IGCSE Biology Workbook Answers - Hodder Education

[Pages:28]IGCSE Biology Workbook Answers

1 Characteristics and classification of living things

Core

1 nutrition ? taking in materials for energy, growth and development

respiration ? the breakdown of food in cells for energy, growth and development

excretion ? the removal from an organism of toxic materials and substances in excess of requirements

sensitivity ? the ability to detect and respond to changes in the environment

reproduction ? making more of the same kind of organism

growth ? a permanent increase in size

movement ? an action by an organism causing a change of position or place [1 mark for each correct statement]

2 Any suitable sentence with seven words linked

to the characteristics of life, e.g. Most Rats Start

Gathering Rice Every Night

[3]

3 Across: 5 excretion, 6 nutrition, 7 respiration [3]

Down: 1 sensitivity, 2 reproduction, 3 movement,

4 growth

[4]

4 Respiration is the release of energy from food

substances in cells. Breathing is the process of

ventilation of the lungs.

[4]

5 ref. to faeces being undigested food; which has not been formed through metabolic processes [2]

6 (fish and amphibians)

Common features ? any two from: cold blooded; have eyes; produce jelly-covered eggs (in water) [2]

Differences: ref. to gills/lungs; fins/legs; scales/

moist skin

[1]

(amphibians and reptiles)

Common features ? any two from: four legs; eyes

and ears; cold blooded; lungs

[2]

Differences: ref. to moist skin/scales; jelly-covered

eggs/waterproof shell

[1]

(birds and mammals)

Common features ? any two from: eyes and ears;

warm blooded; lungs

[2]

Differences: ref. to feathers/fur; two legs/four

legs; eggs with hard shell/live young; beak/no

beak (or ref. to teeth); ears/ears with pinna; no

mammary glands/mammary glands

[1]

7 A insect, B arachnid, C myriapod, D crustacean,

E mollusc, F annelid, G nematode

[7]

8

[3]

Plant 1a 1b 2a 2b 3a 3b Name of plant

A

? ? ? ? Primula vulgaris

B

? ? ? ? Narcissus

pseudonarcissus

C

? ? ? ? Ranunculus ficaria

D

? ? ? ? Hyacinthoides

non-scripta

Extended

9 ai Any three from: multicellular; have roots/ stems/leaves; ref. to seed production [3]

ii Any three from: (cellulose) cell wall; sap vacuole; nucleus; cytoplasm; membrane [3]

b leaf shape ? broad; leaf veins ? parallel;

cotyledons ? two; grouping of flower parts ?

in threes

[4]

10 protoctists, fungi, plants, bacteria

[4]

11 a Fungi ? any two from: presence of hyphae;

ref. to mycelium; chitin in cell walls; no

chlorophyll present; ref. to spores;, enzymes

secreted for food digestion

[2]

Bacteria ? any two from: small; cell wall ? not cellulose or chitin; membrane/cytoplasm present; glycogen granules present; DNA in form of one coiled chromosome; no nucleus [2]

Viruses ? any two from: very small; no special

cell structure; have a strand of DNA/RNA;

surrounded by protein coat/ref. to capsid;

only show reproduction

[2]

b virus, bacteria, fungi

[1]

c require a host cell to reproduce

[2]

Cambridge IGCSE Biology Workbook 2nd Edition ? Hodder & Stoughton Ltd 2014

1

Answers

Exam focus

Core

1 B

[1]

2 Any three from: movement; excretion; nutrition

(feeding); sensitivity (irritability)

[3]

3 a Any two from: movement; excretion;

sensitivity

[2]

b Any two from: growth; reproduction;

respiration

[2]

4 Any three from: sensitivity; nutrition; growth;

excretion

[3]

5 A ? Nucellus lapillus; B ? Calliostoma ziziphinum; C ? Patella vulgata; D ? Littorina obtusata; E ? Cerastoderma edule[5]

2 Organisation of the organism

Core

1 a ? F; b ? F; c ? T; d ? T; e ? F; f ? T; g ? T; h ? F;

i ? T; j ? T

[10]

2 a A membrane, B cytoplasm, C cell wall, D chloroplast, E (sap) vacuole, F nucleus [6]

b chloroplast, cell wall, sap vacuole

[3]

3 chromosome, nucleus, cell, tissue, organ,

organ system, organism

[3]

4 a magnification = observed size

[1]

actual size

b 12 = ? 4.3

[2]

2.8

5

100

=

15 actual

size;

actual

size

=

15 100

=

0.15

mm

[2]

6 a A group of cells with similar structures; working

together to perform a shared function

[2]

b Animal tissues and functions ? any two

examples, e.g. ciliated cells ? waft mucus with

dust or bacteria away from the lungs; muscle

cells ? can contract to cause movement; red

blood cells ? transport oxygen around the

body

[4]

Plant tissues and functions ? any two

examples, e.g. root hair cells ? absorb water

and mineral salts/anchor the plant into the

soil; xylem cells ? transport water and mineral

ions from roots to leaves/provide strength for

the stem

[4]

Extended

7 a contains cell organelles, site of chemical

reactions

[2]

b prevents cell contents from escaping, controls

the passage of substances into and out of cell

[2]

c controls cell activities, controls cell division/

development

[2]

8 Any one plant cell, e.g. root hair cell; on surface of young roots; absorption of water/absorption of mineral salts/anchorage of plant into the soil [3]

Any three animal cells, e.g. sperm cell, produced in testes, fertilisation of egg/reproduction; ciliated cell, found in respiratory tract, waft mucus with bacteria away from the lungs; epithelial cells on villi, on surface of ileum, increase surface area to absorb products of digestion, e.g. glucose [9]

Exam focus

Core

1 a cell membrane, cytoplasm, nucleus b i chloroplast ii chlorophyll, traps light energy for photosynthesis

2 a Any two from: cell wall; chloroplast; sap

[3]

vacuole

[2]

[1]

b controls cell activities and development ? B; contains cell organelles and is the site of

chemical reactions ? D; waft mucus and

[2]

bacteria away from the lungs ? A; controls

what substances enter and leave the cell ? C [4]

2 Cambridge IGCSE Biology Workbook 2nd Edition ? Hodder & Stoughton Ltd 2014

Answers

3 organ ? several tissues grouped together to make a structure with a special function, e.g. heart, leaf [2]; organ system ? a group of organs with closely related functions, e.g. circulatory system, flower [2]; tissue ? a group of cells of similar structure that work together to perform a special function, e.g. muscle, xylem [2]

Extended

4

[10]

Cell

Organelle(s) More/less/ Explanation

none

muscle cell mitochondria more

red blood nucleus cell

none

upper

chloroplasts

epidermal

none

needs a lot of energy from respiration for contracting

provides more space for haemoglobin

makes the cell transparent so light can pass through

Cell

Organelle(s) More/less/ Explanation

none

liver cell mitochondria more

xylem

nucleus

none

carries out many chemical reactions, requiring energy from respiration

allows water to flow freely through the vessel

5 a The leaf contains a number of different

tissues, which work together to carry out

photosynthesis/transpiration.

[2]

b A ? (waxy) cuticle ? waterproofs the leaf;

B ? upper epidermis ? allows light to

pass through/acts a barrier to microbes;

C ? palisade (mesophyll) ? main site of

photosynthesis; D ? xylem ? transports water

and mineral salts; E ? phloem ? transport

products of photosynthesis/carries out

translocation; F ? guard cell ? controls exit of

water vapour from the leaf

[12]

3 Movement in and out of cells

Core

1 movement of a substance from a region of high

concentration to a region of lower concentration

down a concentration gradient

[3]

2 a i oxygen

[1]

ii Any three from: short distance; big concentration gradient; small molecules; large surface area; higher temperature [3]

b i Rate of diffusion would drop; because the molecules have a lower kinetic (movement) energy/molecules move more slowly [2]

ii Rate of diffusion would increase; because

the concentration gradient would increase

or be maintained

[2]

3 a i labels to parts, such as those shown below [4]

ii arrows such as those shown below (through a stoma, through air space in spongy mesophyll, into palisade mesophyll cell) [3]

upper epidermis

palisade mesophyll cell

air space

stoma

b i Upper epidermis has an impermeable layer

of waxy cuticle

[1]

ii The guard cells close the stomata to reduce transpiration, preventing gas exchange [1]

Cambridge IGCSE Biology Workbook 2nd Edition ? Hodder & Stoughton Ltd 2014

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Answers

4 roots, osmosis, higher, lower, membrane, turgid,

flaccid, wilting, small, partially

[10]

5 a Level in the hollow goes down; level in the

dish goes up

[2]

b There is a higher concentration of salt in the dish; so water moves from the hollow to the dish; through the potato cells by osmosis [3]

c Water moves out of the root hair cells by

osmosis; so the cells become flaccid and die;

the plant then dies because it has lost the

ability to absorb water

[3]

Extended

6 The movement of a substance across a membrane

from a region of lower concentration to a region

of higher concentration; against a concentration

gradient; using energy

[3]

7 a plant A: diffusion only ? roots have absorbed nitrate until there is no concentration gradient [2]; plant B: diffusion and active uptake ? the roots have absorbed nitrate against a concentration gradient, building up a higher concentration than that present in the soil [2]

b Plants need energy from respiration to

carry out active transport; cyanide prevents

respiration

[2]

c Nitrate is needed for protein synthesis; protein

is needed for growth

[2]

8

[4]

Substance Diffusion Osmosis

oxygen

water

(accept)

phosphates

carbon dioxide

Active transport

9 Zone A ? as the sugar solution becomes less concentrated, more water enters the potato cells by osmosis, so the tissue gains mass. The more dilute the sugar solution, the more mass is gained [3]

Zone B - as the sugar solution becomes more

concentrated, more water leaves the potato cells

by osmosis, so the core loses mass. The more

concentrated the sugar solution, the more mass

is lost. Between 0.6 mol dm-3 and 1.0 mol dm-3,

there is no additional mass lost as the potato cells

have become fully flaccid in each case

[3]

Zone C - at this point there is no net gain or loss

of mass by the potato core as the water potential

inside the cells is the same as the water potential

of the surrounding sugar solution

[3]

Exam focus

Core

Extended

1 D

[1]

2 a A alveolus/air sac, B capillary, C red blood

cell

[3]

b i arrow from inside the alveolus to a red

blood cell

[1]

ii arrow from blood plasma to inside the

alveolus

[1]

iii arrow along capillary from pulmonary

artery to pulmonary vein

[1]

c i diffusion

[1]

ii ref. to breathing to keep oxygen levels in the

alveoli high; ref. to blood constantly moving

through capillaries, bringing blood low in

oxygen

[2]

3

Type of Substance Process(es) Description Energy

cell

absorbed used

of gradient used?

(water)

osmosis

high to low no

(root hair

1 diffusion

cell)

(phosphate)

2 active

uptake

1 high to low 1 no 2 low to high 2 yes

(villus cell in small (glucose) intestine)

1 diffusion 1 high to low 1 no

2 active uptake

2 low to high 2 yes

[15]

4 a i The concentration of water is higher outside

the cell; so water enters the cell; by osmosis;

the cell becomes turgid.

[4]

4 Cambridge IGCSE Biology Workbook 2nd Edition ? Hodder & Stoughton Ltd 2014

Answers

ii The concentration of water is higher inside

the cell; so water leaves the cell; by osmosis;

the cell becomes plasmolysed, then flaccid.

[4]

b i The concentration of water is lower inside

the cells than in the plasma, so water enters

the cells, by osmosis, the cells become

turgid, then burst because they have no

cell wall.

[3]

ii Red blood cells are no longer able to transport oxygen, so cells are unable to respire, resulting in an energy shortage. [2]

5 a, b

Sugar

Start

concentration / length/

mol dm-3

cm

0.0

5.0

0.2

5.0

0.4

5.0

0.6

5.0

0.8

5.0

1.0

5.0

Length after 1 hour/cm

5.3 5.1 4.7 4.4 4.3 4.3

Change in length /cm

% change in length

0.3

6.0

0.1

2.0

?0.3

?6.0

?0.6

?12.0

?0.7

?14.0

?0.7

?14.0

[4]

c

10.0

5.0

% change in length

0.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 sugar concentration/mol dm?3

?5.0

?10.0

?15.0

?20.0

[4]

d i 0.26 mol dm-3

[1]

ii The concentration of sugar in the potato

cells is the same as the concentration in the

surrounding solution; so there is no net

movement of water molecules.

[2]

e Any two from: leave all the cores in the

solutions for the same amount of time; use the

same volume of solution in each test tube; cut

all the cores to the same diameter

[2]

f Set up two or more cores for each

concentration, measure the length of the cores

in millimetres, weigh the cores instead of

measuring length.

[1]

4 Biological molecules

Core

1 B

[1]

2 a carbon, hydrogen, oxygen

b carbon, hydrogen, oxygen

c carbon, hydrogen, oxygen, nitrogen

[3]

3 a starch; obtaining energy

chemical bond glucose

b fat/lipid; energy/insulation/formation of cell membranes/hormone formation

c protein; growth/tissue repair/enzymes/cell membranes/hormone formation

amino acid

chemical bond

[13]

4 vitamin C ? DCPIP ? colourless; reducing sugar ? Benedict's solution ? brick red; fat ? ethanol ? white emulsion; protein ? Biuret solution ? violet (halo); starch ? iodine solution ? blue?black [5]

Extended

5 a

G

A

T

C

C

T

A

G

glycerol chemical bond

fatty acid

A

G

C

T

[3]

Cambridge IGCSE Biology Workbook 2nd Edition ? Hodder & Stoughton Ltd 2014

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Answers

b double helix

[1]

c mutation

[1]

6 Any six points from: enzymes need water to work in; so they can digest large insoluble food molecules; e.g. starch/fat/protein; digested food molecules can pass through membranes in solution; blood plasma is mainly water;

substances dissolved in it are transported in

blood; e.g. glucose/salts/urea/carbon dioxide/

hormones/soluble proteins; waste or toxic

materials are dissolved in water to form urine;

being diluted in water reduces toxic properties

of, e.g. urea; oxygen dissolves in moist layer in

alveoli to diffuse into blood cells

[6]

5 Enzymes

Core

1 a A substance that increases the rate of a

chemical reaction and is not changed by the

reaction.

[2]

b A protein that functions as a biological

catalyst.

[2]

2 a

enzyme

starch

amylase

maltose

substrate

end product

[3]

b Any two points from: starch is a larger

molecule; starch is insoluble while glucose

is soluble; starch is a polysaccharide/

polymer while glucose is a monosaccharide/

monomer.

[2]

c Protease only digests proteins, amylase only

digests starch. Enzymes are specific. The active

site in protease will not have a complementary

shape to the active site in amylase, so the

substrate (starch) will not fit.

[2]

Extended

rate /arbitrary units

3 a

5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5

0 0

the reaction is speeding up fastest here

the reaction is slow here

optimum reaction rate

denaturing is taking place here

20

40

60

temperature /? C

[4]

b i The reaction would speed up because the

substrate and enzyme molecules would

move faster/gain more kinetic energy; so

there would be more collisions.

[2]

ii There would still be no reaction; because all

the enzyme molecules have been denatured

by the high temperature.

[2]

4 temperature, pH, concentration of substrate [3]

Exam focus

Core

1 a i amylase

[1]

ii maltose

[1]

iii two from: energy source, to convert to cellulose, convert to materials for growth [2]

iv Starch is a large, insoluble molecule while

maltose is smaller and soluble.

[2]

b Enzymes are only active in water; cells become

turgid ? leading to expansion.

[2]

Extended

2 a i lipase

[1]

ii protease/pepsin

[1]

b Enzymes digest molecules causing the stains; the small molecules produced are soluble. [2]

c The enzymes in the powder would be

denatured; so they would not digest

the stains.

[2]

d Amino acids are small, soluble molecules;

while proteins in blood are large, insoluble

molecules.

[2]

6 Cambridge IGCSE Biology Workbook 2nd Edition ? Hodder & Stoughton Ltd 2014

Answers

3 a Any five from: the food molecule is the

substrate; the enzyme has an active site; which

combines temporarily with the substrate to

form an enzyme?substrate complex; bonds

are broken in the substrate molecule; the

products are formed; the products are small

and soluble

[5]

b Enzymes have a specificity; they have a

complementary shape to the substrate

molecule they work on; so the active site and

substrate fit closely together to allow the

reaction to happen

[3]

6 Plant nutrition

Core

1 a carbon + water dioxide

sunlight chlorophyll

oxygen + glucose [2]

b i sucrose

ii starch

[2]

c Chlorophyll traps light energy.

[1]

d Any three from: shortage of oxygen; shortage

of food; shortage of nesting sites; shortage of

hiding places

[3]

2 a palisade (mesophyll) cells

[1]

b guard cells

[1]

c (upper) epidermis cells

[1]

d xylem cells

[1]

e phloem cells

[1]

3 Boil the leaf in water: to kill the leaf ? this makes it permeable.

Boil the leaf in ethanol: to decolourise the leaf, since chlorophyll dissolves in ethanol.

Rinse the leaf in water: boiling the leaf in ethanol makes it brittle, so the water softens it.

Spread the leaf out on a white tile: so the results will be easy to see.

Add iodine solution to the leaf: to test for the

presence of starch.

[5]

Extended

4 a Nitrate ions are needed to form amino acids, to

build proteins; proteins are needed for growth.

[2]

b Magnesium ions are needed to make

chlorophyll; chlorophyll is needed to trap light

energy for photosynthesis.

[2]

5 a i violet and orange/red

[2]

ii green

[1]

b Use a bright light to shine on the Elodea in a

beaker of water. Measure the light intensity

using a light meter, or measure the distance

between the lamp and the plant. Allow the

plant to adjust to the light intensity. Count the

number of bubbles produced by the plant over

a fixed time period (e.g. 1 minute). Move the

lamp further away from the plant. Measure

the new light intensity or the new distance

between the lamp and the plant. Allow the

plant to adjust to the light intensity. Count the

number of bubbles produced by the plant over

the same time period. Repeat the process for at

least five different light intensities or distances.

Keep the temperature of the water the same,

use the same plant, use the same beaker, use

the same time period for counting bubbles.

Alternatively, the oxygen could be trapped

in a graduated container such as an inverted

gas cylinder, so the volume of gas could

be measured.

[6]

Exam focus

Core

2 a i A ? guard cells; B ? upper epidermal cell;

1 De-starch two similar potted plants. Place them

C ? spongy mesophyll cell; D ? palisade

mesophyll cell

[4]

in sealed bell jars/large transparent containers.

To one container add a CO2 absorber. Expose both plants to the same, optimum conditions, e.g. light,

ii B, D, C, A

[2]

b xylem ? transports water, mineral salts from

warmth. Leave for 2 days. Test a leaf from each plant for the presence of starch. Only the control

roots around the plant; phloem ? transports sucrose, amino acids from leaves to storage or

plant leaf (without CO2 absorber) will turn blue?

growth regions of the plant

[6]

black, indicating the presence of starch.

[8]

Cambridge IGCSE Biology Workbook 2nd Edition ? Hodder & Stoughton Ltd 2014

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Answers

Extended

3 B

[1]

4 a i Description ? any two from: plants would

show poor growth; stems weak; lower

leaves yellow/dead; upper leaves turn

pale yellow. Explanation ? nitrates needed

to produce proteins, which are needed for

growth

[3]

iiAny two from: apply animal manure; crop

rotation involving leguminous plants; apply

artificial fertilisers

[2]

b leaves turn yellow/ref. to chlorosis; from the bottom of the stem upwards; poor plant growth, ref. to inability to form chlorophyll [3]

7 Human nutrition

Core

1 a iron

b water

c fibre

d vitamin C

[4]

2 a Any two advantages from: high carbohydrate level ? for energy; good source of calcium ? for strong bones and teeth/to prevent rickets; protein present ? for growth/repair

Any two disadvantages from: high in animal

fat ? can cause heart disease/atherosclerosis/

obesity; lack of fresh fruit/vegetables/fibre ?

to prevent constipation; low in vitamin C ? to

prevent scurvy; low in iron ? to prevent

anaemia

[4]

b Any two from: constipation; risk of obesity/

scurvy/anaemia; risk of heart disease/

atherosclerosis

[2]

c i A diet that contains all the main nutrients in the correct amounts and proportions [2]

ii fibre

[1]

3 A ? mouth; B ? gullet/oesophagus; C ? stomach; D ? large intestine/colon; E ? rectum; F ? anus; G ? small intestine/ileum; H ? duodenum [8]

4 a anus ? muscular, to control the egestion of faeces; colon ? absorption of water;

duodenum ? first part of the small intestine;

ileum ? absorption of the products of digestion

takes place here; mouth ? food is ingested

here; oesophagus (gullet) ? a tube, carrying

boluses of food between mouth and stomach;

rectum ? stores faeces; stomach ? has an acid

pH and proteins are digested here

[8]

b (mouth), oesophagus (gullet), stomach, duodenum, ileum, colon, rectum, anus [7]

5

Name

incisor

Description chiselshaped

Function

biting off pieces of food

canine

slightly more pointed than incisors

biting off pieces of food

premolar

two points/ cusps

one/two roots

tearing and grinding food

molar four/five cusps

two/three roots

chewing and grinding food

[6]

Extended

6 Any three points from: too much food/too little

food; too much carbohydrate/fat/protein; too

little fibre; too few vitamins or minerals; the

wrong balance of food

[3]

Exam focus

Core

1 C

[1]

2 a i A ? root; B ? crown; C ? enamel; D ? dentine;

E ? pulp cavity; F ? gum; G ? cement; H ?

jaw bone; I ? nerve

[9]

ii molar (accept premolar); two cusps visible/

two roots visible

[2]

b i enamel

[1]

ii (vitamin) D, (mineral) calcium

[2]

8 Cambridge IGCSE Biology Workbook 2nd Edition ? Hodder & Stoughton Ltd 2014

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