works

questions

Wasp

in

This

and

takes

branching

you

key

left.

but

Housey

them

each

Start

identify

the

Go

of

the

key,

legs

wings

can

question

to

living

two.

page.

Has

of

identify

identication.

answer

legs

to

you

rst

below

the

key.

statement.

the

to

into

animals

key

from

beginning

to

the

keys

dividing

question

or

differently

the

dichotomous

dichotomous

Dichotomous

A

branching

at

in

animals.

the

each

same

stage.

It

is

way.

set

Start

PRACTICAL

STUD Y Making

Now

try

a

leaf

making

a

key

of

your

Whe n

own.

‘size ’ 1

T ake

six

different

leaves

and

label

them

A

to

Put

the

six

leaves

3

Think

of

a

4

Write

down

5

Now

6

Write

7

Carry

question

think

the

up

these

on

out

in

front

that

will

of

you.

divide

into

two

Write

out

questions

you

your

to

divide

each

group

into

come

to

the

last

pair

of

as

a

branching

key

or

as

a

numbered

the

are

key.

making

a

livin g

muc h

featu re

thing s

in

size.

TIP

exam ination ,

usua lly

rather

key

of

these

pond

animals

below.

it

than

How ever ,

aske d

is

to

easies t

bran chin g damsel

fly

keys

num bered

if

key are

try

key ,

leaves.

keys .

Now

a

good

two.

STUD Y

key

animals

as

so

keys

Pond

a

question.

In

8

not

groups.

down.

until

use

vary

them

mak ing

is

F .

to

2

TIP

key

bran ched

you

mak e

to

a

mak e

key.

Y ou

key

a

may

lar va

also

be

freshwater

aske d

featur es

shrimp

for

that

mak ing

to

iden tify

are

suita ble

keys .

water

beetle

KEY

1

POINTS

Dichotomous

keys

are

used

water

to

scorpion

identify

plants

pond

snail

2

A

and

organisms,

such

as

animals.

dichotomous

key

includes

ramshorn

a

snail

series

or

of

paired

questions

identication. Figure

1.7.3

Pond

1

When

She

a

made

some

laboratory.

Give

b

Make

2

Write

an

Her

each

either

a

could

down

use

an

drawings

drawings

a

a

branching

the

features

a

pages

to

reptile,

8

and

identify

island

and

are

9

each

discovered

brought

on

an

dividing

into

two.

key

to

identify

or

as

to

of

a

would

bird

them

the

some

back

to

insects.

the

right.

name.

key

that

a

she

shown

suitable

dichotomous

as

on

visited

insect

amphibian,

photos

to

QUESTIONS

scientist

a

lead

Dichotomous

animals.

means

SUMMARY

statements

which

and

help

a

enable

Present

you

mammal.

you.)

these

them.

numbered

Now

to

classify

(Y ou

make

vertebrate

your

key

key.

a

a

sh,

can

use

key

that

the

you

groups.

15

PRACTICE

1

Which

QUESTIONS

process

organisms

is

that

carried

live

in

a

out

by

all

the

6

forest?

Which

is

not

associated

with

excretion

from

a

mammal?

A

moulting

A

exhaling

B

photosynthesis

B

release

C

pollination

C

removal

D

respiration

carbon

of

heat

of

dioxide

from

toxic

from

the

waste

the

lungs

skin

products

of

metabolism

D (Paper

1)

removal

of

water

that

the

body

does

not

[1] need

2

What

are

characteristics

of

all

organisms? (Paper

A

excretion

and

respiration

B

ingestion

and

growth

C

photosynthesis

D

respiration

7

The

2)

evolutionary

species

3

(Paper

1)

Which

group

and

and

[1]

are

relationships

shown

in

the

between

ve

diagram.

egestion

V

photosynthesis

[1]

of

animals

includes

those

with

W

a X

segmented

body,

an

exoskeleton

and

jointed

Y

limbs?

A

amphibians

B

arthropods

C

reptiles

D

vertebrates

Z

(Paper

1)

Which

group

time

[1]

An 4

of

vertebrate

includes

those

analysis

DNA dry

scaly

skin

and

A

amphibians

four

of

base

sequences

from

the

with

of

these

ve

species

was

carried

out.

legs?

Which

two

species

will

have

the

most

similar

sequences?

B

sh

C

mammals

D

reptiles

(Paper

5

Each

and

1)

cell

[1]

is

surrounded

contains

by

a

cell

membrane

table

Which

from

A

B

C

D

ve

shows

organisms

other

the

in

all

features

features

ve

of

shown

cells.

by

B

W

W

C

X

and

Z

D

Y

and

Z

and

(Paper

2)

Which

is

feature

X

[1]

an

example

used

in

of

a

classifying

morphological

vertebrates?

A

egg

laying

B

type

of

body

C

type

of

diet

D

pattern

kingdoms?

enzymes

nucleus









































2)

and

cells

chloroplasts

(Paper

16

shows

row

V

cytoplasm.

8

The

A

DNA

ribosomes

[1]

(Paper

2)

of

covering

bones

in

the

front

limb

[1]

9

The

to

drawings

the

same

show

ve

arthropods

(not

drawn

11

(a)

scale).

Five

of

their

the

features

denitions

Match

each

denition

of

by

of

are

the

A

movement

B

respiration

D

a

things

and

below.

features

pairing

C

living

listed

with

letter

its

and

a

number.

sensitivity

nutrition

E

growth

Denitions

A

B

1

A

permanent

2

The

to

increase

chemical

break

release

reactions

down

of

in

size

that

nutrient

occur

in

molecules

cells

with

the

energy

C

3

An

action

change

4

The

by

of

an

ability

to

environment

5

The

taking

Make

a

table

to

compare

the

features

or

detect

and

in

environment (a)

organism

position

of

cause

changes

respond

materials

for

to

a

place

energy,

to

in

the

them

from

the

growth

and

of development

the

ve

arthropods

that

you

see

in

[3]

the

(b) drawings.

Explain

what

is

meant

by

the

term

species

[6]

[2] (b)

Use

in

the

your

features

table

arthropods.

to

that

you

make

(The

key

a

have

key

may

to

be

used

the

(Paper

ve

either

a 12

branching

key

or

a

numbered

3)

key.)

The

drawings

owering

(Paper

10

Copy

plant.

leaves

They

are

from

not

three

drawn

species

to

of

scale.

3)

and

crosses

show

show

[6]

to

the

complete

indicate

features

feature

sh

the

table

whether

or

using

the

ticks

four

and

groups

not.

amphibian

bird

mammal

backbone

ns

A

C

B

wings

(a)

(i)

Identify

the

group

of

owering

plants

fur to

which

each

species

belongs.

homeothermic (ii)

State

the

make (Paper

3)

features

your

that

you

used

to

identications.

[5]

[5]

(b)

List

ve

would

key

to

features

be

shown

useful

identify

in

by

the

devising

species

of

a

leaves

that

dichotomous

owering

plants.

[5]

(c)

(i)

State

ferns

three

have

structural

in

features

common

with

that

owering

plants.

(ii)

Explain

walls,

[3]

why

are

kingdom

(Paper

fungi,

not

with

which

classied

plants.

in

have

the

cell

same

[3]

4)

17

2

Cells

2.1

Structure

of

cells

Cells LEARNING

OUTCOMES

Cells •

Describe

the

structures

Very plant

and

under



a

animal

light

Describe

the

cells

are

the

small

building

blocks

that

as

microscope

differences

small

living

things

such

as

bacteria

An

insect

for

certain

such

as

how

a

y

many

may

contain

cells

there

millions

are

in

animal

plant

State

between

the

functions

of

organisms.

only

one

cell.

a

of

cells.

human

No

being

one



knows

estimates

10

×

12

10

and

50

×

10

seen

under

cells

Plant

cells

the

cell

membrane

the

cell

cell

living

of

cells

structures

light

all

and

Animal



up

made

in 12

between

are

seen

vary structure

make

of

microscope

and

in

the

in

the

animal

wall

plant

cell nucleus

cytoplasm

cell

membrane nucleolus

Figure

2.1.1

A

cheek

cell

(stained

nucleolus with

a

blue

dye).

nucleus

Figure

2.1.2

A

palisade

cell

Differences

Liver

cells

magnied

by

The

differences

this

table.

between

between

plant

plant

and

and

from

animal

animal

cells

are

mesophyll

a

leaf.

cells

summarised

in

×300.

feature

cellulose

cell

plant

wall

cell

animal

present

cell

absent

present; cell

STUD Y

membrane

present surrounded

TIP

permanent

Whe n

you

have

differ ence s

plan t

mak

e

state

wall

shape

determined

by

the

cell shapes

be tw een

shape

wall;

and

sure

of

anim al

you

cells ,

write

shapes

can

abou t

bo th

chloroplasts

nearly

spherical,

like

cylindrical

or

present

in

some

vary

as

there

be cell

wall

box-

cells

absent

cell. large

vacuole

permanent

vacuole

in

containing

present

nucleus

side

the

cytoplasm

18

cell

no

some thin g

type s

to

by

of

cell

present

cytoplasm

cell

(often

the

small

cell

wall)

sap

at

the

close

to

vacuoles

cytoplasm;

do

in

not

contain

cell

present

(found

anywhere

cell)

present

sap

within

the

is

Functions

of

cell

structures

STUD Y

cell

structure



forms

a

barrier

between

the

cell

and

Mak e

its

liver

surroundings





cell

TIP

functions

membrane

keeps

allows

cell,



simple

e.g.

controls

out



contents

of

often

of

cell

oxygen,

carbon

movement

the

cell,

e.g.

described

as

of

to

enter

dioxide

other

and

and

leave

the

the

water

substances

into

and

can

page

the

use

of

palis

cells .

struct ures

write

and

each

label

func tions .

your

ade

Labe l

Y ou

draw ings

permeable

to (see

and

unde rnea th

glucose

partially

cells

meso phyl l

inside

substances

draw ings

help

your

revisi on.

28)



controls

all



controls

how

activities



place

in

the

cell

nucleus

where

cells

many

develop

chemical

reactions

take

place,

cytoplasm e.g.

respiration

and

making

proteins

for

the

cell

chloroplast

(plant



photosynthesis



stores



stops



gives



allows

cells starch

only)

cell

wall

cells

cells

from

shape

to

bursting

when

they

ll

with

water

cells

(plant water

and

dissolved

substances

to

pass

only) through

freely

(often

described

as

freely

or

fully

permeable)

sap

vacuole

(plant



cells

full

of

water

only)



stores

salts

SUMMARY

QUESTIONS

1

complete

Copy

and

indicate

to

maintain

shape

and

‘rmness’

of

cell

if

the

this

structures

and

table

are

cell

cheek

structures

(animal)

by

using

present

cell

Cells

sugars

ticks

or

onion

and

crosses

of

onion

magnied

by

×250.

to

not.

cell

leaf

cell KEY

(plant)

POINTS

(plant)

nucleus

1

A

cell

and cell

epidermis

a

membrane,

nucleus

cytoplasm

are

found

in

wall

both

plant

and

animal

cells.

chloroplasts

2 large

All

plant

cells

have

a

vacuole

cellulose

cell

wall;

some

have

cytoplasm chloroplasts

containing

2

State

the

functions

a

chloroplast

e

cytoplasm

b

cell

of

the

following

membrane

c

parts:

cell

wall

d

cells

vacuoles

cell

not

a

vacuole

sap.

have

Animal

these

parts.

nucleus 3

f

do

and

Refer

for

to

the

the

table

functions

above

of

the

cell

structures.

19

Cell

LEARNING

OUTCOMES

As

you

know,

structures •

State

that

the

organelles

all

cells

contains

ribosomes

endoplasmic

on

Identify

rough

ER

in



State

that

occurs

in

Calculate

and

the

a

cell.

number

These

of

are

small

called

include

mitochondria,

vesicles

and

cell

ribosomes

on

reticulum

diagrams

of

and

The

cells

aerobic

endoplasmic

reticulum

and

endoplasmic

membranes.

respiration

which

reticulum

They

allow

contain

materials

to

(ER)

is

a

complex

uid-lled

be

spaces

transported

system

of

between

throughout

double

the

membranes

the

cell.

the

membranes

mitochondria

the

actual

specimens

as

contain

of

reticulum

Where



cells

cytoplasm

rough

mitochondria

photographs

and

endoplasmic

Rough •

animal

the

vesicles rough

and

and

in

cytoplasm organelles

of

plant

present

magnication

size

of

using

are

biological

of

micrometres

ribosomes

called

rough

rough

ER

is

are

present

on

endoplasmic

to

package

their

outer

reticulum

and

surface,

(ER).

transport

The

proteins

main

function

made

by

the

ribosomes.

units Cells

that

digestive

rough

Small

small

a

lot

in

of

the

protein,

for

alimentary

instance

canal,

those

have

large

making

amounts

of

ER.

pieces

of

vesicles.

rough

Ribosomes

produce

enzymes

ER

rough

In

and

this

ER

may

way

be

pinched

proteins

transported

around

can

the

be

off

at

the

made

cell

in

ends

and

the

to

stored

small

form

in

the

vesicles.

Ribosomes

Ribosomes

cells.

cells

Cisterna

They

but

are

are

smaller

cytoplasm,

The

Lamellae

small

not

function

organelles

about

in

20

prokaryotic

attached

of

that

are

nanometres

to

ribosomes

cells

rough

is

to

found

(nm)

where

in

in

huge

diameter

they

are

numbers

in

in

all

eukaryotic

found

free

in

the

ER.

synthesise

proteins,

such

as

those

of

enzymes

involved

in

respiration.

reticulum

made

of

up

double

Mitochondria membrane

Mitochondria Figure

2.2.1

Structure

of

are

relatively

large

organelles

found

in

all

eukaryotic

rough

cells. endoplasmic

reticulum

They

are

often

visible

under

the

electron

microscope

as

sausage-

(ER).

shaped

Each

structures

about

mitochondrion

controls

many

the

folds

entry

on

has

and

which

1 µm

a

exit

wide

double

of

some

and

the

long.

membrane,

materials.

of

5 µm

The

chemical

the

inner

outer

one

membrane

reactions

of

of

which

forms

aerobic

Folds

respiration

take

Mitochondria

they

Inner

Outer

membrane

Cells

are

the

with

vast 2.2.2

Structure

of

a

mitochondrion.

20

are

sites

high

often

of

described

aerobic

rates

of

as

the

‘power

plants’

of

the

cell

since

respiration.

respiration

have

many

mitochondria

to

provide

membrane

sufcient

Figure

place.

energy .

numbers

of

For

example,

insect

mitochondria.

ight

muscle

and

liver

cells

contain

tnemelppuS

2.2

Look

of

at

1000

cells

the

To

work

Now

larger

1000

out

magnied

we

specimens

photograph

times

magnied

and

can

than

of

in

actual

in

size

use

size

human

life.

of

millimetres.

this

a

This

cell,

Let’s

formula

image actual

some

real

cheek

means

cells.

that

The

they

cells

have

are

been

times.

the

cell

tnemelppuS

Size

to

measure

say

that

work

out

it

the

length

measures

actual

of

one

13 mm.

size:

size

= Human

cheek

cells

(×1000).

magnication

13 So

the

actual

size

of

our

cell

=

=

0.013 mm

1000

There

are

answer

We

as

can

in

1000

to

use

this

T o

a

similar

of

size

actual

using

calculate

the

1

2

Which

a

in

a

in

the

millimetre.

by

when

goldsh.

1000

the

This

of

you

an

image

size

actual

size

We

can

to

give

image

size

time

photograph.

formula

magnication

If

will

there

you

nd

image

we

it

convert

has

has

been

been

calculate

is

the

13 µm.

the

90 mm

reorganise

reduced,

a

sh’s

long.

the

formula:

=

The

image

(×0.33)

of

this

actual

goldsh

is

one

third

size.

QUESTIONS

organelles

manufacture

b

convert

c

control

d

carry

e

package

the

carry

out

the

following

functions?

proteins

light

out

and

( µm)

multiplying

same

a

Copy

of

size

the

magnication

SUMMARY

by

technique

photograph

reduction

actual

micrometres

micrometres

energy

into

substances

reactions

and

in

the

that

pass

aerobic

transport

complete

chemical

by

into

and

out

of

a

cell

respiration

proteins

table

energy

around

using

ticks

the

and

cell

crosses. Figure

2.2.3

An

of

feature

bacterial

cell

liver

cell

palisade

electron

a

micrograph

mitochondrion

cell (×80 000).

cell

wall

rough

ER

KEY

POINTS

chloroplast 1

mitochondrion

Ribosomes

the

on

cytoplasm

rough

make

ER

and

in

proteins.

vesicle 2

Rough

ER

packages

transports

3

a

Measure

the

length

of

the

mitochondrion

in

the

electron 3

micrograph.

It

has

been

magnied

80 000

times

and

proteins.

(x

Aerobic

respiration

occurs

in

80 000). mitochondria.

Calculate

the

micrometres

actual

length

of

the

mitochondrion

in

4

( µm).

Cells

with

high

respiration b

Calculate

the

actual

size

of

the

liver

cells

and

the

rates

have

of

many

onion mitochondria.

cells

on

pages

18

and

19.

21

2.3

Different

T o LEARNING

function

Identify

cell

different

from

types

diagrams

of

of

cells

In Relate

cells

the

to

features

their

the

of

to

body

organism

and

photographs



are

Calculate

and

organisms

have

cell

and

topic

certain

divided

we

between

from

change

look

a

to

at

functions.

different

fertilised

become

some

This

cells

egg,

groups

new

of

of

cells

specialised

examples

means

that

for

that

are

the

cells.

are

functions

an

produced.

certain

specialised

As

These

functions.

cells.

these

functions

cells

magnication

actual

size

of

biological Ciliated

specimens

using

cells

are

found

in

the

air

passages

in

the

lungs

(trachea

and

millimetres bronchi)

as

out

develops

grow

this

carry

Specialised •

many-celled

of

OUTCOMES specialised



efciently,

types

and

in

the

oviducts

in

the

female

reproductive

system.

These

units cells

have

current

cilia

in

the

on

their

uid

surfaces.

next

to

the

Cilia

cell

beat

back

and

forth

to

create

a

surfaces.

cilia move ciliated

these cells

cells

make mucus

In

the

up

to

the

area

root

2.3.1

Ciliated

cells

line

to

hair

to

move

and

throat.

the

the

mucus

In

the

that

traps

oviducts,

cilia

dust

and

move

pathogens

the

egg

from

uterus.

cells

absorb

hair

cilia

nose

ovary

Root

Figure

airways,

the

have

water

long

and

extensions

ions

from

that

the

give

them

a

large

surface

soil.

cells

xylem

vessels

the

airways.

STUD Y

Whe n

a

cell

TIP

explai ning

Figure

2.3.2

Root

and

is

adap ted

hair

to

thin

you

tions

give

featur es

each

one

carry

,

mak

the

say

helps

its

the

are

long

Figure

how

Xylem

vessels

columns

of

like

cellulose

water

and

tubes

the

help

from

are

pipes.

and

ions

Ner ve

cells

to

the

up

soil.

a

cylindrical

The

cell

and

walls

waterproof

to

move

support

cells

are

cytoplasm

form

Red

empty.

are

from

They

thickened

material

the

called

roots

of

nerve

blood

the

highly

like

and

specialised

wires.

impulses

cells

stem

are

carry

small

water

the

stem.

are

arranged

with

bands

lignin.

These

into

or

spirals

to

the

rest

of

the

cells

plant.

allow

They

They

are

around

leaves.

cells.

able

the

protein

that

carries

shaped

This

surface

their

Nerve

cells

carry

like

shape

the

oxygen.

They

thin

extensions

information

in

of

the

body.

blood

cells

attened

provides

volume

a

discs.

large

compared

which

are

with

makes

for Figure

impulses

body.

have

transmit

haemoglobin

area

efcient around

They

to

contain red

the

absorption

of

2.3.5

Red

blood

cells

have

a

substance

oxygen. called

haemoglobin

oxygen.

22

vessels

that

func tion.

Nerve

2.3.4

Xylem

cell

also

Figure

2.3.3

absorb

sure

struct ural

and

out

e

to

its water

func

cells

how

that

carries

Palisade

These

The

cell.

by

plant

cells

have

chloroplasts

have

cell

mesophyll

trap

cell

wall

In

the

cytoplasm

sap.

numerous

light

a

made

Starch

up

of

are

and

chloroplasts

energy

there

grains

photosynthesis

cells

tough

is

a

a

in

in

the

cytoplasm.

photosynthesis.

cellulose

large

found

are

for

which

vacuole

the

which

cytoplasm.

temporary

store

of

Palisade

strengthens

is

lled

These

cells

the

with

are

formed

energy.

Figure

Sperm

the

sperm

female

Egg

of

cells

have

carries

parent.

cells

are

energy .

a

tail

genetic

Genes

much

Genes

and

of

adapted

information

from

bigger

the

are

the

from

father

than

mother

are

sperm

are

for

the

male

present

cells.

found

swimming.

They

inside

in

parent

the

head

to

yolk

nucleus

Leaf

lots

palisade

of

cells

contain

chloroplasts

photosynthesis

for

(×500).

nucleus.

as

of

2.3.6

of

the

sperm

contain

the

The

a

the

store

egg. middle

head

Look

real

To

of

carefully

life.

work

the

This

out

cells

at

Figure

means

the

in

2.3.6.

that

actual

the

size

millimetres.

The

cells

of

cells

have

these

Let’s

are

say

been

cells,

it

500

times

larger

magnied

measure

measures

the

500

than

times.

length

20 mm.

Now

of

we

one

can

a

use

a

formula

to

work

out

the

image actual

size

actual

size

of

the

tail

piece

in

sperm

cell:

size

=

Figure

2.3.7

Sperm

cells

have

a

tail

for

magnication swimming

So

T o

the

actual

calculate

size

the

of

actual

cell

is

magnication

magnication

The

our

20

of

divided

an

image

size

actual

size

by

object

500

we

=

(×2000).

0.04 mm

reorganise

the

formula:

membrane

=

diameter

of

an

egg

cell

cytoplasm

is

0.1 mm.

To

calculate

its jelly

magnication

by

0.1 mm

to

in

Figure

give

SUMMARY

2.3.8

we

divided

the

diameter

of

the

×180.

nucleus

QUESTIONS

Figure

2.3.8

Egg

cells

store

1

Draw

its

a

table

correct

T ype

of

matching

shape

cell

and

the

type

of

cell

in

the

blood

Shape

cells

rst

hollow

like

with

the

air

from

passages

dust

water

and

wires ions

KEY

transmit root

hair

cells

at

energy

tube

transport cells

an

Function

free

ciliated

column

contain

(×180).

function:

keep red

coat

drawing

POINTS

electrical

discs

1

During

development,

cells

impulses change nerve

cells

long

and

thin

transport

often

absorb xylem

vessels

have

cilia

that

their

water

from

their

the

2

Specialised

structure

Here

the

out

are

some

functions

their

other

of

specialised

these

cells

and

cells.

how

Use

they

this

are

book

to

adapted

functions.

nd

to

out

carry

to

carry

muscle

d

pollen

cell

b

goblet

cell

c

white

blood

cells

that

out

a

function,

e.g.

have

to

cilia

along a

and

shape.

move soil

2

structure

oxygen

the

have

a

enables

them

particular

ciliated

move

cells

mucus

windpipe.

cell

cell

23

2.4

Levels

Tissues LEARNING

Dene

the

terms

tissue,

group

organ

Describe

of

same

examples

of

and

that

occur

in

is

work

called

a

tissue.

together

to

All

carry

the

out

a

cells

tissue

and

is

made

so

the

tissue:

blocks

similar

up

of

muscle

identical

tissue

muscle

cells.

in

working

the

groups

look

These

cells

work

system:

same

way

of

tissues

a

working

group

cells

contract

muscle

tissue

is

made

your

heart

is

made

of

cardiac

muscle

cells

that

contract

muscle

and

other

pumps

blood

tissues;

it

2.4.1

Levels

of

organisation

relax

in

the

together

human

An

circulatory

organ

together

The

STUD Y

heart

Lear n

these

book .

deni tions

orga n

and

Mak e

exam ples

plan t

as

work

system .

orga n

working

your

group

of

body

your

and

your

carries

blood

vessels

circulator y

blood

system

around

body

made

up

perform

an

of

a

specic

example

of

different

tissues

that

work

functions.

an

organ.

It

is

made

up

of

different

tissues

TIP such

tissu e,

is

organs

system.

is

to

around

up

which

relax and

heart

make

and of

of

together

together

your cardiac

of

a

list

of

and

orga ns

system s

together

muscle,

to

nervous

pump

blood

tissue,

around

brous

the

tissue

and

blood

that

body.

of The

anim al

tissu es,

cardiac

stomach,

lungs,

brain

and

kidneys

are

all

organs.

orga n

from

and

this

Different

systems

blood

are

to

other

and

a

work

digestive

liver

work

of

perform

vessels

some

The

organs

consist

together



body

of

as

part

organs

as

part

of

an

with

functions.

together

For

of

organ

related

example,

the

system.

functions,

the

circulatory

heart

Organ

working

and

system.

Here

systems:

system

is

made

up

of

the

gullet,

stomach,

pancreas,

intestines.

The

excretory



The

nervous



The

reproductive

and

vagina;

and

penis.

the

together

group

organ



All

24

tissue

contracts.

organ:

cells

together

Figure

a

function.

animals

building

muscle

in

shared

plants

cells:

the

cells

they

the together

above

similar

and

system Muscle



organs

organ the

and

organisation

OUTCOMES

A •

and

of

system

system

in

different

is

is

made

made

system

males

organ

it

is

in

up

up

of

of

the

the

females

the

systems

is

testes,

make

kidneys,

brain,

the

a

spinal

ovaries,

sperm

up

ureters

ducts,

living

and

cord

bladder .

and

oviducts,

prostate

organism

nerves.

uterus

gland

Plant

The

tissues

diagrams

and

show

photosynthesis

in

organs

the

tissues

leaves

is

in

called

a

leaf.

The

tissue

mesophyll.

The

that

cells

carries

out

making

up

DID

layer

of

the

mesophyll

are

called

palisade

cells.

These

cells

word

packed

and

full

of

chloroplasts

so

that

they

are

well

the

absorb

lots

of

light.

The

palisade

cells

make

up

the

tissue.

All

the

cells

making

up

this

tissue

is

are

used

close

like

the

wooden

stakes

palisade used

mesophyll

cells

adapted together

to

‘palisade’

are because

closely

KNOW?

the The

upper

YOU

look

alike

to

make

walls

known

as

and palisades.

do

A

the

leaf

Other

same

is

an

function

organ.

structures,

cells:

the

building



they

Other

such

absorb

plant

as

light

organs

owers

and

for

are

photosynthesis.

roots

fruits,

are

and

stems.

modied

leaves.

blocks

organ:

groups

working

tissue: leaf

similar

cells

of

tissues

together

working

palisade

together

in

the

same

way

the

leaf

food

for

palisade

mesophyll

makes

and

gas

allows

exchange

cells upper

epidermis photosynthesis

takes

place cells

in

the

mesophyll

tissue

organism:

milkweed

spongy

mesophyll

is

cells

made

the

plant

up

of

organs lower

Figure

2.4.2

Levels

of

organisation

SUMMARY

QUESTIONS

1

complete

in

a

owering

epidermis

cells

plant.

STUD Y

Mak Copy

and

the

sentences

using

these

e

words:

TIP

sure

explai n organ

system

cells

tissues

tissue

An

is

organ

made

is

An

formed

is

several

up

a

body

of

that

from

group

of

a

group

organs

carry

out

of

the

same

working

working

together

to

.

adap ted

together.

to

Copy

out

correct

the

organs

system

listin g

the

from

listed

those

on

the

listed

left.

on

Match

the

each

with

trachea

digestive

and

blood

vessels

nervous

brain

and

spinal

cord

gas

KEY

one

Cells

that

oviducts

and

uterus

stomach

and

intestines

the

bladder

following

with

the

are

to

grouped

form

tissues.

Different

tissues

make

up

circulatory

words

smallest

into

and

the

ending

correct

with

to

sequence,

the

system

tissue

do

a

which

work

particular

together

function.

largest: 3

organ

same

reproductive

organs

Arrange

the

excretory

2 and

have

exchange

together

organ

and

each

POINTS

function ovaries,

starting

how

helps.

the

1

3

by

featur es

right.

heart

kidneys

out

System

and

gullet,

is

functions.

Organs

lungs

cell

pho to synt hesis

perform

can

palis ade

carry

explai ning

2

a

function

meso phyl l

A

you

how

organism

cell

Different

together

organs

as

work

organ

systems.

25

PRACTICE

1

Which

QUESTIONS

structure

is

found

only

in

plant

6

cells?

The

diagram

liver A

cell

B

chloroplast

C

cytoplasm

D

nucleus

(Paper

shows

a

mitochondrion

1)

Which

[1]

structure

is

not

found

in

animal

cell

membrane

B

cell

wall

C

cytoplasm

D

nucleus

3

Which

the

is

[1]

the

correct

and

sequence,

ending

with

starting

the

7

tissue,

B

cell,

C

tissue,

D

cell,

organ

system,

organ,

organ

system,

×4000

B

×400

D

×40 000

The

(Paper

tissue,

organ,

organ

system

A

out,

A

CO

in,

specimen.

drawing

×40.

A

The

is

is

drawing

length

140

What

a

mm.

the

of

the

The

actual

5600 mm

of

CO

out,

and

out

of

CO

O

8

Cells

in,

nutrients

in

in,

nutrients

out

2

out,

(Paper

in

2

in,

CO

nutrients

O

out,

nutrients

out

2

2)

of

[1]

organisms

contain

classied

which

of

in

the

the

prokaryote

following?

biological

specimen

of

O

2

in

magnication

size

B

a

in

2

2

[1]

makes

O

2

2

1)

student

move

with

kingdom

4

that

are:

D system

[1]

substances

organ

organ

is:

2)

mitochondria

cell

organ,

diagram

C

largest?

cell,

the

×40

C tissue,

of

A

B A

magnication

(Paper

1)

smallest

µm

cells?

The A

(Paper

a

membrane

1.0

2

from

cell.

the

A

cell

membrane,

B

cell

wall,

enzymes,

nucleus,

vesicles

the

is

cell

membrane,

cytoplasm,

ribosomes

specimen?

C

56 mm

cytoplasm,

DNA,

endoplasmic

DNA,

enzymes,

reticulum,

ribosomes C

35 mm

D

3.5 mm

D

(Paper

1)

Which

is

cytoplasm,

(Paper

5

not

found

in

an

animal

2)

[1]

cell?

9 A

mitochondria

[1]

The

palisade

mesophyll

cell

is

a

type

of

plant

nucleus

B

permanent

C

ribosomes

D

rough

cell.

A

2)

cell

and

complete

is

a

type

of

animal

cell.

Copy

vacuole

endoplasmic

cells.

Copy

think

reticulum

you (Paper

liver

the

think

the

the

table

table

structure

it

is

is

to

and

compare

put

present

a

tick

and

a

these

(✓)

if

cross

two

you

(✗)

if

absent.

[1]

palisade cell

liver

structure mesophyll

cell

wall

cell

membrane

cell

cell

cytoplasm

nucleus

chloroplast

large

(Paper

26

vacuole

2)

[6]

10

The

diagram

shows

three

animal

(iii)

cells.

the

organ

system

for

transport

in

mammals;

(iv)

the

plant

[1]

tissue

that

transports

sugars.

(b)

Distinguish

[1]

between

the

following

pairs

of

terms.

B

A

(a)

Identify

the

(b)

State

the

(c)

State

where

(i)

Organs

(ii)

Cytoplasm

(iii)

Cell

(iv)

Organ

A,

functions

B

and

of

the

C.

[3]

three

cells.

the

body

these

cells

13

(a)

Five

cell

magnication

of

cell

A

is

system

and

and

cell

wall

[2]

organism

[2]

structures

and

their

functions

are

its

actual

size

in

below.

×1000. Cell

The

membrane

[3]

Calculate

11

[2]

3)

listed

(Paper

nucleus

are

found.

The

and

[2]

[3] (Paper

(d)

tissues

C

cells

in

and

millimetres.

structures

[2]

A

nucleus

B

cell

membrane

C

cell

wall

D

large

E

ribosome

F

rough

G

mitochondrion

3)

diagram

shows

three

plant

cells.

D

vacuole

endoplasmic

reticulum

E

Functions

1

controls

into

the

and

movement

out

2

stores

water

3

makes

4

withstands

of

the

and

of

substances

cell

ions

proteins

pressure

of

water

inside

F

the

(a)

Identify

(b)

State

(c)

For

the

each

organ

a

(d)

the

cell,

where

actual

Calculate

D,

functions

different

The

cells

D,

it

E

is

E

of

and

the

and

F,

found.

F.

three

state

In

cells.

a

each

the

5

carries

[3]

6

transports

7

stores

DNA

of

cell

give

organ.

length

[3]

plant

case

[3]

of

cell

D

is

magnication

Match

the

out

each

function

0.05 mm.

of

cell

by

of

(a)

proteins

and

the

within

controls

cell

writing

a

the

the

activities

structures

letter

and

cell

with

a

its

number.

[5]

[2]

(b)

A

student

looked

microscope.

12

respiration

the

drawing.

(Paper

aerobic

She

at

a

cell

made

a

under

a

drawing

light

of

3)

the

cell

the

nucleus

and

showed

the

diameter

of

Name:

(i)

an

animal

cell

which

does

not

have

nucleus;

a

[1]

She

(ii)

a

plant

cell

that

does

not

have

calculated

drawing

size

of

as

the

her

the

drawing

70 mm.

magnication

×10 000.

nucleus

as

in

What

is

the

of

her

actual

micrometres?

Show

a

your nucleus;

in

working.

[2]

[1]

(Paper

4)

27

3

Movement

3.1

in

out

of

cells

Diffusion

Molecules LEARNING

Dene



Describe

in

the

term

liquid

diffusion

and

do

move

the

importance

about

in

a

random

way.

They

bump

into

one

of

gases

Describe

the

water

a

and

as

in

a

out

well,

gas

to

ll

up

although

is

faster

as

all

it

the

takes

the

space

available.

longer

molecules

for

are

them

more

Molecules

to

ll

the

spread

in

a

space.

out.

The

of difference

diffusion

spread

this

Movement

in

speed

between

movement

in

gases

and

liquids

is

important

solutes for

as

gases

OUTCOMES another





and

importance

organisms.

This

movement

of

molecules

is

called

diffusion

of

solvent

water

molecules

substance

in

before

Figure

diffusion

after

3.1.1

Diffusion

in

a

gas.

a

coloured

gas

spread

the

TIP

you

write

molecules

of

them

not

as

that

place

to

they

ano th er ,

that

e

difference

in

A

entrat

one

you

has

a

large

so lu te

given

disso lved

high

is

the

ient.

that

are

easily ,

of

vo lu me

in

a

of

the

where

to

there

where

are

there

low

concentration).

The

difference

between

carry

on

in

two

places

diffusing

molecules

so

until

keep

is

a

they

moving,

diffusion

has

concentration

are

but

spread

there

is

out

no

evenly.

longer

stopped.

movement

to

a

of

molecules

region

of

lower

or

ions

from

a

concentration

region

down

a

the

substances

also

lose

they

some

of

need

their

by

diffusion

waste

from

substances

their

to

their

diffusion.

These

permeable

as

oxygen,

larger

substances

as

they

carbon

molecules.

allow

dioxide

The

have

the

and

to

water

movement

cross

cell

movement

of

to

membranes

of

pass

molecules

small

through

by

diffusion

cell

membranes

is

passive

movement

as

cells

do

not

need

to

use

a to

move

the

molecules.

the

energy

for

of

diffusion

molecules

comes

and

from

ions.

the

The

kinetic

more

energy

molecules

of

random

present,

the

has their

kinetic

energy

and

therefore

their

rate

of

movement.

so lu te

given

that

affect

diffusion

so lven t.

These

factors



distance

The

are



The

as

28

by

not

Factors of

of

They

such

but

across

in

so lu tion

mas s

from

of

The

disso lved

(a

molecules

the

net

partially

molecules

greater

smal l

out

concentration)

gradient.

some

movement

a

of

concentration

gain

energy

dilu te

spread

high

say

so lven t.

A

them

concentrations

concentration

so lu tion

mas s

vo lu me

they

(a

the

grad

conc entrat ed

diffuse

volume

alwa ys

down

ion

liquid.

abou t

surroundings

conc

of

happens

this

surroundings.

mov

a

are

from

sure

many

When

Cells

mak e

ions

given

Molecules

of

diffus ing

or

a

concentration

Diffusion

mo lec ules

in

gradient.

a

Whe n

in

container .

the

STUD Y

Diffusion

water

diffusion

out

are through

3.1.2

after

solute

Molecules

lots of

diffusion

of

through

diffusion

When

Figure

molecules

dispersed

tnemelppuS

before

soluble

water

very

inuence

the

molecules

efciency

have

to

of

travel

diffusion:



note

that

cell

membranes

thin.

concentration

quickly

as

gradient

possible,

so



they

cells

use

keep

a

the

low

substances

that

concentration

diffuse

inside

the

tnemelppuS

cytoplasm.

because

This

the

means

cell

is

that

molecules

maintaining

a

keep

steep

diffusing

into

concentration

the

cell

red

blood

cells

gradient. air



The

surface

give



The

a

area

large

some

surface

temperature

temperature

Gas





to

have

allow

many

molecules

move

increases.

versus

cells

Diffusion

is

cell

membranes

molecules

faster

faster

to

and

at

that

cross

collide

warmer

are

by

folded

diffusion.

more

often

as

the

temperatures.

liquid There

Animals

with

the

and

their

gas

plants

page

and

all

exchange

surroundings

exchange

(see

131).

at

surface

the

gas

is

gases

oxygen

exchange

formed

Blood

transports

in

body.

of

surfaces.

the

these

and

alveoli

two

carbon

In

in

gases

dioxide

red

a

short

cells

Magnication

mammals,

the

is

blood

distance

and

very

thin

opposite

cells

layer

of

the

cells

direction.

into

In

the

Breathing

the

alveoli,

blood.

Carbon

constantly

diffuses

dioxide

refreshes

the

blood

constantly

removes

oxygen

and

brings

air

in

in

the

concentration

gradients

are

always

steep.

carbon

There

the

TIP

Alway s

dioxide,

refer

are

many

give

a

very

large

surface

area

for

gas

dilu te

plants,

cells

gas

provide

exchange

a

large

spaces

between

this

(see

air

the

page

occurs

surface

cells

64).

in

This

300 000

times

faster

Water

as

solvent

a

inside

area

a

is

than

for

plant

the

the

to

and

efcient

through

‘stro ng’

exchange.

leaves.

The

exchange

each

cell

because

spongy

of

There

are

exchanges

gases

with

through

the

air

air

is

SUMMARY

QUESTIONS

1

complete

water.

Copy

and

sentences

A

solution

is

made

up

of

two

parts,

the

solute

and

the

solute

dissolves

in

the

solvent.

If

you

dissolve

sugar

using

in

water

a

sugar

solvent.

can

be

The

solution.

solute

solutes

dissolves

in

a

as

is

not

they

solvent

The

always

can

is

sugar

is

a

solid

dissolve

described

the

in

as

solute

like

sugar.

solvents

being

and

the

water

Liquids

too.

random

is

and

gases

Something

is

sometimes

called

the

universal

gas

is

which

of

soluble

solvent.

the

molecules

a

About

75%

is

water

and

it

is

the

main

component

of

of

from

an

blood,

and

xylem

sap

and

phloem

sap

in

transport

plants.

movement

a

or

an

area

area

of

of

of

as

a

result

of

uids

the like

high

net

concentration cytoplasm

diffusion

the

to Water

words:

you

low make

the

these

solvent. liquid

The

and

so lu tions .

mesophyll

gases.

diffusion

so lu tions ,

alveoli

‘ weak ’

In

to

so lu tions

so

neve r to

the

alveoli.

alveoli

and the

the

a

conc entrat ed and

in

lungs

across

diffuses

the

between

air

lungs

between

oxygen

the

×1500.

STUD Y the

space

to

movement

of

Everything

molecules. transported

of

the

water

KEY

1

is

plants

needed

and

reactions

for

animals

that

digestion

has

occur

and

to

in

dissolve

cells

excretion

in

happen

to

take

water

in

and

water.

most

Also,

2

place.

Diffusion

down

of

a

is

the

high

net

movement

concentration

concentration

Factors

that

surface

area,

affect

to

a

molecules

region

of

or

ions

low

from

diffusion

gradient.

are:

and

how

the

size

of

concentration

molecule,

steepness

of

distance,

the

into

a

distance

b

size

c

surface

d

concentration

e

temperature

of

factors

cells:

molecule

area

3

What

do

the

gradient

terms

concentration

the

following

diffusion

a

gradient.

temperature

concentration

of

State

affect

POINTS

region

2

in

chemical

4

Explain

why

important

and

solution

gradient

water

solvent

is

and

mean?

an

for

animals

plants.

29

3.2

Osmosis

Each LEARNING

of



Dene

the



Describe

the

term

on

and

osmosis

the

Explain

of

the

water

cells

surrounded

effect

animal

and

tissues

the

out

term

allows

cell

the

by

a

cell

small

outside.

membrane.

The

molecules

membrane

is

cell

It

separates

to

described

membrane

pass

as

through

being

has

the

but

tiny

contents

not

partially

holes

large

in

it

ones.

permeable

osmosis

movement

into

using

of

from

of

Osmosis

occurs

is

a

when

special

two

kind

of

solutions

diffusion

are

involving

separated

by

a

water

molecules.

partially

It

permeable

membrane

water Osmosis

is

the

diffusion

of

water

from

a

dilute

solution

into

a

more

potential concentrated

The

tiny

solution

holes

membrane

in

through

a

partially

permeable

membrane.

the

allow

Water

small

molecules

solute diffuse

water

molecules

to

pass

water

through,

solute

too

the

but

the

molecules

big

to

pass

partially

from

a

high

molecule

large

to

a

concentration

lower

water

concentration

are

through

permeable

fewer

membrane.

Water

is water many

diffusing

from

a

place molecules water

where

there

is

a

dilute molecules

STUD Y

TIP

solution

with

a

high

concentration

of

water dilute

If

aske d

to

dene

to

a

place

where

there

is

solution

concentrated

partially

osmos is

it,

mak

that

of

it

or

e

is

wate r

write

sure

the

abou t

you

say

diffus ion

mo lec ules.

concentrated

permeable

with membrane

a

low

concentration

of Figure

3.2.1

Osmosis.

water

Water

to

potential

move

by

available,

water

a

in

dilute

water

In

the

two

solution

of

water

A

dialysis

to

are

lot

is

a

free

a

of

on

a

of

ability

much

of

water

water

pressure

accurate

molecules)

is

exerted

to

say

has

(containing

potential

molecules

high

partially

water

a

on

that

high

fewer

left

since

hand

through

potential

gradient

diffuse

potential

permeable

through

However,

the

molecules

water

the

more

water

water

move

energy.

is

as

solution

water

region

to

It

the

how

water

potential

The

through

by

such

wall.

a

water

present

water

the

factors

cell

there

about

inuenced

concentrated

from

kinetic

of

down

Dialysis

A

potential

by

the

membrane.

molecules

model

by

above,

the

thinking

is

other

low

molecules

movement

right,

a

gradient,

directions

water

has

of

This

(containing

potential.

potential

way

by

cells

diagram

Water

a

also

plant

sides

lower

is

osmosis.

but

molecules)

30

solution

solution

a

the

the

to

a

this

the

water

region

of

membrane.

membrane

there

side,

between

down

are

there

in

many

will

membrane

both

more

be

from

a

net

left

to

gradient.

cell

tubing

tubing

represent

(Visking

to

the

tubing)

represent

cytoplasm.

the

is

partially

cell

permeable.

membrane

and

We

the

can

sugar

use

solution

tnemelppuS

tnemelppuS



is

cell

which

The

plant

cell

OUTCOMES

PRACTICAL

1

Cut

two

pieces

water diffuses

of

into ‘cell’

dialysis

12 cm

tubing,

long.

each

Tie

one

end

sugar

solution

of

each

with

cotton.

dialysis tubing

2

Fill

one

model

cell

with

a (partially

dilute

sugar

solution

permeable

(cell

membrane)

A).

Fill

the

other

model

water

STUD Y cell

with

water

(cell

‘cell

3

Tie

the

other

end

TIP

B).

of

A ’

Y ou

both

may

be

given

water diffuses

model

cells

and

resul ts

weigh out of ‘cell’

them

‘cell

on

A ’

water

a

a

balance.

into

and

beaker

a

Put

beaker

put

‘cell

B’

a

demon stratio n

and

into

the

be

resul ts.

solution

of

30

minutes

to solution

out

the

model

Mak e

the

sure

you

den ition

osmo sis

and

sugar permeable

take

osmo sis

explai n

dialysis tubing

of After

to

a

(partially

sugar .

of

expec ted

remem ber concentrated

the

pract ical

water

of

containing

of

the

resul ts

cells

apply

you

it

can

see.

membrane)

Alwa ys and

weigh

them

again.

‘cell

resul ts

‘Cell

A ’

increases

in

mass

explai n

because

are

molec ules capillar y

water

has

diffused

into

the

‘cell’

level

by

that

B’

due

to

the

water

movin g

by

of

osmo sis.

tube sugar

osmosis.

‘Cell

B’

decreases

in

mass solution

because

water

by

has

the

cell

An

osmometer

diffused

out

of

osmosis.

dialysis

tubing

containing

Y ou

can

you

set

Fill

the

see

up

the

this

partially

membrane

effects

of

osmosis

water

if

concentrated

apparatus.

sugar

solution

permeable

with

a

very

KEY

concentrated

solution

of

1

Tie

it

to

a

capillary

tube

and

stand

it

in

POINTS

sugar.

Osmosis

water

Very

quickly

measure

your

you

how

ideas

will

fast

about

it

see

is

the

liquid

moving

osmosis

to

moving

using

explain

a

up

ruler

why

is

the

diffusion

of

water.

the

and

the

a

tube.

Y ou

stopwatch.

liquid

rises

in

of

can

their

(dilute

Use

the

molecules

of

tube.

higher

their

lower

through

a

a

region

concentration

solution)

(concentrated

from

to

a

region

concentration

solution)

partially

permeable

membrane.

SUMMARY

QUESTIONS 2

A

partially

permeable

membrane 1

Dene

the

following

molecules

diffusion

2

Describe

osmosis

practical

osmosis

how

into

you

a

can

sugar

partially

nd

out

solution.

permeable

how

fast

water

Remember

to

membrane

diffuses

include

pass

tnemelppuS

Explain

all

details.

in

terms

water

potential,

how

water

passes

cells

placed

in

distilled

as

but

molecules.

3

Water

molecules

water

a

potential

water

not

to

large

region

of

diffuse

down

gradient

higher

water

into potential

plant

such

through

solute

a

of

small

by

from

3

allows

terms:

to

a

region

of

lower

water. water

potential.

31

3.3

Osmosis

animal

LEARNING



Describe

enter

OUTCOMES

how

and

water

leave

plant

and

cells

PRACTICAL

can

plant

in

Osmosis

cells

in

potato

cells

by 1

Cut

nine

cores

from

a

potato

so

that

they

are

exactly

the

same

osmosis length.



Describe

affect

how

animal

osmosis

Record

this

length.

can 2

Feel

3

Set

the

cores

to

see

how

rm

and

‘bendy’

they

are.

cells

up

the

following

test-tubes:

B

A

STUD Y

test-tube

A

test-tube

B



distilled



dilute

water

distilled

dilute

water

sugar

sugar

TIP solution solution

Whe n

cell

desc ribin g

mem bran e

say

that

it

is

test-tube

concentrated

the sugar

4

partia

no t



solution.

alwa ys Place

three

cores

of

potato

0

1

2

3

4

5

6

7

8

9 10

0

1

2

3

4

5

6

7

8

9 10

lly into

perm eable,

C

each

test-tube

and

tissue

swells

up

no

change

semileave

perm eable.

5

them

Remove

for

the

measure

60

cores

their

minutes.

C

and

concentrated

sugar

lengths.

solution

Calculate

of cell

the

the

cores

average

in

each

length

test-tube.

membrane

Compared

(partially

to

the

start,

cores

permeable)

will

0

be:

1

tissue water

A

cytoplasm



longer

and

2

3

4

5

6

shrunken

7

8

9 10

and

flaccid

rmer

passes

into

the

B



about

the

C



shorter

same

length

and

rmness

vacuole vacuole

by

and

softer

and

‘bendier’.

osmosis cell

wall

(freely

These

results

are

explained

in

the

text.

permeable)

the

cell

solution

is

less

outside

the

concentrated

Turgidity than

in

the

vacuole

The Figure

3.3.1

Osmosis

in

a

plant

cell

sap

inside

cells

are

there

STUD Y

tnemelppuS

Paper

expec ted

Y ou

4

to

you

use

osmo sis

may

the

As

be

wall

wall

in

and

refer

plan t

is

plant

a

cell

water,

solution

is

partially

the

of

water

gradient

salts

permeable

enters

so

and

the

that

sugars.

and

cells.

water

When

the

cell

This

is

plant

because

molecules

diffuse

enters

osmosis.

it

makes

water

stops

as

the

it

a

can

cell

the

cell

turgor

hold.

It’s

bursting.

swell

up.

pressure.

like

We

a

say

The

blown-up

that

water

Eventually

the

pushes

the

cell

balloon.

cell

is

against

contains

The

turgid.

strong

This

is

the

as

cell

what

or

to

happened

to

the

cells

in

the

potato

cores

in

tube

A.

The

cells

have

water ,

swollen

and

caused

the

core

to

get

slightly

longer .

‘ water T urgid

cells

plants

upright.

give

the

plant

support.

They

keep

the

stems

of

many

to This

is

because

the

cells

within

a

stem

are

supported

movem ent by

out

by

tissu es.

grad ients ’

water

and

tissu es.

the

potential

developing

absorbed

also

poten tial

into

in

water

cells

water

cell

term

has

cells

can

explai n

of

vacuole

placed

a

the

much

abou t

anim al

of

cells

turgor

pressure.

The

water

pressure

within

the

cell

acts

against

the

and inelastic

these

and

32

is

the

TIP into

In

membrane

cell.

cell

cells

leaves

walls,

lose

that

keeping

water,

have

they

lost

the

are

cells

no

water

turgid

longer

wilt

and

rm

rm.

and

However,

turgid.

when

Plant

stems

tnemelppuS

Plasmolysis the solution outside the

cell is more concentrated

When

plant

cells

are

placed

into

a

concentrated

sugar

or

salt

solution than in the vacuole

water

passes

vacuole

limp.

out

starts

We

say

of

to

the

cells

shrink.

that

they

by

These

are

osmosis.

cells

are

accid.

As

As

no

water

longer

more

passes

rm,

water

out,

and

leaves

the

sap

become

the

cells

water

out

the

by

cytoplasm

starts

plasmolysed.

cores

core

in

is

to

test-tube

shorter

move

This

is

C.

than

away

what

The

at

cells

the

from

has

the

cell

happened

have

wall.

to

the

decreased

in

These

cells

cells

in

the

volume

so

are

passes

of

the

cell

osmosis

now

potato

the

whole

as cytoplasm is pulled

start.

away from the cell

The

the

cores

in

water

water

test-tube

potential

potential

overall

about

of

diffusion

the

did

not

change

of

the

sugar

the

cell

sap

of

same

B

water

into

in

solution

in

the

or

out

length

was

potato

of

the

very

about

cells.

cells

much

the

There

so

because

same

has

they

as

been

have

wall, the cell becomes

plasmolysed

the

no

Figure

3.3.2

Water

cell

stayed

passes

by

out

of

a

plant

osmosis.

length.

a

Osmosis

Figure

in

3.3.3

placed

in

animal

shows

different

cell

membrane

The

red

blood

Their

The

cytoplasm

cells

cells

by

them

in

D

in

a

they

so

to

picture

have

cells

has

the

the

blood

blood

salt

been

water.

cells

when

solution.

they

E

same

of

they

are

Remember

passes

not

water

no

blood

shrink

into

proteins,

have

red

have

when

placed

Water

cells

When

(F),

in

red

a

solution

animal

burst.

solution

The

of

that

permeable.

distilled

they

salt

in

the

in

which

are

partially

However,

osmosis.

solution

how

happens

concentrated

were

swelling

by

is

in

a

osmosis.

concentrated

cells

is

what

concentrations

the

cells

cells

as

into

cells

potential

by

and

are

put

size

as

stop

into

out

as

the

blood

sugars.

b

to

passes

in

liquids.

the

wall

water

surrounded

salts

cell

changed

different

a

of

they

cells.

the

are

This

is

plasma.

D These

(a)

Figure

3.3.3

This

shows

water

as

(D)

they

what

and

a

appear

happens

when

concentrated

when

red

blood

solution

suspended

in

of

cells

salt

blood

are

(F).

E

put

into

shows

KEY

distilled

red

blood

epidermal

turgid

1

plasma.

Water

passes

osmosis.

of

what

is

turgid

water

meant

turgor

Some

potato

dilute

sugar

by

each

of

pressure

these

mass

and

accid

2

plasmolysis

If

plant

cores

were

solution.

dried

on

a

weighed

After

paper

2

and

hours,

towel

then

they

and

placed

were

weighed

into

taken

of

of

the

potato

What

does

sugar

solution?

Explain

tnemelppuS

Explain,

cells

are

passes

turgid.

cells

that

is

T urgid

cores

remained

this

tell

you

about

the

your

answer

to

part

a

in

using

the

term

water

These

cells

are

shrinks,

unchanged.

concentration

terms

potential,

when

they

are

placed

into

of

what

distilled

for

stems.

of

into

a

solution,

out

by

osmosis.

are

no

happens

to

for

60

accid.

longer

the

cell

away

As

the

rm,

vacuole

membrane

from

the

cell

wall



the

3

osmosis.

water

placed

sugar

again.

cell

Animal

cores

is

now

cells

into

plasmolysed.

burst

water

if

they

as

are

they

of have

potato

cell

support

young

water

placed

3

plant

the

the

b

are

a

out

moves a

onion

terms:

they

The

red

plant

is

concentrated

solution,

into

A

provide

leaves

2

a

QUESTIONS

cells

Explain

from

plasmolysed.

POINTS

full

1

cells

(b)

cells

by

SUMMARY

and

no

cell

wall

to

resist

the

minutes. increase

in

size.

33

3.4

Active

Active LEARNING

Dene

the

term

Look

tnemelppuS

the Explain

active

the

importance

transport

consuming



Describe

of



ions

the

by

villi

in

as

an

active

plant

glucose

up

molecules

at

the

and

ions

concentration

concentration

of

and

keep

them

in

high

concentrations.

of

magnesium

magnesium

ions

in

ions

the

in

soil

the

root

hair

cell

and

solution:

of

energy-

process

the

in

Describe

take

active

transport



transport

OUTCOMES

Cells •

transport

vacuole

of

root

hair

cell

transport

roots

active

uptake

epithelial

cells

of

in soil

and

kidney

tubes solution

soil

particle

Key:

=

magnesium

Figure

The

of

3.4.1

down

high

root

hair

‘conc

in

of

use

entrat

the

activ e

of

ion

deni

‘ Aga inst

of

cell

ions

to

diffusion

cells

magnesium

than

it

gradient.

inside

in

out

ions

the

of

The

the

by

active

is

far

water

the

transport.

greater

in

root

hair

magnesium

root

hair

the

cell

cell

ions

by

a

inside

soil.

We

into

are

the

vacuole

might

the

soil

expect

water

maintained

process

called

at

a

active

the

grad

term

ient’

a

cell

using

transport

through

energy

is

the

the

cell

released

movement

of

membrane

during

ions

against

or

a

molecules

in

or

concentration

out

of

gradient,

respiration.

tion

4000

a

conc entrat ion

from

to

cell

in

3000

water

outside

gm

conc entrat ion

md

means

3–

a

conc entrat ion.

/

high

is

diffuse

inside

low

ions

tran sport.

grad ient’

a

absorb

transport

TIP

the

a

hair

concentration

Active

No tic e

Root

concentration

the

magnesium

STUD Y

ions

noitartnecnoc

2000

1000

0 +

+

Na

Figure

The

of

a

bar

Ion

chart

against

have

a

the

plant

been

concentration

due

to

in

the

into

active

water

the

gradient

Ca

magnesium

concentrations

and

taken

2+

Mg

potassium

concentration

shows

freshwater

cannot

34

3.4.2

2+

K

sodium

plant

by

Cl

calcium

chloride

transport.

of

in

by

some

which

ions

it

lives.

diffusion.

active

inside

These

They

transport.

the

are

cells

ions

taken

in

tnemelppuS

Active

The

cell

the

with

to

membrane

cell

enter

leave

carrier

change

its

membrane.

and

the

a

and

cell

by

protein.

shape

The

carrier

needs

contains

membrane

or

a

transport

carrier

provide

active

to

carry

protein

proteins.

means

by

transport.

Energy

molecule

energy

from

the

or

reverts

to

First

the

respiration

ion

ion

is

or

to

original

carrier

ions

and

to

the

or

the

the

proteins

molecules

molecule

enables

molecule

released

its

These

which

ion

combines

carrier

inside

inside

of

of

the

span

can

protein

the

membrane

shape.

ions outside

cell

cell

outside

cell

membrane

+

membrane

energy

inside

3.4.3

Carrier

proteins

in

membranes

carry

out

active

transport.

STUD Y Epithelial

absorb

rates

cells

lining

glucose

of

by

the

villi

active

respiration

to

in

the

transport

provide

small

(see

energy

intestine

T opic

for

and

7.8).

this

the

These

active

kidney

cells

TIP

tubules

have

high

Roo t

hair

transport

against

a

upon

concentration

respiration

oxygen

relies

will

would

also

gradient.

affect

reduce

respiration

the

Any

rate

respiration

of

to

take

factor

active

rate

and

up

that

ions

or

affects

transport.

active

the

So

are

molecules

a

rate

lack

up

increase

to

The

a

in

point,

presence

active

temperature

so

of

transport

SUMMARY

tnemelppuS

1

Explain

2

a

3

would

have

such

stop

as

increase

the

the

same

cyanide

man y

transport.

rate

effect

can

their

stop

of

on

respiration,

active

to

transport.

respiration,

Make

a

Make

sure

be

is

meant

the

table

to

State

role

to

that

and

of

active

carrier

of

compare

you

have

‘active

from

think

what

transport,

rate

a

lack

proteins

and

respiration

an

c

the

respira tion

energ y.

in

active

transport

diffusion

with

taking

active

place.

KEY

of

three

columns

transport’.

the

cell’,

some

For

headed

features

‘concentration

other

features

to

transport.

can

gradient’.

in

your

transport

molecules

include

Y ou

Active

movement

‘features’,

you

use

POINTS

effect

in

each

each

case

of

the

give

following

reasons

for

would

your

have

answer:

of

is

ions

across

the

or

the

against

concentration

table.

on

of

membrane,

may

from

cell

a

gradient,

using

respiration.

active

2

Active

transport

cells

to

enables

take

up

root

ions,

and

oxygen

epithelial b

of

in

and

transport.

hair a

pro tei ns

mem bran es

provi de

energy 4

havi ng

altogether.

by

examples

energy

able

villi

activ e

so

1

‘needs

high

by

carrier

cell

of

for

transport.

two

‘diffusion’

and

QUESTIONS

Describe

Give

also

poisons

what

active

b

would

would

cells

adap ted

trans port

of

of

a An

cells

transport.

epith elial

Active

cell

tnemelppuS

Figure

cell

increase

in

of

the

villi

to

temperature take

presence

cells

of

a

poison,

such

as

up

glucose.

cyanide

35

PRACTICE

1

Which

A

is

cell

QUESTIONS

not

partially

membrane

B

cell

membrane

C

cell

wall

D

dialysis

permeable?

of

of

palisade

red

5

mesophyll

blood

cell

Which

A

the

cell

B

1)

A

is

the

best

partially

denition

of

solvent

permeable

concentration

net

of

the

net

molecules

D

through

membrane

down

random

the

of

net

from

molecules

down

of

molecules

against

diffusion

a

a

a

a

movement

of

molecules

in

a

molecules

down

solution

a

membrane

of

water

molecules

permeable

with

with

through

a

a

low

high

membrane

water

water

potential

potential

2)

[1]

Some

fresh

plant

tissue

salt

was

solution

put

for

into

60

a

minutes.

Which

explains

why

the

tissue

became

softer?

liquid

hair

cells

are

surrounded

by

soil

water ,

water

diffused

gradient

[1]

dilute

solution

nitrate

ions

higher

concentrations

hair

water

gas

1)

very

down

gradient

partially

solution

water

cells

and

absorb

of

mineral

magnesium

ions

of

ions.

these

from

soil

ions,

such

Plant

cells

ions.

How

active

B

diffusion

do

C

diffused

water

D

random

into

water

to

the

potential

their

cells

surroundings

so

that

they

out

of

the

cells

so

that

they

plasmolysed

water? the

cells

lost

turgor

pressure

and

became

accid

(Paper

osmosis

a

cells

turgid

diffused

became

root

transport

C

down

the

as

have

D

A

from

which

became is

molecules

a

B Root

a

gradient

A

3

through

a

best

(Paper

water

of

permeable

concentrated

a

molecules

gradient

potential

through

a

6

or

osmosis?

gradient

movement

concentration

D

of

membrane

of

diffusion

water

(Paper

net

water

potential

partially

diffusion?

gradient

movement

concentration

C

of

permeable

diffusion

water

to B

net

denition

[1]

movement

a

diffusion

the

a

Which

best

tubing

C

2

the

partially

a

(Paper

is

7

(a)

2)

Explain

[1]

the

importance

to

humans

of

the

movement following:

(Paper

4

A

1)

[1]

student

cut

up

a

potato

into

pieces

(i)

diffusion

of

oxygen

in

the

alveoli

(ii)

diffusion

of

carbon

dioxide

in

[2]

the

that

alveoli looked

pieces

three

like

as

chips.

‘fairly

different

results

that

the

The

rm’.

student

The

liquids.

pieces

Which

student

described

were

row

[2]

these

put

shows

(iii)

into

absorption

the

the

small

of

glucose

by

diffusion

in

intestine.

[2]

obtained? (b)

Explain

the

importance

to

plants

of

the

following: very very

dilute

salt salt

(i)

fairly

soft

Osmosis

osmosis rm

(Paper

swollen

36

soft

fairly

rm

soft

fairly

rm

and

D

of

magnesium

ions

by

cells.

root

[2]

is

a

type

of

diffusion.

Explain

how

and

rm very

1)

leaves

rm

fairly

soft

absorption

hair

(c)

(Paper

into

[2]

swollen soft

very

dioxide

and

rm very

C

carbon

solution

(ii)

B

of

solution

swollen A

diffusion

water

concentrated

rm

[1]

3)

differs

from

diffusion.

[3]

8

A

group

They

divided

of

of

students

began

10

the

by

peeled

onions

batch

was

and

surface

dried

calculated

The

for

table

small

onions

into

of

salt

two

and

the

50

into

weighed

placed

concentrations

immersion

investigated

peeling

a

hours

reweighed.

their

The

in

B

of

was

the

was

B

mass.

mean

mass

onions

/

set

Some

and

up

bubbled

a

oxygen

A

in

gas

gas

cut

three

solution

with

from

A;

a

solutions,

ions.

rich

a

in

A

each

oxygen

solution

very

solution

mixture.

ions

through

mixture

oxygen;

the

of

potassium

mixture

of

were

in

bubbled

through

gas

investigate

uptake

roots

placed

was

solutions.

to

the

containing

gases

concentration

results.

of

C,

of

received

no

conc.

roots.

and

was

inuencing

washed

mixture

After

students

change

plant

A,

different

batch

factors

plant,

chloride).

each

experiment

by

batches

of

An

the

They

Each

solution

percentage

shows

ve

them.

(sodium

9

osmosis.

onions.

C

The

low

received

roots

were

g

left

for

24

hours

and

then

the

rate

of

uptake

percentage of

of

salt

before

after

immersion

immersion

2

hours

change

potassium

ions

was

determined.

in

/

−3

mass

The

rate

of

uptake

of

potassium

ions

was

g dm

highest 0

147

173

25

153

165

+

in

solution

+

172

100

154

149

Explain

how

149

142

−4.5

200

183

175

−4.5 The

Journal

(a)

and

data

of

in

Biological

Calculate

used

to

vegetable

compile

Education

the

the

pickling,

(1993)

percentage

supply

uptake

table

Ray

27

W

(2),

change

was

of

of

solution

oxygen

to

C

roots

potassium

repeated

containing

temperatures.

gas

osmosis

the

their

experiment

solutions

150

Practical

in

ions.

[3]

−2.0 The

Information

lowest

8.0 inuences

176

and

18.0

(a)

50

A

mixture

results

They

that

are

roots

were

had

all

been

shown

in

with

kept

at

different

provided

given

the

to

with

the

solution

A.

table.

from

temperature

rate

of

/

ions

uptake

of

potassium

James.

pages

in

°C

/

arbitrary

units

90–91

5

3

10

5

20

10

30

20

40

15

mass

−3

for

the

onions

solution.

(b)

State

why

the

percentage

(c)

Plot

(d)

Use

a

which

(Paper

of

is

the

the

to

no

100 g dm

salt

working.

students

graph

there

in

your

change

graph

your

kept

Show

in

[2]

calculated

the

mass.

[1]

results.

nd

the

change

[5]

salt

in

solution

mass.

in

(b)

Draw

a

graph

(c)

Describe

of

the

results.

[6]

[1] the

results

shown

in

your

graph.

[4]

4)

(d)

Explain

uptake

(Paper

10

the

of

effect

Explain

the

(b)

Explain

why

Some

term

resources

and

concentrations

Describe

absorb

by

the

concentration

of

in

is

on

the

roots.

[3]

are

their

by

or

cells,

often

in

as

the

ions.

such

very

[2]

as

low

surroundings.

epithelial

molecules

gradient. [2]

described

molecules

required

ions,

how

contents.

(Paper

ions

diffusion

movement

molecules

(c)

temperature

4)

(a)

net

of

potassium

of

cells

glucose

of

the

from

villi

the

gut

[5]

4)

37

4

Biological

4.1

molecules

Biological

Biological LEARNING

List

in

the

elements

for

present

carbohydrates,

fats

Describe

large

the

synthesis

molecules

from

place

energy

of

cells.

Green

smaller

need

how

They

of

raw Describe

are

in

different

sequences

give

in

plants

from

the

Relate

proteins

chemicals

of

the

that

we

body.

protein

are

mean

These

synthesis,

needed

all

the

by

reactions

and

living

chemical

the

include

growth

organisms

reactions

the

and

release

repair

the

raw

for

complex

chemical

materials.

Carbon

photosynthesis.

compounds

dioxide

The

simple

wide

range

and

that

they

water

sugars

are

the

produced

in

need

are

used

minerals

to

to

make

make

a

some

of

these

of

other

complex

compounds.

compounds.

shapes

the

structure

shape

eat

of

plants

and/or

other

animals

that

feed

on

plants.

and

protein

molecules

that

animals

require

are

present

in

their

diet.

The

molecules different

their

carbohydrates,

different

Biological

to

like

amino

Animals



chemicals

metabolism

cells

make

simple

materials

Plants protein

useful

By

respiration,

photosynthesis acid

complex

of

molecules



fats.

metabolism.

taking

and

proteins



are

OUTCOMES and



molecules

molecules

biological

molecules

needed

for

a

balanced

diet

in

humans

function are

carbohydrates,

proteins,

fats,

vitamins,

minerals,

bre

and

water.

Carbohydrates

These

contain

the

Carbohydrates

a

simple

Glucose

sugar

molecules,

e.g.

in

is

a

b

complex

atoms

sugar

e.g.

and

sugar

and

which

transported

in

(C),

hydrogen

(H)

and

oxygen

(O).

starches.

is

made

the

in

blood.

photosynthesis,

It

consists

of

six

used

carbon

arranged

simple

made

to

is

a

double

sugars

by

bonds.

Plants

catalyse

It

is

stored

Starch

complex

carbohydrate

and

Cellulose

glucose Figure

4.1.1

Different

types

and

glycogen,

a

units.

unlike

The

of

by

two

They

together

starch)

is

animals

molecules

a

by

have

into

another

as

mo lecules

eaten

to

refer

is

also

to

by

the

used

which

an

are

made

animal.

bio logical

to

refer

of

carbohydrates

together

store.

glucose

animal

store

are

chemical

enzymes

long

chains.

complex

of

energy.

muscles.

sugars,

structural

glucose

up

Complex

molecules

energy

glucose

and

complex,

an

join

called

from

liver

sugar

as

that

made

bonds.

units

are

insoluble

carbohydrate

are

held

and

do

made

together

by

not

up

of

bonds

taste

sweet.

thousands

forming

bres,

chains.

which

give

These

plant

cellulose

cells

walls

molecules

their

are

strength

linked

and

of

long

together

rigidity .

TIP

Bio logical

ions,

simple

starch

made

the

molecule

chemical

reactions

unbranched

form

when

many

(sometimes

in

is

by

of

carbohydrate.

STUDY

ring.

sugar

store

the

carbohydrate



a

joined

joining

Glycogen,

starch

into

sucrose

Sucrose

38

simple

respiration

carbon

sugars

glucose

molecules,

c

elements

include

to

by

such

need

organisms.

term

mo lecules

ions,

organisms

T he

described

as

from

nutrient

nitrate

their

T hey

(or

in

only

T o pics

ions,

become

nutrient

4 .1

sodium

environment.

food

mo lecule)

and

ions

4 .2.

and

mo lecules

is

often

Beware



used

it

magnesium

to

Proteins

Proteins

are

complex

oxygen,

but

they

molecules

also

contain

made

up

nitrogen

of

(N)

carbon,

and

hydrogen

many

have

STUD Y

and

sulfur

Y ou (S).

Proteins

are

long-chain

molecules

made

up

of

smaller

TIP

may

compa re called

amino

acids.

After

formation

Topic

5.1)

they

are

either

folded

shapes

(see

or

become

arranged

into

long

of

bres.

to

compa re

peptide

head ings

bond

of

acid

part

molecules

of

a

protein

4.1.2

How

a

protein

is

made

from

amino

are

about

20

different

types

of

acids.

amino

this

acid.

and

will

Molecules

of

be

table

Whe n There

are

made

into

chains

as

you

can

see

in

the

diagram.

It

is

of

the

different

amino

acids

in

the

chain

usin g

as

‘Nam e

molec ules

‘Elem ents’.

which

able

in

to

add

T opic

nam ing

to

7 .2.

the

alwa ys

use

the

full sequence

table

amino

elem ents acids

such

a

molecule

Y ou

Figure

Mak e

them

biolog ical

grou p’ amino

to

three

biolog ical

molec ules.

different

aske d

these

into

grou ps different

be

molecules

nam es,

no t

determines

their

their

sym bo ls. the

type

the

chain

tnemelppuS

The

of

by

different

molecules.

to

protein

their

that

means

of

a

sequences

These

function.

is

formed.

chemical

of

amino

different

shapes

Enzymes

are

Each

bond

acids

of

individual

called

give

peptide

different

protein

proteins

a

amino

that

a

joins

bond.

shapes

molecules

provide

acid

can

to

be

surface

protein

related

fatty

acid

glycerol

molecule

for

molecule

reactions

are

to

take

proteins

enables

with

them

pathogens

place

to

and

a

called

structure

bind

with

make

the

the

‘active

that

has

chemicals

pathogens

site’

(see

binding

called

stick

page

sites

on

antigens

together

47).

its

on

(see

Antibodies

surface.

the

page

This

surface

of

120).

Figure

KEY

Fats

Fats

and

Each

to

fat

this

these

oils

made

molecule

are

can

energy

are

three

form

storage

is

up

made

fatty

the

up

acids.

different

and

of

fats

thermal

of

elements

one

There

with

carbon,

molecule

are

different

different

insulation

of

in

hydrogen

glycerol

types

properties.

the

of

and

and

fatty

Fats

oxygen.

acid

are

1

attached

for

body .

A

Carbohydrates

up

of

hydrogen

Proteins

of

the

List

the

Give

components

of

a

balanced

diet

for

a

a

fats

are

and

are

made

elements

plus

sulfur.

(e.g.

one

example

of

each

of

the

simple

sugar

ii

a

complex

are

simple

glucose),

and

human.

carbohydrates

such

following: as

i

same

and

Carbohydrates

complex b

fat.

QUESTIONS

sugars a

of

elements

oxygen.

up

2

1

and

the

carbon,

nitrogen

SUMMARY

molecule

POINTS

made

and

used

4.1.3

carbohydrate

found

in

starch,

glycogen

and

plants cellulose.

iii

a

complex

carbohydrate

found

in

animals 3

2

a

Which

in

elements

are

carbohydrates

present

and

in

proteins,

but

are

not

found

Small

fats?

Name

the

small

molecules

that

are

joined

together

to

Give

d

State

three

examples

of

proteins

that

are

made

in

the

the

Name

made

and

Amino

function

of

each

protein

that

you

named

in

the

molecules

that

are

reacted

together

to

into

acids

are

part

A

molecule

make

of

of

a

fat

is

made

c

combining

three

fatty

acid

a molecules

molecule

proteins.

body.

by

a

are

glycogen

chain

make

4

3

joined

long

molecules.

made c

are

make

Sugars

starch,

cellulose. protein

to

molecules.

into b

molecules

together

with

a

molecule

of

fat. glycerol.

b

Give

two

uses

of

fats

in

the

body.

39

4.2

Chemical

tests

biological

Simple LEARNING

how

the

following

and

are

carried

vitamin

can

be

used

to

identify

starch,

sugars,

proteins,

it

is

important

you iodine

test



Benedict’s

to

carry

out

these

tests

on

pure

forms

of

these

out: compounds.



C.

chemical First,

tests

tests

molecules

OUTCOMES fat

State

chemical

for

for

should

For

rst

example,

carry

out

if

you

the

are

testing

chemical

test

a

food

on

a

for

reducing

glucose

sugars,

solution.

starch Then

test

for

keep

the

results

to

compare

with

your

results

from

testing

other

reducing materials,

such

as

foods

or

animal

and

plant

tissues.

Y ou

should

also

sugars do



biuret

test



ethanol

for

a

emulsion

test

for

test

for

water

so

that

you

can

see

the

negative

from

the

material

result

as

well.

vitamin

will

need

to

make

an

extract

you

are

testing.

fat This

DCPIP

with

protein You



test

C

involves

water

The

with

eye

so

a

pestle

chemicals

Safety:

Safety:

grinding

will

Some

always

of

wear

and

be

the

eye

up

a

small

mortar

in

amount

or

solution

chemicals

of

putting

in

the

used

the

it

material

into

a

with

some

blender.

extract.

in

these

tests

are

corrosive,

protection.

protection

T esting



Half

ll



Add

two

Iodine

• Figure

4.2.1

Test

for

A

a

tests

If

drops

usually

result

the

contain

are

for

the

of

food

iodine

looks

starch

extract

if

wish

to

test

for

starch.

solution

yellow

is

you

the

or

light

iodine

brown.

extract

remains

a

yellow

or

solution

light

turns

brown

blue–

colour

it

does

starch.



as

they

‘food

can

any

anim al

be

sugars

Put

a

known

mad e

in

a

volume

of

the

extract

you

wish

to

test

for

reducing

test-tube.

carried

plan t



Place

a

beaker



Carefully

half

(or

the

on

a

heat-proof

mat.

and

or

up

ll

the

beaker

with

boiling

water

from

a

kettle

on

in

place

beaker

on

a

tripod

and

gauze

and

boil

the

water

the with

labo ra to ry.



Add

a

Bunsen

the

burner).

same

containing

Safety:

reducing

tests’,

mater ial

so lu tions

for

of ten

sugars

on

three

with

TIP

know n

but

or

positive

T esting

out

test-tube

starch.

not

T hese

starch

solution

black.

STUD Y

for



Benedict’s



A

positive

volume

the

food

solution

test

for

of

Benedict’s

extract

is

and

bright

simple

put

solution

it

into

the

to

the

hot

test-tube

water.

blue.

sugars

is

when

Benedict’s

solution

turns

eye red

or

orange

(if

you

look

carefully

you

can

see

it

turn

green

and

protection then

cool



d

t

you

can

present.

B

o

You

yellow

t

will

use

If

of



Test

for

reducing

colour

If

the

a

reducing

lot

colour

of

a

orange).

If

you

leave

the

test-tube

to

precipitate.

test

to

changes

sugars.

sugars.

reducing

remains

sugars.

reducing

40

see

Benedict’s

the

the

contains

4.2.2

also

turning

tell

to

how

much

green,

the

simple

extract

sugar

is

contains

only

a

o

little

Figure

before

blue

If

it

turns

a

deep

orange

colour

then

sugars.

then

the

extract

does

not

contain

any

it

T esting

for

protein Safety:



Half

ll



Add

ve

copper

a

test-tube

to

six

drops

sulfate

Safety:

T ake



solution

with

of

solution

care

as

the

extract

biuret

and

sodium

you

wish

solution

sodium

to

(this

solution

for

solution

hydroxide

hydroxide

test

protein.

contains

solution).

is

corrosive. S od

h

Biuret



A

positive

violet



If

the

or

usually

test

for

looks

protein

blue

is

if

in

the

colour.

biuret

solution

turns

C

um

yd ro x

s o

ut

e d

s

remains

Fats

will

for

not

solution

of

is

formed.



Chop

(Do



Put

up

not

the

blue,

then

the

extract

does

not

contain

protein.

Figure

4.2.3

Test

a

Put



Add



Shake

fat

in

water

ethanol

grind

add

in

a

small

water

extract

is

to

into

a

but

they

added

to

amount

make

clean

of

the

will

dissolve

water

a

material

extract

test-tube

cloudy

you

this

and

in

ethanol.

white

wish

to

If

a

1

emulsion

test

for

Describe

in

each

what

of

stopper

some

the

white

over

the

distilled

test-tube

water

contents

emulsion

positive

test

for

starch

b

a

positive

test

for

protein

c

a

positive

test

for

a

time.)

add

enough

ethanol

to

to

and

make

shake

the

up

the

test-tube

of

the

test-tube

once

d

a

negative

half

e

a

positive

test

for

that

looks

cloudy

does

not

for

Describe

of

is

vitamin

that

loses

C

its

happen,

juices,

can

Put

2

Fill

a

the

white

extract

or

a

milky

colour

is

does

not

contain

such

as

freshly-squeezed

made

from

when

it

volume

or

vitamin

comes

into

C

lemon

tablets.

contact

juice.

DCPIP

with

is

a

A

with

test

an

blue

vitamin

for

of

DCPIP

solution

in

a

dropping

pipette

with

a

a

juice,

the

e.g.

liquid

orange

one

drop

demonstrating

liquid

3

C.

You

the

are

each

the

colour

If

the

blue

of

DCPIP

solution

of

vitamin

C

a

glucose

given

are

a

to

carry

sugar

test

solution

four

a

of

test-tubes

different

glucose.

labelled

you

do

A,

not

B,

C

know

and

the

then

of

glucose

in

time.

the

the

test

test

is

is

positive

for

vitamin

tube.

C. have

been

told

to

nd

negative. which

most

is

the

solution

concentrated

least

is

the

and

which

concentrated.

POINTS Describe

the

procedures 1

Iodine

2

Benedict’s

solution

gives

a

blue–black

colour

when

added

to

solution

turns

orange

when

boiled

with

simple

to solution

gives

a

purple

or

violet

colour

when

you

would

and

the

observations

sugars. you

Biuret

practical

that

starch.

follow

3

how

reducing

containing

and

out

KEY

food

juice.

at

disappears

persists

a

sugar

or

You

colour

of

test-tube.

each

If

extract

reducing

concentration

Add

would

the

solution

D

3

of

procedures:

making

out

be

syringe

C

fat.

They a

vitamin

a

C

colour

known

for

you

each

concentration 1

starch.

fats.

vitamin

in

test

how

out

using C

for

more.

b

T esting

test

full.

to

Vitamin

sugar

contents.

a

this

see

a

following

positive

If

would

following:

a

carry



you

the

fats.

2

A

protein.

it.





for

QUESTIONS

reducing

cover

on

fats

dissolve

or

fate

ut

corrosive

SUMMARY

T esting

op p e

u

s o

on

purple,

lilac.

colour

eye

protection

added

would

give

expect.

safety

Remember

precautions.

to

protein. 4

Describe

the 4

A

white

emulsion

forms

when

fat

dissolved

in

ethanol

is

you

to

would

use

compare

C

content

of

the

different

water.

fruit

5

test

added

vitamin to

how

DCPIP

Vitamin

C

decolourises

DCPIP

juices.

solutions.

41

4.3

DNA

tnemelppuS

The LEARNING

Each •

Describe

structure

the

structure

of

two

to

form

strands

coiled

chromosome

double

State

that

DNA

chemicals

Describe

called

up

how

in

the

the

how

for

we

eye

the

bases

same

place

in

we

could

DNA

TIP

DNA

of

unravel

The

so

is

the

G,

of

DNA.

show

bases,

A,

each

are

Y ou

C,

remem ber

a

The

no t

need

what

colour

we

look

and

like.

height.

For

instance,

Some

genes

there

code

enzymes

that

control

all

the

chemical

reaction

thread

a

chromosome,

would

the

of

long

be

acid).

made

it

would

A

thread

gene

that

up

is

of

a

form

an

chemical

extremely

made

makes

up

up

a

of

a

called

long

short

DNA

length

chromosome

contains

genes.

belongs

to

acids.

a

complex

called

a

Each

DNA

group

of

molecule

biological

nucleotide.

A

single

is

made

up

molecules

nucleotide

of

known

is

thousands

made

up

of

of

as

units

three

phosphate



a

sugar



a

base

sugar

the

and

DNA

phosphate

strand.

The

molecules

bases

are

join

up

attached

and

to

form

the

the

sugar

backbone

molecules.

struct ure

nucl eo tid e

show n

you

look

at

Figure

4.3.1

you

will

see

that

DNA

is

made

up

of

two

in strands

Figu re

and

hair

to of

the

like

information

in

If

a

arranged

genetic

T

arrang ed

do

genes

the

molecules:



DNA.

of

block ’

diag rams

and

of

carry

a nucleic

how

that

always

hundreds

nucl eo tid e

T he

thousands

way

of

‘build ing

of

genes

cells.

(deoxyribonucleic

A

up

the

grow

colour,

production

take

thread.

STUD Y

is

bases

If pair

made

It

strands

that



is

necklace.

affects

genes

for

contain

a

helix are



in

together that

a

DNA

DNA beads

as

of

OUTCOMES

of

nucleotides.

It

is

rather

like

a

ladder.

The

whole

molecule

4 .3.2. is

twisted

bases

as

into

the

a

double

helix



a

bit

like

a

spiral

staircase

with

the

steps.

phosphate

base

P

sugar

The

DNA

looks

like

Figure

molecule

a

4.3.2

A

spiral

single

nucleotide.

phosphates

make

The

up

the

sugars

and

‘uprights’

of

staircase

the

ladder

and

the

bases

make

up

the

‘rungs’.

Base

A

T

So

C

G

If

how

you

Each

T

A

G

C

on

Figure

42

4.3.1

A

DNA

model.

of

bases

the

the

the

look

pair

at

of

The

DNA

don’t

bases

molecule

Figure

bases

bases

thymine

(You

pairs

is

different



form

pairing

in

4.3.3

held

you

together?

can

together

see

by

that

weak



have

to

adenine

(A)

remember

pair

up

in



each

the

of

same

the



cytosine

(A)

(C)

pairs

pairs

with

with

thymine

guanine

(T)

(G)

(C)

names,

way:

steps

adenine

bases

bonds.

cytosine

staircase



the

join

There

together.

are

four

DNA:

(T)

always

is

held



guanine

just

their

(G)

letters.)

are

the

weak,

double

bonds

there

helix

in

are

holding

many

of

the

two

them.

chains

So

of

nucleotides

altogether

they

tnemelppuS

Although

together

keep

the

DNA

shape.

cytosine

guanine

adenine

thymine

A

student

shows

(guanine)

thymine

examines

the

pairs

is

of

yellow

a

model

bases.

and

C

In

of

DNA

this

that

model

(cytosine)

is

G

red.

adenine

phosphate

guanine

cytosine

sugar

weak

Figure

4.3.3

How

SUMMARY

1

Figure

4.3.4

of

bases

pair

up

in

DNA.

QUESTIONS

molecule.

letters

the

bonds

shows

Copy

the

a

and

partially

completed

complete

missing

the

section

diagram

by

of

the

writing

DNA

in

the

bases.

James

the

They

G

Figure

2

The

table

DNA

below

from

four

C

A

T

Watson

structure

they

are

and

of

posing

made

in

Francis

DNA

with

by

Crick

worked

building

their

Cambridge

nal

in

the

out

models.

model

early

that

1950s.

4.3.4

shows

the

different

percentages

of

the

four

bases

in

KEY

POINTS

organisms.

1

percentage

of

each

base

The

two

DNA

molecule

strands

coiled

consists

of

together

organism

to A

C

G

T

human

31

19

19

31

locust

29

21

21

29

2

form

Each

a

double

strand

chemicals

and

yeast

32

18

18

32

bacterium

15

35

35

15

3

A

C

a

Explain

b

In

A.

c

an

the

pattern

organism

What

Explain

shown

26%

percentage

how

organisms

it

is

such

percentages

of

of

the

DNA

be

to

humans

bases.

the

table.

bases

would

possible

as

in

C?

have

and

in

4

DNA

Show

two

yeast

are

your

very

with

found

to

very

similar

called

always

bonds

bonds

chromosome

long

bases

bond

with

with

is

A,

C,

G

together.

T;

G.

made

super-coiled

up

strand

of

of

DNA.

working.

different

contains

which

always

A

a

be

T ,

helix.

5

A

gene

that

of

a

is

a

codes

length

for

particular

the

of

DNA

production

protein.

43

PRACTICE

1

What

QUESTIONS

are

the

chemical

A

carbon,

hydrogen

B

carbon,

hydrogen,

elements

and

in

Use

proteins?

the

nitrogen

and

molecules

molecules

oxygen

shows carbon,

hydrogen,

of

nitrogen,

oxygen

a

are

known

questions

6–8.

small

part

of

sub-unit

nucleotides.

of

a

DNA

The

diagram

molecule.

and

B

carbon,

(Paper

for

composed

as

sulfur

D

DNA

oxygen DNA

C

diagram

nitrogen,

oxygen

and

sulfur

1)

[1]

C A

2

The

small

proteins

molecules

that

are

built

up

into

are:

A

amino

B

fatty

acids

acids

(Paper

1)

Which

row

C

glucose

D

glycerol

[1]

D

3

four

gives

chemical

the

positive

results

for

the

tests?

Benedict’s

biuret

iodine

emulsion

test

test

test

test

green

violet

yellow

Adenine

no A

X

suspension

6

Which

of

the

labelled

parts

of

DNA,

A,

B,

C

or

D,

no B

blue

blue

indicates

yellow

a

base

pair?

suspension

(Paper

2)

Which

of

[1]

cloudy C

yellow

red

blue suspension

D

orange

7

indicates

blue-

cloudy

black

suspension

4

Water

1)

is

because

[1]

an

it

important

is

molecule

in

8

organisms

a:

A

solute

C

solvent

B

solution

D

suspension

What

9

5

1)

Enzymes

regions

that

form

[1]

and

of

bind

antibodies

these

to

parts

of

DNA,

A,

B,

C

or

proteins

other

specic

are

proteins.

have

molecules.

shapes

A

molecules

of

B

molecules

with

because

D,

different

[1]

the

structure

labelled

X?

A

adenine

(A)

C

guanine

(G)

B

cytosine

(C)

D

thymine

(T)

The

2)

[1]

diagram

molecule

below

increases

shows

in

how

specic

a

starch

length.

A

Special

Proteins

they

2)

is

(Paper

(Paper

labelled

nucleotide?

violet

(Paper

(Paper

the

a

shapes

can

have:

lengths

different

numbers

of

amino (a)

Name

molecule

(b)

Name

two

A.

[1]

acids

C

molecules

with

different

sequences

places

where

starch

is

stored

plants.

amino

[2]

acids (c)

D

molecules

with

other

molecules

or

Describe

to

plant

would

nd

out

whether

tissue

contained

details

of

the

starch.

test

in

Include

your

the

answer.

[4]

[1]

(Paper

44

you

them practical

2)

how

ions a

attached

(Paper

in

of

3)

10

The

diagram

shows

a

protein

5

molecule:

Repeat

steps

1

to

4

with

the

juices

to

be

tested.

The

(a)

Name

the

sub-unit

molecules

that

results

are

shown

in

the

table.

are

volume

assembled

into

the

protein.

added

to

DCPIP

[1] 3

test

(b)

Name

two

proteins

found

in

the

solution

substance

/

cm

human

body.

1

2

3

mean

1.8

1.9

2.1

1.9

2.4

2.6

2.3

2.4

3.2

3.1

2.9

3.1

9.6

9.1

9.4

9.4

[2]

−3

(c)

(d)

State

two

places

many

proteins

Some

seeds

the

are

are

chemical

in

the

body

in

that

10 g dm

where

made.

rich

test

human

proteins.

orange

Describe

would

use

juice

to grapefruit

determine

whether

different

types

of

rich

details

in

of

proteins.

the

test

Include

in

your

the

answer.

[4]

The

Explain

why

readings

3)

(b) 11

juice

practical

(a)

(Paper

juice

seed apple

are

diagram

shows

a

molecule

of

a

Use

the

the

for

results

(Paper

13

juices.

Name

the

(a)

components

of

the

DNA

of

vitamin

Show

molecules

X

and

Y.

the

your

C

in

the

three

working.

[3]

two

places

are

stored.

State

in

the

human

body

a

double

what

this

helix

means.

[2]

the

precise

site

of

DNA

in

an

cell.

[2]

where The

sequence

of

bases

in

a

small

sample

[2] of

three

have

Explain

[2] animal

State

calculate

[3]

molecule (b)

labelled

(c)

substance.

4)

structure.

fats

three

Y

X

List

to

test

took

fat.

fruit

(b)

student

each

concentration

(a)

C

solution

[2]

you

vitamin

roles

of

fats

in

the

DNA

is:

human ATAGATCCCGAA

body.

[3] (c)

(d)

Oils

have

the

same

molecular

structure

Write

out

opposite

fats.

Many

seeds

are

rich

in

oils.

chemical

test

to

nd

out

whether

different

owering

plant

The

oil

or

not.

Include

strand

DNA

of

of

the

test

in

your

A

student

the

used

vitamin

the

C

is

DCPIP

test

present

in

answer.

to

The

concentration

of

nd

out

different

the

the

DNA

molecule.

[1]

determines

of

a

a

small

protein.

above

to

explain

Use

how

determine

the

sequences

base

of

[4] acids

in

a

protein.

[1]

how In

2007,

scientists

compared

the

degree

fruit of

juices.

in

practical

(e)

much

this

structure

sequence

amino

12

in

sequence

the

sequences details

bases

species the

contain

of

seeds part

from

sequence

Describe (d)

a

the

as

DCPIP

similarity

between

some

of

the

DNA

solution taken

from

the

nuclei

of

white

blood

cells

−3

was

10 g dm

.

The

student

followed

these of

a

domesticated

cat

and

several

other

instructions. mammalian

species.

The

results

are

below.

3

1

Put

2

Use

2 cm

of

DCPIP

solution

into

a

test

tube. percentage

a

graduated

pipette

or

burette

to

similarity

between

add domesticated

cat

and:

−3

a

10 g dm

vitamin

C

solution

drop

by wild

drop

to

the

DCPIP

solution.

Shake

the

tube

human

dog

cow

rat

mouse

90

82

80

69

67

cat

gently

add

of

after

the

the

adding

vitamin

DCPIP

C

each

drop.

solution

solution

Continue

until

the

to

colour

99

disappears.

What 3

Record

that

4

the

was

Repeat

of

vitamin

C

a

(Paper

procedure

mean

two

more

do

you

conclude

from

these

results?

[3]

solution

added.

the

calculate

volume

times

4)

and

volume.

45

5

Enzymes

5.1

Structure

and

action

of

enzymes

A LEARNING

catalyst

end



Dene

the

substance

term

that

catalyst

speeds

chemical

reaction

changed

by

the

and

as

up

is

a

of

speed

Dene

enzymes

the

up

act

not

How

as

as

speed

biological

up

the

tnemelppuS

Explain

using

rate

how

the

an

‘lock

enzyme

and

key’

works

too

catalyses

many

of

in

Breaking

is

2

They

take

keep

are

different

of

3

of

storage

are

known

place

in

organisms

many

as

at

organisms,

biological

organisms.

alive

different

reaction.

shows

its

(see

we

will

Topics

of

3D

enzymes

Most

discuss

7.5

and

up

in

nutrition

the

large

cell

the

one

when

that

they

These

unless

types

they

of

enzymes

the

that

catalysts

reactions

are

enzyme

speeded

as

work

each

inside

cells,

here

work

outside

cells,

for

7.7).

gut

for

as

work

of

large

to

down

small

cells

and

types.

and

their

are

broken

then

food

used.

and

we

reason.

joined

inside

starch,

three

molecules

absorbed

break

from

into

ones

food

be

same

are

divided

ones

together

to

speed

structural

to

up

make

the

large

formation

molecules

such

as

plants.

small

chemical

as

be

small

the

glucose,

such

can

can

enzymes

enzymes

walls

into

molecules

such

molecules,

for

so

release

into

These

catalyse

molecules

ones

fungi

Converting

molecule

reactions

that

into

occur

another

inside

cells

involve

small

an

changes right)

that

molecules,

Many

image

that

gut

enzymes

cellulose

computer-generated

those

large

and

molecules.

to

molecules,

such

as

adding

or

removing

atoms

or

groups

shape.

of

atoms.

from

For

example,

compounds

Figure

5.1.1

breakdown

shows

of

a

there

during

the

are

enzymes

that

remove

hydrogen

respiration.

way

in

which

an

enzyme

catalyses

the

molecule.

TIP

writi ng

enzy mes

abou t

alwa ys

enzy mes

reactio ns.

say

enzyme

substrate

substrate

active

cata lyse

Figure

Figure

from

46

to

There

small

Building

Small

that

reactions

important

into

release

Whe n

a

the

reactions

Bacteria

STUD Y

unchanged

by

model

down

the

remains

produced

work

slowly

enzymes.

example

This

(on

and

reactions

1

enzyme

reaction

proteins,

of

The

This

reactions.

enzymes

chemical

by

but



chemical

are

catalysts

one chemical

chemical

proteins

up to

a

Enzymes

reaction

happen that

up

reaction.

a

Many •

speeds

OUTCOMES

in

enzyme

products

site

released

5.1.1

5.1.2

two

shows

smaller

how

an

enzyme

molecules.

is

involved

in

building

a

molecule

Enzymes

are

made

All

enzymes

have

1

They

are

all

2

Each

enzyme

3

They

can

4

They

are

inuenced

by

temperature.

5

They

are

inuenced

by

pH.

ve

of

protein

important

properties.

proteins.

be

catalyses

used

one

again

reaction.

and

again.

active

site

substrate

Enzymes

are

made

of

protein

molecules.

These

molecules

can

be enzyme

folded

a

into

shape

many

that

explains

different

makes

why

there

it

shapes.

suitable

are

many

for

Each

type

catalysing

different

of

enzyme

one

enzymes

type



one

molecule

of

has

reaction.

enzyme

for

This

each

substrate

in

reaction. active

Enzymes

catalyse

products.

Look

reactions

at

enzyme

matches

and

substrate

the

together.

Once

Figure

the

t

which

5.1.1.

shape

have

they

in

of

Notice

the

shapes

substrates

that

together

that

substrate

are

the

the

are

converted

shape

molecule.

of

part

The

complementary

reaction

can

take

site

into

of

the

enzyme

so

place.

they

t

product

Other

released

substrates

involved

have

in

the

the

wrong

reaction

shape

catalysed

to

t

by

into

this

the

enzyme

enzyme.

so

When

will

the

not

be

reaction

is

Figure

5.1.2

This

shows

enzyme

over

the

product

or

products

leave

the

enzyme

and

another

tnemelppuS

As

you

an

join

two

substrate molecules

molecule

how

can

together.

enters.

can

substrate(s)

This

way

of

key’

model.

lock

to

see

t

in

Figure

and

describing

The

form

an

5.1.2

where

the

how

enzyme

the

part

reaction

enzymes

and

of

work

substrate

enzyme-substrate

the

takes

is

enzyme

place

is

known

combine

like

where

the

as

a

the

active

the

key

site.

‘lock

substrate

A

substrate

B

and

entering

a

complex enzyme

Figure

5.1.3

Only

the

SUMMARY

Copy

and

complete

the

sentences

using

these

words:

1

Enzymes

catalysts

proteins

are

biological

that

up

the

rate

.

type

Enzymes

of

are

the

meant

3

Use

a

terms

by

the

why

the

‘lock

each

all

and

each

enzyme

why

an

rate

Enzymes

catalyse

in

substrate

reactions

acts

which

complementary

and

key’

enzyme

key’

model

will

and

active

model

act

to

of

site

to

enzyme

explain

what

is

only

on

molecules,

action.

explain:

3

one

converted

or

breaking

All

enzymes

molecules.

substrate

enzyme

can

be

used

to

catalyse

a

large

quantity

to

molecules

the

product

either

up

where b

the

.

‘lock

and

increase

reactions.

by

building

down.

are

Part

protein

of

the

reaction

enzyme

occurs

has

of

a

complementary

shape

to

substrate

the c

why

high

destroying

the

temperature

active

stops

site

the

by

heating

enzyme

from

the

enzyme

working

to

substrate

molecule(s).

a

4

The

of

active

the

site

enzyme

substrate

reaction

ts

is

the

part

where

and

tnemelppuS

tnemelppuS

Use

biological

that

chemical

are

2

are

of

2 chemical

one

t

site.

reactions

of

on

will

POINTS

catalysts speed

Enzymes

A

active

QUESTIONS KEY

1

substrate

enzyme’s

the

where

the

occurs.

47

5.2

Factors

affecting

action:

The LEARNING

activity

Carry

the

out

an

effects

enzyme

investigation

of

into

temperature

on

reaction

measuring

substrate

the

activity

Describe

enzyme

the

effects

temperature

on

that

how

is

e.g.

the

is

determined

enzyme

much

used

reaction

time, •

an

temperature

by

measuring

the

rate

of

OUTCOMES the



of

enzyme

product

over

a

measured

per

catalyses.

is

period

in

This

formed

of

time.

quantity

of

may

or

by

The

done

either

measuring

rate

product

be

or

is

like

how

the

substrate

by

much

speed

per

of

unit

of

minute.

of

enzyme

Effect

of

temperature

on

enzymes

activity

Explain

the

effects

activity

of

enzymes

is

inuenced

of 6.0

by temperature

on

temperature.

This

graph

shows

enzyme

effect

of

increasing

temperature

nim

the

1–

activity

on

the

rate

of

an

enzyme-catalysed

tcudorp

reaction.

the

can

reaction:

slow

are

use

this

some

from

the

answ er .

say

the

low

temperatures,

10 °C

desc ribin g •

like

at

at

increases

as

the

increases

to

40 °C

etar

alwa ys

your

of

observe

4.0

3.0

2.0

fo

you

grap h

take n

rate

and

noitcaer

is

e.g.

a

graph

TIP •

Whe n

the

/

that

STUD Y

at

gm

Look

5.0

temperature

one,

1.0

gu res

grap h

Here



reaches

a

maximum



decreases

at

0

40 °C

in

10

at

5.6

mg

min ute

at

high es

greater

t

prod uct

per



is

zero

the

than

be

describ e the

tempe rature

enzy mes,

4

aske d

40 °C

and

effec t

and

but

will

explai n,

enzyme.

fungal



human



some

which

Here

and

plant

are

the

some

maximum

37 °C

enzymes

rate

This

examples

enzymes:

enzymes:

of

the

temperature.

of

is

20 °C

temperature

produced

by

reaction

best

optimum

approximately

(body

of

the



bacteria

for

is

for

temperatures:

(see

see

occurs

temperature

page

T opics

use

in

250)

7.5

and

industry:

7.7)

90 °C.

be

saw

in

the

T opic

5.1,

an

enzyme

substrate

molecules.

by

between

molecule

The

shape

is

of

folded

an

into

a

enzyme’s

shape

active

that

site

bonds

different

parts

of

the

molecule.

is

Remember

that

the

shape

into

the

enzyme

of

the

active

site

determines

whether

the

substrate

will

t

on for

the

reaction

to

occur .

in

aske d

At

rst,

will

increasing

increase

have

the

greater

there

are

the

rate.

kinetic

more

temperature

This

is

energy.

chances

of

of

because

They

them

an

enzyme-controlled

enzyme

move

and

around

colliding,

the

substrate

more

reaction

molecules

quickly

substrate

tting

and

into

remem ber the

are

tempe ratures

of

we

of

pH

pH.

active

site

and

a

reaction

taking

place.

protei ns

denat ured

extrem es

by

and

At

higher

together

site,

We

so

say

temperatures

start

the

to

break

substrate

that

catalyse

48

at

optimum

maintained

only

you

enzy mes

are

the

to

inu ence enzy mes. Whe n

high

5.2.1

60 °C.

temperature

accepts

to exp lain ho w thes e fact ors

that

at



As

you

60

°C

TIP

may

Paper

50

/

40 °C .

called

Y ou

40

rate

The

STUD Y

30

temperature

Figure

is

20

temperatures

you

the

the

the

no

enzyme

reaction.

bonds

down.

This

longer

has

holding

the

changes

enzyme

the

shape

molecule

of

the

active

no

longer

ts.

been

denatured

and

it

can

tnemelppuS

tnemelppuS

The •

PRACTICAL

Investigating

Amylase

is

changes

iodine

iodine

an

the

enzyme

like

not

temperature

breaks

down

blue-black.

change

starch

When

colour.

on

enzyme

to

starch

Draw

a

action

maltose.

is

broken

table

for

Starch

down,

your

this.

temperature

and

will

of

that

solution

solution

results

effect

starch

at

which

was

kept

/

amylase

time

°C

taken

fully

for

broken

starch

down

/

to

be

min

Figure

5.2.2

T esting

starch

the

in

solution

for

iodine.

3

1

Put

A,

5cm

B,

C,

of

starch

and

solution

into

each

of

four

test

tubes

labelled

D.

2

Put

test

tube

A

into

the

refrigerator

3

Put

test

tube

B

into

a

test

4

Put

test

tube

C

into

a

water

tube

and

note

the

temperature.

and

note

the

temperature.

rack

bath

at

about

35°C

and

note

the

temperature.

5

Put

test

tube

D

into

a

water

bath

at

about

80°C

and

note

the

temperature.

3

6

Collect

7

Put

a

of

10cm

drop

spotting

of

amylase

iodine

solution

solution

into

in

a

clean

each

of

boiling

the

wells

tube.

on

a

tile.

3

8

Add

2cm

note

9

At

the

amylase

test

iodine

When

solution

to

each

of

the

four

tubes

and

KEY

time.

two-minute

the

10

of

intervals

solution

solution

the

from

on

each

the

amylase

use

a

clean

test

tube

spotting

solution

pipette

and

to

remove

add

it

to

a

some

drop

of

1

of

has

broken

down

all

the

Increasing

of

tile.

POINTS

an

iodine

solution

will

no

longer

turn

blue-black.

temperature

reaction

increases

reaction

up

to

a

the

rate

of

maximum,

starch which

the

the

enzyme-controlled

They

occurs

at

the

optimum

will temperature.

brown.

on

What

the

does

this

tell

you

about

the

effects

of

amylase?

This

is

because

energy

SUMMARY

QUESTIONS

is

number

enzyme

1

a

Sketch

a

graph

temperature

to

on

show

the

rate

the

of

effect

a

of

increasing

reaction

catalysed

enzyme,

such

as

salivary

Describe,

in

words,

what

is

Suggest

what

each

reaction

catalysed

of

by

the

shown

a

following

human

At

higher

by

your

a

temperature

below

b

a

temperature

of

c

a

temperature

of

temperatures

the

would

do

of

reaction

decreases

graph.

to

the

rate

of

it

stops

acting

as

a

catalyst.

enzyme: This

a

between

substrate

amylase.

until

2

collisions

and

kinetic

greater

a

rate

b

of

a

molecules.

by

2 human

greater

causing

tnemelppuS

light

temperature

tnemelppuS

stay

10 °C

is

shape

37 °C

due

of

to

the

means

the

longer

t.

a

change

active

site

substrate

The

in

can

enzyme

the

which

is

no

now

50 °C

tnemelppuS

denatured.

3

Use

the

‘lock

enzymes

are

and

key’

model

denatured

at

to

high

explain

what

happens

when

temperatures.

49

5.3

Enzymes

The LEARNING

Describe

enzyme



Carry

the

effects

of

pH

enzymes

on

i.e.

action

out

the

an

at

a

that

low

of

pH

tnemelppuS

Explain

active

in

the

is

can

be

present

affected

stomach

work

in

the

by

the

best

stomach,

pH

in

acidic

so

of

the

conditions,

pH.

bile

is

that

present

are

in

active

the

rst

here

part

work

of

best

the

in

small

alkaline

intestine,

so

conditions,

the

i.e.

at

a

activity

the

effects

of

pH

pH.

on

Most enzyme

enzymes

work

best

inside

cells

where

the

conditions

are

neutral.

action

The

optimum

Enzymes

Enzymes

Many

pH

of

and

are

these

is

therefore

about

pH

7.0.

pH

inuenced

enzymes

enzymes

work

by

best

the

in

pH

of

neutral

their

surroundings.

conditions,

but

some

work

best

substrate

enzyme

in

Enzyme



the

acidic

conditions

and

some

in

alkaline

conditions.

denatured

substrate

fits

Figure

are

acid

on

high



reaction

Hydrochloric

investigation

effects

enzymes

enzyme

enzyme-controlled

surroundings.

Alkaline

into

of

pH

OUTCOMES its



rate

and

no

active

longer

site

Look

and

at

the

graph

in

Figure

5.3.2

showing

the

action

of

enzymes

X

Y .

5.3.1



Enzyme



The



Up

X

works

optimum

best

pH

for

at

pH

2.0

enzyme

Y



is

that

pH

is

its

optimum

pH.

8.0.

6.0

to

pH

2.0

the

rate

of

reaction

increases

for

enzyme

X

and

then

5.0

between

pH

2.0

and

pH

5.5

it

decreases.

There

is

no

reaction

above

1–

fo

tcudorp

noitcaer

nim

pH

5.5.

4.0



3.0

Between

Y

and

pH

then

gm

etar

reaction

4.5

and

between

below

pH

pH

pH

4.5

8.0

the

8.0

and

rate

and

pH

above

of

reaction

10.0

pH

it

increases

decreases.

for

There

enzyme

is

no

10.0.

2.0

enzyme

X

enzyme

Y

As

we

vital

0

0

1

2

3

4

5

6

7

8

9

10

11

pH

if

have

it

is

structure

seen,

to

of

the

three-dimensional

function.

the

Many

enzyme

are

of

the

weak

shape

chemical

bonds.

If

of

an

bonds

these

enzyme

holding

bonds

is

the

that

acid

Figure

5.3.2

STUD Y

TIP

hold

the

enzyme

then

the

shape

reaction

is

that

substrate

At

is

say

kille d’.

no t

enzy me

Enzy mes

orga nism s.

are

pro te in

T he

co rrec t

dena tured.

50

‘the

are

T hey

mo lec ules.

wo rd

to

use

is

at

the

these

can

Never

molecule

of

values

affect

the

zero,

the

the

of

rate

extremes

denatures.

the

of

in

active

shape

of

molecules

pH

of

its

shape

site

the

will

enzymes

reaction

pH

are

can

be

active

no

are

an

by

altered.

site

longer

has

the

changed

Small

denaturing

enzyme

changes

When

in

pH,

rate

so

of

much

t.

denatured.

without

range

broken

changes

the

becomes

in

enzyme,

unstable

pH

but

and

tnemelppuS

/ 1.0

PRACTICAL

The

effect

Egg

white

egg

pH

on

contains

investigate

in

of

the

white.

a

lot

effect

You

the

of

will

action

of

protein.

protease

also

of

see

a

In

this

from

how

protease

the

pH

experiment

stomach

affects

the

you

on

will

the

way

protein

the

enzyme

works.

1

Set

up

a

water

bath

2

Using

syringe

put

3

Add

2 cm

4

Add

2 cm

at

40 °C

and

label

three

test

tubes

1–3.

3

a

of

5 cm

egg

white

into

each

test

tube.

3

of

sodium

of

water

carbonate

(an

alkali)

to

tube

1.

This

is

a

model

of

protease

that

breaks

3

to

tube

2.

down

proteins

intestine.

It

to

amino

works

best

acids

at

a

in

pH

the

of

small

about

8.5

3

5

Add

2 cm

6

Compare

each

of

the

tube

to

dilute

hydrochloric

pH

each

of

dip

into

test

the

acid

tube

by

solution

to

tube

using

and

a

then

3.

and

clean

touch

glass

the

rod

pH

at

37 °C.

for

test KEY

POINTS

paper.

7

Place

all

three

8

Add

9

Compare

test

tubes

in

the

water

bath

at

40 °C

for

ve

1

minutes.

Most

one

enzymes

value

of

work

best

at

pH.

3

of

protease

to

each

test

tube.

2 the

appearance

of

the

tubes

every

minute

until

At

either

side

optimum is

no

further

the

table

pH

value,

enzyme

At

some

shape white

appearance

+

changes 5

plus:

values

of

the

of

pH

active

the

site

after

pH

tube protease

decreases.

below. 3

egg

their

change. activity

Complete

of

there

tnemelppuS

1 cm

so

that

substrate

minutes

molecules

no

longer

t.

3

2 cm

of

sodium

1 carbonate

solution

3

2

2 cm

of

water

3

2 cm

of

3 hydrochloric

SUMMARY

1

Sketch

the

a

QUESTIONS

graph

optimum

2

Use

3

An

the

‘lock

to

pH

and

investigation

Eight

The

test

acid

tubes

show

is

7.0

key’

was

were

concentration

of

the

and

effect

there

model

carried

set

up

to

reducing

increasing

no

explain

out

at

of

is

a

into

activity

what

the

sugar

pH.

a

Plot

a

b

Explain

of

graph

the

reducing

to

show

effects

of

sugar

these

pH

produced

of

was

the

pH

pH

They

(product)

pH

concentration

on

happens

effects

different

pH

below

rate

4.0

when

on

were

then

of

and

an

enzymes

the

action

incubated

estimated.

4.0

5.0

6.0

1

12

26

enzyme-catalysed

none

are

of

in

above

The

enzyme

water

bath

results

are

reaction,

where

10.0.

denatured

the

a

pH

at

extremes

amylase

at

30 °C

shown

6.5

7.0

8.0

9.0

32

33

27

13

on

for

in

of

pH.

starch.

1

the

hour .

table.

10.0

5

results.

on

the

action

of

amylase

in

this

investigation.

51

PRACTICE

QUESTIONS

1

the

Which

is

correct

statement

about

enzymes?

5

In

an

enzyme-catalysed

binds A

Enzymes

are

biological

catalysts

to

B

inside

Enzymes

only

C

are

outside

catalysts

function

Enzymes

and

are

inside

are

used

they

catalyse.

up

of

protein

Enzymes

only

substances

catalyse

are

made

the

by

cells

reactions

reactions

broken

substrate

down

in

into

site

B

complementary

as

C

reaction

D

substrate

site

site

site

2)

[1]

which

smaller

6

Albumen

and

in

1)

is

the

at

a

protein

blood.

75 °C

A

and

found

solution

then

in

egg

of

added

white

protease

to

a

was

solution

of

[1] albumen.

The

the

molecule

the:

active

kept

2

enzyme

that

molecules.

(Paper

as

A

(Paper D

reaction,

the

that

cells.

during

of

cells.

made

continually

they

part

that

known function

the

equation

shows

a

reaction

catalysed

by

No

reaction

occurred.

an Which

is

the

most

likely

explanation?

enzyme.

A

75 °C

is

below

the

optimum

temperature

lipase of fat

+

water



fatty

acids

+

B

The

progress

of

the

reaction

the

protease

glycerol

can

be

albumen

cannot

be

broken

down

by

followed proteases

by

detecting

the

decrease

in

pH.

This

is C

the

protease

D

there

is

denatured

because:

A

fat

is

an

acidic

the

B

fatty

acids

they

lower

are

one

of

the

products

the

no

D

the

reaction

is

a

1)

Starch

and

kinetic

energy

for

2)

[1]

stops

when

the

pH

decreases

7

The

diagram

possible

shows

an

enzyme

and

four

substrates.

reactant A

(Paper

enough

pH

further

water

not

reaction

and

(Paper

C

was

substance

C

B

D

[1]

enzyme

3

together

human

at

salivary

different

temperature

will

amylase

were

temperatures.

give

the

fastest

mixed

Which

rate

of

starch

digestion?

A

20 °C

B

60 °C

C

37 °C

Which

of

substrate D

(Paper 1)

shown

is

the

enzyme?

pH

2)

of

enzyme-controlled

reactions

changed

affect

the

from

rate

of

pH

the

A

always

increases

B

always

decreases

C

has

effect

D

may

the

(Paper

no

change

on

the

7

to

pH

8.

How

does

The

optimum

reactions?

the

the

the

rate

rate

rate

rate

or

have

no

temperature

effect

reaction

is

the

for

an

enzyme-

temperature

at

which:

this

on

rate.

1)

[1]

may catalysed

52

substances

this

[1]

8 The

be

for

10 °C

(Paper

4

the

[1]

A

least

B

most

C

the

D

the

(Paper

substrate

product

rate

of

is

broken

is

down

formed

reaction

reaction

2)

is

is

at

completed

its

in

fastest

the

longest

time

[1]

9

(a)

Explain

the

following

statements.

A

(i)

Only

small

required

(ii)

Cells

quantities

inside

make

of

enzymes

cells.

many

B

are

[2]

different

types

of

1

3

enzymes,

The

the

table

shows

relative

solution

at

not

the

activity

pH

just

one.

effect

of

an

of

[2]

temperature

enzyme

kept

in

on

C

a

7.

2

relative temp

/

°C activity

5

4

15

8

(a)

State

(b)

Use

the

the

when

25

16

35

32

45

30

55

7

(c)

(d)

the

when

(b)

Explain

why

kept

the

at

all

the

same

reaction

mixtures

were

pH?

Draw

a

graph

(d)

Describe

of

the

results

in

the

table.

results

Hydrogen

shown

in

the

graph. [4]

(a)

model

to

is

what

a

happens

reaction.

known

explain

enzyme

what

molecule

temperatures

peroxide

is

produced

metabolism.

as

[4]

‘lock

or

happens

changes

extremes

of

shape

pH.

[4]

is

a

very

toxic

substance

The

by

cells

enzyme

peroxide

and

as

part

of

catalase

is

found

their

breaks

in

down

organisms

in

3) all

10

model

[3]

4)

hydrogen (Paper

describe

catalyses

C.

[6] which

the

and

[2] 12

(c)

the

B

[2]

the

high

(Paper

to

enzyme

why

A,

key’.

Use

in

of

diagram

an

Explain

and

names

Explain

the

following

kingdoms.

statements.

catalase (i)

Amylase

digests

starch,

but

proteases Hydrogen

do

not.

Human

enzymes

catalyse

reactions

student

but

not

at

73 °C.

table

shows

enzyme

kept

35 °C.

the

in

relative

solutions

activity

of

investigated

in

yeast

by

the

activity

measuring

of

the

the

enzyme

volume

of

a

different

collected

over

time.

The

graph

of

shows

the

results.

pH 3

human

water

[2] oxygen

The

+

at catalase

37 °C,

oxygen

[1]

A (ii)

peroxide

mc

at

7

/

relative

3

detcelloc

pH

activity

5

32

9

10

emulov

7

fo

14

negyxo

5

6

5

4

3

2

1

×

0

0

11

20

40

60

80

time

(a) (b)

Explain

why

all

the

reaction

mixtures

Use

at

35 °C?

Draw

a

graph

Describe

the

results

catalase

of

the

results

in

the

table.

140

on

shown

to

hydrogen

describe

the

[4]

Explain

results

shown

in

the

why

catalyse

catalase

the

is

the

breakdown

only

of

enzyme

hydrogen

graph. [4] peroxide.

(Paper

3)

(c)

Describe

catalyses 11

The

diagram

reaction.

effect

peroxide.

[6] to

(d)

120

s

[3]

(b) (c)

the

/

were of

kept

100

4

shows

an

[2]

what

a

happens

reaction.

when

an

enzyme

[4]

enzyme-catalysed

(Paper

4)

53

Plant

nutrition

6.1

Photosynthesis

The LEARNING

process

When





Dene

State

the

the

term

Describe

leaf tnemelppuS



for

State

photosynthesis

word

how

equation

for

look

round,

green

energy

to

into

to

test

a

green

starch

the

you

at

cells

Photosynthesis

raw

is

called

carbon

sugars.

This

the

materials

dioxide

process

process

using

Describe

the

by

can

role

of

chlorophyll

carbon

be

dioxide +

balanced

+

equation

This

is

full

of

not

that

TIP

tnemelppuS

this

is

there

of

the

balanced

write

it

out.

are

the

atoms

their

see

use

many

light

surroundings

photosynthesis

plants

make

carbohydrates

light.

in

of

and

this

word

equation:

chlorophyll

glucose

equation

6H

for

photosynthesis

and

a

case.

H

6

There

different

photosynthesis

are

oxygen

is:

C

that

+

chlorophyll

O

suggests

the

by

energy

transferred

sure

you

plants

many

is

one

reactions

in

O 12

+

6O

6

simple

2

reaction.

photosynthesis,

each

enzyme.

chloroplasts.

Light

Make

from

2

This

catalysed

STUDY

from

Green

water

2

are

called

summarised

chemical

6CO

cells

microscope

water

which

energy

light

plant

the

photosynthesis

The

These

and

is

light



under

chloroplasts.

chemical Photosynthesis

for

leaf

structures

convert

simple

from

balanced

equation

some

photosynthesis

photosynthesis



of

OUTCOMES

equation

when

you

Make

same

form

the

The

becomes

sure

are

the

carbon,

As

by

to

a

is

a

water

used

to

are

the

bond

Glucose

as

chemical

from

is

result,

starch

chlorophyll.

as

ions

chemical

produced.

converted

energy

hydrogen

carbohydrate.

number

absorbed

chlorophyll

carbohydrates

process

oxygen.

is

by

used

to

in

simple

store

of

energy

to

the

energy

in

carbon

simple

that

During

leaves

that

produced;

and

and

to

chlorophyll

sugars

is

ions

dioxide

by

is

reactions

hydrogen

absorbed

sugar

light

the

dioxide.

into

reduce

from

drive

carbon

water

energy

energy

one

and

split

light

The

energy

other

it

is

parts

of

plants.

hydrogen

and

both

of

sides

oxygen

the

on

Photosynthesis

arrow.

that

feed

show

that

oxygen

carbon

dioxide

on

where

in

it

provides

plants

oxygen

its

is

is

own

used

energy

directly

or

produced

respiration

by

other

for

plants

indirectly

as

or

it

a

and

(see

for

by-product.

may

all

page

diffuse

other

244).

The

out

plant

into

organisms

The

equations

may

the

use

atmosphere

organisms.

Sun

oxygen chlorophyll

Investigating

photosynthesis

light traps

light

energy

energy

Green

if

too

a

very

plants

much

make

sugar

simple

is

sugars

dissolved

in

from

the

carbon

cell

sap

of

dioxide

plant

and

cells

water .

it

However ,

would

make

sugar

cells

to

concentrated

by

osmosis

make

very

together

effect

starch

Figure

6.1.1

A

simple

overview

photosynthesis.

54

of

out

on

in

to

and

thick

form

leaves.

cause

cell

Y ou

As

you

This

the

walls.

larger

osmosis.

whether

solution.

will

cells

T o

starch

can

to

see

iodine

in

has

so

this,

water

much

glucose

which

solution

Topic

been

make

swell

prevent

molecules

use

photosynthesis

would

6.2

are

to

we

that

in

they

insoluble

for

use

or

from

the

this

not.

other

would

molecules

test

can

happening

move

are

and

need

linked

have

presence

test

to

no

of

nd

tnemelppuS

6

PRACTICAL

T esting

a

leaf

for

starch

Safety:

eye 1

Submerge

This

it

kills

easier

a

leaf

in

the

leaf

as

to

extract

boiling

it

water

destroys

the

for

one

wear

At

this

boil

3

Put

point,

the

the

turn

is

ethanol

ammable

minute.

membranes,

making

chlorophyll.

boiling

2

Safety:

protection

off

any

Bunsen

burners

used

water

ethanol

to

water.

leaf

into

chlorophyll

is

a

test-tube

extracted

by

of

ethanol.

dissolving

The

into

the

ethanol.

4

Stand

the

test-tube

in

a

beaker

of

hot

water

for turn

about

10

off

Bunsen

burner

minutes.

iodine

5

Wash

the

ethanol

makes

6

some

7

If

and

it

Spread

leaf

the

leaf

stays

to

leaf

drops

cold

water.

rehydrates

easy

the

in

of

out

there

is

SUMMARY

QUESTIONS

1

complete

and

oxygen

on

plants

chloroplasts

for

this

made

make

the

process

in

the

are

leaves

white

on

softens

surface

is

own

leaves

and

present.

and

put

If

it

Safety:

using

chlorophyll

food

traps

these

careful

2

To

nd

carry

of

this

out

out

a

if

process

is

the

by

the

are

.

Green

Sun’s

.

.

changed

gas

photosynthesis

to

burn

yourself

dioxide

in

Raw

Simple

to

.

the

materials

sugars

The

are

waste KEY

product

not

words:

carbon

and

some

be

photosynthesis

carbon

and

it

starch.

water

their

the

it.

sentences

starch

of

which

starch

no

the

energy

Green

a

solution

blue-black,

red/brown

Copy

leaf

removes

out.

at

iodine

goes

the

spread

This

has

POINTS

.

taken

place

in

a

leaf

we

can

1

test.

Chlorophyll

absorbs

energy

is

that

used

light

in

photosynthesis. Copy

out

correct

the

stages

reason

on

listed

the

on

the

left.

Match

each

one

with

the

right.

2

Photosynthesis

by Stage

in

test

which

the

leaf

in

cold

water

to

test

for

to

soften

to

remove

raw

the

leaf

add

drops

in

ethanol

iodine

solution

the

ethanol

the

glucose

leaf

rehydrate

using

from

light.

Carbon

the

dioxide

and

water

and

are to

materials

it

3 of

process

starch energy

boil

the

make

Reason

from wash

is

plants

the

raw

materials

for

leaf

photosynthesis. dip

the

leaf

in

boiling

water

to

extract

the

chlorophyll

4 3

Write

out

the

word

equation

for

photosynthesis

and

The

are the

raw

materials

and

Using

only

information

in

this

topic,

explain

why

plants

to

our

of

and

photosynthesis

oxygen.

A

leaf

that

has

been

exposed

are to

vital

glucose

products.

5 4

products

identify

light

will

give

a

positive

survival. test

for

starch.

55

6.2

What

is

needed

for

photosynthesis?

The LEARNING

requirements

Green



List

the

raw

needed



for

Describe

materials

that

plants

need

for

the

following

in

order

to

carry

out

photosynthesis:



light,

which

provides



chlorophyll,

energy

for

the

process

photosynthesis

the

that

dioxide

photosynthesis

are

experiments

chlorophyll,

and

light

are

a

green

pigment

that

absorbs

the

energy

from

light.

that Chlorophyll

prove

for

OUTCOMES

is

in

the

chloroplasts

of

the

leaf

carbon



carbon



water,

dioxide,

which

diffuses

into

the

leaves

from

the

air

needed

photosynthesis

Water

which

and

If

a

needed

plant

them

To

as

be

starch.

certain

leaves

the

dark

is

then

that

given

we

out

If

are

cannot

the

no

all

the

that

plant’s

raw

roots

from

materials

chlorophyll,

the

of

as

will

investigation

48

at

things

(It

the

hours.

is

that

plant

is

is

for

carbon

make

the

soil.

photosynthesis.

dioxide

it

is

to

water

do

so

a

you

sugars

will

not

must

and

this,

a

and

make

make

light

plant

that

plant

can

for

the

water

for

so

hardly

store

starch.

sure

is

left

de-starching.

except

show

by

it

we

called

needs

required

is

To

simple

then

valid,

start.

This

difcult

water

the

it

photosynthesise

starch

testing.

most

are

the

photosynthesis

least

photosynthesis,

things;

it

that

at

by

photosynthesis.

have

for

dioxide

demonstrate

for

carries

the

absorbed

carbon

Investigations

are

is

that

in

The

plant

substance

is

needed

many

‘take

it

for

other

away’.)

PRACTICAL

Showing

T ake

as

a

a

that

de-starched,

leaves

is

important

affect

to

understand

photosynthesis

in

the

order

to

factors

that

variegated

needed

plant

for

photosynthesis

such

are

means

white

chlorophyll

some

because

parts

there

of

is

the

no

there.)

increase

Place crop

is

geranium.

(‘Variegated’

It

chlorophyll

the

plant

in

sunlight

for

about

6

hours.

yields.

Draw

one

leaf

to

show

the

white

and

green

parts.

Now

STUD Y

TIP

the

test

this

starch

variegated

test

described

leaf

in

for

starch

T opic

using

6.1. Variegated

No te

and

that

carb on

wate r

mater ials;

sour ce

no t

a

of

are

the

ligh t

dioxid e

raw

is

energy ,

the

and

Y ou

should

The

green

that

parts

photosynthesis

only

contain

to

make

the

green

parts

chlorophyll

of

the

which

is

leaf

needed

blue-black.

for

starch.

white

parts

contain

no

chlorophyll,

so

no

photosynthesis

mater ial. occurs

here.

Therefore

the

starch

the

white

parts

of

the

leaf

give

a

negative

result

with

test.

Safety:

56

go

leaves.

is The

raw

nd

geranium

wear

eye

protection

STUD Y

Showing

for

You

that

carbon

dioxide

and

light

are

Y ou

needed

photosynthesis

could

own

prove

food

except

by

that

a

carbon

it

dioxide.

mus t

explai n

plant

providing

TIP

needs

with

Then

carbon

everything

test

to

see

if

dioxide

it

needs

it

has

to

for

make

in

we

to

need

these

experim ents .

photosynthesis

made

able

why

cont ro ls

its

be

starch.

PRACTICAL

Showing

1

T ake

a

that

de-starched

absorbs

2

Leave

carbon

carbon

the

plant

described

in

dioxide

plant.

dioxide.

in

the

Topic

needed

Enclose

(Soda

light

6.1.

is

for

The

a

leaf

it

in

lime

a

for

plastic

absorbs

few

hours.

should

photosynthesis

bag

Test

show

with

carbon

a

a

a

chemical

that

dioxide.)

leaf

negative

for

starch

result

for

as

the

plastic

starch

bag

test.

Deprived

make

of

carbon

dioxide

the

leaf

is

unable

to

photosynthesise

and

starch.

soda

lime

elastic

band

A

control

the

soda

carbon

can

This

dioxide

dioxide

Y ou

experiment

lime.

that

also

should

means

removed.

caused

show

the

that

a

be

the

Then

lack

we

of

plant

set

plant

up

in

can

starch,

needs

in

exactly

the

be

sure

and

light

the

control

it

not

to

same

was

the

keeping

carry

way

experiment

out

but

does

absence

the

plant

without

not

of

have

carbon

inside

the

plastic

bag.

photosynthesis.

PRACTICAL

Showing

that

light

is

needed

for

photosynthesis

aluminium

1

T ake

a

de-starched

plant.

Cover

part

of

the

leaf

with

some foil

aluminium

2

Leave

3

T est

the

the

foil

to

plant

leaf

for

of

the

test

leaf

of

the

leaf

that

prevent

in

the

starch

that

light

light

as

were

for

getting

a

few

described

left

in

through.

hours.

T opic

uncovered

6.1.

go

Only

the

blue-black.

parts

The

parts starch

carry

out

covered

photosynthesis

SUMMARY

1

were

did

and

so

not

receive

could

not

light

make

and

could

no

Describe

b

Explain

how

why

show

that

c

What

is

d

Describe

you

it

is

would

de-starch

necessary

plants

need

to

light

use

to

a

a

plant.

de-starched

carry

out

plant

to

photosynthesis.

KEY a

variegated

how

carbon

you

could

dioxide

POINTS

leaf?

carry

out

an

investigation

to

show 1

is

needed

for

Plants

need

in State

whether

the

following

light,

chlorophyll,

photosynthesis. carbon

2

starch

starch.

QUESTIONS

a

that

present

not

statements

are

true

or

dioxide

order

to

and

carry

water

out

false.

photosynthesis. a

Plants

get

all

b

Plants

need

their

food

from

the

soil.

2 chlorophyll

to

carry

out

We

can

light, c

Water

d

Leaves

for

photosynthesis

is

are

de-starched

absorbed

give

a

to

see

through

the

chlorophyll

blue-black

colour

with

are

needed

Explain

what

is

by

for

not

giving

iodine. plants

3

carbon

when photosynthesis

tested

that

and

leaves. dioxide

that

test

photosynthesis.

meant

by

a

control

experiment

each

testing

of

leaves

these

for

and

starch.

57

6.3

Products

of

photosynthesis

The LEARNING

products

and



State

the

products

in

outline

that

how

show

they

the

are

used

procedures

oxygen

of

the

is

such

as

glucose,

of

the

glucose



Some

of

the

glucose

in



Some

for

of

make

use

the

cell

Glucose

plant

needs

for

food

are

made

in

the

leaves.

is

used

for

respiration

in

the

leaf.

in

is

the

changed

future,

into

e.g.

at

starch

and

stored

in

the

night.

is

plant



Plants

get



Glucose



Plants

also

to

to

make

sucrose

phloem

be

(see

converted

nitrogen

and

Sugars

The these

the

need

energy

used

cellulose,

which

is

needed

to

by

nitrate

and

Topic

to

other

absorbing

are

used

transported

to

to

other

parts

of

8.4).

substances:

nitrate

form

ions

amino

from

the

acids,

soil.

which

are

built

proteins

enzymes



is

converted

in

can

into

glucose

walls.

Glucose

up

in

a

that

produced

food

which

Some

the

makes

sugars





proteins

and

are

in

for

growth

and

cell

repair

and

for

making

hormones.

converted

to

oils,

which

are

an

efcient

way

to

store

seeds.

importance

of

photosynthesis

wheat

plants.

Think

what

soya

STUD Y

sugars,

in

photosynthesis

Photosynthesis

simple

and

leaves Describe

are

are

photosynthesis

plants.



photosynthesis

oxygen.

Most

formed

of

OUTCOMES

TIP

If

about

you

beans

you

eat

the

eat

food

comes

and

meat

you

have

from

eaten

plants

like

in

the

rice,

last

24

maize,

hours.

wheat,

A

lot

of

potatoes,

nuts.

or

sh

then

that

comes

from

animals

that

have

eaten

plants.

Mak e

conc

how

a

diag ram

map

plan ts

simpl e

to

use

a

you

learn

mad e

T his

them

Oxygen

Some

is

58

is

is

is

a

a

by-product

product

used

upon

plants?

so

why

are

made

from

plants.

of

photosynthesis

by

the

of

photosynthesis.

plant’s

It

respiration,

is

but

not

the

usually

main

there

product.

is

most

it

is

diffuses

called

a

out

of

the

leaves

into

the

more

than

atmosphere.

by-product.

products

provide

more

about

also

timber

depends

is

needed,

Plants

food

margarine

all.

Plants

this

and

will

Plant

of

oil

in

That

much

cooking

the

is

How

like

show

Oxygen suga rs

pho to synt hesis.

help

or

Products

ept

and

us

with

this

on

provide

a

cotton.

including

digitalis,

extracted

from

the

our

food

page

range

Many

which

rosy

and

of

raw

food

materials

medicines

is

also

for

our

livestock.

There

248.

a

heart

periwinkle

have

drug,

from

for

been

and

industry,

such

discovered

two

in

anti-cancer

Madagascar.

as

plants

drugs

Plants

are

the

dominant

organisms

in

almost

all

environments.

As DID

such

they

provide

rainforests

support

make

more

habitats

up

than

only

half

for

6%

the

animals

of

the

and

microorganisms.

Earth’s

world’s

land

species

of

surface,

animals

but

and

YOU

Plants

they

plants.

provide

everything

works The

concentrations

of

gases

in

the

atmosphere

are

kept

constant

Without

green

plants,

the

concentration

of

of

in

the

air

would

increase

and

the

concentration

of

art.

Lignum

The

for

of

to

that

the

grows

in

is

the

hardest

wood

used

oxygen Fast-growing

trees

decrease. provide

is

PRACTICAL

Oxygen

1

timber

wood

vitae

commercially. would

with

construction

carbon Jamaica

dioxide

us

from

by tree

photosynthesis.

KNOW?

The

Set

the

collect

in

of

as

fossil

a

biofuel

form

fuels

of

(see

that

energy,

page

282).

photosynthesis

apparatus

bubbles

wood

renewable

unlike

produced

up

a

to

gas

gas

rich

in

oxygen

given

off

by

the

Canadian collecting

pondweed

(Elodea

canadensis).

light Canadian

A

lamp

provides

the

light

STUD Y

pondweed

energy

that

the

plant

Plasticine

Carbon

in

the

dioxide

water.

sodium

is

to

to

dioxide

Rem embe r

dissolved

Add

of

some

hydrogencarbonate

powder

This

is

the

water

make

in

the

sure

TIP

needs.

and

that

the

in

stir

to

there

dissolve.

is

always

by

the

respira tion.

carbon

that

water.

some

produc ed If

there

is

not

enough

carbon

dioxide

then

produc ed

the

down.

plan t

T his

is

fo r

its

means

oxyg en

is

no t

photosynthesis

into slows

some

pho to synt hesis

used

enough

that

oxyg en

relea sed

atmos phere

or

wate r .

2

Place

gas

3

Test

the

to

apparatus

the

gas

Standing

dioxide

for

the

the

oxygen

funnel

dissolved

photosynthesis

A

in

light

and

allow

a

few

hours

for

the

collect.

water

plant

downward

in

on

the

does

is

with

glowing

plasticine

water

not

used

a

slow

because

displacement

of

to

splint.

gives

reach

a

gap

the

to

allow

pondweed

carbon

so

down.

it

is

easy

to

collect

the

gas

by

water.

KEY

SUMMARY

1

QUESTIONS

POINTS

Products

include

1

What

a

are

the

glucose

following

b

starch

products

c

made

cellulose

in

d

plants

used

protein

e

to

for?

photosynthesis

glucose,

make

amino

oils

of

starch,

acids

which

is

used

cellulose,

(and

then

proteins). 2

a

Describe

as

a

how

you

by-product

practical

of

would

show

that

photosynthesis.

plants

produce

Remember

to

oxygen

include

all

2

Photosynthesis

it

details.

provides

medicines; b

How

would

you

show

that

light

is

necessary

for

us

it

is

important

with

helps

food

to

as

and

keep

oxygen

constant

concentrations

of

production?

carbon

3

Plants

are

important

because

they

provide

us

food

Give

three

b

fuels

examples

c

of

building

plants

materials

that

provide

d

us

and

oxygen

in

with: the

a

dioxide

atmosphere.

medicines

with

each

of

these.

59

6.4

Rate

When LEARNING

plants

Describe

how

effect

varying

of

temperature

dioxide

rate

of

to

investigate

light

and

the

much

by

carbon

concentration

the

products

intensity ,

on

photosynthesis

describe

carry

photosynthesis

out

photosynthesis

they

produce

oxygen.

We

can

OUTCOMES determine



of

the

as

by

results

that

starch

nding

use.

and

how

can

are

or

out

Instead,

we

or

slow

oxygen

the

an

is

dioxide

in

conditions

be

Starch

as

such

as

done

but

it

oxygen

by

the

light

is

is

described

measuring

concentration

occurs

by

an

be

in

T opic

rate

of

is

6.3.

method

much

This

oxygen

is

to

easier

done

produced.

temperature

of

the

how

measured

easy

produced

volume

the

can

not

intensity,

inuence

measuring

measuring

production

mass,

much

plant

by

can

dry

how

aquatic

or

This

made.

change

bubbles

Environmental

photosynthesis

produced.

measuring

use

counting

carbon

fast

and

photosynthesis.

PRACTICAL

Photosynthesis

Y ou

the

can

use

rate

1

Cut

2

Put

of

a

this

and

light

apparatus

intensity

to

measure

the

effects

of

light

intensity

Canadian

on

photosynthesis:

piece

of

pondweed

about

5 cm

in

length.

stream

a

paperclip

on

the

pondweed

to

stop

it

oating

to

the

surface.

of

bubbles

3

Put

a

lamp

close

to

the

plant

and

measure

the

distance

between

the metre

plant

4

and

Count

times

5

the

and

Repeat

The

less

number

this

the

of

of

bubbles

lamp

is

close

photosynthesis

energy

bubbles

the

for

the

released

over

5

minutes.

with

the

should

to

is

plant

the

high.

and

lamp

at

decrease

plant

As

the

the

the

rate

different

as

of

sis ehtnysotohp

of

In

the

light

lamp

distance

intensity

is

moved

graph

are

dark

very

fo

the

rate

as

the

the

This

away

some

plant.

lamp

gives

the

results

intensity

is

no

and

the

light

the

plant

plant

lots

intensity

etar

investigating

an

the

oxygen

intensity

increase

energy

on

of

of

increases.

energy

decreases;

experiment

rate

of

photosynthesis.

of

light

not

the

so

the

there

is

any

available

the

effect

At

further .

light

The

until

the

of

different

the

plant

for

intensities

rate

at

a

Increasing

to

measure

effect

photosynthesis.

low

produced.

increases

to

of

photosynthesis

certain

the

there

light

light

intensity

intensity

photosynthesis.

light

intensities

it

is

intensity

important

The

effect

light

of

increasing

intensity

on

the

to

T emperature

keep

can

the

be

other

kept

environmental

constant

by

conditions

putting

a

the

same.

thermometer

into

rate

the

beaker

of

water

and

adding

hot

or

cold

water

if

the

temperature

photosynthesis.

changes.

The

by

The

lamp

concentration

adding

dissolve.

60

high.

bubbles

the

from

decreases.

light

does

increases

of

is

there

few

increases

6.4.1

several

between

further

shows

increasing

the

When

Figure

distances

photosynthesis

The

light

Repeat

average.

procedure

of

rule

lamp.

calculate

number

When

rate

the

sodium

This

may

of

give

carbon

off

heat,

dioxide

so

in

hydrogencarbonate

ensures

that

the

plant

the

the

to

will

temperature

water

the

not

can

water

run

out

be

and

of

may

kept

increase.

constant

letting

carbon

it

dioxide.

PRACTICAL

Photosynthesis

and

To

of

nd

the

of

beakers

of

different

lamp

water

kept

at

one

The

to

similar

into

a

range

all

the

of

time

hydrogencarbonate

make

number

of

apparatus

test-tubes

temperatures.

across

distance

Sodium

test-tubes

constant.

placed

different

temperatures

constant.

the

at

are

sure

carbon

bubbles

of

The

10 °C

so

is

about

the

added

dioxide

be

are

used.

put

minimum

to

that

oxygen

can

which

ve

40 °C.

light

to

is

the

The

intensity

water

concentration

produced

inside

at

etar

in

temperature

fo

is

is

effect

pondweed

sis ehtnysotohp

Pieces

temperature

is

different temperature

temperatures

can

be

counted

in

the

same

Figure

Figure

6.4.2

shows

the

results

you

might

/

˚C

way.

expect.

The

6.4.2

The

effect

of

increasing

maximum temperature

rate

of

photosynthesis

occurs

at

the

optimum

temperature.

on

photosynthesis.

actual

temperature

depends

on

the

plant

that

is

used.

Plants

in

lower

temperate

than

those

latitudes

that

grow

have

in

optimum

the

temperatures

The

rate

of

rate

that decreases

grow

the

The

that

are

because

at

chloroplasts

tropics.

high

enzymes

are

temperatures

in

the

denatured.

PRACTICAL

The

same

Adding

water

of

carbon

apparatus

different

increases

dioxide

can

be

the

modied

quantities

the

on

of

for

sodium

concentration

of

rate

this

of

photosynthesis

investigation.

hydrogencarbonate

carbon

dioxide.

At

to

least

the

ve

deewdnop

The

effect

fo

sodium

test-tubes

You

can

intensity

see

that

and

the

the

light

intensity.

photosynthesis.

If

As

is

is

a

different

mass

of

added.

of

the

there

the

with

temperature

effect

photosynthesis

each

must

increasing

same

no

carbon

as

carbon

the

carbon

dioxide

be

effect

dioxide

kept

constant.

dioxide

of

on

the

etar

the

used

increasing

there

can

concentration

be

fo

light

of

be

hydrogencarbonate

The

rate

can

sisehtnysotohp

different

no

carbon

Figure

there

is

an

increase

in

the

rate

of

photosynthesis.

dioxide

concentration

increases

Above

a

6.4.3

The

on

concentration

SUMMARY

the

rate

remains

List

the

the

of

rate

carbon

of

dioxide

photosynthesis.

constant.

QUESTIONS KEY

1

effect

certain

main

environmental

factors

that

inuence

the

rate

POINTS

of 1

The

release

of

oxygen

photosynthesis. from

2

A

student

used

the

distances

25,

30 cm

the

and

and

apparatus

the

24,

shown

numbers

40 cm

and

of

18,

opposite.

bubbles

60 cm

per

and

He

wrote

minute:

10,

20 cm

100 cm

to

down

and

Explain

how

the

student

kept

other

conditions

Make

a

c

Explain

table

of

the

results

and

plot

them

as

a

constant.

line

Light

and

intensity,

the

your

graph

does

not

look

like

Figure

is

used

of

temperature

concentration

dioxide

are

of

three

graph. environmental

why

rate

6.

carbon

b

plants

the

photosynthesis.

and

2

a

aquatic

measure

6.4.1.

that

inuence

factors

the

rate

of

photosynthesis. 3

Describe

carbon

the

effect

dioxide

on

the

rate

concentration,

of

photosynthesis

and

b

increasing

of

the

a

increasing

temperature.

61

6.5

Glasshouse

tnemelppuS

We

LEARNING



Dene



Identify

the

OUTCOMES

the

term

and

limiting

environmental

in

of

the

enrichment,

use

light

of



Temperature



Carbon

carbon

and

in

inuences

dioxide

These

to

three

intensity,

the

rate

determines

concentration

enzymes

light

inuence

intensity

is

a

use

to

raw

temperature

of

activity

there

is

and

photosynthesis

energy

material

make

are

the

the

increases

factors

available

of

for

carbon

in

to

enzymes

photosynthesis.

in

the

photosynthesis,

more

of

it

dioxide

plants.

available

chloroplasts.

so

if

for

the

chloroplast

carbohydrates.

limiting

factors

optimum

Limiting temperature

that

Light

conditions

dioxide

seen



different

Explain

optimum

factor

explain

photosynthesis



limiting

factors

have

concentration

production

factors

glasshouse

systems

A

limiting

short

Light

dioxide sisehtnysotohp

CO

2

is

of

In

of

fo

CO

etar

2

something

it

restricts

does

water

and

energy

this

case

increases

increases

also

see

because

that

the

warm

rate

environment

of

if

in

photosynthesis.

the

is

the

6.5.1

of

plant

temperature

intensity

light

rate

rate

matter

Figure

the

the

photosynthesis

light

In

in

such

processes.

the

not

a

for

present

life

influences

it

photosynthesis.

intensity

0.04%

Y

l o w,

and

shortage

high.

is

that

intensity

intensity

0.4%

factor

supply

and

can

photosynthesis

intensity

becomes

is

the

rate

that

constant

for

as

however

is

very

rate

light

The

Yo u

much

a

be

the

the

f a c t o r.

light

carbon

there

increases.

limiting

the

of

cannot

factor

see

If

lots

because

the

limiting

you

has

rate

can

the

light

X

light

Figure

6.5.1

The

is

f a c t o r,

must

it

dioxide

intensity

effect

intensity

of

be

on

the

photosynthesis

concentrations

of

at

carbon

on

page

certain

reactions

move

61

grap h

and

you

a

the

ruler

from

lines

the

rate

a

grap h

alon g

left

The

substrates

and

more

can

the

rate

see

rate

by

as

enzymes

from

of

when

longer

the

temperature

the

increase

graph

in

photosynthesis

the

increases

enzymes

often

at

(see

to

higher

are

or

limiting

carbon

with

Figure

6.4.2

in

rate

reaches

because

the

To p i c

the

The

of

and

a

and

energy

increase

rate

until

maximum

kinetic

chloroplast

5.2).

increases

a

of

then

the

they

photosynthesis

Here

on

you

because

To p i c

the

enzymes

in

5.3).

Look

at

the

graph

in

Figure

6.5.1.

rate

of

photosynthesis

at

point

X.

rate

of

photosynthesis

at

point

Y .

Light

intensity

Another

is

factor

limiting

is

the

limiting

This

could

be

carbon

the

dioxide

right or

temperature.

or

H o w e v e r,

can

grap h

cond ition s

to

(see

the

trend s

the

temperatures

denatured

to

alwa ys

concentration

the

starts

cons tant .

62

use

ques tion,

follo w

nd

such

no

TIP

patte rns.

rule

that

decreases.

chloroplasts

a

catalysed

Yo u

temperature

decreases

Whe n

else

now

two

collide

answ er

something

is

rate

dioxide.

STUD Y

intensity

increasing

intensity

temperature. of

Light

concentration.

Chemical light

increased.

to

carbon

there

is

you

can

dioxide

more

see

that

the

concentration

of

this

raw

rate

is

of

photosynthesis

increased

material

from

available.

This

remai n

factor

at

Y

is

carbon

dioxide

to

means

when limiting

increases

0.04%

concentration.

0.4%

that

if

as

the

Growers

best

try

to

possible

Conditions

earlier



grow

in



improve

inside

grow

The

production

the

conditions



in

a

yield

for

of

their

crops

photosynthesis

glasshouse

the

places

following

tnemelppuS

Glasshouse

allow

to

plants

by

giving

take

them

the

place.

to:

year

where

they

conditions

would

inside

not

normally

glasshouses

are

grow

well.

controlled.

T emperature

Sunlight

The

heats

glass

up

stops

a

the

lot

inside

of

this

of

the

heat

glasshouse.

from

escaping. Glasshouses

Electric

heaters

Ventilator



glass

when

and

lets

light

in

opened

in

sunlight.

intensity

shading

cold

to

weather.

cool

dioxide

Growers

can

gas

pump

dioxide

which

the

too

the

as

glasshouse

of

lighting

low.

Blinds

temperature

carbon

dioxide

concentration.

provides

temperature

Articial

gets

lowers

Carbon

carbon



are

used

on

hot

can

temperature,

control

light

limiting

intensity

factors,

and

such

humidity.

days.

Light

The



aps

are

carbon

They

in

cold

used

out

also

grow

plants

strong

light

countries.

burn

also

to

very

glasshouses

can

and

be

keep

tropical

into

dioxide

glasshouses

in

can

heat

to

increase

butane

to

raise

or

natural

the

weather.

Water

Many

and

All

glasshouses

humidiers

these

factors

concentration,

process

data

which

are

automatic

ensure

monitored

humidity,

from

SUMMARY

have

the

light

watering

plants

and

sensors

and

always

controlled

intensity

systems

and

control

get

by

using

enough

all

heating,

Water

so

detect

few

staff

changes

ventilation,

QUESTIONS

are

in

lighting

needed.

these

and

Explain

process

2

State

what

of

is

meant

by

the

photosynthesis

which

factors

term

to

would

help

be

limiting

explain

limiting

factor.

your

of

shading

Give

your

reasons

in

each

glasshouse

Use

A

for

factors.

in

crop.

the

carbon

dioxide

Computers

glasshouse.

POINTS

limiting

factor

is

a

factor

the

in

the

in

such

environment

that

is

answer.

photosynthesis

in

short

supply

that

it

the restricts

following.

a

Sensors

limiting

KEY

1 1

misting

water.

computers

temperature

sprinklers

a

life

process,

such

as

case. photosynthesis.

a

Plants

growing

on

a

high

mountainside

early

in

the

2

Light

intensity,

temperature

morning.

and b

Plants

c

A

d

The

e

A

growing

in

a

dense

tropical

forest

at

carbon

dioxide

midday. concentration

eld

of

same

maize

eld

early

late

on

in

a

the

very

bright

morning.

factors

plant

in

a

photosynthesis.

shaded

position

in

a

warm

room.

Carbon

light

dioxide

intensity,

temperature 3

Explain

how

each

of

the

following

can

be

controlled

to

give

optimum

conditions

for

carbon

b

light

dioxide

and

controlled

glasshouse

in

systems

give

optimum

conditions.

concentration This

intensity

humidity

are

growth:

to a

concentration,

in

modern glasshouses

limiting

afternoon. 3

house

of

are

c

ensures

that

the

rate

of

temperature photosynthesis

is

plants

maximum

produce

kept

high

so

yield.

63

6.6

Leaves

The LEARNING

of



Identify

a tnemelppuS



and

label

the

parts

of

a

and

Leaves

Explain

how

leaf

of

absorbing

into

leaf

of

shape

a

leaf

makes

it

ideally

adapted

to

carry

out

its

functions

OUTCOMES

is

the

out

light

of

for

the

photosynthesis

leaf

and

allowing

gases

to

diffuse

tissues.

have:

structure

adapted



a

large



a

thin



many

surface

area



to

absorb

light

rays

for shape



so

gases

can

diffuse

in

and

out

easily

photosynthesis

place



veins

the

leaf



to

nd



to

absorb

light

for

the

reactions

that

take

photosynthesis

to

leaf

Inside

To

chloroplasts

in

support

cells,

all

a

and

other

the

to

leaf

take

parts

of

surface

sucrose

the

and

and

to

carry

amino

water

acids

and

away

ions

from

to

the

plant.

leaf

out

how

a

leaf

works

we

can

look

at

the

structure

of

a

typical

leaf. A

leaf

has

an

ideal

shape

for

photosynthesis.

upper

layer

epidermis:

of

cells

with

chloroplasts.

cuticle:

down

waterproof

the

water

layer

lost

by

that

also

straight

cuts

lots

of

Most

mesophyll:

air

spaces

more

rounded

between

cells

vein:

with

and

lower

epidermis:

no

thick

cuticle.

Has

here

contains

that

ions

tiny

holes

called

stomata

(singular:

allow

gases

to

diffuse

in

and

the

water

leaf

tubes

that

and

take

stoma) away

These

to

xylem

bring

lots phloem

of

the

contain

chloroplasts.

vessels

them

mesophyll:

cells

photosynthesis

occurs

of

goes

evaporation

palisade

lots

Light

through

palisade

spongy

single

no

sucrose

and

amino

out acids stoma guard

6.6.1

Leaf

cell

structure.

Some

of

the

internal

features

are

adaptations

for

photosynthesis.

PRACTICAL •

Palisade

upper Looking

at

a

leaf

surface

Observe

a

transverse

a

leaf

on

a

the

are

leaf

to

packed

tightly

maximise

together

absorption

near

of

light

the

slide

is

where

its

highest.

section •

of

of

cells

section

intensity

1

mesophyll

under

There

are

many

chloroplasts

in

the

palisade

mesophyll

cells

to

the absorb

as

much

light

as

possible.

microscope.



Look

for

the

tissues

in

Stomata

dioxide

6.6.1

under

low

(usually

in

the

lower

epidermis)

open

to

allow

carbon

Figure to

diffuse

into

the

leaf.

Carbon

dioxide

is

a

raw

material

for

power . photosynthesis.

Now

look

tissue

64

at

under

each

high

type

of

power.



Leaves

the

are

thin

so

atmosphere

that

to

the

carbon

cells

of

dioxide

the

does

palisade

not

and

have

to

spongy

diffuse

far

mesophyll.

from

tnemelppuS

Figure

There

are

large

intercellular

air

spaces

within

the

spongy

tnemelppuS



mesophyll palisade

layer.

This

makes

mesophyll

from

cell

cells.

to

it

easy

for

Diffusion

carbon

through

dioxide

air

is

to

diffuse

much

faster

to

all

than

cells

the

diffusion

cell.

spongy



Xylem

in

veins

bring

water

and

ions

to

the

mesophyll

cells.

Water

is cells CO

a

raw

by

material

the

cells

to

for

photosynthesis

make

and

magnesium

ions

are

2

needed

chlorophyll. CO 2



The

sugar

produced

in

photosynthesis

is

converted

to

sucrose

lower

and

epidermis

transported

away

from

the

leaf

in

the

phloem

in

CO

veins.

guard

cell

2

Figure

6.6.2

Carbon

into

Stomata

the

dioxide

leaf

diffuses

for

photosynthesis.

Stomata

to

are

diffuse

small

into

epidermis,

pores

and

but

out

some

(holes)

of

the

plants

in

the

leaf.

like

epidermis

Stomata

water

lilies

are

that

allow

usually

have

them

in

in

gases

the

the

lower

upper closed

stoma

epidermis.

guard pore

In

cells

partly

closed

sunlight:



carbon

dioxide



oxygen

made



water

diffuses

in

vapour

in

for

photosynthesis

photosynthesis

diffuses

diffuses

out

out.

chloroplast

Opening

and

closing pore

Stomata

are

Stomata

usually

cells

by

opened

open

osmosis.

Carbon

dioxide

diffuses

out.

and

during

This

into

vapour

by

the

makes

diffuses

Water

closed

guard

day.

them

the

also

Water

bend

leaf

for

so

passes

the

into

stoma

the

guard

opens.

photosynthesis

diffuses

and

oxygen

out. Figure

At

night

osmosis

the

and

stomata

prevent

stomata

they

pores.

the

SUMMARY

Water

straighten

The

plant

close.

stomata

passes

and

move

also

close

out

closer

in

of

the

guard

together

hot,

dry

so

cells

closing

weather

to

6.6.3

Closed

by

Match

function

on

the

STUD Y

the

leaf

See

parts

on

the

left

with

their

open

help

wilting.

of

and

the

QUESTIONS

each

stoma

stoma.

TIP

T opic

your self

1

open

cells

which

correct

into

right:

is

3.2

to

abou t

how

and

remin d

osmo sis,

water

out

of

moves

guar d

cells. stomata

palisade

spongy

carry

mesophyll

water

allow

mesophyll

up

gases

to

from

pass

the

into

stem

and

out

of

leaf

contain

chloroplasts

for

photosynthesis

cuticle

contain

chloroplasts

for

photosynthesis

veins

prevent

too

much

water

being

lost KEY

2

a

Which

gas

would

pass

b

Which

gas

passes

out

into

a

leaf

during

1 of

a

leaf

during

POINTS

daylight?

The

diagram

structure

3

Leaves

Lay

a

have

leaf

area

by

Find

out

same

a

large

onto

graph

counting

if

leaf

leaves

area.

surface

the

area

paper,

to

draw

absorb

around

light.

it

different

and

work

out

have

its

carry

squares.

from

Record

the

top

your

and

results

bottom

and

of

the

internal

daylight?

of

a

explain

plant

them.

have

the

2

a

leaf

important

shows

which

each

functions

to

out.

Stomata

of

of

tissues

gases

control

into

the

and

diffusion

out

of

a

leaf.

65

6.7

Mineral

Plants LEARNING

need

Describe

the

nitrate

ions

ions

plant

in

importance

and

Explain

the

They

Nutrients

of

magnesium

active

are

light,

need

absorbed

transport

effects

of

carbon

in

the

mineral

dioxide

from

roots

salts

and

the

soil

(see

(also

water

in

Topic

called

for

small

plant

healthy

quantities

nutrients).

as

ions

by

3.4).

nutrients

nitrate

Nutrients and

also

nutrition

Plant •

than

OUTCOMES growth.



more

requirements

magnesium

deciency

are

needed

for

healthy

growth

of

plants.

They

are

used

for

on

a

variety

of

purposes

in

plants.

If

these

nutrients

are

lacking

in

the

soil

plants

then Use

do

not

grow

well

and

show

certain

symptoms

known

as

hydrogencarbonate

solution

to

exchange

kept

in

investigate

of

the

an

light

aquatic

and

deciency

symptoms.

which

are

used

plants

decient

Plants

need

nitrate

ions

to

make

amino

acids

gas

in

to

make

proteins.

As

proteins

are

required

for

growth,

plant

the

in

nitrate

show

poor

growth.

dark

Magnesium

Leaves

as

for

the

may

ions

plants

chlorosis.

and

If

of

are

absorbed

decient

Plants

need

in

by

plants

chlorophyll

phosphate

for

and

look

used

to

yellow,

making

a

make

chlorophyll.

condition

compounds

known

such

as

DNA

respiration.

soil

does

add

more

not

as

contain

enough

fertiliser

to

nutrients,

replace

the

farmers

missing

and

growers

nutrients.

tnemelppuS



plants

PRACTICAL

The

effects

Some

of

plants

grown

in

culture

nutrients

on

growth

are

water

to

show

that cotton

seedling

plants

need

different

wool

nutrients.

1

Set

up

some

normal

test-

culture

tubes

as

shown solution

here.

This

plant

has

magnesium

deciency.

Cover

the

tubes 1

with

black

black

paper

to

to

prevent

growing YOU

in

3

4

no

distilled

magnesium

nitrates

water

keep

algae out

DID

2

no

paper

light

the

KNOW?

water.

Legume

plants,

such

as

peas

and

Each beans,

have

bacteria

in

their

has that

are

able

nitrogen

plants

(see

can

page

clover

back

are

into

nitrogen

66

into

to

a

use

‘x’

252).

that

make

Plants

grown

the

soil

content

all

of

lacks

a

certain

nutrient

except

test-tube

1

which

them.

atmospheric

form

to

solution

roots

and

to

for

the

3

Leave

4

After

5

Y ou

the

apparatus

in

good

light

for

6

weeks.

proteins

such

ploughed

increase

crops.

6

weeks

you

could

examine

the

colour

and

size

of

leaves.

as

the

could

growth.

measure

length

of

stems

and

roots

to

compare

All

exchange

living

in

organisms,

plants

including

plants,

carry

out

respiration

all

the

time. tin

Plants

they

are

need

waste.

At

During

In

no

a

supply

night,

the

bright

different

day,

light,

of

from

plants

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other

oxygen

plants

tnemelppuS

Gas

and

exchange

carry

there

out

is

organisms.

a

they

T o

produce

these

gases

carry

carbon

with

photosynthesis,

high

rate

of

out

dioxide

their

as

foil

respiration

as

pond

weed

a

surroundings.

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photosynthesis,

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of hydrogen

the

oxygen

aerobic

of

is

the

produced

respiration.

plant.

used

by

The

in

The

their

rest

carbon

chloroplasts

chloroplasts

of

the

dioxide

for

is

oxygen

used

is

produced

photosynthesis.

not

by

by

mitochondria

required

so

mitochondria

However ,

this

is

for

diffuses

in

carbonate

indicator

out

respiration

not

enough Test

so

carbon

dioxide

diffuses

in

from

the

tube

Figure

Gas

exchange

in

aquatic

plants

is

1

Test

carbon

solution.

dioxide

This

and

solution

investigated

two

pH

contains

with

it

dissolves

in

water

indicators.

it

forms

Carbon

dioxide

is

an

to

Hydrogencarbonate

carbonic

atmospheric

air

through

indicator

it.

This

acid,

solution

gives

which

is

acid

a

the

is

prepared

indicator

a

by

red

Explain

why

in

Set

up

three

test

tubes

as

shown

colour .

2

3

plants

in

Figure

Describe

a

the

plant

Add

3

Cut

in

hydrogencarbonate

two

each

pieces

of

test

of

indicator

pondweed

tubes

1

and

to

in

to

each

length

test

and

tube.

place

plant

at

growth

and

Put

test

5

Leave

If

carbon

tube

1

in

darkness

test

tubes

near

a

ii

is

added

hydrogencarbonate

to

by

covering

it

in

carbon

dioxide

is

light

the

indicator

taken

up

carbonate

for

water

solution

from

indicator

2–3

In

test

tube

dioxide

1,

was

the

the

by

the

will

plant,

turn

water

solution

indicator

released

by

the

Plant

from

for

the

by

the

red

to

plant,

roots

will

turned

turn

yellow

pondweed

In

test

tube

2,

the

indicator

turned

was

taken

up

by

the

from

red

because

during

purple

pondweed

nutrients

ions

needed

growth.

Nitrate

ions

are

to

amino

needed

acids;

to

magnesium

purple. are

make

carbon

used

by

the

plants

to

chlorophyll.

respiration.

because

for

nitrate

healthy

yellow.

If

mineral

ions

are

lacking,

carbon a

dioxide

absorb

the

3



i

sunshine.

hours.

ions



surroundings

bright

POINTS

make hydrogen

its

in

foil.

2 If

gas

between

2.

including

dioxide

the

occurs

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1 the

without

explain

that

and

night,

KEY

4

appearance

6.7.1.

solution

10 cm

likely

ions.

Describe

a

2

need

ions.

exchange

1

plants

bubbling

nitrate

respiration

QUESTIONS

gas.

of

and

3

weak

PRACTICAL

Photosynthesis

tube

provide

mineral acid.

Test

hydrogencarbonate

hydrogencarbonate

1 When

2

6.7.1

SUMMARY indicator

tube

surroundings.

plant

develops

deciency

photosynthesis. symptoms.



The

purpose

of

test

tube

3

was

to

act

as

a

control. 4

The

indicator

The

colour

the

plant

oxygen

to

solution

changes

in

the

light

dissolves

monitor

the

in

only

are

or

to

absorbed

water

changes

responds

nothing

it

in

does

by

not

oxygen

to

do

changes

with

the

the

plant

change

in

carbon

oxygen

in

the

dark.

and

by

pH.

If

you

concentration

you

would

have

an

oxygen

probe

and

a

data

pond

weed

solution

remains

same.

at

is

low

red

as

kept

light

the

in

a

test

intensity,

rates

of

carbon

photosynthesis

by

oxygen.

only

At

night

carbon

respiration.

Hydrogencarbonate

indicator

logger . solution

If

up

to 5

use

in

use

produce

dioxide

wanted

plants

release

plants

When

the

light

dioxide

dioxide.

released

In

tube

the

of

hydrogencarbonate

colour

of

photosynthesis

the

and

solution

indicator

usually

respiration

are

the

changes

is

in

used

carbon

concentrations

of

gas

to

as

exchange

detect

dioxide

a

by

result

aquatic

plants.

67

PRACTICE

1

Photosynthesis

cells.

out

Which

occurs

in

structure

palisade

inside

mesophyll

these

cells

light

carbon

intensity

concentration

A

chloroplast

B

cytoplasm

C

nucleus

D

vacuole

The

1)

raw

materials

A

carbon

B

light

energy

/

A

high

low

30

B

low

high

20

C

low

low

30

D

high

high

35

for

photosynthesis

dioxide

C

light

energy,

D

water

and

nitrate

(Paper

2)

(Paper

and

ions

Which

feature

good

and

carbon

carbon

supply

a

dioxide

and

ions

cellulose

B

chlorophyll

large

B

many

C

thin

are

used

by

plants

for

D

xylem

internal

air

a

cells

spaces

chloroplasts

cuticle

on

in

the

and

and

palisade

lower

phloem

mesophyll

cells

epidermis

in

veins

2)

[1]

Hydrogencarbonate

atmospheric

indicator

air

is

solution

bubbled

is

red

through

it.

A

oils placed

a

piece

1)

[1]

tube

Y

that

contained

T ube

Y

was

covered

was

Which

represents

the

movement

of

of

pondweed

inside

test

through

the

open

stomata

of

a

repeated

leaf

uncovered.

indicator

completely

test

tube

Z,

in

but

solution.

foil.

the

This

tube

Both

tubes

were

left

in

was

bright

during sunshine.

the

for

this

gases left

After

60

minutes

the

colour

of

the

day? indicator

gas

into

leaf

gas

out

of

was

leaf

A A

oxygen

carbon

in

B

water

vapour

carbon

tube

purple.

pondweed

carbon

D

oxygen

dioxide

Which

does

water

vapour

pondweed

dioxide

had

the

in

and

in

tube

reason

absorbed

for

Z

this?

pondweed

in

carbon

Z

had

dioxide

Y

had

the

produced

pondweed

in

carbon

Z

had

oxygen

[1]

not

occur

during

pondweed

dioxide,

photosynthesis?

A

absorption

of

light

by

B

conversion

of

glucose

to

carbon

dioxide

to

of

molecules

using

light

9

energy

The

see 2)

Which

row

would

provide

in

Y

pondweed

in

carbon

Z

had

dioxide

had

in

Z

produced

had

oxygen,

absorbed

but

oxygen

2)

[1]

diagram

transverse

(Paper

carbon

pondweed

(Paper

water

produced

pondweed

a

carbohydrate

splitting

had

sucrose

the of

Y

the

chlorophyll

D

reduction

in

but

absorbed

it

in

a

on

the

section

next

page

through

a

shows

leaf

as

a

you

would

microscope.

[1]

of

the

table

the

(top

of

conditions

next

for

(a)

Name

photosynthesis

of

a

the

tropical

the

(b)

Describe

tissues

labelled

E,

F,

G

and

H. [4]

column)

the

functions

of

the

parts

of

the

highest

leaf of

and

correct

oxygen

C

rate

Y

yellow

the

carbon

produced

1)

was

is

dioxide

B

(Paper

in

and

produced

C

Y

What

dioxide

dioxide

labelled

I

and

J.

[3]

plant?

(c)

Explain

and

68

ensure

the

proteins

(Paper

6

to

to

making:

student

D

dioxide

leaf?

A

when

C

adaptation

dioxide

8

5

an

carbon

water

(Paper

4

is

of

[1]

A

fats

[1]

water

1)

Magnesium

D

°C

are:

inside

C

temperature

[1]

7

3

dioxide

carries

photosynthesis?

(Paper

2

QUESTIONS

G

how

are

cells

in

adapted

the

for

tissues

labelled

photosynthesis.

F

[3]

I

(a)

State

how

the

student

would:

E

(i)

vary

the

light

(ii)

determine

intensity;

the

rate

of

[2]

photosynthesis;

[2]

F

(iii)

maintain

constant

a

constant

carbon

throughout

the

temperature

dioxide

and

concentration

investigation.

[4]

G

(b)

J

for

3)

plants,

several

K

and

days.

L,

were

They

placed

were

then

in

the

placed

dark

into

carbon

L

was

the

student’s

results.

the light

apparatus

if

shows

etar

T wo

below

fo

10

graph

sisehtnysotohp

H

(Paper

The

shown

dioxide

provided

below

is

in

the

required

with

for

carbon

K

light

to

nd

photosynthesis.

Using

dioxide.

the

L

(Paper

12

the

limiting

shown

in

the

factors,

explain

graph.

[4]

4)

groups

that

were

M

group

term

results

T wo

Group

bag

intensity

out

N

of

seedlings

decient

was

was

in

grown

grown

were

two

grown

ions

without

without

that

in

solutions

plants

nitrate

need.

ions;

magnesium

ions.

bag

Group

O

received

all

the

ions

that

plants

require.

soda

lime

The

band

results

are

shown

in

the

table.

band

group

of

colour

of growth

seedlings

(a)

Explain

why

the

plants

were

put

in

leaves

reduced

the

growth

yellow

dark

for

several

days.

but

[2] (especially

M

Explain

why

the

plants

were

well

watered

lower

kept

in

bright

light.

Describe

how

you

did

not

carry

would

out

any

show

that

leaves



plant

photosynthesis

inside

the

bag,

but

plant

L

did.

Explain

why

plant

L

was

included.

A

student

investigated

intensity

the

effect

of

varying

normal

growth

Explain

the

on

the

apparatus

rate

of

shown

the

effects

of

the

deciencies

of

the ions

and

magnesium

ions

as

shown

photosynthesis in

using

green

green

nitrate light

reduced

growth

3)

(a) 11



[2]

O

(Paper

leaves

[4]

pale (d)

severely

N upper

while

N

[2]

yellow K

in

leaves)

lower (c)

much

seedlings

group and

as

the as

(b)

not

the

table.

[4]

below.

(b)

Why

was

seedlings

(c)

Many

it

in

crops

grown

in

(Paper

group

to

achieve

the

yields.

world

Explain

controlled

high

the

[2]

throughout

are

include

O?

glasshouses.

conditions

to

necessary

in

are

how

glasshouses

[6]

4)

69

7

Animal

nutrition

7.1

A

A LEARNING

balanced

balanced

Dene

what

balanced



Describe

and

provides

an

adequate

intake

of

the

biological

OUTCOMES molecules



diet

diet

is

meant

by

a

health

and

and

energy

needed

to

sustain

the

body

and

ensure

good

growth.

diet

how

activity

age,

affect

gender

dietary

needs



Describe

the

pregnancy

on



the

diet

Describe

effects

and

of

the

of

breast-feeding

the

mother

effects

malnutrition

on

of

heart

disease

Figure

STUD Y

A

TIP

7.1.1

balanced

Which

diet

carbohydrates,

Rem embe r

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energy

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as

Each

of

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T o

these

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The

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4.1).

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12 500

10 000

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kilogram

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per

day

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than

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men.

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Figure

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they

daily

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7.1.2

energy

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pressure

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7.1.2

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Figure

7.1.3

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exercise: 2

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(left)

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POINTS

carbohydrates,

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layer

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the

in

rough

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QUESTIONS

is

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quantity

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energy

1

day

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KEY

SUMMARY

per

day

Cholesterol

as

inherit.

kJ

deposited

blood

years

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8

kJ

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smooth

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Figure

increase

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involve

physical

breast-feeding.

recommended

Why

Fat

of

diets.

Women

are

jobs

vigorous

protein

development.

when

active

in

kJ

ii

a

2-year-old

iv

a

male

child

Requirements

depend

gender

athlete

on

a

and

of

the

diet

person’s

how

age,

active

they

are. 2

a

What

are

b

Explain

the

health

risks

associated

with

a

diet

high

in

fat?

3 how

a

person

may

reduce

the

fat

content

of

Saturated

fats

cholesterol diet.

(You

may

nd

it

useful

to

look

at

pages

73

and

answering

this

blood

which

is

linked

to

74

narrowing before

increase

their

of

the

arteries

and

question.)

heart

disease.

71

7.2

Sources

Eating LEARNING



State

of

nutrients

healthily

OUTCOMES

some

good

components

of

and

the

describe

sources

a

of

balanced

Diets

in

different

from

each

parts

of

the

world

vary.

However,

we

should

all

eat

the of

the

food

groups

shown

in

the

food

guide

pyramid.

diet

importance

of

Carbohydrates them

Carbohydrates •

Describe

the

source symptoms

due

to

lack

mineral

C

sugars

and

starches,

which

provide

us

with

a

ready

of

energy

and

salts

D,

iron

and

and

that

is

easily

respired.

Simple

sugars

are

absorbed

almost

of

immediately vitamins

include

deciency

by

the

stomach

into

the

blood

to

give

an

immediate

result

of

respiration.

source

the

of

energy .

of

carbohydrates

This

energy

is

released

as

a

Good

sources

calcium

are

rice,

potatoes,

bread,

yams,

sugar

and

honey .

Proteins

fats,

oils,

sweets

In

it

order

needs

protein

meat,

poultr y,

yogurt,

beans,

cheese

your

protein

into

body

to

to

grow

make

amino

new

acids

and

and

cells.

then

develop,

You

use

digest

these

to

fish,

make

milk,

for

eggs,

your

own

proteins.

There

are

20

different

nuts

types

of

fruit

of

these

Cell

amino

to

acid

make

membranes

and

its

your

own

and

body

protein

cytoplasm

must

(see

have

Topic

contain

a

all

4.1).

great

vegetables

deal

bread,

or

cereal,

pasta,

rice

of

protein.

damaged

your

food

growth

daily

Figure

7.2.1

exercise

The

food

and

guide

weight

energy.

control

for

and

Y our

cells

so

this

as

repair

Good

it

body

you

well.

may

sources

may

need

If

protein

be

are

need

to

enough

is

respired

meat,

sh,

replace

protein

not

to

old

in

used

for

provide

milk

and

nuts.

pyramid.

Fats

Fats

are

under

the

releases

one

STUD Y

can

now

infor mation

you

each

(e.g.

in

starte d

featu re

energy

kJ)

write

mak e

0

add

to

in

(e.g.

provi de

gram

the

Fats

are

Fats

also

a

4 .1.

long-term

around

than

twice

the

as

carbohydrate

energy

heart

much

or

store.

and

kidneys.

energy

protein.

The

than

When

One

can

we

fat

be

are

is

stored

gram

of

fat

released

short

of

from

thick

you

uses

also

energy

fat.

good

give

layer

the

thermal

buoyancy

of

blubber.

to

insulators,

marine

Good

since

animals,

sources

are

they

for

cut

down

example

butter,

heat

whales

cheese,

fat

in

loss.

have

meats

For sh,

nuts.

inclu de

sure

and

if

Water you

for

Water

when

the

you

up

drink

two-thirds

or

of

your

body

mass.

You

take

in

water

eat.

answ er

vitam ins,

water

makes

each

do

energy ).

not

You

could

in

few

to

a

take

go

without

food

days

without

water.

place

in

water.

in

the

that

your

in

Waste

urine,

faeces,

72

of

and

a

conten t

bre ,

any

table

body

and

even

min erals

more

T opic

someth ing

nutri ent

is

skin

more

as

TIP our

Y ou

important

solution.

intake

sweat

water

of

and

in

water

are

our

number

is

blood

day

of

weeks,

needed

for

transports

passed

sweat

each

breath.

a

Water

The

chemicals

and

for

out

of

cools

equals

bodies

down.

your

you

substances

our

us

but

chemical

loss

It

of

in

is

would

die

reactions

dissolved

solution

important

water

in

urine,

Vitamins

We

be

of

need

and

small,

healthy.

If

minerals

regular

these

deciency

amounts

are

lacking

of

in

vitamins

the

diet

and

we

minerals

can

develop

if

we

are

to

symptoms

diseases:

deciency

rich

symptoms

food use

name

in

body (deciency

source

disease)

oranges,

tissue

lemons,

resistance

repair, bleeding

vitamin

C

other

gums

to (scurvy)

citrus

sh

fruits

oil,

butter vitamin

disease

milk,

D made

strengthens

soft

by

bones

bow

the

and

outwards T angerines

are

a

good

source

of

vitamin

C.

(rickets)

Sun)

used

in

formation

liver,

legs

skin teeth

in

bones,

(also

meat,

of

haemoglobin

in

tiredness,

lack

of DID

YOU

KNOW?

iron cocoa,

eggs

red

blood

cells

energy

(anaemia)

In for

transport

1747,

James

Lind,

a

Scottish

of

ship’s

surgeon,

was

able

to

oxygen

show weak, milk,

sh,

strengthens

green

bones

teeth

The

Fibre

bre

cabbage,

the

The

or

bulk

gut

muscles

helps

the

plant

part

to

of

the

the

and

our

from

comes

cell

of

sweetcorn

adds

entire

roughage

from

important

Fibre

disease

preventing

the

citrus

walls.

diet.

food.

gut

Although

High-bre

Since

to

wall

of

plants.

it

It

is

made

cannot

foods

be

up

digested,

include

bran

Fibre

from

diet

it

anus

need

food

constipation

bacteria

lowers

reduces

the

the

in

is

not

and

digested,

does

something

the

not

to

alimentary

it

passes

provide

fruits

provided

C

the

push

canal

down

any

energy.

against.

by

Fibre

KEY

(see

Topic

7.3).

Fibre

POINTS

peristalsis

absorbs

Carbohydrates

in

our

gut.

Many

doctors

believe

concentration

risk

of

heart

of

disease

cholesterol

and

bowel

in

that

the

List

the

a

each

of

an

balanced

diet

and

give

a

2

good

source

one.

2

Explain

why

3

Explain

the

quick

of

energy,

energy

while

fats

store.

blood.

cancer.

Protein

is

needed

repair

Lack

can

a

a

high-

QUESTIONS

components

are

poisonous

3

SUMMARY

of

on

vitamin

it

and

1

sailors

years;

cereals,

are bre

for

mainly

source wastes

affected

voyages

celery.

mouth

movement

from

1 so

as

successfully

remedy.

cellulose

an

lemons,

cramps

in

is

and

(rickets),

long

of

such

weakness

teeth and

Dietary

fruits,

and muscle

vegetables

citrus

bones oranges

and calcium

brittle

that

of

of

calcium

cause

lack

of

and

lack

and

rickets

iron

of

for

growth

tissues.

vitamin

(soft

causes

D

bones);

anaemia

vitamin

C

causes

scurvy.

the

diet

must

contain

each

component.

4

Roughage

of

term

deciency

food

helps

through

the

the

passage

gut.

disease

73

7.3

Balancing

Getting LEARNING

the

reasons

why

put

• Describe

on

food

as

a

result

If

health

in

a

day

should

provide

you

with

enough

energy

to

day.

risks

happens

if

we

eat

too

much?

of

malnutrition

the

eat

that

and

What

you

eat

more

food

than

you

need,

your

body

stores

the

extra

as

fat.

associated Your

with

you

through

weight

obesity

constipation

• List

right

some get

people

balance

needs

OUTCOMES

The • State

the

energy

energy

intake

is

the

energy

you

get

in

your

food

in

a

day

in

obesity proteins,

• Explain

the

role

of

Your

(bre)

in

the

carbohydrates

and

fats.

roughage energy

output

is

the

energy

your

body

uses

in

a

day.

If

diet energy

body

intake

and

body

overweight

page.

that

or

People

become

greater

mass

even

with

diet

foods

low

or

a

energy

increases.

We

Obesity

basal

obese

contains

with

than

obese.

a

overweight

their

rened

is

of

may

is

run

than

the

rate

those

foods,

added

then

dened

metabolic

fattening

lot

output,

risk

in

stored

box

high

in

the

becoming

are

higher

as

is

of

the

(BMR)

with

such

fat

on

the

more

BMRs.

fat

next

likely

It

is

foods

to

likely

and

sugar.

Obesity

In

rich,

suffer

if Many

children

do

not

eat

this

sort

of

meal

a

industrialised

from

person

countries,

overeating

takes

in

than

more

like

from

energy

Britain

eating

in

and

too

food

the

little.

than

they

USA,

As

more

we

use,

have

then

people

seen,

the

at

excess

is

stored

as

fat.

T aken

to

extremes,

people

can

put

on

so

much

lunchtime!

weight

Major



high

that

of

obesity

intake

of

fatty



too



social

People

Exercise

helps

ght

heart

disease

and

74

growing

and

rened

foods

containing

a

lot

emotional

are

people

9.5),

sugar

stress,

overweight

to

have

high

(see

Topic

and

health

blood

leading

obese

and

‘comfort

are

problems

pressure,

10.3)

to

eat



take

of

much

such

as

diabetes

arthritis

eating’.

more

heart

caused

(worn

likely

than

disease

by

high

joints).

could

someone

lose

weight?

could:



A

a

foods

obesity.

They

is

and

Topic

How

Obesity

include:

exercise

who

thinner

obese.

sugar

little

blood

become

causes

added

(see

they

less

high-energy

more

sensible

exercise

approach



a

balanced



a

gradual



having

diet

foods

(increase

to

with

increase

(lower

slimming

a

in

their

lower

their

energy

energy

should

intake

of

intake)

output).

combine:

energy

exercise

problem.

an

ideal,

but

achievable,

target

for

weight

reduction.

DID

YOU

KNOW?

Obesity

STUD Y

There

are

two

ways

in

which

people

can

identify

being

Y ou • being

20%

above

the

recommended

weight

for

his

or

TIP

obese:

her

do

no t

remem ber • having

a

body

mass

index

(BMI)

greater

than

body

mass

index

mass

/

inde x,

kg

be

2

/

the

but

metres

awar e

person

with

a

BMI

of

less

than

20

is

underweight;

between

is

severely

body

overweight;

obese.

mass

These

same

is

If

in

your

the

calculations

way

for

more

BMI

than

is

in

acceptable

are

for

children

30

the

the

obese;

range

of

more

20

to

than

24,

40

then

or

indigestible

but

is

grea ter

is

The

BMI

is

calculated

interpretation

important

is

bulk

to

our

in

the

for

a

healthy,

balanced

diet.

It

TIP

is

food.

This

is

important

for

moving

down

the

alimentary

canal.

The

muscles

of

the

gut

die ts

that

to

squeeze

the

food

along.

Soft

foods

do

not

stimulate

to

contract

as

effectively

as

the

harder,

indigestible

too

little

foods

muc h that

form

roughage.

If

the

movement

of

food

is

slow

it

will

result

making

it

difcult

to

defecate.

or

A

diet

containing

fruit

and

vegetables

contains

lots

of

certai n

far

are

the

best

foods

to

relieve

complete

Copy

and

the

exercise

sentences

energy

you

take

.

long

by

in

more

than

Eating

periods

eating

of

foods

time

can

less

lead

foods

using

muc h

is

to

the

List

four

health

problems

that

are

A

is

stored

added

Calculate

person

can

more

as

KEY

lose

weight

1

the

the

body

BMI

mass

category

index

in

for

each

linked

the

.

to

people

their

a

man

1.70 m

b

a

woman

in

1.75 m

height

in

is

following

people

a

man

a

State

1.85 m

in

height

a

body

with

a

mass

body

of

mass

110 kg

of

Obesity

and

a

50 kg

with

a

body

mass

of

two

good

sources

of

Explain

the

effects

of

a

roughage

lack

output

can

lot

intake

rened

of

in

the

than

(in

their

(in

their

exercise).

be

of

roughage

in

of

caused

fatty

by

a

foods

added

of

too

foods

containing

sugar

little

plus

the

exercise.

A

diet

lacking

in

roughage

diet.

(bre) b

greater

weight

75 kg

3 4

on

intake

and

effects c

put

energy

case:

with

height

roug hage .

obesity.

high

a

of

die t

POINTS

Some

if

2 name

fo rm

the

over

energy

3

as

words:

excess

with

.

taking

in

a

fatty

use,

foods

lack ing

food) 2

of

obesity

fat

you

and

and

these

sugar

high-energy

If

shor tage

constipation.

is

1

too

compo nent s.

malnu trition

QUESTIONS

or

compo nent s

Cons tipat ion

SUMMARY

a

roughage;

those these

too

there

energy

energy ,

in

of constipation

no t

beca use

the

is muscles

are

wall

bala nced contract

refers

keeping

to food

their

30.

different.

Malnu trition adds

is

your

STUD Y

bre

if

than

is

Constipation

Roughage

someo ne

obese

range.

adults.

but

is

as

mas s

shou ld

25

BMI 30

body

you

that

classi ed

and

to

to

=

height

A

how

30.

calcul ate

body

have

height

the

can

lead

to

diet. constipation.

75

7.4

Starvation

and

nutrient

deciency

People

can

water.



Describe

the

effects

upon

of

are

starvation

This

its

no

tnemelppuS

Describe



Discuss

the

effects

of

of

many

weeks

causes

vitamin

without

and

in

the

The

During

body

muscles

wasting

energy

by

to

a

lack

the

to

are

of

the

dietary

food

fat

food,

provided

starvation,

and

protein

starvation

uses

stored

use

as

a

the

fat

source

the

they

for

basal

and

body

have

energy,

draws

but

metabolic

then

breaks

there

rate

down

of

energy.

This

leads

to

In

(swelling

abdomen

legs);

hair;

appearance.

that

and

(PEM).

energy

or

with

shown

lack

on

the

In

which

of

so

its

worst

terms

are

food.

in

suggests,

are

These

two

In

given

have

The

protein

form

to

is

it

caused

can

describe

lead

the

ways

conditions,

However,

adapted

food.

is

this

different

both

marasmus.

marasmus

when

undernutrition

term

protein.

more

with

better

of

the

PEM.

to

though

children

are

and

marasmus,

responds

respond

form

As

it

better

is

to

symptoms

in

children

of

lack

of

these

left.

of

kwashiorkor:

and

emaciated

common

children

body

conditions

the

of

underweight,

thought

oedema

an

most

kwashiorkor

which

Symptoms

and

malnutrition

appearance

sparse,

aky

both

cases,

frequent

causes

children

servings

cells

enzymes

of

are

of

the

are

small

in

pancreas

secreted

danger

quantities

and

and

the

and

of

feeding

food.

intestine

surface

to

area

should

This

die,

for

is

so

involve

because

fewer

absorption

PEM

digestive

of

digested

skin;

food

is

reduced.

During

starvation,

there

are

deciencies

of

the

accumulation

protective in

water.

reduced.

Worldwide,

fat

carbohydrate,

of

iron

deciencies

dry

of

periods

and

D

of

of

during

scurvy

muscle

effects

for

because

stores

is

protein

the

is

stores

(BMR) •

survive

OUTCOMES

vitamins;

people

are

at

risk

of

developing

infectious

communities

in

developing

diseases.

liver.

Dietary

shown

of

surveys

that

cells,

with

has

these

Children

such

as

of

with

to

poor

be

which

used

conditions

who

these

other

and

are

protein

as

are

develop

cassava

content,

Symptoms

of

protein,

an

the

in

foods.

be

energy

suffering

potato;

protein,

Staple

used

for

source.

from

symptoms

sweet

low

should

a

may

while

so

This

lack

be

fed

need

such

on

a

have

and

that

energy

in

be

wheat

repair

children

the

tropical

high

to

as

nations

growth

shows

of

having

they

foods

the

diet.

crops

energy

supplemented

and

rice

will

marasmus:

satisfy

very

low

mass;

energy

legs;

muscle

we

also

76

is

found

seen,

symptoms

protein

of

two

energy

This

can

Vitamin

protein

malnutrition.

C

have

calcium

of

needs

a

in

oranges,

deciency

of

lemons

and

vitamin

C

other

leads

citrus

to

the

fruits.

disease

called

face.

gums.

forms

protein.

old-

scurvy.

Typical

enough

fat;

As

7.4.1

provide

arms

Vitamin wizened,

Figure

also

little

or

looking

and

body

thin

Nutrient and

intake

by

C

helps

bones

used

helps

cause

in

to

and

make

the

bleeding

bond

teeth.

skin,

healing

of

in

cells

parts

of

together

Vitamin

tendons,

wounds

C

is

the

body,

and

helps

used

ligaments

and

the

to

particularly

in

form

and

the

an

blood

formation

of

use

the

of

important

vessels.

scar

It

tissue.

tnemelppuS

LEARNING

It

is

also

D

needed

needed

Deciency

rickets

is

in

children.

children

body.

Rickets

the

of

can

Iron

bones

is

found

iron.

It

Foods

needed

in

red

is

to

rich

in

a

of

iron

iron

grow

the

the

of

by

In

bend

carry

oxygen

day.

liver,

At

is

puberty,

rich

soft,

weight

in

leads

protein

the

of

vitamin

gives

to

a

so

the

D

like

rise

to

softening

which

combined

is

with

body.

If

occur.

girls

become

the

cells.

causing

haemoglobin

a

cocoa.

can

bone

fractures.

around

meat,

in

bones

deciency

which

protein

anaemia

in

and

foods

of

calcium.

calcium

with

adults,

chance

blood

of

absorb

calcium

eating

milk.

to

properly

bones

Haemoglobin

called

each

to

fail

increased

include

disease

lack

and

cells.

to

deposition

osteomalacia,

make

blood

needed

diet,

16 mg

an

as

intestine

the

prevented

eggs

known

and

the

walking

be

small

include

Bones

start

butter,

condition

the

the

oil,

the

regulate

symptoms

when

sh-liver

to

for

there

An

need

to

is

a

adult

make

lack

of

needs

sure

iron

in

about

they

have An

enough

iron

in

their

diet

as

they

start

to

menstruate

(have

X-ray

bowed

The

lack

The

main

of

iron

shortness

of

breath,

SUMMARY

1

a

leads

symptoms

to

of

a

reduction

anaemia

heart

are

in

the

number

tiredness

palpitations

and

a

and

pale

of

red

lack

of

blood

the

main

inadequate

are

causes

the

of

symptoms

kwashiorkor

Explain

why

frequent

starvation

in

terms

of

servings

of

of

very

below

is

mouth

are

these

small

two

conditions

/

amounts

of

as

a

box

containing

breakfast

Fat

/

/

g

per

a

result

much

energy

would

How

c

The

to

3

Make

the

in

a

this

table

fat

of

How

get

diet.

the

much

protein

much

mass

to

2

Scurvy

be

in

a

150 g

serving

of

the

is

to

body,

in

good

with

a

cereal

in

a

75 g

adult

serving

female

would

a

of

the

needs

female

cereal?

per

have

day

to

3

iron,

table

dietary

The

fallen

C

in

in

a

very

of

the

eat

vitamin

C

and

and

the

vitamin

about

D

their

deciency

in

roles

diseases

4

cause

bones

a

parts

iron

in

of

of

D

by

can

the

anaemia

Vitamin

plus

a

low

fat

and

lack

of

a

vitamin

and

in

ability

of

infections.

of

diet

transport

information

sources

nutrient.

Lack

cause

is

protein?

your

each

be

young

more

of

have

vitamin

lack

caused

bleeding

the

with

wasting,

deciency

there

there

compare

Include

associated

would

enough

results

mass

particularly

mass

60 g.

not

resistance

cereal?

b

scurvy.

POINTS

muscle

3

How

of

Starvation

in

a

has

teeth

100 g

83

g

the

cereal.

6

Carbohydrate

who

and

food.

1800

g

person

diet.

body

Protein

a

involves

1

kJ

of

inamed

marasmus?

from

Amount

/

and

of:

ii

treatment

information

Energy

bones

rickets.

an

KEY The

weakened

with

diet.

the

2

the

child

complexion.

out

c

a

cells.

gums

i

of

energy,

The

What

legs

QUESTIONS

Explain

b

showing

periods).

C

cause

of

the

body,

gums.

the

diet

which

the

tnemelppuS

tnemelppuS

Vitamin

can

affects

blood

to

oxygen.

deciency

softening

causing

of

can

the

rickets

and

osteomalacia.

77

7.5

Digestion

During LEARNING

the

different



Dene

mechanical

Dene

ingestion,

Ingestion

the

and

be

along

the

alimentary

canal,

a

number

of

identied.

the

taking

and

of

lipase,

amylase,

Digestion

into

of

substances

(food

and

drink)

into

the

mouth.

is

the

and

soluble

breaking

the

molecules

down

so

that

of

large

they

can

insoluble

pass

molecules

through

the

into

gut

wall

blood.

listing •

substrates

the

egestion

function

protease

the

is

through

small

State

food

absorption, •

assimilation



of

can

digestion body



processes

and •

chemical

passage

OUTCOMES

the

Absorption

is

the

movement

of

small

food

molecules

and

ions

endthrough

the

wall

of

the

intestine

into

the

blood.

products •

Assimilation

cells



of

the

Egestion

is

absorbed,

The

large

gut,

food

which

system

the

the

as

mechanically

is

body

out

are

of

with

2.4).

food

the

This

the

digestive

used,

that

has

proteins

happens

liver

and

the

food

When

food

molecules

becoming

part

not

of

been

into

the

the

cells.

digested

or

anus.

starch,

chemically.

Topic

of

are

through

molecules

and

they

passing

faeces

together

(see

movement

where

in

and

the

pancreas

has

fats.

form

been

Digestion

alimentary

your

occurs

canal,

or

digestive

digested,

it

is

absorbed

mouth

through

the

molecules

wall

can

of

go

the

small

through

intestine

the

gut

into

wall

the

they

blood.

must

be

Before

the

dissolved.

food

Large

food

food

molecules

through

the

molecules

wall

of

another

digestive

are

the

are

wall

insoluble;

of

the

soluble.

small

body

They

intestine

uid

that

they

small

will

not

intestine.

will

and

dissolve

enter

absorbs

the

and

dissolve,

On

so

the

therefore

other

they

blood

can

and

transports

fat

hand,

get

the

cannot

small

through

lymph,

(see

page

get

food

the

which

is

114).

enzymes

gut

Mechanical

digested

digestion

food

Mechanical

smaller

digestion

pieces

of

food

is

the

breakdown

without

changing

of

the

large

food

pieces

of

food

molecules.

into

This

anus

starts

in

pieces

7.5.1

Digestion

in

the

alimentary

canal.

STUD Y

that

continue

faeces

Figure

broken

about

n

‘diges

deni

tions

tion’

dige stion’

prepar

,

‘mec

the

hani

‘chem

to

e

the

betw een

body

Muscular

small

globules

digestion

can

into

use

by

in

food

small

digestion

into

contractions

intestine,

large

emulsication

the

next

few

by

into

of

the

globules

bile.

smaller

stomach

of

There

fat

is

are

more

topics.

that

has

been

eaten,

the

food

must

be

molecules.

is

smaller

the

breakdown

soluble

of

molecules

the

by

large

the

insoluble

action

of

food

enzymes.

be occurs

in

the

mouth,

stomach

and

small

intestine.

Mechanical

distin guis h

differ

them .

ence

gives

a

larger

surface

area

for

the

enzymes

to

work

on.

s)

The

three

types

carbohydrases

specic

to

remind

of

enzymes

and

enzyme

lipases.

because

yourself

breakdown

78

the

food

ical

digestion

(giv

In

down

digestion

down

molecules

and

swallowed.

breaks

cal

This

ed

chewing

of

Chemical

and

be

where

process.

smaller

Chemical

TIP

stion’

can

this

into

broken

dige

mouth

mechanical

Before

Lear

the

about

proteins,

in

the

Each

they

the

alimentary

type

have

of

food

different

reason

carbohydrates

for

and

canal

are:

molecule

shapes.

having

fats.

proteases,

needs

See

different

Topic

a

5.1

enzymes

to

a

protein

many

molecule

different

is

amino

made

up

amino

of

protease

down

a

starch

molecule

acids

acids

is

made

up

enzymes

protein

break

molecules

of glucose

many

glucose

molecules

amylase

starch

a

fat

fatty

molecule

acid

and

is

made

glycerol

up

to

maltose

break

(a

down

sugar)

of

fatty

molecules

lipase

fatty

enzymes

acid

down

enzymes

fat

acids

break

molecules

glycerol

glycerol

Figure

The

7.5.2

The

chemical

carbohydrase

breakdown

enzyme

that

of

protein,

breaks

starch

down

and

starch

fat.

is

called

amylase

KEY

SUMMARY

POINTS

QUESTIONS

1

Mechanical

the 1

Name

the

enzymes

and

end-products

involved

in

the

particles

starch

b

protein

c

surface

a

Explain

why

b

Explain

the

digestion

is

necessary.

of

large,

is

difference

between

mechanical

digestion

chemical

what

happens

to

food

after

it

has

been

graph

into

food

smaller,

molecules

by

water-

the

shows

the

activity

of

the

enzymes

of

enzymes.

digested.

2 The

Chemical

breakdown

digestion.

action Outline

the

and

soluble

3

increase

insoluble

molecules

c

to

area.

fat digestion

2

of

of:

their a

is

breakdown

chemical

food digestion

digestion

physical

amylase

Amylase

breaks

down

and starch

molecules

to

glucose

pepsin. molecules.

a

i

At

what

ii

How

pH

does

pepsin

work

best?

Protease does

hydrochloric

acid

in

the

stomach

breaks

molecules pepsin

to

What

are

formed

when

pepsin

breaks

down

i

At

what

ii

What

is

amino

protein

acids.

pH

does

formed

amylase

when

the

work

breaks

down

fats

to

proteins?

fatty b

to

work?

Lipase iii

down

help

acids

and

glycerol.

best?

amylase

breaks

down

starch?

iii

Why

is

it

useful

that

saliva

contains

an

alkali?

emyzne

pepsin

fo ytivitca

amylase

2

3

4

5

acid

6

7

pH

8

9

10

11

12

alkaline

79

7.6

T eeth

The LEARNING

teeth

breaks

The •

Describe

the

structure

in

teeth

and

mechanical

surface

their

State

the

decay

care

mechanical

area

into

of

smaller

digestion

food

is

pieces

increased

so

when

chewing

so

making

making

it

food.

it

easier

This

easier

to

swallow.

for

enzymes

catalyse

the

reactions

needed

for

chemical

digestion.

digestion

causes

and

of

out

food

function

Adult



down

of

to human

carry

OUTCOMES

of

describe

tooth

the

They

humans

have

have

different

32

teeth,

shapes

but

for

not

all

of

performing

the

teeth

different

are

the

same.

functions:

proper •

incisors

are

chisel-shaped



canines

are

pointed



premolars



molars

for

biting

and

cutting

teeth

are

Counting

there

8

teeth

During

teeth,

small.

to

be

the

uneven

‘cusps’

premolars

number

4

in

of

and

each

and

for

are

type

tearing

grinding

for

of

and

chewing

tooth,

chewing

up

you

food.

should

nd

that

our

are

canines,

lives

back

we

small

Between

will

8

premolars,

and

12

molars,

which

makes

all.

replaced

teeth

our

like

piercing

are:

incisors,

32

have

for

the

by

come

have

teeth

two

and

ages

our

of

or

6

of

and

when

wisdom

teeth.

are

only

12

permanent

through

molars

sets

there

we

8

these

teeth.

are

at

The

rst

molars

teeth

The

least

set,

as

or

our

gradually

last

18,

of

if

our

at

milk

jaws

fall

are

out,

permanent

all!

These

are

teeth

enamel

pulp

A

child

usually

has

20

milk

cavity

crown

teeth.

dentine

canine molar

gum

premolar

root

STUD Y

Mak e

TIP

sure

iden tify

type s

from

of

you

ner ves

can

the

differ ent

hum an

tee th

pho to grap hs

their

and

Figure

7.6.1

Adult

Figure

teeth.

7.6.2

Vertical

section

through

molar.

and

Enamel

the

tions

part

forms

above

the

hard,

the

gum.

outer

layer

Inside

this

of

is

the

crown

softer

of

the

dentine,

tooth,

which

is

which

more

is

like

in bone

in

bony

socket

structure.

A

layer

of

cement

xes

the

root

of

the

tooth

into

a

dige stion.

The

pulp

blood

Tooth

to

in

the

cavity

jaw.

is

a

The

root

space

in

is

the

the

part

tooth

that

is

below

containing

the

gum.

nerves

and

vessels.

Healthy

80

vessels

socket

incisor

a

can

func

mecha nica l

and

bony blood

diag ram s

state

that

teeth

decay

form

is

and

caused

plaque,

by

which

gums

bacteria

is

a

layer

in

your

that

mouth.

sticks

to

They

your

mix

teeth

with

and

saliva

gums.

decay

enamel

dentine

DID

pulp

YOU

KNOW?

Periodontal

abscess

No

pain

Slight

toothache

Severe

toothache

the

7.6.3

Stages

in

tooth

if

space

between

get

tooth

to

the

forming

base

an

of

abscess

can

make

The

bacteria

holding

decay.

and

After

a

meal,

Bacteria

in

respiring

of

a

this

be

be

this

will

your

should

plaque

and

acid

will

make

the

of

very

The

starts

attack

red

food

the

acid

off

the

painful

gums

sugary

changes

anaerobically.

tooth

away,

particles

tooth

and

cause

may

sugar

can

dentine.

and

the

between

acid

the

the

7.6.4

on

the

degrees,

your

brush

teeth

with

up-and-down

at

the

45

Clean

gentle,

of

your

short

the

gently

movements.

sure

inside

teeth

back

not

surface

moving

to

and

your

the

The

shows

of

Brush

brush

forwards.

forget

the

also

the

is

worn

pulp

acid

how

both

Be

with

the

teeth.

short,

and

the

make

gums

They

can

rot

teeth

them

unhealthy.

the

in

fall

bres

position

out.

STUD Y

TIP

cavity

can

our

biting

upper

the

are

No te

also

surfaces

lower

scrubbing

that

uo rid e

streng then s

teeth

of

outside

the

can

into

surface

brushed.

clean

get

teeth.

they

the

enamel

reaches

toothache.

Figure

your

because

enamel

When

cavity

severe

swollen.

left

into

attack

decay.

If

be

a

Holding

bacteria

Agony!

bacteria

Figure

disease

occur

the

tee th ,

hard

the

exterio r

KEY

POINTS

KEY

POINTS

enam el

giving

them

surf ace.

of

teeth

strokes.

1

back

Incisors

are

cutting,

for

biting

canines

for

and

piercing

teeth.

Figure

7.6.4

Make

SUMMARY

sure

you

clean

all

surfaces

of

your

Copy

tearing,

and

molars

and

complete

the

and

chewing.

sentences

using

these

Tooth

decay

bacteria

words:

in

changes dentine

crown

mechanical

bite

enamel

chew

are

of

is

used

to

digestion.

gum

and

the

a

hard,

which

is

and

Each

which

outer

similar

layer

of

to

tooth

is

tted

the

your

consists

into

tooth;

a

of

food.

a

is

above

bony

inside

This

this

.

is

the

a

a

Name

b

For

c

What

the

The

softer

3

Tooth

by

each

is

type

the

permanent

d

Describe

e

State

in

part

types

a,

difference

of

caused

to

by

which

acid

that

the

of

enamel

the

and

tooth.

decay

good

can

be

brushing

toothbrush,

foods

and

avoided

with

a

avoiding

visiting

the

regularly.

teeth.

describe

between

its

the

shape

milk

and

teeth

its

function.

and

the

teeth?

the

three

main

sugar

regular

sugary

.

four

is

plaque,

type

the

dentist

2

grinding

bone dentine

teeth

premolars

for

socket attacks

root

The

and

are

QUESTIONS

2

1

and

teeth.

stages

ways

in

of

tooth

which

decay.

tooth

decay

can

be

prevented.

81

7.7

Mouth,

and

stomach

Chewing LEARNING

Describe

the

events

that

during

the

and

of

chewing

food,

of

Describe

Describe

in

the

the

digestion

of

TIP

rst

our

enzy me

food

amyl ase.

what

starch ,

they

mou th

smal l

the

are

is

Mak e

and

pieces.

digestion

the

moistened

into

a

ball

molar

It

easier.

food

or

salivary

through

and

the

canine

mouth.

teeth

bite

When

it

into

is

teeth

grind

important

to

these

chew

chunks

your

of

food

food

well

The

tongue

mixes

the

food

with

as

saliva

is

chewed

by

the

teeth.

The

food

is

then

bolus

mucus,

to

act

a

glands

slimy

down

amylase,

the

pro te in

pass

to

the

saliva,

that

which

contains:

lubricates

the

passage

of

the

food

throat

enzyme

that

catalyses

the

breakdown

of

starch

to

maltose.

no te s

nasal

to

and

from

end

intest ine.

wher e

make

substance

the

ball

prod uced

they

body

teeth

saliv ary

happ ens

enzy mes

them ,

premolar

smaller

makes

bolus



as

The

much

rolled

food



on

the

stomach

STUD Y

on

into

incisor

peristalsis

The

T he

the

saliva

and



ingested

mouth,

including

this



are

the

and

into action

drink

enters

chunks. swallowing

the

swallowing

take food

place

and

OUTCOMES

Food •

oesophagus

the

passage

food

fat

the

of

The

food

soft

palate

pushes

your

the

List

that

of

act

This

stops

going

on

up

upwards.

the

food

your

hard

nose!

palate

enzy mes Before

and

you

swallow,

what your

tongue

food

into

rolls

the

do. epiglottis

opening

So

food

the

The

covers

to

food

your

your

doesn’t

wrong

the

trachea.

go

and

down

a

soft

pushes

back

of

it

your

ball

to

the

mouth

way!

squeezes

epiglottis

oesophagus.

into

past

trachea

your

Gulp!

oesophagus

Figure

7.7.1

Events

during

swallowing.

muscle direction

The

oesophagus

Food

passes

contracting food

is

moving

stomach.

ball

longitudinal

of

down

The

the

oesophagus

oesophagus

muscles

in

its

(also

from

known

as

the

the

mouth

gullet)

to

the

has

circular

and

wall.

food

The

movement

muscular

of

food

contraction

down

called

the

oesophagus

peristalsis.

The

occurs

circular

by

a

wave

muscles

of

contract

muscles

and

relaxing

it

the

along.

longitudinal

In

front

longitudinal Figure

7.7.2

Peristalsis

in

contraction

the

82

the

muscles

relax

bolus,

contract

the

to

behind

circular

widen

the

food

muscles

the

bolus

relax

oesophagus

to

and

to

push

the

allow

the

the

bolus oesophagus

of

muscles

is

to

stomach.

a

wave

pass

of

food

to

move

along.

Movement

of

food

in

the

small

and

of

food

to

large

intestines

also

occurs

by

peristalsis,

though

to

a

lesser

extent.

The

oesophagus

stomach liver

stomach

The

stomach

food

but

can

stomach

The

a

walls

juice.

tnemelppuS

Gastric

a

muscular

stretch

number

of

This

proteins

is

the

smaller

juices

also

the

that

usually

accommodate

things

stomach

contains

to

to

of

bag

happen

make

a

molecules

contain

more.

to

pepsin

called

about

When

1

food

litre

of

reaches

the

it.

digestive

protease

holds

juice

which

known

starts

as

the

gastric

digestion

of

polypeptides.

hydrochloric

acid

which

carries

out

gall

two

bladder

important

functions

due

to

its

low

pH. pyloric



It

kills

any

bacteria

in

the

food.

The

low

pH

denatures

the

sphincter

enzymes

pancreas

in

any

harmful

microorganisms

in

the

food.

bile

duct pancreatic



The

the

acid

pH

action

of

of

about

the

1.5

to

protease

2.0

gives

enzyme

the

optimum

conditions

for

small

pepsin.

duct

intestine

Figure

7.7.3

Upper

part

of

the

digestive

system.

The

mixture

chyme.

making

is

a

of

The

sure

type

of

contents

of

food,

gastric

muscular

that

it

is

walls

mixed

mechanical

the

juice

of

and

the

well

with

digestion.

stomach

are

like

a

hydrochloric

stomach

the

After

juices.

2–3

runny

churn

acid

up

This

hours

of

is

the

called

food

muscular

KEY

POINTS

action

churning,

1

the

Food

by A

ring

of

muscle

called

the

pyloric

sphincter,

is

teeth.

liquid.

opens

to

let

the

the

a

little

at

a

time

into

the

duodenum

which

is

the

rst

is

up

then

actions

by

the

swallowed

of

the

tongue,

food saliva,

pass

chewed

It

part

soft

pallette

and

of epiglottis.

the

small

intestine.

2

Peristalsis

of

that

3

In

the

the

carrying

oesophagus

mouth

a

wave

contractions

squeeze

bolus,

salivary

involves

muscular

it

to

food

down

the

stomach,

the

stomach.

food

is

churned

gland

up

and

and

mixed

with

hydrochloric

gastric

acid.

juice

This

oesophagus

starts

liver

SUMMARY

the

digestion

of

proteins.

QUESTIONS

stomach

1

With

reference

events

that

to

take

the

place

following,

when

describe

food

is

the

chewed

pancreas

and

swallowed:

a

saliva

c

the

tongue

b

mucus

d

the

epiglottis

a

Describe

small

2

one

function

of

the

muscle

layers

in

intestine

the

b

i

stomach

Name

wall.

the

type

of

protease

produced

large

by

the

walls

of

the

stomach.

intestine

ii

Describe

the

function

of

this

type

of

enzyme.

c

Explain

briey

why

a

different

enzyme

is

rectum appendix

required

anus

food Figure

7.7.4

The

digestive

for

the

digestion

of

each

type

of

substance.

system.

83

7.8

Small

intestine

and

absorption

The

The •

Describe

small

the

digestion

small

in

the

small

the

emulsifying

its

role

of

bile

Dene

the

The

fats

term

Describe

how

intestine

is

efcient

after

the

the

absorption

for

of

food



amylase



trypsin

lipase

Bile

a

globules

emulsied

globules

to

of

of

are

to

increase

Bile

is

fo r

TIP

lipas e

no t

a

incr eases

of

of

as

chan ged

it

is

the

about

large

6

metres

intestine.

long;

The

rst

duodenum

that

leads

into

the

ileum

to

the

down

duodenum

the

duct

to

by

meet

the

pancreatic

food

arriving

duct.

juice

from

contains:

to

protease

starch

that

to

breaks

maltose

down

proteins

and

polypeptides

do

the

enters

the

not

also

stomach.

to

the

made

fatty

well

in

in

an

and

acidic

glycerol.

environment,

hydrogencarbonate.

along

the

a

liver

neutralises

This

acids

duodenum

duodenum

uid

and

to

sodium

enters

the

fats

work

alkali,

which

alkaline

in

down

gives

from

tube

and

the

the

stored

the

in

for

bile

the

which

pH

so

pancreatic

neutralises

the

stomach.

called

acid

best

the

This

duct.

gall

was

is

bladder

added

enzymes

Bile

in

to

the

the

small

work.

emulsies

Cells

globules.

over

fat

fats

which

into

fatty

lining

the

by

breaking

These

the

minute

enzyme

acids

ileum

and

down

large

droplets

lipase

can

globules

have

act

to

a

much

break

of

fats

larger

down

into

surface

molecules

glycerol.

make

enzymes

that

complete

the

digestion

of

food.

fat



Proteases



Sucrase



Maltose

which

break

down

peptides

to

amino

acids.

act which

breaks

down

sucrose

to

glucose

and

fructose.

is

chem ical

the

a

down

fats

Emul sica tion

dige stion

no t

area

enzy mes

type

ows

breaks

food

intestine

of

upon .

as

of

area.

area

surf ace

the

connected

breaks

enzymes

smaller

Emul sica tion





also

food

smaller

fat

surface

fat



yellow-green

Bile

the

is

Pancreatic

contains

acidic

STUD Y

small

that

peptides

juice

their

is

juice

stomach.

These

Large

so

than

small

adapted



7.8.1

really

less

stomach,

pancreas

to

Figure

is

absorption

the •

not

in

Pancreatic •

is

diameter

intestine, part,

including

intestine

of however

food

intestine

OUTCOMES

of

the

is

broken

epithelium

down

lining

by

maltase

the

small

to

glucose

on

the

membranes

intestine.

is

chem ically .

Absorption

Absorption

the

microvilli

wall

of

the

the

movement

intestine

into

of

the

digested

blood

or

food

the

molecules

lymph.

through

Digested

food

forming

includes brush

is

simple

sugars,

amino

acids,

fatty

acids

and

glycerol.

These

border

molecules

goblet

diffusion

cell

The

small

pass

or

by

through

active

intestine

is

the

wall

of

the

small

intestine

either

by

transport.

adapted

for

efcient

absorption

of

food

as

it

has:

nucleus



a

very

large



a

thin

lining

surface

area

of

about

9

square

metres

basement

membrane

the

Figure

7.8.2

Detailed

structure

epithelial

small

84

cells

of

lining

intestine.

the

the

wall

into

(only

the

one

cell

blood

thick),

and

so

lymph.

digested

food

can

easily

cross

tnemelppuS

LEARNING

It

is

possible

because

has

villi

a

the

such

lining

villus).

called

a

large

intestine

inner

(singular:

cell

t

small

folded

projections

the

to

is

of

the

area

long

millions

epithelial

microvilli.

membrane

very

with

The

surface

cells

These

epithelial

(at

of

least

tiny,

tnemelppuS

wall

cell

is

small

metres

in

space

an

adult).

projections

the

villi

have

the

absorptive

(see

Figure

acids

It

called

microscopic

area

of

7.8.2).

and

sugar

molecules

only

are one

6

a

increase

amino villus

such

nger-like

lining

vastly

cells

into

absorbed

through

the

thin

villus

thick

wall

into

the

blood

capillar y Villi

increase

the

surface

area

of

the

small

intestine.

blood

capillar y

fatty

acids

absorbed

and

into

glycerol

the

are

lacteal

lacteal

(lymph

blood

pick

coming

up

lymph

food

to

capillar y)

villus

blood

to

coming

to

takes

away

molecules

to

lymph

villus

fluid

glycerol

Figure

The

7.8.3

digested

capillaries)

to

the

in

liver

lymph

walled

result,

the

lymph.

slowly

veins,

the

food

portal

through

enter

to

the

and

molecules

body

carries

away

to

vein.

of

Fatty

the

lymphatic

enter

lacteals

molecules

Movement

eventually

not

capillaries

Absorbed

hepatic

the

does

reaches

villi.

moves

like

fat

the

in

of

fatty

rest

of

acids

and

body

villus.

food

by

transported

the

A

food

rest

into

acids

gut

blood

too

(lymph

transported

and

glycerol

empties

vessels,

the

bloodstream

are

the

which

near

quickly

(see

are

lacteal

are

the

quickly

and

thin-

heart.

page

As

a

115).

KEY

1

SUMMARY

POINTS

Bile

fat

1

Match

with

each

its

part

correct

of

the

emulsies

duodenum.

QUESTIONS

digestive

function

in

oesophagus

makes

bile

stomach

moves

food

the

system

second

in

the

rst

lipase

column:

2

from

the

stomach

to

globules

surface

column

the

area

can

Enzymes

intestine liver

makes

pancreatic

in

the

smaller

have

a

upon

larger

which

act.

produced

pancreas

ileum

fats

The

and

the

by

the

small

complete

chemical

juice

digestion. gall

bladder

carries

pancreas

mixes

duodenum

food

food

stores

to

the

with

stomach

gastric

by

peristalsis

3

juice

bile

Absorption

is

of

food

digested

through

2

a

State:

i

the

components

of

bile,

ii

the

organ

where

bile

iii

the

organ

where

bile

is

wall

movement

molecules

of

the

is intestine

produced,

the

the

into

the

blood

and

stored. lymph.

b

Describe

two

ways

in

which

bile

aids

the

digestion

of

fats. 4

3

a

How

are

conditions

conditions

in

the

in

the

small

stomach

different

from

the

The

for

small

absorption

long,

intestine?

lining b

State

the

composition

of:

i

gastric

juice,

ii

pancreatic

intestine

having

with

a

by

is

adapted

being

folded

millions

of

very

inner

tiny

villi.

juice.

85

7.9

Large

intestine

intestinal

The LEARNING

Describe

the

large

its

Describe

diarrhoea

symptom

intestine

the

is

about

appendix,

1.5

the

metres

colon

long

and

and

the

can

be

divided

into

rectum.

Explain

as

of

cholera

how

cholera

the

time

food

gets

to

the

colon

there

is

not

much

useful

food

left.

a

It

is

now

it

has

mainly

been

bre,

absorbed

dead

in

cells,

the

bacteria

small

and

some

water,

as

most

of

intestine.

bacteria

3

cause

diarrhoea

The

and

small

food

dehydration

intestine

passes

absorbs

along

the

about

colon,

5 – 10 dm

more

water

of

is

water

every

absorbed

into

day.

the

As

blood



3

about

The

0.3 – 0.5 dm

solid

faeces

waste,

are

per

or

egested

day.

faeces,

through

are

stored

the

anus.

in

the

The

rectum.

passing

Eventually

out

of

the

digestible

stomach

food

liver

through

the

anus,

in

the

form

of

faeces,

is

called

egestion

Cholera

Cholera

is

cholerae.

a

water-borne

The

dehydration.

main

Diarrhoea

Some

people

suffer

from

infected

the

disease

symptom

is

the

with

disease

of

loss

the

and

caused

cholera

of

the

called

bacterium

diarrhoea

watery

cholera

are

by

is

faeces

bacterium

as

a

from

may

symptomless

Vibrio

result

the

not

of

body.

actually

carriers

colon

Transmission caecum

small

Cholera

tends

sanitation,

anus

The

large

that

of

the

is

people

is

transmitted

Almost

acidic

seen

in

an

on

all

the

cholera

and

mucous

as

in

reach

lining

by

by

occur

food

conditions

survive

cholerae

can

handling

Effects

where

supply

there

or

is

a

lack

of

contaminated

proper

food.

Water

when

their

infected

people

pass

out

large

faeces.

the

by

or

drinking

water

or,

containing

contaminated

utensils

more

the

water ,

without

rarely,

food

bacteria.

by

washing

infected

their

hands.

body

the

the

the

of

material

cooking

bacteria

in

ingestion

faecal

ingested

stomach.

small

wall

of

by

However,

intestine.

the

humans

Here

intestine

some

they

and

are

killed

pathogens

burrow

start

by

to

the

may

through

produce

a

the

toxin.

electron

Molecules

of

this

toxin

enter

the

epithelial

cells

of

the

intestinal

wall.

(×13 000).

Here

they

epithelial

the

from

and

disrupt

cells.

intestine

lumen

cells

water

functioning

a

ions

intestinal

water

and

from

of

the

Chloride

(the

creates

the

symptoms

86

areas

contaminated

bacteria

contaminated

T ransmission

microscope

in

water

intestine.

Cholera

Vibrio

occur

unclean

become

numbers 7.9.1

an

rectum

supplies

Figure

to

intestine

appendix

tnemelppuS

tnemelppuS



large

caecum,

function

By •

intestine

intestine the

and

disease

OUTCOMES

The •

large

and

the

blood

cholera



of

This

cell

surface

the

cells

the

into

Water

the

lumen

dehydration

and

membrane

into

the

accumulation

gradient.

blood

into

the

out

lumen).

potential

from

the

pass

of

ows

lumen.

of

the

of

space

ions

by

diarrhoea.

the

inside

in

the

osmosis

Movement

intestine

of

of

cause

ions

the

tnemelppuS

Oral

To

rehydration

treat

diarrhoeal

infected

not

people

effective

drinking

being

and

An

lost.

because

or

to

water

to



sodium



glucose

bottled

is

like

is

not

water,

treated

This

cholera

possible.

is

by

is

important

giving

absorbed

does

not

giving

oral

it

Just

by

them

the

contain

people

a

rehydration

to

rehydrate

water

is

intestine,

the

ions

solution

therapy

and

that

of

are

salts

(ORT).

contains:

rehydrate

ions

as

water

drink.

solution



soon

Cholera

glucose

ORT

diseases

as

water,

therapy

to

the

blood

replace

the

and

ions

other

lost

tissues

from

blood

and

tissue

uid

Cholera

to

provide

energy

for

the

active

uptake

of

sodium

there

from

the

other

is

a

most

lack

easily

of

transmitted

clean

water

and

where

sanitation

is

intestine poor



is

ions

ions

such

as

potassium

and

chloride

to

replace

ions

lost

or

non-existent.

in

diarrhoea.

and

made

a

a

cholera

glucose

into

person

until

are

a

to

solution

water

ions

cells

that

with

boiling

and

is

with

The

a

water.

given

powder

contents

This

regularly

of

containing

each

takes

and

sachet

little

in

salts

are

training

large

for

volumes

recover.

these

epithelial

sachets

available.

administer

people

When

outbreak,

made

are

reabsorbed,

decreases

was

lost

in

and

the

water

water

is

potential

absorbed

to

of

make

the

up

for

the

diarrhoea. A

child

during

SUMMARY

1

a

What

QUESTIONS

sort

of

receives

the

KEY

organism

causes

1

cholera?

How

does

c

What

are

the

the

organism

symptoms

enter

of

the

Diarrhoea

a

What

b

How

sort

of

conditions

2

cholera?

encourage

the

spread

of

effective

treatment

of

drinking

water

help

control

sewage

the

is

the

Why

are

these

developing

measures

not

put

and

the

spread

of

is

tnemelppuS

Explain

in

how

th e

into

place

in

a

Diarrhoea

be

disease

caused

treated

The

diarrh o ea

and

loss

bact eriu m

of

br in g s

s a lts

f rom

caused

by

by

by

cholera

using

oral

the

a

bacterium

toxin

that

causes

a bout

blo od

ions

to

pass

into

the

in intestine.

the

watery

therapy.

cholera

chloride dehydration,

of

some

4

cholera

loss

intestine.

cholera?

countries?

detail

2010.

chlorination

produces 3

in

bacterium.

rehydration c

the

from

Cholera

can of

therapy

Haiti

cholera?

3 can

in

body?

a 2

rehydration

epidemic

POINTS

faeces b

oral

cholera

tnemelppuS

During

This

causes

water

to

intestine. pass

out

resulting

the

in

by

osmosis,

diarrhoea

dehydration

the

cells

loss

of

and

ions

from

blood.

87

PRACTICE

1

The

QUESTIONS

breakdown

of

large,

insoluble

food vitamin

molecules

into

small,

water-soluble

molecules

C

vitamin

D

calcium

gums

bowing

of

bleed

leg

iron

is:

muscle A

absorption

B

digestion

C

egestion

D

ingestion

weakness

A

(Paper

and

1)

[1]

tiredness

bones cramps

bowing

muscle gums

B 2

Which

is

a

correct

description

of

the

action

of

leg

tiredness

of

weakness

bleed bones

a

and

cramps

protease?

A

breaks

down

fat

into

fatty

B

breaks

down

protein

C

breaks

down

starch

D

converts

acids

and

C

scurvy

rickets

D

tiredness

rickets

anaemia

soft

gums

glycerol

muscle into

amino

acids

bones

bleed

weakness

amino

into

acids

glucose

into

proteins (Paper

(Paper

1)

The

an

[1]

[1] 6

3

2)

drawing

incisor

shows

a

vertical

section

The

drawing

shows

part

of

the

digestive

system.

1

through

tooth.

1

2 2

3 3

4

What

part

is

1,

the

function

stored

in

A

to

digest

B

to

increase

C

to

acidify

D

to

digest

of

part

proteins

the

the

2

liquid

and

to

produced

released

amino

surface

into

by

part

3?

acids

area

of

fat

droplets

4

Which

parts

row

is

shown

the

in

correct

the

identication

drawing

of

(Paper

above?

2

3

fats

contents

to

fatty

of

part

acids

4

and

glycerol

the

7 1

the

The

2)

[1]

following

events

occur

during

the

passage

4

of

A

cement

pulp

enamel

dentine

B

dentine

enamel

pulp

cement

1

starch

through

Amylase

is

the

alimentary

secreted

in

saliva

canal.

from

salivary

glands.

C

enamel

dentine

pulp

cement

D

pulp

cement

dentine

enamel

2

4

1)

A

C

is

a

anaemia

rickets

symptom

B

D

Which

to

4

Glucose

enters

5

Glucose

is

into

epithelial

the

surface

of

intestine.

breakdown

of

glucose.

the

blood

plasma.

absorbed

by

active

transport

cholera

the

cell.

scurvy

1)

Amylase

catalyses

the

breakdown

of

starch

[1]

row

the

the

small

of

of

the

table

(top

of

next

deciency

symptoms

for

maltose.

column) Which

gives

onto

the

catalyses

to

5

in

maltose

6

(Paper

secreted

cells

Maltase

[1]

Diarrhoea

is

epithelial

3

(Paper

Maltase

vitamin

is

the

correct

sequence

for

these

C, events?

vitamin

D,

calcium

and

iron? A

1,6,2,3,5,4

B

6,1,3,2,4,5

C

2,3,1,6,5,4

D

3,2,6,1,4,5

(Paper

88

2)

[1]

8

Which

area

of

a

villus

increases

12

surface

The

diagram

alimentary

capillaries

B

goblet

C

lacteal

D

microvilli

Copy

its

absorption?

A

(Paper

9

feature

for

shows

a

villus

from

the

canal.

cells

2)

[1]

the

diagram

from

question

6. A

(a)

On

the

diagram

oesophagus,

label

the

stomach,

following:

pancreas

and (a)

duodenum.

Copy

and

(b)

Draw

arrows

on

the

diagram

to

show

taken

by

food

as

it

passes

the

parts

of

the

alimentary

canal

on

(c)

State

the

diagram

use

label

lines

and

lacteal.

the

part

villi

F

an

letters

site

of

Name

three

to

the

secretion

of

hydrochloric

H

the

With

that

secretes

molecules

of

place

13

with

organ

A

State

diet

what

provided

It

is

is

an

that

alkaline

stores

essential

reference

A

meal

in

a

an

balanced

State

three

increased

that

they

that

a

increased

components

[4]

(a)

starch,

Describe

good

should

health.

The

be

diet.

[4]

when

woman’s

quantity

she

is

components

and

explain

should

be

diet

of

the

in

bread

diagram,

the

from

A

[3]

explain

alimentary

and

cheese.

cheese

starch

canal.

In

that

diagram

is

the

canal.

[6]

Bread

contains

digested

your

and

molecule

where

molecule

you

shows

molecule

in

answer

protein.

the

state

where

the

to

describe

a

small

places

1

break

place.

[5]

protein

along

proteases

help

take

the

and

it

2

act

on

down.

should

1

certain

2

1

breast-feeding.

that

why

it

should

is

be

important

increased.

(b)

[6]

How

many

after

the

two

fragments

molecule

will

has

be

been

produced

digested

by

proteases?

[1]

3)

(c) The

to

villi

and

how

changes

the

11

of

contains

contains

pH

bile

for

components

important

include

(Paper

pass

villus.

4)

the (b)

that

the

3)

balanced

(a)

into

a

the

10

canal

[1]

substances

diagram

alimentary (Paper

alimentary

acid

protease

a

the

located.

show:

(Paper organ

G

[2]

of

are

signicance the

capillaries

the

(d) following

E

the

[2]

on On

label

the

diagram.

(c)

and

through where

the

diagram

the (b)

direction

the

[4]

liver

performs

important

functions

in

Suggest

protein digestion

and

assimilation

of

food.

One

why

protease

2

cannot

act

on

the

the in

the

same

places

as

protease

1.

of [4]

these

is

the

production

of

an

alkaline

digestive (d)

juice

that

breaks

down

large

globules

of

State

the

where (a)

(i)

Name

the

digestive

juice

secreted

liver.

proteases

Explain

how

The

this

digestive

alimentary

canal

protein.

[2]

fragments

produced

by

digestion

by

the

food

in

the

1

and

2

are

not

absorbed

into

juice the

reaches

the

[1] proteases

(ii)

in

digest

by (e)

the

organs

fat.

small

blood.

Explain

why

this

is

so.

[2]

intestine. (f)

Describe

what

happens

to

these

fragments

[3] so (iii)

Explain

why

this

digestive

juice

that

alkaline.

down

(b)

Explain

(Paper

how

large

what

is

completely

broken

[2]

[2]

(Paper Outline

protein

is down.

(iv)

the

is

this

digestive

globules

meant

by

of

juice

4)

breaks

fat.

assimilation.

[4]

[2]

4)

89

8

Plant

transport

8.1

Transport

Most LEARNING

living

organisms

State

and



the

and

functions

of

xylem

the

positions

phloem

sections

of

transport

rely

phloem

Identify

in

of

xylem

stems

on

and

such

diffusion

Vertebrates

so

transport

system.

tube.

This

blood

systems:

and

have

for

throughout

water

root

Only

very

from

of

transport

regnans

is

the

tallest

in

the

so

remove

as

food

systems

same

and

and

move

up

to

90

two

of

a

dioxide.

have

water,

uids

through

within

pump

separate

are

plant

body

in

in

from

upwards

xylem,

to

Topic

in

and

the

the

unlike

These

stems

mineral

soil.

stem

in

composed

2.3).

roots,

water

ions

stem

tissues

(see

each

(the

heart)

transport

the

the

in

The

enter

phloem,

is

that

are

are

found

in

roots

the

leaves,

absorb

xylem

owers

one

in

the

the

and

fruits.

direction

only



leaves.

Phloem

xylem

sucrose

cells

leaves.

ions.

These

to

of

tissues

and

tissue

transports

phloem

sucrose,

owering

acids

and

bud

metres.

hormones

sunlight

YOU

have

can

ow

leaf

DID

not

they

carbon

amino growing

do

that

direction

consisting

have

worms,

at,

organisms

such

mass

system

or

phloem

plant

the

via

large

in

plants

some

and

transport

called

circulatory

Flowering

and

are

moves

is

and

small,

substances,

These

uid

transports

water

of

a

so

oxygen

plants

transport

mineral

roots

uptake

the

are

obtain

carry

transport

travel

Transport

plant,

small

phloem

the

tissue

and

and

of

phloem

specialised

Xylem

to

vessels.

and

to

bodies.

of

xylem

Xylem

Xylem

all

type

Vertebrates

and

their

protoctists

bodies

owering

systems

that

bacteria,

Their

alone

and

throughout

tubes

as

systems.

transport

transverse

roots,

leaves

Eucalyptus

a

OUTCOMES organisms,



need

systems

the

throughout

plant.

Sucrose

is

KNOW? energy

a

carbon

The

world’s

redwood

It

is

in

114 m

tallest

tree

is

a

giant

dioxide

California.

tall.

simple

made

simple

made

sugars

sugars

from

and

the

minerals

soil

sugar

which

made

especially

for

transporting

energy.

It

leaves

is

made

with

the

from

moves

growing

root

growing

bud

down

or

up

and

to

to

in

sugars

photosynthesis

from

storage

as

water

is

by

into

sucrose

complex

photosynthesis

sucrose

water

soluble,

starch

organs,

swollen

roots

in

such

and

and

stems. minerals

taken

by

up

roots

Figure

8.1.1

Substances

from

leaves

buds;

90

also

Transport

are

to

in

the

transported

roots

from

and

storage

xylem

in

the

upwards

organs

to

and

phloem.

phloem

from

new

in

two

leaves

stems

to

directions:

owers,

and

leaves.

downwards

fruits

and

Hormones

They

also

Inside

control

control

the

cell

the

nd

the

to

give

transverse

root

and

growth

root

To

and

transport

hairs

for

of

growth

owers

of

and

the

stem,

fruits

roots

(see

and

page

leaves.

170).

stem

tissues

of

roots

and

stems,

we

cut

across

them

sections.

absorb

mineral

division

water

ions

cortex

stores

some

food

This

as

starch phloem

amino

transports

acids

from

sucrose

the

are

used

to

make

at

root

as

it

Figure

the

root

cap

the

through

8.1.2

transports

ions

up

The

root

the

root

tip

tip

cells

the

grows

internal

structure

of

a

make

new

red

dye

the

for

xylem

with

dye.

water

root

as

the

cells

divide

vascular

phloem,

bundle

is

cambium

made

and

up

xylem

new

The

and

a

are

root.

of

xylem

in

strands

soil

a

cambium

lled

standing

red

tip

protects

grows

vessels

left

The

new and

cells

was

hours.

leaves xylem

which

celery

several

and

tissue

in

the

centre

of

this

root

is

phloem cortex

as

the

plant

xylem,

grows

which

between

the

is

stained

xylem

are

red.

The

phloem

green

areas

tissue.

pith

epidermis

is

a

single

layer phloem

of

cells

on

the

outside

amino the

stem

which

the

stem

and

acids

See

up

xylem

loss

8.1.3

Topic

sucrose

to

the

and

roots

to

the

flowers

and

fruits

reduces

transports

mineral

Figure

down

protects and

water

transports

of

The

6.6

for

internal

the

structure

positions

of

of

a

ions

up

water

to

the

and

leaves

stem.

xylem

and

phloem

in

the

leaves.

A

transverse

Note

SUMMARY

QUESTIONS

1

complete

the

KEY

Copy

and

the

sentences

using

these

sucrose

water

amino

ions

fruits

blood

heart

have

a

Flowering

transport

plants

system

have

two

Xylem

vessels

mineral

made

up

transport

of

a

the

transports

and

up

the

,

owers

and

.

and

acids

Phloem

the

stem

from

the

Phloem

tissue

from

leaves

to

all

parts

Using

the

roots

leaves.

vessels

made

transport

in

the

leaves

photosynthesis

and

in

transports

of

the

organs,

to

other

parts

plant, the

plant.

organs.

3 2

to

roots

of as

water

the

Xylem

storage

such

from

and

systems.

during to

transport

ions

stem

sucrose, tissue

stem.

storage

2 .

young

vessels

up

Vertebrates

a

POINTS

and mineral

through

bundles.

words:

1 leaves

section

vascular

the

diagrams

above,

state

the

functions

of

each

of

Xylem

and

phloem

are

these distributed

in

a

central

core

issues: inside

a

phloem

e

root

b

xylem

c

cambium

d

f

root

cortex

root.

Inside

a

stem

epidermis they

cap

a

are

vascular

organised

into

bundles.

91

8.2

LEARNING

Water

uptake

Water

by

The •

Identify

root

hairs

as

the

main

microscope

take

their

structure

to

hairs.

Soil

water

such State

the

pathway

taken

through

root,

of

and

roots

are

mineral

to

anchor

ions.

Just

the

plant

behind

the

in

the

root

soil

tip

and

are

small

Water

passes

into

the

root

hairs

by

osmosis

as

is

a

dilute

nitrate

and

solution

of

potassium.

various

Root

solutes

hairs

including

have

thin,

mineral

permeable

ions,

cell

by

walls water

water

water

uptake



functions

up

and root

relate

roots

seen to

under

uptake

OUTCOMES

stem

and

provide

a

large

surface

area

to

absorb

water .

The

cell

sap

and

in

the

root

hair

cells

is

a

more

concentrated

solution

than

soil

water .

leaf

This

is

because

solutes

water

particle

soil

as

diffuses

hair

sugars.

from

cells

The

the

water

also

cell

soil

cell

then

Most

walls

From

the

hair cells

of

here

stem

enters

cortex water

passes

up

in

the

by

by

the

other

permeable

so

osmosis.

cortex

of

the

the

in

water

the

moves

spaces

through

between

the

the

a

from

xylem

water

and

to

cell

in

the

cell

to

the

moves

the

Water

centre

up

leaves

cells.

walls,

cell.

cells.

the

of

the

xylem

where

Much

eventually

of

evaporates

it

through

enters

the

to

root.

the

water

form

water

and

then

diffuses

through

stomata

to

xylem

the water

across

mesophyll

vapour stem

of

cells

have

the

airspace

Absorption

of

and

the

spongy

8.2.1

hair

passes

moves

reaches

Figure

root

partially

and

B

Some

root

the

is

ions

vessel

root.

A

mineral

membrane

into

Water xylem

absorb

atmosphere.

root.

We

describe

and

into

Water

a

hair

movement

xylem

passes

potential

root

the

in

vessel

down

the

cell.

potential

lower

water

in

in

in

the

potential

in

cells

soil

the

to

a

root

hair,

potential

gradient,

lower

from

cortex

xylem

a

water

passes

of

the

of

into

potential

the

turn,

in

water

terms

water

solution

Water

water

a

of

the

and

(see

from

water

root

across

a

the

Topic

high

potential

hair

cell

eventually

to

to

an

cortex

3.2).

water

in

a

tnemelppuS

soil

such

root

the

lower

even

vessel.

PRACTICAL

Look

then

with

at

Root

hairs

on

as

can

a

a

92

hairs

of

a

germinating

bean

seed.

a

at

a

root

are

also

section

have

of

a

hairs.

long

look

germinating

or

a

osmosis

hairs

microscope.

the

bean

They

by

root

closely

Look

You

Root

at

a

and

at

thin.

root

hairs

seedling

such

radish.

large

and

surface

mineral

area

ions

through

are

which

absorbed

by

water

active

is

absorbed

transport.

tnemelppuS

Looking

Xylem

that

vessels

lls

instead

are

them.

it

is

like

pipes

Water

pulled

is

by

as

not

the

they

are

pushed

empty

from

evaporation

of

the

except

roots

for

up

the

to

water

the

leaves,

water.

tnemelppuS

STUD Y

Transpiration

pull Mak e

T ranspiration

cells

in

the

vapour

is

leaves

can

the

evaporation

and

diffuse

TIP

the

out

loss

of

the

of

of

water

water

leaf

from

vapour

when

the

the

to

surfaces

the

stomata

of

mesophyll

atmosphere.

are

sure

the

correc t

We

say,

leaves

The

is

by

This



is

As

from

up

the

xylem

transpiration

water

wilting.

up

‘pulled’

used

water

the

mass

for

is

xylem

ow

cohesion



of

the

stem

from

the

roots

to

the

and

the

photosynthesis

up

vessels,

lost

rather

up

water

or

the

and

from

like

xylem

molecules

to

stop

the

water

relies

tend

being

on

to

the

leaves,

plant

more

‘ water

vapo ur

each

of

‘ water

the

leaf’

goes

out

of

leaf’.

sucked

up

properties

attract

not

out

from

is

sucked

two

use

Water

pull

used

water

the

in

you

term inolog y.

open.

diffus es

Water

that

a

straw.

of

other,

water:

sticking

together

adhesion

the

So

xylem

there

is

a



the

water

molecules

also

tend

to

stick

to

the

inside

of

vessel.

continuous

ow

of

water

from

the

roots

to

the

leaves.

This STUDY

movement

of

water

up

the

xylem

is

called

the

transpiration

When

SUMMARY

QUESTIONS

1

complete

TIP

stream

you

and

the

sentences

using

these

in

stomata

osmosis

large

transpiration

are

for

2

into

taken

taking

leaves

of

passes

also

up

a

.

root

A

water

by

the

Look

up.

cell

root

and

This

is

hair

hair

cell

mineral

ions.

controlled

ions

the

.

a

water

xylem,

Mineral

leaf

water

of

that

from

with

water

pulls

the

in

the

roo ts.

surface

Water

by

the

start

evaporation

area

by

has

how

words:

always

Water

are

explaining

moves

Copy

tnemelppuS



the

is

lost

from

opening

and

the

closing

.

at

the

diagram

of

the

root

hair

in

the

soil:

A B

KEY

1

POINTS

Water

enters

osmosis.

the

cells

osmosis

It

a

root

then

of

the

hair

passes

root

before

cell

by

across

cortex

passing

by

into

the

C

xylem

D

F

the

and

then

up

the

stem

to

leaves.

E

2 a

Name

the

parts

labelled

A

to

Root

the

b

Explain

c

Give

how

water

gets

into

tnemelppuS

3

Explain,

root

using

hair

vessels

other

cells,

and

up

the

functions

term

across

to

the

water

the

cells

leaves,

of

a

root

root

hair

hair

potential,

of

are

well

cell

from

the

absorption

the

where

cells.

how

cortex,

it

is

lost

to

have

have

water

into

passes

the

the

of

adapted

water

for

since

soil. they

two

hairs

F .

into

xylem

atmosphere.

3

Loss

a

of

‘pulls’

stem

thin

large

water

more

from

cell

walls

surface

from

water

the

transpiration

the

up

roots

and

area.

leaves

the

in

the

stream.

93

8.3

Transpiration

Plants

absorb

water



Dene



Describe

the

term

transpiration

passes

where

it

is

diagram how

water

is

related

to

cell

lost

of

are

spaces

Describe

and

how

temperature,

light

from

humidity

can

There

and

affect

rate

tnemelppuS

how

a

the

leaf

atmosphere

you

will

see

through

the

soil.

as

that

stems

Much

water

there

and

of

vapour.

are

many

If

enters

this

you

air

leaves

look

spaces

at

a

by

mesophyll

cells

which

have

damp

cell

inside.

walls.

from

this

huge

internal

surface

so

the

air

spaces

Water

become

wilting

with

water

vapour.

in

is

usually

the

outside

the

air.

more Describe

water

up

stomata

variations

intensity

transpiration



of

moves

surfaces,

saturated



quantities

roots,

to

lined

evaporates air

into

vapour These

loss

large

OUTCOMES

The

air,

more

so

water

water

from

water

water

lost

the

vapour

vapour

from

the

in

the

diffuses

spongy

air

spaces

through

than

the

mesophyll

there

stomata

cells

is

is

in

into

replaced

by

xylem.

occurs

Transpiration

evaporation

the

of

diffusion

is

the

loss

water

of

at

water

of

water

the

vapour

surfaces

vapour

of

through

from

the

the

plant

mesophyll

leaves

cells,

by

the

followed

by

stomata.

Wilting

More

the

T wo

open

transpiration

stomata

are

open

the

Carbon

during

place

during

the

dioxide

the

day

is

a

during

so

raw

day

that

the

and

day

closed

carbon

material

than

at

at

night.

dioxide

for

night

can

because

The

diffuse

photosynthesis

into

and

stomata.

diffuses

The

STUD Y

into

stomata

chloroplasts

close

as

Whe n

form s

refer

water

evapor ates

water vapo ur .

to

at

night

in

mesophyll

to

reduce

cells.

the

volume

of

water

lost

by

TIP transpiration.

xylem

open

stomata

leaf.

takes

it

as

just

Do

air

lost

in

may

also

close

transpiration

is

in

not

hot,

being

dry

conditions

replaced

by

during

water

the

from

day

the

soil.

it

not

‘ water

vessel

water

They

’.

space

The

stomata

enough

so

much

are

rm

plant

close

water

it

water

and

that

give

becomes

up

will

reduce

they

the

soft.

to

start

to

are

plant

The

transpiration.

wilt

no

(see

longer

support.

stem

is

above

no

If

If

the

plant

on

the

right).

turgid

the

or

cells

longer

full

of

become

upright

and

still

Its

does

cells

water .

T urgid

accid

the

not

then

leaves

get

have

lost

cells

the

droop.

water

evaporates

off

cell

wall

stoma

vapour

Wilting

is

not

a

bad

thing.

The

leaves

move

downwards

so

are

diffuses

out

of

the

direct

rays

of

the

Sun

so

do

not

get

as

hot.

When

the

out

temperature Figure

8.3.1

Loss

a

94

of

leaf.

water

vapour

decreases

and

they

can

absorb

from

by

transpiration

the

leaves

will

recover.

more

water

than

is

lost

tnemelppuS

LEARNING

Factors

As

factors

see

the

light

intensity

of

In

very

humidity

is

a

dry

the

is

of

the

measure

is

of

rate

high.

of

the

are

air

rate

and

the

of

the

transpiration

Figure

the

other

Y ou

8.3.2.

increases

conditions,

temperature.

the

air

in

transpiration

by

quantity

when

As

environmental.

factors

determined

conditions

transpiration

humid,

that

these

of

water

humidity

becomes

is

etar

the

Humidity

air .

increases,

maximum

as

of

etar

such

a

transpiration

two

fo

to

of

fo

up

affecting

effects

noitaripsnart

can

transpiration

noitaripsnart

Other

affecting

vapour

low,

more

the

and

in

the

25

rate

more

50

75

humidity

decreases.

Figure

8.3.2

10

100

/

15

T wo

20

temperature

%

factors

affecting

the

rate

/

25

°C

of

transpiration.

The

rate

of

transpiration

increases

as

the

air

temperature

increases.

KEY

Transpiration

evaporation Light

causes

stomata

to

open.

As

the

light

intensity

increases,

wider .

As

light

intensity

decreases

when

it

is

cloudy

or

stomata

close

so

that

less

water

is

lost

by

transpiration.

conditions,

there

may

be

nearly

as

much

water

vapour

followed

in

water

as

concentration

low.

In

dry

vapour

cell

out

rate

the

surfaces

water

air

conditions

the

inside

the

gradient

diffuses

inuences

cells

in

of

leaf.

have

of

inside

for

the

water

vapour

the

concentration

the

leaves

of

temperature

more

kinetic

This

so

the

the

water

rate

and

is

that

of

from

very

enter

the

is

steep

so

such

molecules

air

2

is

inside

as

the

not

easy

velocity

the

leaf

the

If

water

water

rate

of

transpiration

but

you

can

use

to

water

lost

slightly

roots.

This

and

in

is

is

measure

less

because

keeping

cells

the

rate

than

some

the

of

of

water

volume

the

water

uptake.

of

is

water

used

The

taken

up

in

volume

in

by

potometer

shown,

is

making

allowed

bubble

is

is

to

a

sure

form

in

loss

of

by

the

in

increasing

the

greater

plants

lack

of

of

rate.

than

wilt

and

turgor

in

leaves.

of

photosynthesis

the

of

submerging

stem

in

the

capillary

the

rate

of

it

in

water.

stopper

tube.

The

water

is

It

is

set

air-tight.

distance

up

An

air

moved

cut

by

bubble

1

How

you

rate

shoot

of

State

a

capillar y

rate

set

measure

how

explain

a

the

by

it

a

cut

works.

how

conditions

of

up

uptake

Explain

and

an

to

water

these

the

reser voir

would

potometer

the

uptake.

air

QUESTIONS

as

of

A

rate

the

2

8.3.3

the

while

is

stems

shoot?

Figure

Increasing

wind

turgid.

lled

measure

and

decreases

SUMMARY

The

increases

rate.

uptake,

opens

a cells

potometer

diffusion

intensity

and

transpiration,

as

transpiration

measure

the

through

increases

humidity

to

the

atmosphere.

light

stomata

because is

the

temperature

the

on

to

transpiration

3

It

by

vapour

Increased

the

water

vapour .

Measuring

at

mesophyll

no

T emperature

surfaces,

water

there

transpiration

stomata.

increases,

energy

means

gradient

through

evaporation

As

leaves.

water

the stomata

atmosphere

of

the

In of

humid

of

towards cells

evening,

the

stomata surfaces

open

is

tnemelppuS

tnemelppuS

1

Explanations

POINTS

each

affects

transpiration:

increase

in

light

intensity

tube

bubble

b

a

decrease

c

an

in

increase

temperature

in

humidity

potometer.

95

8.4

Translocation

tnemelppuS

Food LEARNING

is

made

in

include



Dene



State

that

the

term

acids

move

parts

translocation

sucrose,

of

the



to

Explain

plant

a

sink

the

sucrose

a

in

at

phloem

from

a

The

act

as

a

parts

a

of

Compare

transport

source

times

to

growth

a

and

during

the

take

converted

plant

photosynthesis.

in

solution

which

and

in

means

fatty

the

acids.

The

soluble

These

phloem.

‘from

place

to

This

are

products

carried

transport

is

to

all

called

place’.

food

regions

place.

in

where

of

the

takes

of

The

leaves

growth

place

storage

simple

into

or

from

or

to

regions

sugars

sucrose.

storage

regions

to

is

production

where

produced

This

occur

of

by

respiration

or

photosynthesis

transported

provide

(the

to

energy.

parts

are

of

Sucrose

the

is:

plant •



by

acids

amino

leaves)

some

different

of

and

sink

that

may

life

leaves

amino

plant

translocation

source

the

OUTCOMES

transpiration

with

broken

down

by

an

enzyme

to

give

simple

sugars

that

are

used

in

respiration

translocation •

changed



used

and



to

Leaves

in

use

make

are

also

DID

tissues.

make

where

If

the

the

the

and

can

stylet

sap

so

be

of

stylet

collected

above

for

96

are

crop

on

phloem

their

piercing

pests.

sap

They

by

using

mouthparts.

the

at

the

and

photosynthesis

cells

are

are

cuticle

for

isotope

of

and

in

seeds

growing

root

tip

all

over

made

stored

on

the

and

the

in

in

attract

nitrate

plant

shoot

many

upper

animals.

to

and

seeds

surface

ions

make

root

as

of

tips.

oils

the

and

leaves.

to

some

the

and

sap

insert

of

maple

tubes

trees.

through

which

buckets.

feed

the

the

study

on

the

called

stem

into

the

sap

stylets

a

phloem

aphid

aphid

single

tube

with

cut,

the

phloem

which

can

phloem

causes

it

be

tube.

to

of

plants.

inserted

The

pass

along

food.

transport

is

in

the

of

sugars

sugary

sap

in

the

will

phloem.

pass

out

time.

sucrose

aphid

and

in

that

inside

phloem

tree

transport

the

feeding

below

from

the

collects

provide

used

a

from

and

cortex

sweet

needed

mouthparts

surface

Isotopically-labelled

feed

into

insects

piercing

of

root

walls

them

that

waxy

prepared

holes

small

the

stylet

the

of

Aphids

new

phloem

pressure

cell

from

are

acids

and

Aphids

8.4.1

These

Aphids

the

Figure

sugars

fatty

for

is

drill

have

the

KNOW?

syrup

are

in

new

make

and

through

living

acids.

to

ows

They

are

for

sap

Aphids

tubes

simple

needed

Farmers

Phloem

fruits

especially

Maple

the

the

YOU

storage

cellulose

some

also

for

tip

amino

proteins,

Leaves

starch

make

shoot

stored

to

to

stylets,

leaf.

the

can

be

that

The

injected

have

been

contents

passage

of

the

of

into

a

leaf

inserted

the

sucrose

sap

and

into

can

traced.

be

samples

the

stem

analysed

In

plant

transport,

journey

Water

empty

relies

a

is

called

and

owers

and

ions

and

upon

tension

The

the

in

part

of

absorbed

(the

the

The

sinks).

by

plant

part

roots

Xylem

where

where

(the

are

of

water

in

evaporation

of

water

vapour

xylem.

stream.

This

pulls

up

T ranspiration

xylem

water

is

it

a

substance

ends

source)

vessels

movement

the

transpiration

translocation

source.

are

fruits

cells.

the

a

tnemelppuS

Transpiration

its

and

from

from

greatest

travel

columns

vessels

the

the

on

is

(or

to

leaves

dry

is

to

a

its

sink

leaves,

pipes)

passive,

roots

hot,

begins

journey

of

dead,

since

it

producing

give

and

the

windy

days.

Black

Translocation

is

an

active

process

which

occurs

in

phloem.

The

food

are

the

source

of

food

substances

and

the

sinks

are

the

bean

and

tissues,

regions

of

growth

(root

and

shoot

tips)

cells

active

tubes

the

such

that

as

the

contain

transport

to

build

sinks.

root

some

of

up

cortex

sucrose

a

and

cytoplasm.

head

Translocation

at

of

is

the

the

source.

pressure

most

seeds.

Movement

Water

that

active

Phloem

in

on

the

regions

tubes

forces

sunny,

the

are

phloem

enters

the

days

very

spraying

are

producing

increased

levels

of

rapidly.

sap

Movem ent

in

sugar.

is

the

way



roots.

in

the

b

What

the

term

translocation

substances

are

translocated

in

the

T he

What

are

the

materials

transported

in

the

phloem

both

used

and

for?

leave s

2

3

Draw

a

table

Substances

the

xylem

to

are

and

compare

transpiration

transported

in

plants

with

from

translocation.

sources

to

sinks

to

grow th

in

sink

of

for

substances substances

substances

in

in

in

the

from

stem

In

it

is

leave s

tips,

and

to

from

wher e

and

this

of

phloe m

season

fruits

ques tion

only

from

trans port

occu rs,

owe rs,

is

upwa rds

answ ering source

them

and

direct ions.

Rem embe r

phloem.

water

xylem

upwa rds

down ward s

phloem?

of

grow ing

roots c

control

to

when

QUESTIONS

Dene

Farmers

TIP

subs tanc es

a

of

aphids

insecticide.

STUD Y

the

1

plenty

living

one

SUMMARY

is

requires

ions plants

there

favourable,

of

phloem

phloem

warm

are

respiring

and

by

storage

When

conditions

reproduce

plant

aphids.

leaves

to

seeds.

when

Sum mary

3b.

transported

transport

in

the

plant

the

plant

the

KEY

POINTS

xylem

1

transport

Translocation

movement

the

is

the

in

of

sucrose

and

phloem

amino

acids

from

the

leaves

(translocation)

to

regions

growth a

Copy

are

in

and

complete

transported

each

in

the

each

table

tissue

by

giving

and

one

two

substances

source

and

one

Explain

2

Regions

called

case.

how

a

root

tuber

can

be

a

source

and

a

sink

times

of

the

Aphids

feed

on

storage,

How

are

b

Suggest

are

are

regions

respiration

called

and

sinks.

Transpiration

is

a

passive

plants.

they

used

to

investigate

movement

in

involving

why

farmers

and

growers

control

dead

tissue.

phloem? Translocation

spraying

and

year.

process a

production

at

3 4

of

sources

growth different

respiration,

storage.

that

sink

of b

of

and

aphids

by

process

is

an

involving

active

living

tissue.

insecticides.

97

PRACTICE

1

In

QUESTIONS

which

water

conditions

by

would

a

plant

lose

of

most

environmental

caused

transpiration?

A

cool

and

dry

C

hot

and

dry

B

cool

and

humid

D

hot

and

humid

it

to

conditions

is

likely

to

have

wilt?

air light

2

(Paper

1)

Which

row

transported

in

describes

the

the

phloem

amino

B

amino

D

glucose

(Paper

3

acids

sucrose

Which

is

and

molecule

A

root

leaf

B

and

and

and

and

of

ions

sucrose

sucrose

ions

water

and

and

amino

sucrose

correct

water

ions

it

taken

moves

xylem

cell,

mesophyll

pathway

as

mesophyll,

hair

D

low

B

low

low

high

C

high

low

high

D

low

high

low

water

acids

and

(Paper

water

and

7

Which

water

ions

air

cortex,

root

moves

in

by

Which

through

root,

root

cortex,

air

spaces

spaces

hair

root

in

leaf,

xylem

a

phloem

C

xylem

down

in

xylem,

cortex,

leaf

D

xylem

from

water

potential

a

down

a

a

water

water

low

in

2)

mesophyll,

8

Which

statement

xylem,

mesophyll

the

from

root

water

from

B

mesophyll

D

xylem

of

spaces

best

the

to

high

which

the

water

pathway

is

lost

water

vapour

from

stomata

intercellular

into

the

from

of

water

and

mesophyll

diffusion

cells

of

through

soil? into

the

atmosphere.

hairs Evaporation

and

vessel

of

diffusion

into

water

of

the

from

water

mesophyll

vapour

cells

through

the

atmosphere.

[1]

potato

plant

grows

in

a

eld

Evaporation

sunlight.

Which

row

shows

the

of

carbohydrate

in

the

source

destination carbohydrate

A

glucose

leaves

tubers

B

glucose

tubers

leaves

C

sucrose

leaves

tubers

D

sucrose

tubers

leaves

9

The

A

diffusion

of

water

stomata

into

2)

water

for

6

days.

vapour

the

from

air

spaces

atmosphere.

[1]

diagrams

root,

B

show

stem

and

transverse

C

after

being

Which

leaf.

B

[1]

wilted

cells

2)

A

has

mesophyll

of

carbohydrate

plant

from

phloem?

(Paper

of

water

correct through

movement

of

in and

left

combination

C

98

gradient

potential

describes

by

through

Evaporation

D

without

gradient

leaves?

air

cell,

1)

potted

potential

potential

water

mechanism

cuticle

A

gradient

[1]

Diffusion

C

6

potential

atmosphere.

root

(Paper

water

[1]

absorbs

type

down

(Paper

atmosphere

C

bright

of

leaf

1)

sweet

movement

cells?

stem,

A

cuticle

A

the

leaf

from:

B

stomata

5

into

plant?

cell

A

(Paper

explains

stem

a

water

4

the

mesophyll

B (Paper

statement

atmosphere

cells,

stoma,

stoma,

[1]

A

and

xylem,

2)

from

Water

water

stoma

C

high

[1]

cortex,

root

xylem?

1)

the

high

xylem

acids

C

A

substances

phloem

A

humidity temperature

[1]

best

intensity

sections

of

(a)

Copy

that

the

diagrams

represent

phloem

in

A,

the

B

and

shade

positions

and

the

of

11

areas

xylem

and

C.

[3]

A

leafy

into

Copy

and

complete

functions

term

sap

of

the

refers

xylem

table

to

the

and

to

was

a

balance.

uptake

two

from

and

Topic

The

the

a

plant

8.3)

table

rate

and

which

shows

of

placed

was

the

rate

transpiration

the

leafy

shoot

during

a

hot,

dry

day.

The

transported

in rate

these

cut

(see

compare

phloem.

liquid

on

water

by the

shoot

potometer

placed

of (b)

a

tissues.

time

/

of

water

rate

of

water

h –1

loss

feature

phloem

composition

direction

of

of

the

ow

/

g

–1

h

absorption

/

g

h

xylem

midnight

4

7

0300

6

9

0600

12

12

0900

18

14

1200

24

17

1500

22

19

1800

18

20

2100

8

14

midnight

6

10

sap

in

the

stem

destinations

[6]

(c)

Describe

how

pathway

through

above

(Paper

10

A

you

taken

the

would

by

parts

water

of

the

discover

as

it

the

travels

plant

that

are

ground.

[3]

3)

potometer

measure

(see

water

Topic

uptake

8.3)

by

a

was

used

leafy

to

(a)

Plot

(b)

Calculate

rate

shoot.

a

of

1200

time

the

Describe

move

A

cool,

humid

air

in

B

cool,

dry

/

min

(d)

Explain

daylight

C

warm,

dry

D

warm,

humid

air,

in

daylight

E

warm,

humid

air,

at

night

in

air,

the

daylight

in

of

percentage

loss

your

the

change

between

Show

in

0600

table.

in

[5]

the

hours

working.

and

[2]

the

changes

over

the

in

water

24-hour

loss

and

water

period.

[4]

the

how

stem

water

to

the

moves

from

atmosphere.

the

cut

end

[4]

4)

6

daylight

rate

data

2

(Paper air

the

100

of

Calculate

hours.

absorption

mm

(a)

the

water

show

water

conditions to

to

taken

(c) for

graph

1

3

60

water

movement

in

−1

mm min

E,

(b)

and

Draw

the

for

each

present

a

ve

bar

of

your

chart

to

conditions

the

conditions,

answers

show

on

the

in

the

a

table.

effect

rate

of

A

From

the

of

movement

(d)

State

two

shoot

with

(Paper

a

[5]

results,

conditions

that

state

affect

through

ways

would

[3]

water

movement.

(c)

to

be

in

three

the

the

of

water

plant.

which

affected

transparent

environmental

rate

the

if

plastic

it

air

[3]

around

was

bag.

the

covered

[2]

3)

99

9

Transport

9.1

Describe

The

circulatory

Most

animals

the

one-way

ow

around

the

Describe

the

of

pump

the

ow

heart

of

as

a

of

valves

blood

to

and

circulatory

system

vessels.

that

consists

Circulatory

systems

of

in

blood,

some

animals

useful

permit

substances

surface

and

such

nutrients

as

oxygen

from

the

absorbed

part

of

the

from

gut

a

gas

that

is

the for

absorption.

Circulatory

systems

also

transport

waste,

only such

one-way

a

blood

pump

adapted

role

and

body

exchange

for

have

of

transport



system

OUTCOMES

sort blood

humans

Circulation

LEARNING



in

as

carbon

dioxide,

from

all

over

the

body

to

the

gas

exchange

ow surface.



Describe

of



a

the

single

circulation

sh

Describe

Blood

the

circulation

double

of

a

The

mammal

heart

its

the

blood

very

ows

body.

close

their

The

flow

let

the

Valves

towards

blood

close

to

stop

heart

from

The

wastes

from

blood

delicate

so

helps

to

the

they

blood

the

through

blood

vessels.

heart

to

the

different

organs

the

and

a

blood

so

heart

to

in

veins

a

veins.

are

good

can

have

The

smallest

capillaries.

supply

their

of

Cells

oxygen

carbon

are

and

dioxide

and

efciently.

allows

to

the

receive

one-way

giving

maintain

capillaries,

capillaries

reduce

to

arteries

removed

pumps

this

back

capillaries

system

heart

getting

arterioles

ows

these

circulatory

small

pressure

a

but

it

ow

pressure

one-way

high

the

blood

so

that

ow.

pressure

muscular

before

of

it

This

vessels

blood

enters

ows

is

blood

blood

around

inside

good

will

the

for

damage

known

as

capillaries

(you

flowing

nd

out

more

about

arterioles

on

page

107).

When

blood

leaves

backwards

capillaries Figure

circulates

away

connect

capillaries

and

can the

that

arteries

the

blood

which

arteries

Blood

to

other

body.

to

pump

in

vessels

nutrients

open

a

advantages

of

Valves

is

and

Blood explain

circulation

9.1.1

How

semi-lunar

permit

one-way

the

blood

pressure

is

even

lower.

valves

ow

of

There

are

semi-lunar

valves

in

veins

to

make

sure

blood

does

blood.

not

ow

backwards

happens,

valve

of

gills

has

the

back

veins

swell

three

blood

to

ll

away

of

and

these

pushes

the

from

the

the

blood

pockets.

against

heart

is

The

them,

(see

not

circulated

valves

but

Figure

open

they

9.1.1).

when

close

If

properly.

when

the

this

Each

pressure

blood

ows

pockets.

arteries

heart

A

semi-lunar

the

between

heart

the

single

Fish

body

9.1.2

Fish

have

a

circulation

ows

once

the

100

are

valves

chambers

chambers

of

in

to

the

heart

enter

the

at

the

arteries.

heart

(see

places

There

page

are

where

also

blood

valves

102).

circulation

veins

organs

Figure

leaves

single

in

in

a

body.

the

circuit

a

single

during

from

the

oxygen

which

through

have

once

it

a

organs

and

circulation

complete

is

ows

called

because

circuit

into

the

of

the

heart

blood

body

from

deoxygenated

ows

(see

veins.

blood.

through

Figure

This

The

the

9.1.2).

blood

heart

heart

Blood

has

little

pumps

blood

blood

into

blood

ows

an

artery

that

takes

it

to

the

gills

to

be

oxygenated.

heart

around

on

from

the

gills

in

arteries

to

the

body

organs.

The

tnemelppuS

detanegyxo

detanegyxoed

doolb

doolb chambered

There

tnemelppuS

A

double

circulation

lungs

Mammals

twice

have

during

a

one

this

by

The

mammalian

is

a

circulation.

complete

following

septum

double

the

heart

thick

circuit

pathway

wall

Blood

around

that

blood

ows

the

through

body.

takes

is

divided

into

two

of

muscle

that

separates

You

around

halves:

right

the

the

can

heart

conrm

Figure

and

two

9.1.3.

left.

halves

The

of

the right

heart

that

stops

blood

in

the

right

side

mixing

with

blood

in

the

side

left

side

left of

heart

of

heart

side.

Blood

circulation



right

The

and

side

back

to

has

of

the

two

the

functions:

heart

heart

pumps

again.

The

deoxygenated

pressure

blood

required

to

to

the

force

lungs

blood the

to

the

the

lungs

lungs

occurs

as

as

absorbs

returns

is

not

they

blood

the

are

a

ows

oxygen

to

very

and

high

spongy

in

a

is

little

lled

capillaries

carbon

vein.

there

tissue

through

loses

heart

since

with

in

dioxide.

This

blood

resistance

the

The

is

air.

Gas

lungs.

to

red

heart

in

exchange

Blood

oxygenated

bright

ow

in

blood

colour

rest

and

of

body

is



shown

The

of

left

the

red

side

body

leaving

is

in

the

much

of

on

the

and

left

more

diagrams

heart

back

side

to

is

the

pumps

the

much

resistance

of

to

circulation.

oxygenated

heart

again.

greater

ow

than

than

blood

The

on

there

to

pressure

the

is

right

through

the

of

rest

Figure

9.1.3

Mammals

side

the

as

exchange

such

and

as

occurs

muscles,

carbon

capillaries

the

dioxide

and

as

blood

gut,

liver

enters.

ows

ows

and

The

through

through

kidneys.

capillaries

Oxygen

deoxygenated

veins

is

dark

blood

red

in

in

leaves

that

colour,

shown

as

ows

through

twice

in

but

may

and

be

complete

KEY

2

the

sentences

using

these

words

body

veins

The

heart

right

.

The

is

Here

of

it

gas

blood

it

side

of

tissues

left

lungs

deoxygenated

the

pumped

to

to

mammalian

absorbs

is

returns

and

carbon

right

dioxide

3

oxygen

heart

and

removed

from

the

the

side

the

is

of

where

pumps

now

blood

the

it

to

in

complete

circuit

valves

up

lungs.

and

from

its

of

ensure

a

a

around

system.

single

passes

once

the

blood

circulation,

through

during

one

the

circuit

body.

Blood

ows

heart

the

twice

during

body

in

a

th ro u gh

one

circuit

m a mmal.

the

blood.

the

have

blood

the

called

heart

gives

blood

ow

circulatory

Fish

of The

a

body.

POINTS

heart

(some

twice):

oxygenated

the

blue.

QUESTIONS

used

blood

heart

is

so

Copy

the

blood

leaves

the

1

double

organs

the

one-way

SUMMARY

a

which

lungs.

1 always

in

there

of

Gas

have

circulation

blood

4

The

heart

pumps

low

pressure

to

blood

the

at

lungs

The

and

at

rest

of

high

pressure

to

the

here

and

the

body

in

a

double

is

circulation. now

the

2

3

called

heart

blood.

in

what

double

circulation

Explain

the

Blood

b

Blood

c

Veins

passes

back

to

the

side

of

.

Explain

a

It

is

5

meant

following

the

terms

statements

on

the

right

on

the

left

contain

by

side

side

of

of

semi-lunar

the

the

single

about

heart

heart

is

circulation

the

is

at

low

high

ows

in

from

the

veins

towards

arteries

heart.

Blood

away

ows

in

and

mammalian

at

Blood

the

heart.

heart.

pressure.

pressure.

valves.

101

9.2

The

Heart LEARNING

Describe

the

four

human

the

heart

and

locate

of

blood

vessels

and



State

that

the

with

the

place

The

page

one

heart

consists

of

that

away

from

blood

the

two

pumps

and

the

lying

left

side

side

of

by

the

side.

The

heart

is

almost

entirely

of

cardiac

muscle

tissue

one

to

is

aorta

pumped

heart

body

body

vena

cava

(main

into

vein) pulmonary

arteries

heart



and

in

Explain

of

the

returns

to

to

right

lung

importance

septum

to

left

oxygenated

deoxygenated

lung

in pulmonary

separating

artery

the

veins

the

right

another

events

during

from

State

of

pump

24).

heartbeat



consists

is

heart

sequence

take

heart

valves (see

associated

the

the pump.

major

heart

chambers side

of

structure

OUTCOMES

The •

heart

veins

and

blood

from



Locate

the

and

name

the

valves

heart right

atrium left



Explain

why

ventricles

those

of

the

are

the

walls

thicker

atria

of

left

than

ventricle

than

and

the

is

why

thicker

valve

right

cava

TIP

left

Whe

n

tendons

valve*

vena

STUD Y

atrium

the

atrioventricular

the

lungs

in

you

look

at

ventricle

a right

diag ram

the

it

hear t

from

or

draw ing

you

of

ventricle

from

are

*Supplement septum

the

fron t

of

the Figure

body

the



so

hear t

side

of

the

is

the

lef t

on

the

side

YOU

9.2.1

The

septum

right

draw ing.

KNOW?

Al-Nas

physician

was

the

the

the

side

On

each

are

called

have

was

He

an

of

13th

the

suggested

puried

in

the

show

how

the

blood

moves

through

the

heart.

(wall

mixing

of

tissue)

side

of

atria

When

much

prevents

the

oxygenated

heart

(singular:

the

atria

more

they

with

deoxygenated

there

contract

the

are

atrium).

muscular

pump

blood

blood

out

the

into

left

empties

pump

than

the

chambers.

Blood

they

walls

two

on

blood

on

the

blood

atria.

arteries

side.

The

into

into

chambers

from

ventricles,

When

at

upper

them

the

higher

which

ventricles

pressure.

Arab

person

functions

lungs.

102

of

rst

was

arrows

righ t

contract Ibn

The

of

veins.

DID

body

view ing

century.

to

He

connect

heart

that

lungs.

and

blood

Between

prevent

right

walls

each

the

and

blood

left

than

further

atrium

owing

ventricles

the

than

and

atria

the

ventricle

back



into

contract.

because

atria

to

a

right

to

or

left

have

pump

lungs

valve.

and

ventricles

have

the

one-way

the

The

they

either

is

to

The

valves

atrium

more

when

the

muscular

the

blood

the

tissues

much

of

the

body.

The

left

ventricle

because

more

it

tnemelppuS

contract,

The

at

more

pump

to

pumps

the

muscular

blood

around

wall

the

than

body

the

right

and

has

ventricle

to

from

from

heart

relaxation

overcome

ow.

two

sides

same

blood

chamber

chamber

the

a

action

heart

each

to

resistance

Heart

The

has

has

when

gets

contracts

of

the

time.

it

heart

The

its

smaller

relaxes

work

the

relaxation

phase,

During

the

contraction

and

so

it

contract.

squeezes

lls

together.

ventricles

During

muscles

contract

blood

up

the

with

The

and

ows

When

relax

into

the

blood

blood

atria

the

out.

the

atria

phase

filling

After

again.

contract

at

muscles

and

same

from

relax

right

left

atrium

atrium

time.

the

veins.

left

phase:

ventricle



The

atria

between

against

contract

and

force

the

and

ventricles

atria

blood

into

open

the

due

ventricles.

to

the

The

valves

pressure

of

blood

right

them.

ventricle

heart



Then

The

The

the

valves

right

artery.

aorta

The

ventricles

close

left

(main

phase

They

they

prevent

pumps

ventricle

to

force

blood

blood

owing

to

pumps

blood

the

blood

out

into

the

arteries.

back

into

the

atria.

lungs

to

the

in

the

rest

of

of

full

blood

to

to

lungs

body

pulmonary

the

body

in

the

artery).

semi-lunar

arteries.

to

ventricle

The

contract

valves

act

shut,

like

occur

the

at

the

ones

preventing

in

base

of

Figure

back

ow

the

aorta

9.1.1.

of

and

During

blood

into

pulmonary

the

the

relaxation

ventricles. heart

During

the

the

lungs

contraction

and

the

phase

they

open

allowing

blood

to

leave

to

contraction

body.

Figure

Deoxygenated

blood

returns

to

the

right

atrium

in

the

vena

9.2.2

The

cardiac

changes

cava

heart

(main

vein).

pulmonary

phase

pumping

Oxygenated

blood

returns

to

the

left

atrium

in

cycle

that

during



the

occur

one

in

the

heartbeat.

the

veins. KEY

1

POINTS

The

heart

muscular

consists

pumps

of

two

divided

by

a

septum. SUMMARY

QUESTIONS

2

1

a

What

are

the

two

upper

b

What

are

the

two

lower

chambers

chambers

of

of

the

the

heart

heart

called?

Ventricles

blood

make

called?

one c

What

is

the

function

of

the

Explain

each

The

atria

The

left

blood

ows

in

The

atria

have

less

muscular

statement.

have

less

muscular

walls

than

the

ventricle

has

a

much

more

than

the

ventricles,

as

ventricles. they

b

that

force

valves

direction.

walls a

sure

to

arteries;

septum?

3 2

contract

into

muscular

wall

than

only

force

blood

into

the

the ventricles.

right

ventricle.

4 3

In

each

of

the

following

cases,

which

blood

vessel

The

right

blood

a

blood

to

the

rest

of

the

blood

from

the

lungs

c

blood

from

the

body

to

to

to

the

forces

lungs,

then

the

body left

b

ventricle

carries:

the

the

left

atrium

right

atrium

as

a

ventricle

it

has

to

pressure

greater

is

more

pump

that

muscular,

blood

at

overcomes

resistances.

103

9.3

Heart

There LEARNING



State

can

be

to

the

activity

in

monitored

pulse

rate

sounds

of

the

by

heart

monitored.

These

listening

the

Investigate

listening

valves

of

The

the

state

physical

pulse

Explain

control

activity

variety

the

activity

of

the

sounds

of

the

heart

valves

(ECGs),

heart

pulse

may

rate

be

and

closing.

(ECG)

of

of

the

heart

heartbeat

disorders

depends

can

upon

produce

electrical

activity.

irregularities

in

this

activity.

on electrocardiogram,

or

ECG,

is

a

useful

diagnostic

tool

that

can

rate

the

effect

of

on

the

these

defects.

Electrodes

are

taped

at

various

positions

on

the

physical body

activity

to

electrocardiogram

detect



which

and

The the

by

electrocardiograms

closing

A effect

methods

include

ECG,

and

The •

different

exercise

OUTCOMES

that

taking

are

and

heart

and

the

electrical

activity

of

the

heart

is

then

displayed

on

a

rate monitor.

ECGs

The

its

Figure

for

a

9.3.1

heart

resultant

trace

characteristic

contracting,

the

P ,

the

ventricles,

shows

a

normal

ECG,

while

Figure

9.3.2

shows

disorder.

can

be

QRS

QRS

and

compared

and

T

‘spike’

the

T

waves.

with

The

immediately

wave

represents

the

P

normal

wave

ECG

shows

precedes

the

ventricles

with

the

atria

contraction

of

relaxing.

R

egnahc lacirtcele

A

boy

an

using

ECG

to

an

exercise

monitor

his

bicycle

heart

while

T

P P

having

Q

function.

S

0

0.1

0.2

0.3

0.4

0.5

0.6

time

Figure

Heart

ECG A

normal

(ECG)

the

of

the

this

example

one

heart

0.9

1.0

s

beats

takes

0.8

seconds.

sounds

The

heart

The

noise

of

During

fibrillation

contractions

In

0.8

trace

sound

ventricular

9.3.1

/

0.7

ventricles

are

extremely

valves

of

the

your

the

respond

blood

contraction

to

force

blood

pressure

of

blood

pressure

when

heartbeat

contract

to



the

changes

valves

open

during

and

a

close

cardiac

make

cycle.

the

‘lub-dub’.

phase,

out

of

the

muscular

the

pulmonary

walls

of

the

artery

and

ventricles

aorta.

The

irregular

shut,

rst

complete

heart

the

ventricles

atria

and

part

During

block

are

preventing

beating

independently

high

of

the

9.3.2

A

normal

ECG

trace

ECG

traces

disorders.

for

in

the

the

going

sound

from

back



phase,

arteries

blood

atrioventricular

into

the

valves

atria.

causes

This

them

produces

to

the

‘lub’.

the

ventricles

causes

going

the

relax.

The

semi-lunar

backwards

into

blood

valves

the

to

under

shut,

ventricles.

produces

the

second

part

of

the

heart

sound



‘dub’.

Doctors

are

heart

able

any

104

heart

the

and

This two

blood

relaxation

pressure

preventing Figure

the

against

to

listen

to

irregularity

these

in

the

heart

sounds

heartbeat.

with

a

stethoscope

and

identify

tnemelppuS

The

heart

During

order

exercise,

to

muscles

These

and

your

contract.

dilate

changes

exercise

muscles

So

the

increase

the

an

increase

in

supply



an

increase

in

removal

can

time

you

can

wrist.

the

detect

the

left

same

the

You

as

the

The

resting

The

tter

The

same

energy

faster

are,

of

of

and

carbon

blood

a

and

from

respiration

arteries

in

supplying

muscles

and

result

in:

glucose

through

arteries

passes

pulse

per

to

dioxide.

wave

your

pulses

heart

ow

oxygen

nd

of

pulse

you

blood

beats,

can

number

of

ow

ventricle

feel.

The

more

beats

(widen).



You

need

heart

by

minute

along

feeling

is

your

as

a

the

an

‘pulse’.

arteries

artery

pulse

at

rate

Each

which

your

and

this

is

rate.

rate

the

A

gives

lower

a

good

your

indication

resting

pulse

of

a

rate

person’s

(see

person

minute

but

with

of

blood

fewer

is

being

passed

out

of

the

heart

and

shows

levels

of

the

taken.

POINTS

per

heartbeats. ECG

traces,

sounds

table

pulse

tness.

1

The

their

table).

KEY volume

having

general

relationship

between

resting

pulse

rate

used

of

to

pulse

valves

monitor

rate

and

closing

heart

the

can

be

activity.

tness.

2

pulse

less

rate

than

level

50

of

tness

Pulse

rate

and

then

resting

pulse

with

decreases

to

rate.

outstanding

3 50–59

Physical

activity

increases

the

excellent

heart 60–69

good

70–79

fair

ow

80

increases

activity

and

over

rate,

to

more

muscles,

oxygen

removing

poor

increasing

blood

supplying

and

carbon

glucose

and

dioxide.

PRACTICAL

Investigating

the

Sit

a

still

and

get

effect

partner

of

to

exercise

measure

on

your

pulse

pulse

SUMMARY

rate

rate

at

rest. 1

Try

doing

step-ups

for

1

minute

(light

QUESTIONS

a

State

pulse

exercise).

what

rate

happens

when

a

to

person

exercises. As

soon

as

you

have

nished,

sit

down

and

count

your

pulse

rate.

b

Wait

until

your

pulse

returns

to

the

resting

rate.

Explain

pulse

how

rate

and

why

changes

with

exercise. Now

do

(heavy

step-ups

exercise).

Remember

have

the

exercise

until

that

same

each

your

as

quickly

Then

to

make

person

time,

pulse

as

count

this

doing

rest

returns

for

to

you

your

a

valid

the

5

its

can

pulse

for

3

minutes

rate.

2

investigation

exercise,

minutes

resting

do

the

between

you

should

same

each

type

can

your

also

results

repeat

more

the

tests

and

Draw

b

Explain

to

of

exercise

T

or

calculate

an

average

to

make

Pulse

can

explain

how

reliable.

the

results

in

terms

the

normal

what

heart

ECG

is

at

trace.

happening

P ,

QRS

and

waves.

of

supplying

substances

rate

certain

be You

a

rate. 3

You

a

is

risk

some

the

affected

factors.

of

result

these

of

a

by

Explain

can

person’s

to lifestyle.

your

muscles

and

removing

their

wastes.

105

9.4

Blood

Blood LEARNING

ows

them

arteries Name

to

the

and

and

arteries

to

all

main

from

blood

the

in

and

veins.

This

table

organs

shows

of

you

the

body

some

of

and

the

heart,

organs

vessel

Describe

the

function

of

structure

arteries,

lungs

liver

kidneys

and

veins

and

vena

cava

right

atrium;

to

hepatic

artery;

bringing

blood

renal pulmonary

hepatic

(see pulmonary

the

functions

vein

artery

vein

arterioles,

venules

page

(see 146)

of

and

artery

portal

to

organ State

away

important

veins.

lungs

kidney

capillaries



ows

most

vessels

heart



the

OUTCOMES from



in

vessels

to

left

atrium

page

144)

shunt taking

pulmonary

blood

artery

away

right

from

aorta

organ

ventricle

vessels tnemelppuS

from

hepatic

vein

renal

vein

pulmonary •

Explain

how

the

structure

of

ventricle;

(see

page

(see

page

vein arteries,

are

veins

adapted

and

for

capillaries

their

functions

from

left

144)

head,

and

vena

thick

146)

neck

arms

cava

outer

layer

lungs pulmonar y pulmonar y

vein arter y

aorta

vena

which

blood

thick

and

right

left

atrium

atrium

cava

flows

layer

elastic

of

right

left

ventricle

ventricle

hepatic

muscle

vein

fibres

liver

hepatic

arter y Figure

9.4.2

An

artery. hepatic

portal

vein

renal

gut

vein

renal

kidneys

body

arter y

and

legs

two

are

outer

layers

thinner

outer

layer Figure

than

9.4.1

Main

blood

vessels

of

the

body.

arteries

Structure

large

space

When which

and

function

of

blood

vessels

through

blood

your

heart

muscles

contract

they

force

blood

into

at

muscle

and

a

high

the

pressure.

blood

to

Arteries

ow

have

along.

quite

They

a

have

narrow

thick

space

walls

and 9.4.3

in

made

fibres

106

arteries

the

centre

elastic

for

Figure

the

flows

A

vein.

elastic

bres

to

withstand

the

pressure

of

blood.

of

muscle

Veins

have

thinner,

veins

is

walls.

that

The

a

less

There

squeeze

are

in

branch

so

tnemelppuS

blood

and

than

one

it

is

less

valves

times

very

wall

easy

elastic

at



the

a

do

to

substances

adapted

to

such

veins

to

(see

cell

can

from

to

a

and

their

inside

thick

ensure

page

branches

blood

are

pressure

heart

pass

and

need

along

the

made

to

The

not

smallest

red

is

arteries

walls.

intervals

capillary

are

than

they

back

until

a

ow

so

narrow;

of

for

vessels

to

arteries

direction

are

The

blood

have

in

many

Capillaries

cells

for

semi-lunar

through.

thin

How

lower

ows

arteries

capillaries.

space

muscular

much

blood

very

wider

100).

form

only

single

from

just

layer

the

of

blood.

functions

red

The

like

elastic

a

bres

piece

original

of

where

it

the

elastic

length.

maintaining

in

The

its

walls

when

recoil

enters

an

you

of

pressure.

As

organ

is

of

the

stretch

elastic

a

arteries

a

and

bres

result

only

it

the

little

stretch

then

helps

less

let

to

pressure

than

and

then

recoil

it

return

to

push

blood

along

at

the

when

end

it

left

of

is

estimated

that

there

are

over

80

000

km

of

capillaries

so

heart.

in

9.4.4

A

capillary

body.

These

tiny

vessels

provide

a

huge

surface

area

magnied

capillary

between

blood

and

cells.

Blood

ows

through

slowly

(about

substances

cells

the

with

diffusion

This

makes

and

to

it

the

by

pressure

mm

As

to

of

from

second)

walls

blood

the

oxygen

dioxide

in

and

the

blood

is

for

from

and

exchange

one

cells

nutrients,

other

of

time

made

and

veins

contraction

giving

are

between

supply

carbon

pressure

per

the

distance

easy

remove

As

1

cells.

is

layer

very

such

as

of

surround

the

are

other

wastes.

very

body

low,

it

is

muscles

squeezed

and

other

along

KEY

POINTS

organs Arteries

in

the

circulatory

system.

elastic

blood

have

much

small

subdivisions

of

arteries

that

carry

blood

blood

networks.

from

ow

blood

pressure.

hormones

in

Like

They

the

arteries,

transport,

order

through

muscular

receive

to

they

have

arterioles

nerve

regulate

are

muscle

important

impulses

their

in

and

diameter.

their

in

withstand

less

tissue

Blood

Veins

muscle

and

have

pressure

and

thin

in

veins

low.

walls.

regulating

respond

This

to

pressure.

to is

Apart

thick

walls

high

walls.

capillary

have

veins.

vessels

the

removed

cells).

short.

elastic

are

blood

glucose,

Arterioles

Arterioles

section

red

of

and

There

view

thin

1 that

actually

capillaries to

very

is

for cylindrical,

exchange

×2500

the

(the

human

cells

capillar y

artery

Figure

It

a

its

an

the

blood

inside

to

2

are

various

regulates

Capillaries

one

have

cell

substances

blood

and

capillaries.

out

of

walls

thick

can

the

so

that

that

pass

easily

blood

in

in

body

tissues.

Venules

Venules

are

from

the

veins

which

small

blood

capillary

beds.

transport

vessels

These

whose

function

thin-walled

deoxygenated

is

vessels

blood

back

to

collect

then

to

blood

unite

the

to

SUMMARY

QUESTIONS

form

1

heart.

Make

a

table

differences

Shunt

and

vessels

veins.

columns:

A

shunt

vein,

allowing

Shunt

In

vessel

vessels

is

the

can

endotherms

response

and

to

a

blood

vessel

to

control

thereby

heat

that

bypass

blood

(warm-blooded

cold,

reducing

blood

links

the

ow

off

artery

capillaries

by

directly

in

certain

constriction

animals),

cutting

an

the

shunt

blood

and

vessels

ow

to

areas.

dilation.

the

show

Include

feature,

the

main

arteries

three

artery,

vein.

a

constrict

to

to

between

in

extremities

2

In

what

well

ways

adapted

materials

and

body

are

for

the

capillaries

exchange

between

the

of

blood

tissues?

loss.

107

9.5

Coronary

heart

disease

(CHD)

You LEARNING

need

muscle



Describe

the

coronary

State

nature

heart

the

of

disease

possible

preventative

coronary



Describe

CHD

(CHD)

causes

measures

heart

the

may

get

then

blocked

to

be

in

could

the

and

heart

heart

cause

in

the

blood

heart

to

around

keep

coronary

could

it

7.2

arteries.

die

Slowing

Healthy

which

the

arteries

However,

people

from

each

cause

countries.

death

The

become

is

for

one

starved

have

a

smooth

cholesterol,

This

can

condition

narrow

is

which

the

called

lining,

is

letting

made

artery

and

in

the

slow

blood

liver,

down

death

It

rate

in

is

with

can

from

has

the

CHD

There

are

these

differences

of

atherosclerosis

Fatty

deposits

break

Fatty

deposit

of

a



blood

9.5.1

The

artery

clot

and

the

healthy

Blood

walls

block

108

blocked

formed

with

of

is

if

can

the

the

become

vessel.

artery

gets

or

angina.

rough,

The

coronary

activity

called

flow

arter y

along

stops.

Atherosclerosis.

coronary

heart

blockage

artery

partly

emotion

It

is

which

is

causes

caused

by

cause

called

a

serious

blocked

makes

can

it

the

not

can

blood

to

thrombosis

problems.

cause

heart

the

work

enough

chest

pains,

harder.

oxygen

getting

to

by

to

fatty

deposits.

further

the

narrow

healthy

artery

muscle.

Angina

should

a

attack.

heart

total

act

blockage

and

the

unless

as

or

a

warning

thrombosis

supply

the

beating

follow

Compare

arter y.

artery.

stop

has

the

flow

chest

artery

blocks

them.

happens,

it.

their

blood.

many

A

above

to

of

is

the

artery.

stick

ow

lowest

This

the

easily.

the

especially

clot

and

the

If

blood

oxygen

many

Narrowing

coronary

are

arteries

in

Figure

A

of

ow

the

the

A

these

ow

3

Cross-section

If

coronary

year.

country

Japan

rate.

reasons

diet

of

death

Ukraine;

Heart

These

attack

2

highest

body.

and

treated

million

disease

leading

your

contracting.

KNOW?

world

heart

the

muscle

a

1

Around

pump

oxygen

of

disease

ways

This

This

YOU

heart

glucose

to

walls.

DID

healthy

needs

transported

die. •

a

OUTCOMES

of

affected

oxygen

part

altogether

the

heart



of

this

starts

to

the

can

is

cause

cut

the

is

sufferer

off.

heart

called

beating

a

It

is

because

heart

attack.

causes

a

again

The

arrest.

within

may

lead

When

severe

damaged.

cardiac

it

this

pain

heart

Death

minutes.

to

in

the

may

will

Risk

These



factors

are

factors

eating

can

less

a

diet

increase

page

71).

fresh

being



smoking

People



These

age



sex

fruit



too

increase

much

concentration

diet



down

and

of

eating

on

fried



but

other

inherited

the

from

control

chances

men

risk

are

parents

the

of

more

likely

to

getting

the

reduce

little

or

fat,

which

blood

sh,

less

CHD:

red

the

no

(see

which

meat

are

and

risk.

exercise

stress

risk

cannot



CHD

metabolism

getting

to

taking

these

factors

in

and

eating

helps

of

(animal)

poultry

foods;



about

chance

cholesterol

more

vegetables

something

the

saturated



genes



the

good

do

life,

genes



with

to

overweight

can

of

CHD

thought

cutting



way

A

fatty;

more

for

CHD

get

factors

be

avoided

tends

of

fat

to

than

changing

such

run

and

increase

CHD

by

in

their

as:

families.

cholesterol

with

age

women.

tnemelppuS

Figure

Treatment

of

9.5.2

Three

you

A

coronary

of

CHD.

the

arm

below

A

artery

blood

or

the

leg,

bypass

vessel

and

is

narrowed

is

can

taken

attached

or

relieve

from

to

blocked

patients

another

the

coronary

area.

with

part

of

the

the

artery

Depending

on

above

the

CHD,

a

number

of

separate

grafts

may

be

there

is

just

one

incidence

of

narrowing,

or

severity

STUD Y

angioplasty

widen

open.

it.

and

A

This

tube

Antiplatelet

the

arteries.

people

with

angina,

involves

small

metal

is

may

be

inating

tube

called

a

medicines,

T aking

CHD,

attack,

SUMMARY

is

then

carried

out.

This

is

a

less

ao rta

a

small

then

balloon

inserted

to

inside

help

like

the

keep

artery

the

aspirin

stroke

coronary

or

prevent

daily

other

stent

and

is

blood

part

forms

of

of

bypass

clots

the

forming

treatment

heart

Dene

d

a

T hey

a

If

the

disease,

tissu es

in

vent

for

of

ricles

blood

the

to

atria

the

and

.

e.g.

surgery.

heart

disease

b

thrombosis

c

angina

1

arrest

heart

POINTS

Coronary

caused

is

full

of

blood,

then

why

does

it

need

its

heart

by

disease

blockage

arteries

of

that

is

the

supply

own the

blood

the

tran sport

coronary 2

of

QUESTIONS

coronary

cardiac

base

abov e

valv es.

to

artery

oxyg enat ed

aspirin,

the

just

complex

KEY

1

put

a

stent

low-dose

known

heart

can

disease.

arterie s

from

semi-l unar operation

that

heart

TIP

co rona ry

the coronary

of

of

needed.

blockage,

risk

usually

and

bran ch If

at

symptoms

body,

T he the

activities

CHD

heart

with

glucose

and

supply? oxygen.

b

How

c

Why

is

the

heart

muscle

supplied

with

oxygenated

blood?

2 does

the

heart

muscle

need

this

oxygenated

Risk

factors

control

3

There

are

getting

risk

heart

factors

that

can

increase

the

of

a

person

sex.

disease.

List

some

of

the

factors

that

cannot

b

List

some

of

the

factors

that

can

c

What

advice

would

attack?

are

you

give

to

a

be

be

controlled.

person

recovering

diet,

exercise

controlled.

3

from

a

genes,

Avoidable

include

a

heart

chances

which

we

cannot

blood?

CHD

and

may

aspirin

be

and

angioplasty

risk

age

and

factors

stress,

lack

of

smoking.

treated

surgery

and

by

(stents,

bypass).

109

9.6

Blood

Blood LEARNING



List

as

the

red

components

blood

cells,

of

Y ou

have

and

cell



platelets

white

Identify

cells

as

red

and

and

seen

microscope,

5

litres

fragments

of

blood

suspended

in

in

your

a

body.

yellow

Blood

liquid

is

called

made

of

plasma.

cells

The

red

blood of

blood

is

due

to

the

pigment

haemoglobin

in

red

blood

cells.

plasma

white

under

in

about

blood

colour cells,

composition

OUTCOMES

blood

the

light

plasma

photographs



liquid

part

of

blood

(55%

of

blood

volume).

3

Plasma

10 cm

and



in

consists

of

water

with

chemicals

dissolved

in

it:

diagrams

Describe

cells

and

that

they

the

the

role

of

red



nutrients,



wastes,



blood



hormones,

and

blood

such

mineral

as

ions,

such

as

glucose,

e.g.

urea

amino

sodium

and

acids,

and

carbon

lipids,

chloride

vitamins

ions

dioxide

haemoglobin

contain

in

proteins,

such

as

albumen

and

antibodies

oxygen such

as

insulin,

glucagon,

and

adrenaline.

transport 3

5 cm



State

the

roles

of

white

blood and

cells,

platelets

and

red

Figure

9.6.1

When

it

Blood

There

Red

are

they

shows

cells

red

with

smear

blood

their

seen

cells

nuclei

with

and

a

light

two

stained

are

white

in

in

three

no

of

a

centrifuge

(or

left

to

stand

for

24

hours),

is

full

layers.

have

cell

nuclei

molecules

a

colourless

shown

the

blood

in

bacteria

process

group

as

nuclei.

they

do

the

and

of

centrifuge

in

blood.

have

cytoplasm

haemoglobin

They

(see

not

look

Figure

have

for

white

that

transporting

when

9.6.1).

separated

Under

haemoglobin

of

oxygen.

or

a

by

microscope

see

them,

stain

has

to

be

added

as

in

the

any

blood

other

of

photograph.

and

is

takes

known

white

blood

One

them

as

group

into

white

vacuoles

phagocytosis

cells

of

makes

where

(see

protein

blood

cells

smear

they

Figure

are

9.7.1).

molecules

searches

digested.

Another

called

antibodies

cells

to

protect

that

us

invade

Platelets

example

transport

dioxide

against

the

are

as

of

and

different

types

of

disease-causing

organisms

body.

tiny

when

substances

fragments

you

cut

listed

ions,

in

of

yourself.

Figure

nutrients,

cells

which

The

9.6.1.

such

as

cause

plasma

Among

glucose

blood

contains

its

to

functions

and

clot,

many

amino

are

for

soluble

the

acids,

carbon

hormones.

platelets

Red

Red

and

white

and

platelets.

blood

blood

cells

transport

oxygen

cells

Red

a

blood

large

to

110

types

have

of

cells

blood

To

This

9.6.2

spun

blood

phagocyte

Figure

main

cells

pigment.

out

lymphocyte

is

into

microscope

blue.

red

three

blood

spinning

blood

cells

blood

separates

thousands

White

blood

cells

blood

many

This

platelets

plasma

cells

surface

absorb

are

disc-shaped

area

oxygen.

compared

with

with

the

their

middle

pushed

volume

and

in.

this

They

helps

have

them

Haemoglobin

have

red

this

enough

blood

is

in

(see

more

Haemoglobin

special

iron

cells

makes

a

type

of

protein

diet

to

make

your

anaemia

space

for

combines

on

page

that

contains

enough

77).

As

iron.

You

haemoglobin

the

cells

have

for

no

must

your

nuclei

haemoglobin.

easily

with

oxygen

in

the

lungs

to

form

oxyhaemoglobin:

haemoglobin

Look

at

the

+



oxygen

diagram

oxyhaemoglobin

below:

There

are

5

million

red

blood

cells

like

these

3

in

molecules

an

of

in

the

Oxygen

the

to

diffuses

blood.

the

The

from

oxygen

haemoglobin

in

the

alveoli

attaches

the

red

millimetre

(mm

)

of

blood.

in

lung

the

1

cubic

alveolus

capillaries oxygen

every

lungs

into

temporarily

cells

making

red

blood

cell

oxyhaemoglobin.

4

The

cells

for

red

blood

return

more

to

the

lungs

oxygen. haemoglobin

cell

membrane 2

The

carr y

the

red

the

cells

blood

cells

oxygen

which

to

Figure

need

9.6.3

Red

blood

cells

magnied

it. ×2500.

red

blood

cells 3

The

oxygen

leaves

oxyhaemoglobin

out

The

of

the

blood

and

to

just

diffuses

the

oxyhaemoglobin

now

the

cells.

is

haemoglobin

again.

SUMMARY

capillaries

body

cells

in

body

tissues

1

a

List

9.6.4

Transport

of

oxygen

from

the

lungs

to

body

Notice

that

capillaries



oxyhaemoglobin

in

the

alveoli

Oxyhaemoglobin

capillaries

in

gives

body

in

forms

the

out

while

blood

ows

found

as

blood

ows

c

through

a

a

the

is

cell

white

white

How

ways

blood

Name

of

tissues.

three

red

from

lungs.

oxygen

plasma.

Give

a

through

2

KEY

chemicals

tissues.

b



four

tisses

in

Figure

QUESTIONS

in

which

blood

two

main

blood

the

in

differs

cell.

types

cell.

red

blood

POINTS cell

adapted

for

oxygen

transport? 1

The

main

components

of

blood

are

plasma,

red

blood

cells,

b white

visible

blood

under

cells

and

the

light

platelets.

Red

and

white

blood

cells

i

What

microscope.

ii

Where

with 2

Red

blood

cells

contain

haemoglobin

which

combines

is

haemoglobin?

are

does

oxygen

to

form

combine

and

what

with molecule

oxygen

it

is

formed?

oxyhaemoglobin.

111

9.7

Blood

tnemelppuS

White LEARNING

how

white

such

as

blood

lymphocytes

them

protect

cells

than

the

red

defend

blood

us

against

cells.

The

disease.

two

There

groups

of

are

far

white

fewer

blood

cells

and described

phagocytes

from

cells

blood of

cells

blood

defence

OUTCOMES

White • Describe

in

in

T opic

9.6

are

phagocytes

and

lymphocytes

body

disease

Phagocytes •

State

in



the

role

producing

Describe

of

lymphocytes

These

antibodies

the

process

of

are

white

blood

cells

that

ingest

pathogens,

such

as

bacteria.

blood They

surround

the

pathogens,

ingest

them

and

take

them

into

food

clotting vacuoles.

The

Then

process

is

they

called

entrapment

food

digest

them

by

using

enzymes

and

this

kills

them.

phagocytosis

of

formation

particle

food

of

vacuole

within

cell

nucleus

tiny

vacuoles

filld

with

food

enzymes

vacuole

cell

membrane

cytoplasm

bacteria This

image

was

microscope

computer

blood

The

It

image

a

and

then

program.

cells

shows

taken

and

can

white

was

phagocyte

an

with

see

in

ingesting

red

cells.

the

a

ingested

a

two

blood

taken

being

electron

coloured

Y ou

three

below

with

same

yeast

way.

cell.

digestion

of enzymes

added

to

bacteria the

Figure

When

They

Find

9.7.1

A

white

pathogens

can

out

squeeze

about

blood

invade

the

through

tissue

cell

destroys

body,

on

vacuole

bacteria.

phagocytes

capillary

rejection

some

food

move

towards

them.

walls.

page

151.

Lymphocytes

Lymphocytes

enters

not

Like

112

be

the

are

body

there.

a

type

the

white

Lymphocytes

enzymes,

antibodies

Enzymes

have

active

Similarly,

each

type

one

of

type

of

blood

lymphocytes

sites

of

then

are

make

with

combine

has

When

that

proteins

proteins

that

antibody

pathogen.

cell.

recognise

a

it

a

is

called

many

with

bacterium

‘foreign’

binding

site

virus

should

antibodies

different

their

or

and

shapes.

substrates.

that

combines

with

attack



they

make



they

dissolve



they

neutralise

some

There

After

a

you

produce

the

have

their

Blood

again.

in

together

cell

the

a

number

of

ways:

(agglutinate)

membranes

toxins

(poisons)

that

some

pathogens,

such

as

produce.

had

of

pathogens

stick

different

more

body

When

them

bacteria,

is

the

tnemelppuS

Antibodies

type

a

antibody

disease,

the

This

of

such

appropriate

makes

you

as

for

each

measles,

antibodies

immune

to

type

of

pathogen.

lymphocytes

should

that

the

are

ready

pathogen

particular

to

enter

disease.

clotting

you

cut

yourself

you

Like

the

two

white

white

Before

long,

platelets

help

the

thicken

and

the

bleeding

thickened

clot.

blood

Without

has

clotting,

formed

blood

lost

and

pathogens

cell

in

this

of

smear

is

a

is

another

way

would

that

The

skin

the

in

blood

of

is

a

cells.

are

They

small

the

the

is

cut

are

body.

and

blood

blood

However

starts

called

come

there

like

fragments

made

the

in

blood

the

The

fibrinogen.

in

contact

with

a

blood

vessel

is

The

of

the

fibrinogen

threads

make

into

a

threads

net

over

of

Whe n

they

the

white

fibrin

writi ng

blood

to

plasma

into

sure

you

use

‘phag ocyt es’

are

bres.

which

Red

forms

blood

a

these

The

threads

cells

clot

to

the

get

hardens

to

time

keeps

the

the

skin

cut

heals

a

clean.

and

no t

blood

their

call

cells ’.

Red

blood

cells

get

caught

in

the

net

clot.

scab

and

make

cut.

The

the

New

With

a

blood

clot

skin

dries

clot

to

which

make

a

seals

the

grows

under

the

scab.

POINTS

scab.

scab 1 Figure

falls

when

of

KEY which

e

trapped

the

make

mak

nam es

and

do

‘ white

protein

meshwork

make



the

2

in

,

desc ribin g

the

in

them

brin,

abou t

cells

platelets

change

insoluble

cell

When

brinogen

the

white

cut.

func tions protein

smaller

bone

cells.

damaged,

substances

soluble

larger

blood

When

air

you release

a

TIP

protein

‘lym phoc ytes ’ a

of

leaking

is

scab

marrow

photograph

phagocyte.

disease. turn

Platelets

these

The

enter .

platelets

against

110,

stained.

lymphocyte.

STUD Y

defends

page

a

out

This

on

been

would

1

be

have

stops. fibrin

The

smear

cells

blood threads

to

blood

bleed.

9.7.2

Blood

Phagocytes

ingest

pathogens

clotting.

off. and

digest

them

using

enzymes.

2 SUMMARY

Lymphocytes

that

protect

pathogens 1

a

b

State

where

Explain

how

white

blood

cells

lymphocytes

act

are

to

defend

the

body

from

3

After

a

how

a

disease,

person

can

become

immune

to

an

the

to

like

a

b

Explain,

What

has

had

a

lymphocytes

for

that

more

pathogen

measles.

in

detail,

would

exposed

c

body.

infectious

if

3

the

produce

antibodies

disease

in

person

remain

Explain

antibodies

against

made.

pathogens.

2

make

QUESTIONS

Describe

to

role

happen

the

the

the

air

at

process

if

a

of

a

of

platelets

person’s

in

the

blood

cut?

phagocytosis.

clotting

did

not

of

clot

disease

again.

blood.

when

the

4

This

Platelets

encountered

called

help

brinogen

blood

is

is

to

to

immunity

convert

brin

during

clotting.

113

9.8

Lymph

tnemelppuS

Tissue LEARNING

Describe

the

exchange

between

tissue

blood

Describe

tissue

the

lymphatic

functions

of

gaps.

the

vessels

lymphatic

and

lymph

uid

the

may

protect

uid.

from

our

disease

immune

Experiments

have

all

able

to

cells

stable

the

cells.

squeeze

stay

in

the

environment

substances

glucose

and

Most

Fluid

but

know

cut

of

is

and

waste

to

White

out

of

blood.

for

diffuse

the

oxygen

found

is

blood

the

cells,

which

capillaries

Tissue

uid

through

‘bathes’

the

and

tissue

of

it

uid

like

then

owing

drains

from

out

of

urea

pass

passes

from

into

tissue

cells.

our

the

uid

Useful

out

back

of

into

plasma

lymphatic

into

cells.

cells

the

and

into

the

blood

back

into

system.

system

produced

white

not

cells

a

the

so

stress,

than

is

circulatory

our

heart

system

beating



we

and

videos.

Not

glucose,

all

taken

amino

vitamins,

Our

other

But

feel

circulatory

system

the

beneath

glands



the

fluid

and

tonsils

lymphatic



these

vessels.

In

are

the

Unit

7,

lymph

page

lower

nodes

85,

leaves

at

the

This

is

a

thin-walled

vessel

that

absorbs

part

of

the

lymphatic

when

veins

system

jaw,

think

you

that

saw

are

a

fat

from

the

lacteal

gut

system.

of

in

the

tissue

one-tenth

of

capillaries.

(e.g.

acids,

ions)

oxygen,

fatty

acids,

uid

it

returns

enters

Once

a

to

plasma

separate

inside

these,

waste

(e.g.

the

products

carbon

metabolites,

in

blood

system

of

tissue

given

dioxide,

excess

capillaries.

capillaries

uid

is

called

called

lymph

out

unwanted

ions)

the

venule

arteriole

capillary

network

back

arteriole

the

rest

enters

lymph

The

blood

our

lymphatic

your

some

9.8.1

see

see

those

nutrients

the

by

another

lymph

of

skin.

obvious.

adenoids

villus.

About

end

feel

and

non-humorous

capillaries

blood

can

signicantly

and

tissue

our

we

humorous

blood

reduced

about

that

in

114

the

form

them.

into

pass

chemicals

constantly

some

ourselves,

connected

Figure

of

to

and

about watching

watching

walls

systems. –

had

a

lymphatic

through

more

constituents

capillary

our we

videos

the

the

KNOW?

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people

surrounds

are

blood

helps

like

plasma,

The

boost

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dioxide

capillaries.

bodies

of

in

nodes

tissue

Laughter

some

gaps

system

Carbon

YOU

that

shape,

providing

substances

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tissues,

small

system

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as

body

through

the

cells

Outline

out

uid

change

these



reaches

move

uid can



uid

capillaries the

and

uid

of plasma

materials

tissue

OUTCOMES

When •

and

formation

of

tissue

uid

and

vessel

lymph.

of

the

the

tissue

lymph

fluid

capillaries

tissue

into

fluid

the

passes

capillaries

but

capillaries

will

lymph

not

the

vessels.

thin-walled

ows

let

in

and

one

have

tiny

lymph

These

valves

pass

have

contain

a

that

out

allow

again.

structure

semi-lunar

the

They

similar

valves

to

tissue

join

to

uid

up

to

veins;

make

sure

to

tnemelppuS

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enter

form

they

are

lymph

direction.

The

lymphatic

The

contraction

system

of

has

no

pump

surrounding

so

the

muscles

ow

helps

of

to

lymph

make

it

is

slow.

ow.

STUD Y right

into

lymphatic

the

right

duct

empties

subclavian

left

vein

TIP

subclavian

vein

Plas ma,

lym ph

that

tissu e

are

are

very

compo sitio n,

in

the

the

thoracic

duct

out

differ ent

body .

text

uid

three

uids

simila r

but

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e

they

in

occu r

places

in

throug h

carefu lly

wher

and

to

are

nd

and

remem ber! lymphatic

from

of

lymph

Figure

Lymph

join

9.8.2

to

subclavian

the

blood

lymphatic

from

form

the

two

veins,

before

lacteals

small

in

villi

intestine

nodes

The

ows

up

vessels

system.

tissues

large

under

joining

to

lymph

the

the

the

heart.

vessels

collar

vena

The

which

bones.

cava

smaller

empty

Here

just

the

before

lymph

into

lymph

it

vessels

the

mixes

enters

the

with

heart. KEY

At

intervals

along

the

length

of

the

lymph

vessels

are

lymph

1 There

are

many

lymphocytes

in

the

nodes

and

during

an

POINTS

nodes. When

tissue

lymph they

multiply

by

cell

division

and

make

antibodies.

Some

uid

enters

the

infection capillaries

it

is

termed

leave lymph

lymph

nodes

patrolling

an

and

for

important

circulate

fresh

part

around

invasions

of

the

of

body’s

the

body

pathogens.

immune

in

the

The

blood,

constantly

lymphatic

system

is

2

system.

Lymph

and

has

SUMMARY

QUESTIONS

a

What

is

tissue

uid

no

large

3 1

and

what

are

its

The

consists

white

red

What

is

lymph

and

what

are

its

Explain,

in

as

much

detail

as

you

slow

and

how

the

circulation

can,

is

What

main

are

lymph

function?

nodes,

where

are

proteins.

lymphatic

why

the

ow

of

lymph

system

circulation

has

a

which

lymph

to

the

blood.

is Lymphocytes

are

in

lymph

maintained. nodes

3

but

or

functions?

4

so

cells

functions?

returns

2

plasma

cells,

blood

plasma

separate

b

of

blood

they

found

and

what

is

their

during

where

an

produce

they

multiply

infection

and

antibodies.

115

PRACTICE

1

Which

the

QUESTIONS

chamber

of

the

heart

pumps

blood

into

4

Which

row

shows

components

aorta?

A

left

atrium

B

left

ventricle

of

the

the

correct

functions

of

the

blood?

red plasma

blood

platelets cells

C

right

atrium

D

right

ventricle

antibody

oxygen

formation

transport

A

(Paper

1)

clotting

[1] B

2

The

plan

system.

diagram

Which

is

shows

the

the

human

pulmonary

antibody

oxygen

formation

transport

clotting

circulatory

transport

artery?

of

oxygen

C

clotting ions

transport

A head

and

oxygen

antibody

fore-limbs

D

clotting transport

(Paper

formation

1)

[1]

D

5

In

a

single

through

circulation

the

circulation

C

leaves

the

heart

of

the

of

once

body.

a

sh,

the

during

What

a

blood

ows

complete

type

of

blood

heart?

B

lower

and

A

deoxygenated

blood

at

high

B

deoxygenated

blood

at

low

C

oxygenated

blood

at

high

D

oxygenated

blood

at

low

pressure

pressure

pressure

pressure

body

hind

limbs

(Paper

2)

[1]

Key

oxygenated

deoxygenated

3

(Paper

1)

Which

is

owing

A

B

6

blood

blood

blood

the

correct

body



the

vena

pathway

human

cava

taken

ventricle



lungs

left

ventricle



aorta

cava

lungs





atrium

right

body

(Paper

1)

arteries

to

veins

B

arteries

to

capillaries

that

transport

C

capillaries

to

veins

left

D

capillaries

to

venules

system?

atrium



(Paper

right



body

2)

pulmonary



left

ventricle



right

artery

ventricle



[1]

→ Blood

capillaries

are

exchange

vessels.

They

atrium

aorta







the

exchange

of

substances

between:

left A

cells

and

lymph

B

plasma

and

lymph

C

plasma

and

tissue

D

lymph

aorta

lungs



uid

atrium

and

tissue

uid

[1]

(Paper

116

vessels

A

permit

D

blood

blood

circulatory



left

by

7

C

are

from:

[1]

through

vena

Arterioles

2)

[1]

8

Prevention

of

coronary

heart

disease

may

11

The

diagram

shows

the

heart.

involve:

A

A

angioplasty

B

eating

C

putting

D

taking

B

(Paper

9

This

saturated

stents

more

into

fats

coronary

arteries

exercise

C

2)

is

seen

more

a

[1]

drawing

with

a

light

made

of

a

blood

smear

as

microscope. E

F

H

D

(a)

(i)

Name

(ii)

Give

A

to

the

E.

[5]

letters

from

the

diagram

that

G

indicate

(a)

(i)

Name

(ii)

State

the

the

cells

F,

G

functions

and

of

H.

the

oxygenated

[3]

cells

F

to

(b)

H

The

magnication

×1100.

(c)

Calculate

Show

your

Some

blood

separate

of

the

the

drawing

diameter

(c)

is

of

cell

was

the

in

a

components.

centrifuge

The

to

(Paper

the

why

lower

rest

of

vessels

contain

blood.

happens

capillaries

blood

[1]

to

in

blood

the

owing

pressure

the

that

than

as

it

ows

lungs.

to

the

blood

[4]

lungs

owing

body.

is

to

[3]

3)

(a)

Copy

and

complete

the

table

to

compare

results.

arteries, (i)

what

the

blood

diagram

12 shows

a

the

[2]

spun

Explain

at

H.

working.

Describe

through

[3]

(b)

the

Identify

the

veins

and

capillaries.

cells J

that

would

found

in

feature

be

regions

arteries

veins

capillaries

K relative

and

L.

Give

reasons thickness

for

your

answer.

[3]

of

(ii)

Name

the

uid

at

thin

very

thin

some

none

K

wall

J muscle

and

describe

its

role tissue

in

the

body.

L

[5]

elastic some (Paper

10

3)

tissue

T aking

the

health

of

pulse

is

one

way

to

monitor

direction

the

heart the

of

heart.

to

arteries

to

blood organs

veins

ow (a)

What

is

(b)

Describe

during

the

pulse?

what

and

[2]

happens

after

to

the

pulse

exercise.

rate

[5]

[4] (b)

(c)

State

of

two

the

other

heart

can

ways

be

in

which

monitored

the

health

helps

3)

it

how

to

the

carry

structure

out

its

of

an

artery

function.

[3]

[2] (c)

(Paper

Explain

Describe

muscle

(Paper

how

cells

substances

by

are

capillaries.

provided

to

[4]

4)

117

10

Diseases

10.1

and

immunity

Disease

Pathogens LEARNING

that



Dene

and

the

terms

Describe

cause

disease

how

pathogens

are

spread

from

person

that

The

Outline

the

against

disease

body’s

humans

cause

fungi,

protoctists

transmissible

or

are

disease.

transmitted,

bacteria

and

diseases

from

one

and

Most

of

worms.

because

person

viruses.

the

organisms

The

the

to

Other

diseases

that

pathogens

another.

They

they

are

are

also

infectious

diseases.

to

person



are

in

can called

be

organisms

disease

pathogens

pathogen

transmissible

cause

passed, •

are

OUTCOMES

table

shows

different

ways

in

which

diseases

are

transmitted.

defences method

examples

of

of

description diseases

transmission

pathogens

are

in

tiny

droplets inuenza,

of through

the

liquid

from

the

airways

and

air

tuberculosis, lungs

of

infected

people

(see common

photo

people

not

preparing

wash

contaminated

are

food

human

not

their

food

hands;

cooked

do

foods

properly; cholera,

and

drink

water

direct

contact

faeces

supplies;

insect

uninfected

people

people,

infected

people

the

e.g.

droplets

her

of

nose

she

is

water

and

using

a

are

bodies

touch

or

items,

have

of

an

that

athlete’s

foot

used

feed

infected

malaria,

dengue

vectors and

then

feed

on

an

fever

person

handkerchief,

containing

mouth

transfer

mosquitoes,

blood

uninfected though

their

infected

person

Even

ies

on

insects,

typhoid

contaminate

pathogens

on

cold

opposite)

pathogens

entering

the

blood

from

air

and

from

person

an

enters

infected

the

blood

of HIV/AIDS,

may

be

inhaled

by

others.

body

uids

an

uninfected

person,

an

unsterilised

e.g.

in hepatitis

between

drug

pathogens

sexual

activity

person

blood,

Defences

We

have

prevents

three

These

houseies

may

have

picked

up

third

their

and

bodies

human

them

118

to

while

wastes

uncooked

feeding

and

are

meat.

on

bacteria

now

rubbish

transferring

that

line

pathogens. on

different

pathogens

pathogens

The

against

to

break

pass

semen

shared

addicts

from

sexual

or

infected

HIV/AIDS,

partner

in

specic

vaginal

uid

(NSU),

non-

urethritis

chlamydia

disease

lines

entering

of

defence

the

through

produces

needle

body;

the

antibodies

rst

that

against

the

line

disease.

second

and

defend

line

enters

us

The

rst

destroys

the

against

line

any

blood.

specic

Barriers

to

infection

STUD Y The

defences

chemical

we

have

against

entry

of

pathogens

are

mechanical

barriers.

Y ou

Mechanical

The



The

dead

barriers:

outer

layers

of

the

skin

form

a

barrier

to

entry

(see

T opic

in

the

nose

trap

larger

particles

that

you

breathe

are

The



Topic

Cells

that

small

from

The

If

dust

is

a

Blood

White

enter

and

The

are

is

and

and

know

diseas es

show n

in

How ever ,

you

in

the

acid

that

kills

pathogens

in

up

(trachea

and

bronchi)

microorganisms.

to

swallowed

the

and

throat

any

by

The

cilia

make

mucus

(see

pathogens

are

mucus

is

Topic

moved

easier

me th ods

food

that

it

you

fo r

traps

of

may

learn

the

tran smis sion

learn

each

to

an

exam ple

one.

away

11.3).

destroyed

by

acid.

get

second

through

line

of

these

barriers

to

enter

the

blood,

then

defence.

defences

blood

the

cells

body’s

viruses

into

process

white

during

airways

particles

pathogens

there

hydrochloric

if

the

lungs

mucus

any

makes

7.7).

line

the

stomach

to

barriers:

stomach

(see

the

tran smitt ed

ways

nd



have

of

in.

table. Chemical

no t

14.8)

the hairs

do

exam ples

that •

TIP

and

of

a

line

or

vacuoles

of

the

cells

infection

which

by

defence

blood.

where

phagocytosis

blood

an

form

tissues

they

is

against

are

digested

described

produce

pathogens

any

Phagocytes

in

and

T opic

antibodies.

they

produce

pathogens

engulf

that

bacteria

destroyed.

9.7.

Lymphocytes

When

activated

antibodies

which

are All

proteins

that

have

a

variety

of

effects,

such

as

stopping

outdoor

activities

involve

some

risk

of

pathogens infection.

moving

engulf

through

them.

antibodies

the

body

Vaccination

and

give

and

is

a

making

way

long-term

to

it

easier

make

protection

for

phagocytes

lymphocytes

against

to

produce

certain

KEY

POINTS

diseases.

1

A

pathogen

causing SUMMARY

Copy

and

complete

the

Pathogens

from

following:

one

through Pathogens

are

that

cause

disease.

Human

diseases

by

bacteria,

and

.

The

airways

have

that

make

to

trap

kills

.

any

pathogens

form

in

The

pathogens

stomach

that

the

a

.

barrier

lining

enter

the

Dead

to

cells

makes

on

the

Explain

why

you

always

b

never

c

always

d

use

e

never

wash

share

and

your

hands

towel

your

surface

of

the

3

The

are

pathogens.

before

with

hands

handling

skin

and

of

Explain

how

dog

the

and

vectors

in

the

barriers

nose

to

pathogens.

Mucus

in

acid

the

in

lick

climber

in

airways

stomach

and

are

someone

after

when

your

the

going

to

the

barriers.

toilet

Phagocytes

are

white

blood

sneezing

face

that

digest

engulf

them;

antibodies 3

hairs

mechanical

cells

a

food

animal

food

5 handkerchief

let

by

mosquitoes).

chemical

a

droplets,

in

should:

a

wash

in

contact,

which

4 a

air

transmitted

another

body

entry 2

be

to

cells

(e.g. people

can

host

the

direct

water

when

disease-

are by

caused

a

QUESTIONS

2

1

is

organism.

the

photograph

is

at

risk

of

to

pathogens

lymphocytes

attack

and

make

pathogens

infection.

that

enter

the

blood.

119

10.2

Defence

tnemelppuS

If LEARNING

pathogens

Explain

has

that

each

antigens,

own

specic

pathogen

each

with

Explain

that

specic

is

their

provided

antibodies

shapes

that

to

have

by

the

our

help

the

blood

mechanical

and

chemical

may

and

destroy

in

order

antibodies

to

engulf

defences,

nd

and

produced

by

engulf

them.

Many

are

the

shapes

of

these

have

are

chemicals

made

lymphocytes

respond

the

on

Describe

how

antigens

are

help

lymphocytes.

the

of

by

on

their

protein.

making

surface

of

surface

When

you

antibodies,

the

called

antigens.

catch

which

a

disease

can

‘lock

your

on’

to

pathogens.

They

active

cause

for

Some

This

STUD Y



TIP

no t

becom e

be tw een

is

a

all

begin

Unit.

helps

Bacteria

prod uce

secre ted

help

are

‘anti-’

antibody

molecules

attack



such

as

group

stick

together

to

nd

agella

can

them

in

a

and

to

to

group.

engulf

that

This

much

them.

that

the

to

and

blood.

combine

them

move

and

stop

Each

have

pro te ins

that

destro y

If

Antito xins

that

type

shapes.

a

mak e

a

is

walls.

kill

bacteria

This

causing

the

you

of

The

3

shape

have

that

an

and

and

healthy

antigens

diphtheria

with

cells

the

by

cell

the

‘punching’

to

burst.

its

own

walls

so

on

bind

receptors

on

ts

a

If

again,

to

toxins

through

enters

by

you

Lymphocytes

week

strain

will

are

or

which

against

antigen.

have

each

The

specic

type

of

antibody

antigen

has

a

shape

as

the

common

symptoms.

two

you

of

the

virus

not

get

the

responsible

for

will

that

same

this

You

be

cold,

will

back

causes

you

then

to

the

are

be

your

to

You

will

activated

ill

for

feel

normal,

common

symptoms.

and

will

begin

cold

not

be

during

an

response

virus

are

large 4

lymphocytes

born

with

number

of

a

very

different

lymphocytes

are

activated

and

types 5

divide

active

secrete

of

lymphocytes.

lymphocytes

antibodies

These

to

6

to

antibodies

virus

are

different

the

specic

antigens

surfaces

of

of

bacteria,

particles

throughout

particles

bind

cells

the

body

viruses

and

other

throughout

pathogens.

body

pathogen

When

invades,

lymphocytes

antibodies

person

10.2.1

so

to

virus

the

are

antigen.

such

of

antigens

made

the

the

variety

a

the

are

around

infection,

have

within

self.

has

that

specific

inhaled

spread

the

moving.

release

holes

water

You particles

virus

them

harmless.

directly

weakens

pathogen

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