Answers To Workbook

Cambridge
ANSWERS
IGCSE Biology
Practice Book
Answers
1 Characteristics of living (Breathing) is the process of getting oxygen into the
lungs and the removal of carbon dioxide.
6 Ref. to faeces being undigested food, which has not
things been formed through metabolic processes.
1 Characteristic Definition Exam focus

nutrition the breakdown of food in 1 B
cells to release energy 2 Any three from: movement, excretion, nutrition
(feeding), sensitivity (irritability).
an increase in size, mass and 3 (a) Any two from: movement, excretion, sensitivity.
respiration
complexity of an organism (b) Any two from: growth, reproduction, respiration.
4 Any three from: sensitivity, nutrition, growth,
producing offspring, which excretion.
excretion prevents extinction of the
species
this involves feeding

2 Classification of living
sensitivity
obtaining nutrients
for growth, energy and organisms
maintaining health
1 protoctists, fungi, plants, bacteria
in response to changes, e.g. 2 A (a) (dragonfly) insect
reproduction presence of a predator, to (b) Key features any two from: three pairs
find food or a mate of legs, two pairs of wings, one pair of
antennae, body divided into three parts, one
the ability to detect pair of compound eyes.
growth
changes in the surroundings B (a) (earthworm) annelid
(b) Key features any two from: elongated,
getting rid of the waste cylindrical body, segmented body, clitellum
movement products made by chemical present.
reactions in cells C (a) (snail) mollusc
(b) Key features any two from: has a shell,
2 Any suitable sentence with seven words linked
muscular foot, eyes on tentacles.
to the characteristics of life, e.g. Most Rats Start
D (a) (spider) arachnid
Gathering Rice Every Night.
(b) Key features any two from: four pairs
3 Across 5 excretion 6 nutrition 7 respiration Down
of legs, body divided into abdomen and
1 sensitivity 2 reproduction 3 movement 4growth
cephalothorax, several pairs of simple eyes,
4
chelicerae for biting prey.
Organism Product Process 3 Any two from: no backbone, have exoskeleton,
plant 1 carbon dioxide/ respiration segmented bodies, jointed limbs.
water 4 (fish and amphibians)
2 oxygen photosynthesis Common features any two from: cold blooded,
animal 1 carbon dioxide/ respiration have eyes, produce jelly-covered eggs (in water).
water Differences: ref. to gills/lungs, fins/legs, scales/moist
skin.
2 urea deamination
(amphibians and reptiles)
5 (Respiration) is the release of energy from food Common features any two from: four legs, eyes
substances in cells. and ears, cold blooded, lungs.
Cambridge IGCSE Biology Practice Book Hodder & Stoughton Ltd 2013
1
Differences: ref. to moist skin/scales, eggs jelly
4 Cell structure and
ANSWERS
covered/waterproof shell
(birds and mammals)
Common features any two from: eyes and ears, organisation
warm blooded, lungs.
Differences: ref. to feathers/fur, two legs/four legs, 1 (a) F
eggs with hard shell/live young, beak/no beak (or (b) F
ref. to teeth), ears/ears with pinna, no mammary (c) T
glands/mammary glands. (d) T
5 (a) (i) Any three features from: multicellular, have (e) F
roots, stems, leaves, ref. to seed production. (f) T
(ii) Any three features from: (cellulose) cell wall, (g) T
sap vacuole, nucleus, cytoplasm, membrane. (h) F
(b) (leaf shape) broad (i) T
(leaf veins) parallel (j) T
(cotyledons) two 2 (a) A membrane, B cytoplasm, C cell wall,
(grouping of flower parts) in threes D chloroplast, E (sap) vacuole, F nucleus
6 (a) (fungi) Any two from: presence of hyphae, ref. (b) chloroplast, cell wall, (sap) vacuole
to mycelium, chitin in cell walls, no chlorophyll 3 Cell part Description
present, ref. to spores, enzymes secreted for food
cell wall a fluid-filled space surrounded
digestion.
by a membrane
(bacteria) Any two from: small, cell wall not
cellulose or chitin, membrane/cytoplasm present, a round or oval structure
glycogen granules present, DNA in form of one chloroplast containing DNA in the form
coiled chromosome, no nucleus. of chromosomes
(viruses) Any two from: very small, no special cell
structure, have a strand of DNA/RNA, surrounded a tough, non-living layer made
by protein coat/ref. to capsid, only show of cellulose, which surrounds
reproduction. cytoplasm
the membrane
(b) virus, bacteria, fungi
(c) only show reproduction as a characteristic of life
jelly-like, with particles and
Exam focus membrane
organelles in it
1 B
2 (a) (i) Any two from: exoskeleton, segmented body, an organelle containing
nucleus
segmented limbs. chlorophyll
(ii) Any two from: five pairs of legs, two pairs
of antennae, exoskeleton in the form of a a partially permeable layer
carapace, compound eyes. sap vacuole that forms a boundary around
(b) Ref. to maintaining constant body temperature/ the cytoplasm
warm blooded, moves around more to find food
or to find a mate. 4 (a) contains cell organelles, site of chemical reactions
3 Using simple keys (b) prevents cell contents from escaping, controls the
passage of substances into and out of cell
(c) controls cell activities, controls cell division/
1 A insect, B arachnid, C myriapod, D crustacean,
development
Emollusc, F annelid, G nematode
2
Plant 1a 1b 2a 2b 3a 3b Name of plant
Exam focus
A Primula vulgaris 1 (a) cell membrane, cytoplasm, nucleus
(b) (i) chloroplast
B Narcissus
(ii) chlorophyll, traps light energy for
pseudonarcissus
photosynthesis
C Ranunculus 2 (a) Any two from: cell wall, chloroplast, sap vacuole.
ficaria
(b) Function Cell part
D Hyacinthoides
non-scripta controls cell activities and develop- B
ment
Exam focus contains cell organelles and is the
site of chemical reactions
D
1 A Nucellus lapillus
B Calliostoma ziziphinum waft mucus and bacteria away A
C Patella vulgata from the lungs
D Littorina obtusata controls what substances enter and C
E Cerastoderma edule leave the cell
2
3 (a) Any five parts compared from: 6 Any five named leaf cells (max. 3 marks for each),
ANSWERS
Cell part Liver cell Palisade mesophyll cell with features described and functions stated, such as:
Epidermal cell: thin, transparent, no chloroplasts
cell wall
present, allows light through/acts as a barrier to
membrane disease organisms.
cytoplasm Palisade mesophyll cell: columnar, packed with
nucleus chloroplasts, for photosynthesis/to trap light energy.
chloroplast Spongy mesophyll cell: mostly spherical shaped,
chloroplasts present, for photosynthesis/allows
sap vacuole
gaseous exchange within the leaf due to air spaces
(b) Functions of six parts, such as: between cells.
cell wall prevents the cell from bursting Guard cell: found in pairs, mainly in lower epidermis,
membrane controls what substances enter contains chloroplasts, controls opening of stomata.
and leave the cell Xylem cell: long and thin, with lignified cell wall,
cytoplasm contains cell organelles lacks end wall/cell contents, transports water and
nucleus controls cell activities mineral salts.
sap vacuole contains sugars and salts Phloem cell: sieve plate present in end wall,
chloroplast traps light energy for transports sugars and amino acids/ref. to
photosynthesis. translocation.
7
5 Levels of organisation Name Location Function
1 chromosome, nucleus, cell, tissue, organ, plant root hair on surface of absorption
organ system, organism cell cell young roots of water/
2 Example Term absorption of
mineral salts/
leaf cell anchorage of
plant into the
soil
heart animal sperm produced in fertilisation
organ cell 1 cell testes of egg/
reproduction
skeleton animal ciliated bronchus/ waft bacteria
cell 2 cell oviduct or mucus
tissue away from
root hair the lungs/
move egg
from ovary to
organ system uterus
spongy mesophyll
animal villus cell small absorbs
cell 3 intestine digested food
molecules/
worm organism
water
3 (a) magnification = observed size
actual size Exam focus
12 1 Organ several tissues grouped together to make a
(b) = 4.3 structure with a special function, e.g. heart, leaf.
2.8
Organ system a group of organs with closely
15 15
4 100 = ; actual size = = 0.15mm related functions, e.g. circulatory system, flower.
actual size 100
Tissue a group of cells of similar structure that
5 (a) a group of cells with similar structure, work together to perform a special function, e.g.
performing a special function muscle, xylem.
(b) Any two animal tissues and any two plant tissues 2
and their functions: Cell Organelle(s) More/ Explanation
e.g. ciliated cells waft mucus with dust or less/
bacteria away from the lungs none
muscle cells can contract to cause movement
muscle mitochon- more need a lot of
red blood cells transport oxygen around the
cell dria energy from
body
respiration for
root hair cells absorb water and mineral salts/
contracting
anchor the plant into the soil
xylem cells transport water and mineral ions red blood nucleus none provides more
from roots to leaves/provide strength for the cell space for
stem. haemoglobin
(Continues overleaf)
3
2 (Continued) upper
ANSWERS
epidermis
Cell Organelle(s) More/ Explanation
less/
none
palisade
upper chloroplasts none makes the cell mesophyll
epidermal transparent so cell
cell light can pass
through
liver cell mitochon- more carry out many
dria chemical reac-
tions, requiring
energy from
respiration
xylem nucleus none allows water
to flow freely air space
through the vessel
3 (a) The leaf contains a number of different tissues,
which work together to carry out photosynthesis/ stoma
transpiration.
(b) (b) (i) Upper epidermis has an impermeable layer of
Leaf Name Function waxy cuticle.
part (ii) The guard cells close the stomata to reduce
transpiration, preventing gas exchange.
A (waxy) cuticle waterproofs the leaf
4 (a) F
B upper epidermis allows light to pass (b) T
through/acts a barrier to (c) F
microbes (d) F
C palisade main site of photosynthesis (e) T
(mesophyll) (f) T
D xylem transports water and 5 the movement of a substance across a membrane
mineral salts from a region of lower concentration to a region
E phloem transports products of of higher concentration, against a concentration
photosynthesis/carries out gradient, using energy
translocation 6 (a)
F guard cell controls exit of water Process(es) Reason
vapour from the leaf plant A roots have absorbed nitrate
until there is no concentration
diffusion only gradient
6 Diffusion and active plant B the roots have absorbed
nitrate against a concentration
transport diffusion and active gradient, building up a higher
transport concentration than that present
1 movement of a substance from a region of high in the soil
concentration to a region of lower concentration (b) Plants need energy from respiration to carry out
down a concentration gradient active transport. Cyanide prevents respiration.
2 (a) (i) oxygen
(ii) Any three points from: short distance, big Exam focus
concentration gradient, small molecules, large 1 D
surface area, higher temperature. 2
(b) (i) Rate of diffusion would drop, because the
molecules have a lower kinetic (movement) Type of Substance Process(es) Gradient: Energy
energy/molecules move more slowly. cell absorbed used high to low/ used?
(ii) Rate of diffusion would increase, because the low to high?
concentration gradient would increase or be root water osmosis high to low no
maintained. hair cell phosphate 1. diffusion 1. high to 1. no
3 (a) (i) labels to parts as shown in the following low
diagram 2. active 2. low to 2. yes
(ii) arrows as those shown in the following transport high
diagram (through a stoma, through air space villus glucose 1. diffusion 1. high to 1. no
in spongy mesophyll, into palisade mesophyll cell in low
cell) small in- 2. active 2. low to 2. yes
testine transport high
4
3 (a) A alveolus/air sac B capillary C red blood cell concentrated the sugar solution, the more mass is
ANSWERS
(b) (i) arrow from inside the alveolus to a red blood lost. Between 0.6moldm-3 and 1.0moldm-3, there
cell is no additional mass lost as the potato cells have
(ii) arrow from blood plasma to inside the become fully flaccid in each case.
alveolus Zone C at this point there is no net gain or loss
(iii) arrow along capillary from pulmonary artery of mass by the potato core as the water potential
to pulmonary vein inside the cells is the same as the water potential of
(c) (i) diffusion the surrounding sugar solution.
(ii) Ref. to breathing to keep oxygen levels in the 6 (a) Ref. to transport medium/moves mineral salts or
alveoli high; ref. to blood constantly moving sucrose or amino acids around the plant
through capillaries, bringing blood low in maintains the turgidity of cells/to keep cells firm/
oxygen. to prevent wilting.
4 (a) A capillary absorbs digested food molecules, Ref. to raw material for photosynthesis.
e.g. glucose, amino acids (b) (i) Ref. to root hair cells, absorb water by
B lacteal absorbs fatty acids, glycerol osmosis, from a high concentration in the soil,
C epithelial lining one cell thick for efficient to a lower concentration in the cell.
absorption/has microvilli to increase surface (ii) Ref. to cortex cells, have a lower
area for absorption concentration of water than epidermal
(b) to increase surface area for efficient absorption/ cells, so water moves by osmosis, until water
to increase rate of diffusion reaches xylem, ref. to transpiration pull.
(c) (i) diffusion (iii) Water in leaf cells evaporates, into air spaces,
(ii) Any two from: walls are one cell thick, form a higher concentration of water vapour in air
network to provide a large surface area, close space than in atmosphere, so molecules move
to the surface of the villus. out of leaf by diffusion, through stomata.
(d) (i) When the concentration of glucose in the
intestine is the same as/lower than the Exam focus
concentration in the capillary. 1 (a) (i) The concentration of water is higher
(ii) Energy is required. outsidethe cell, so water enters the cell, by
osmosis, the cell becomes turgid.
(ii) The concentration of water is higher inside the
7 Osmosis cell, so water leaves the cell, by osmosis, the
cell becomes plasmolysed, then flaccid.
1 roots, osmosis, higher, lower, membrane, turgid, (b) (i) The concentration of water is lower inside the
flaccid, wilting, small, partially cells than in the plasma, so water enters the
2 (a) Level in the hollow goes down, level in the dish cells, by osmosis, the cells become turgid, then
goes up. burst because they have no cell wall.
(b) There is a higher concentration of salt in the (ii) Red blood cells are no longer able to
dish, so water moves from the hollow to the dish, transport oxygen, so cells are unable to
through the potato cells by osmosis. respire, resulting in an energy shortage.
(c) Water moves out of the root hair cells by 2 (a) (b)
osmosis, so the cells become flaccid and die. The
Sugar Start Length Change %
plant then dies because it has lost its ability to
concentration length/ after in change
absorb water.
/mol dm-3 cm 1 hour/ length/ in
3
cm cm length
Substance Diffusion Osmosis Active
0.0 5.0 5.3 0.3 6.0
transport
oxygen 0.2 5.0 5.1 0.1 2.0
water (accept ) 0.4 5.0 4.7 0.3 6.0
phosphates 0.6 5.0 4.4 0.6 12.0
carbon 0.8 5.0 4.3 0.7 14.0
dioxide
1.0 5.0 4.3 0.7 14.0
4 There is a higher water potential in the soil than in
the root hair cells, so water passes into the root hair (c) 10.0
by osmosis. The sap in the root hair cell develops
a higher water potential than the cell next to it 5.0
(cortex cell), so water moves across from cell to cell
% change in length
until it reaches the xylem. Water moves up the xylem 0.0

0.0 0.2 0.4 0.6 0.8 1.0 1.2
vessels, so a water potential gradient is maintained. sugar concentration/mol dm3
5 Zone A as the sugar solution becomes less 5.0
concentrated, more water enters the potato cells by
osmosis, so the tissue gains mass. The more dilute 10.0
the sugar solution, the more mass is gained.
Zone B as the sugar solution becomes more 15.0
concentrated, more water leaves the potato cells
by osmosis, so the core loses mass. The more 20.0
5
(d) (i) 0.26moldm-3 makes the bread dough rise. The ethanol evaporates
ANSWERS
(ii) The concentration of sugar in the potato as the bread is baked.

cells is the same as the concentration in Brewing, e.g. beer or wine. Enzymes in yeast convert
the surrounding solution, so there is no net sugar to ethanol and carbon dioxide. The ethanol
movement of water molecules. makes the drink alcoholic; carbon dioxide gives the
(e) Any two from: leave all the cores in the solutions drink its fizz.
for the same amount of time, use the same Cheese-making. The enzyme rennin, extracted from
volume of solution in each test tube, cut all the cows stomachs, is used to clot milk.
cores to the same diameter. Making baby foods. Trypsin (a protease) is used to
(f) Any one from: set up two or more cores for pre-digest baby foods.
each concentration, measure the length of the 6 (a) (i) Stir the mixture of feedstock and
cores in millimetres, weigh the cores instead of microorganisms/distribute the heat through
measuring length. the liquid.
(ii) Extracts the microorganisms from the filtrate.
8 Enzymes (iii) Provides nutrients for the microorganisms to
grow, respire and produce enzymes.
1 (a) a chemical that speeds up the rate of a reaction (b) fungi, bacteria
without being changed itself (c) Microorganisms are filtered from the feedstock,
(b) a biological catalyst, protein in nature, which then crushed and washed with water.
speeds up the rate of a reaction
2 (a) Exam focus
1 (a) (i) lipase
enzyme
(ii) protease/pepsin
(b) Enzymes digest molecules causing the stains, the
amylase small molecules produced are soluble.
starch maltose (c) The enzymes in the powder would be denatured,
so they would not digest the stains.
(d) Amino acids are small, soluble molecules while
substrate end product
proteins in blood are large, insoluble molecules.
2 (a) (i) amylase
(b) Any two from: starch is a larger molecule, starch (ii) maltose
is insoluble while glucose is soluble, starch is (iii) Any two from: energy source, to convert to
a polysaccharide/polymer while glucose is a cellulose, convert to materials for growth.
monosaccharide/monomer. (iv) Starch is a large, insoluble molecule; maltose
(c) Protease only digests proteins, amylase only is smaller, soluble.
digests starch. (b) (i) Ref. to water passes through the micropyle.
The active site in protease will have a different (ii) Enzymes are only active in water; cells
shape to the active site in amylase, so the become turgid leading to expansion.
substrate (starch) will not fit.
3 (a)
optimum reaction
9 Nutrition and nutrients
rate
1 (a) (i) starch (ii) obtaining energy
5.0
4.5
the reaction is (iii)
speeding up denaturing is
4.0
rate / arbitrary units
fastest here taking place

3.5 here
3.0 chemical bond
2.5 glucose unit
2.0 (b) (i) fat/lipid (ii) energy/insulation/formation
the reaction is
1.5 slow here of cell membranes/hormone
1.0 formation
0.5 (iii)
0
0 20 40 60
temperature/ C
(b) (i) The reaction would speed up because the

substrate and enzyme molecules would move
glycerol chemical fatty acid
faster/gain more kinetic energy, so there bond
would be more collisions.
(ii) There would still be no reaction because all (c) (i) protein (ii) g
rowth/tissue repair/enzymes/
the enzyme molecules have been denatured cell membranes/hormone
by the high temperature. formation
4 temperature, pH, concentration of substrate (iii)
5 Any two from:
Baking, e.g. bread. Enzymes in yeast convert sugar amino acid
to ethanol and carbon dioxide. The carbon dioxide chemical bond
6
2
Exam focus
ANSWERS
Food tested Chemical reagent used Colour for a
positive result 1 A vitamin C
2 B amino acids
reducing iodine 3 (a) Any two from: less saturated fat, more fibre,
blue-black
sugar solution more calcium.
(b) (i) Any one from: other red meat, liver, kidney,
eggs, green vegetables, chocolate, etc.
Benedicts (ii) n eeded for the formation of haemoglobin in
fat solution violet (halo)
red blood cells
(iii) Ref. to anaemia, constant tiredness, lack of
energy.
ethanol (c) (i) filamentous fungus
protein brick red (ii) better flavour, cheaper to produce
(d) Any two from: the food is cheaper to produce,
farmers have no vets bills, less energy lost/more
Biuret solution
white energy available.
(sodium
starch hydroxide+ copper
sulfate solution)
emulsion
10 Plant nutrition
3 (a) iron 1 (a)
(b) water light
(c) calcium carbon dioxide + water glucose + oxygen
chlorophyll
(d) fibre
(e) vitamin C
4 (a) Yeast is mixed with flour, some sugar and water (b) (i) Sucrose
to make dough. The dough is kept warm to (ii) Starch
allow the yeast to respire the sugar, producing (c) Chlorophyll traps light energy.
pockets of carbon dioxide. These make the (d) Any three from: shortage of oxygen, shortage
dough rise. Baking kills the yeast. of food, shortage of nesting sites, shortage of
(b) Bacteria (e.g. Streptococcus thermophilus and hiding places.
Lactobacillus bulgaricus) are used to ferment 2 (a) palisade (mesophyll) cells
milk at 46oC. As a result, lactic acid is produced (b) guard cells
(as fermentation progresses the pH drops). (c) (upper) epidermis cells
The lactic acid makes the milk coagulate. The (d) xylem cells
temperature is then reduced to 5oC to prevent (e) phloem cells
further bacterial action. 3 (a) Nitrate ions are needed to form amino acids, to
5 Any three from: build proteins. Proteins are needed for growth.
Name of Function Advantage Disadvantage (b) Magnesium ions are needed to make chlorophyll.
group of additive Chlorophyll is needed to trap light energy for
photosynthesis.
antioxidants stop food stop the may have side
4
reacting taste of the effects for
rapid death decay death of
with food being some consum-
leaching algal of by aquatic
oxygen spoiled/ ers, e.g. stom- growth algae bacteria animals
stop colour ach problems,
changing kidney stones 5 Boil the leaf in water: to kill the leaf this makes it
colourings improve food may be permeable.
the becomes hazardous to Boil the leaf in ethanol: to decolorise the leaf, since
appearance more health/trigger chlorophyll dissolves in ethanol.
of the food attractive allergic reac- Rinse the leaf in water: boiling the leaf in ethanol
tions/cause makes it brittle, so the water softens it.
hyperactivity Spread the leaf out on a white tile: so the results will
in children be easy to see.
Add iodine solution to the leaf: to test for the
flavourings enhance improve e.g. sugar
presence of starch.
the taste the flavour increases
6 (a) (i) violet and orange/red
of the calorific
(ii) green
food value, risking
(b) Use a bright light to shine on the Elodea in a
obesity, artifi-
beaker of water. Measure the light intensity using
cial sweeten-
a light meter, or measure the distance between
ers can have
the lamp and the plant. Allow the plant to adjust
side effects
to the light intensity. Count the number of bubbles
preserva- increase food can some produced by the plant over a fixed time period
tives the shelf be kept for additives, e.g. (e.g. 1 minute). Move the lamp further away from
life of the longer sodium ni- the plant. Measure the new light intensity or the
food trite, may be new distance between the lamp and the plant.
carcinogens Allow the plant to adjust to the light intensity.
7
Count the number of bubbles produced by the (b) Any two from: constipation, risk of obesity/
ANSWERS
plant over the same time period. Repeat the scurvy/anaemia, risk of heart disease/
process for at least five different light intensities atherosclerosis.
or distances. Keep the temperature of the water (c) (i) a diet that contains all the main nutrients in
the same, use the same plant, use the same beaker, the correct amounts and proportions
the same time period for counting bubbles. (ii) fibre
Alternatively, the oxygen could be trapped in 2 Any three from: too much food/too little food, too
a graduated container such as an inverted gas much carbohydrate/fat/protein, too little fibre, too
cylinder, so the volume of gas could be measured. few vitamins or minerals, the wrong balance of food.
3 (a) Any two from: addiction (alcoholism), cirrhosis
Exam focus of the liver, stomach ulcers, cancer of the digestive
system, heart disease.
1 B palisade mesophyII
(b) Increases risk of miscarriage, results in a decrease
2 (a) (i) (Description): Any two from: plants would
in average birth weight.
show poor growth, stems weak, lower leaves
4 (a) Any three points and descriptions from:
yellow/dead, upper leaves turn pale yellow.
climate change and natural disasters, e.g.
(Explanation): nitrates needed to produce
flooding or drought
proteins, which are needed for growth.
pollution can lead to breaks in the food chain,
(ii) Any two from: apply animal manure, crop
poisoning of food sources, chronic diseases
rotation involving leguminous plants, apply
could adversely affect workforce responsible for
artificial fertilisers.
producing food
(b) Leaves turn yellow/ref. to chlorosis, from the
shortage of water, due to diversion of rivers,
bottom of the stem upwards, poor plant growth,
building dams for hydroelectricity
ref. to inability to form chlorophyll.
eating future seed stock due to food shortage
3 (a) an external factor, which restricts the effects of
poor soil, or lack of fertiliser or inorganic ions, so
others
crops are poor
(b) Any two from:
desertification due to soil erosion, as a result of
Carbon dioxide needed as a raw material for
deforestation
photosynthesis, converted into carbohydrate.
destruction of forests, reducing numbers of
Temperature increased temperature speeds up
animals to hunt or food to collect
photosynthesis, as enzymes work faster at higher
shortage of money for agriculture
temperatures.
war, making it too dangerous to farm the land
Light intensity light energy needed for
use of land for building houses or roads
photosynthesis, more light speeds up the process,
pest damage or disease
so more carbohydrate produced.
increase in population.
4 Destarch two similar potted plants. Place them in
(b) Any two from: transport in chilled containers,
sealed bell jars/large transparent containers. To one
picking fruit before it is ripe, preserving the
container add a CO2 absorber. Expose both plants
food, e.g. canning, storage in salt or vinegar,
to same, optimum conditions, e.g. light, warmth.
freezing food.
Leave for 2 days. Test a leaf from each plant for
the presence of starch. Only the control plant
leaf (without CO2 absorber) will turn blue-black,
Exam focus
indicating the presence of starch. 1
5 (a) (i) A guard cells Component Function Good food
B upper epidermal cell source
C spongy mesophyll cell 1 carbohydrate source of e.g. rice, potato,
D palisade mesophyll cell energy yam, cassava,
(ii) B D C A bread, cakes, etc.
(b) Xylem transports water, mineral salts from 2 fat/oil source of butter, milk,
roots around the plant. energy cheese, egg
Phloem transports sucrose, amino acids from yolk, fatty meat,
leaves to storage or growth regions of the plant. nuts, etc.
3 protein growth, meat, fish, eggs,
11 Human diet tissue repair, soya, nuts, milk,
formation of Quorn, etc.
1 (a) Any two advantages from: enzymes, etc.
high carbohydrate level for energy
4 fibre/ adds bulk vegetables,
good source of calcium for strong bones and
roughage to the diet fruit, wholemeal
teeth/to prevent rickets
to maintain bread, etc.
protein present for growth/repair.
peristalsis
Any two disadvantages from:
high in animal fat can cause heart disease/ 5 water formation of drinks, fruit,
atherosclerosis/obesity blood, medium vegetables
lack of fresh fruit/vegetables/fibre to prevent in which
constipation enzymes work,
low in vitamin C to prevent scurvy transport of
low in iron to prevent anaemia. nutrients, etc.
8
2 (b)
ANSWERS
oeso- duo-
mouth phagus
stomach
denum
lleum
Deficiency Constituent Symptoms Food
disease
scurvy vitamin C bleeding citrus fruits,
under blackcurrants, anus rectum colon
the skin, cabbage, etc.
bleeding 3
gums
Name incisor canine premolar molar
rickets vitamin D/ soft bones, (for vitamin D)
calcium which milk, cheese, Description chisel- slightly two four/five
become egg yolk, fish shaped more points/ cusps
deformed, liver oil pointed cusps
bow- than
(for calcium) incisors one/two two/three
leggedness
milk, cheese, roots roots
fish Function biting biting tearing chewing
off off and and
12 Digestion and pieces

of food
pieces
of food
grinding
food
grinding
food
absorption 4 (a) Physical digestion involves breaking large pieces

of food into smaller pieces. This increases the
1 A mouth surface area of the food, achieved by chewing
B gullet/oesophagus food in the mouth and churning food in the
C stomach stomach and intestine.
D large intestine/colon Chemical digestion involves the use of enzymes
E rectum to break down large insoluble molecules into
F anus small, soluble ones.
G small intestine/ileum (b) Starch is digested in the mouth and duodenum
H duodenum by amylase in slightly alkaline conditions. It is
2 (a) broken down to maltose. Maltase then breaks
down the maltose to form glucose.
Protein is digested in the stomach and
anus food is ingested here. duodenum by protease. Conditions required
are acid in the stomach and alkaline in the
duodenum. The end products are amino acids.
5 Arguments for:
a tube, carrying boluses of food Tooth decay among children using the water supply
colon
between mouth and stomach decreases.
There is no need to buy fluoridated toothpaste.
Arguments against any two from:
It is a form of mass medication, so people have no
has an acid pH and proteins choice about whether or not they want the treatment.
duodenum
are digested here Fluoride can cause mottling of the teeth/white
patches/fluorosis.
Fluoride is only a benefit to growing children
adults do not benefit.
ileum first part of the small intestine If people take proper care of their teeth,
fluoridation is unnecessary.
absorption of the products of

Exam focus
mouth 1 C
digestion takes place here
2 (a) (i) molar (accept premolar), 2 cusps visible/
2 roots visible
(ii) Aroot
oesophagus muscular, to control the B crown
(gullet) egestion of faeces C enamel
D dentine
E pulp cavity
F gum
rectum absorption of water G cement
H jaw bone
I nerve
stomach stores faeces (b) (i) enamel
(ii) (vitamin) D, (mineral) calcium
(iii) fluoride (reject fluorine)
9
(c) Any six from: ref. to bacteria present on the (b) Named plant:
ANSWERS
surface of teeth, food collects on teeth, combines e.g. cactus. Leaves reduced to spines this
with bacteria to form plaque, bacteria feed on reduces the surface area for transpiration.
sugars, producing acids, acid reacts with enamel, Reduced number of stomata. Stomata are
forming hole, dentine is softer so dissolves faster, closed during the day when conditions for
cavity forms. transpiration are greatest. Fleshy stem to store
3 (a) Ref. to too large and insoluble to be absorbed water.
through the gut wall. e.g. marram grass. Very long roots to search
(b) diffusion, active transport for water deep down in sand dunes. Leaves
(c) Any two from: ref. to large surface area, have the ability to roll up in dry weather to
presence of microvilli, one cell thick (explanation) increase humidity around stomata, reducing
speeds up diffusion. transpiration. Sunken stomata create high
(d) 1 (blood capillaries) absorb glucose, amino acids, humidity and reduce transpiration. Fine hairs
transport them away to maintain diffusion surround stomata, reducing air movement, so
gradient humidity builds up and transpiration is reduced.
2 (lacteal) absorbs fatty acids, glycerol e.g. pine tree. Leaves are needle-shaped to
4 (a) reduce surface area for transpiration. Sunken
Part Name Function Structural stomata to create high humidity and reduce
feature transpiration. Thick waxy cuticle on the
epidermis to prevent evaporation from the
A oesoph- moves food presence of
surface of the leaf.
agus/ from mouth to circular and
(c) Any three from: ref. to spraying onto the leaves
gullet stomach longitudinal
of the plants, absorbed into the leaf, transported
muscles for
by translocation; pest feeds on plant sap and
peristalsis
takes in the pesticide; which kills the pest.
B ileum/ digestion presence of
small
intes-
of maltose,
peptides/
villi to increase
surface area for
Exam focus
tine absorption of absorption 1 C
products of 2 D
digestion (accept 3
absorption of Process Definition Explanation
water) diffusion the movement oxygen diffuses
(b) (i) protein of a substance from the air into a
(ii) Ref. to secretion of protease, hydrochloric from a higher leaf, carbon dioxide
acid, muscular churning to mix food with concentration to diffuses out of a leaf,
enzyme. a lower concen- mineral salts diffuse
(iii) Ref. to deamination, excess amino acids tration down a from soil into root
broken down, urea formed, energy source concentration hairs
produced. gradient
osmosis the movement osmosis is used to
13 Transport in plants of water from
a higher con-
absorb water by
roots, cells absorb
1 Transpiration the loss of water vapour from the centration to a water by osmosis
leaves through the stomata by diffusion. lower concentra- to become turgid,
Translocation the movement of sucrose and amino tion through a which keeps young
acids from regions of production/storage to regions partially perme- stems rigid
of use for respiration or growth. able membrane
2 (a) Any three from: anchoring the plant in the soil, active the movement of plants obtain mineral
absorption of water, absorption of mineral salts, transport a substance from salts by active trans-
food storage organ. a lower concen- port when the con-
(b) Root hair cells have a cell extension, increasing tration to a higher centration of salts in
the cells surface area to make it more efficient concentration the soil is lower than
for absorbing water and minerals. against a concen- in the root cells
(c) root hair cell, cortex, endodermis, xylem tration gradient,
3 (a) Any three from: increase in temperature, using energy
increase in air movement, decrease in humidity, transpira- the loss of water transpiration results
increase in light intensity. tion vapour from the in more water being
(b) Wilting happens when the amount of water lost leaves through drawn through
from the leaves of a plant is greater than the the stomata, by the plant, carrying
amount taken into the roots. This results in the diffusion mineral salts from
plant having a water shortage. Cells become the roots
flaccid and no longer press against each other.
Stems and leaves then lose their rigidity and wilt. 4 (a) Water enters the leaf in the xylem vessels
4 (a) Xerophyte (A), then passes into the surrounding spongy
mesophyll cells (B). A thin layer (C) forms on
10
the surface of the cells, which evaporates and (cause) (preventative measure)
ANSWERS
saturates the air in the air spaces (D), then the Smoking stop smoking
water molecules diffuse into the atmosphere Obesity go on a controlled diet/take regular
through the stomata (E). exercise
(b) Transpiration from the leaves loses more water Stress find ways of relaxing/identify
than is being taken in by the roots, cells in causes of stress and reduce them
young stems lack water, become flaccid and stop Inherited make sure other factors are
pressing against each other, so stems and leaves factors reduced/monitor health
lose their rigidity and wilt. 5 outer layer, made of tough
fibrous tissue to hold contents
together
14 Transport in humans lumen, much narrower

than in a vein. This helps to
maintain high blood pressure
1 (a) left atrium, left ventricle
thick wall, made of muscles,
(b) aorta, pulmonary vein, coronary artery elastic fibres and fibrous
2 (a) a group of cells of similar structure, carrying out tissue, which prevents
bursting and maintains
the same function pressure wave
(b) (cardiac) muscle 1 mark for correct shape, 1 mark each for labels of
(c) Cardiac muscle can contract. up to two features, 2 marks for annotations
(d) It needs to build up enough pressure, to move 6 (a) lungs labelled in upper box, body labelled in
blood to all organs, while the right ventricle only lower box
moves blood to the lungs. (b) arrows in blood vessels and heart correct (see
3 Ref. to vena cava, with valves, to prevent backflow diagram below)
of blood, into right atrium, which contracts, to (c) right atrium, right ventricle, vena cava,
increase blood pressure, to move blood through pulmonary artery shaded
tricuspid valve, into right ventricle, which contracts,
lungs
to increase blood pressure, tricuspid valve closes,
to prevent backflow of blood, ref. to pulmonary
artery, semilunar valve closes, to prevent backflow
of blood.
4 (a) x-axis drawn and labelled time/min, y-axis drawn
and labelled pulse rate/beats per min, points
plotted accurately, line drawn between points
140
120
pulse rate/beats per min
100 rest of body

80
7 Across 3 plasma 4 lymphocyte 5 platelet
60 Down 1 haemoglobin 2 nucleus
40 Stretch and challenge

8 Any three of the following:
20 Permeable wall to allow diffusion of materials
between the capillary and surrounding tissues.
0
0.0 2.0 4.0 6.0 8.0 10.0
Wall is one cell thick allows fast diffusion/allows
time/min
white blood cells to squeeze between cells of the wall.
Lumen is one blood cell wide slows down blood
(b) (i) 60 beats per minute flow to allow diffusion of materials and transfer of
(ii) at 1 minute tissue fluid.
(iii) at 8 minutes Valves are absent blood pressure is high enough to
(iv) Heart must beat faster to circulate more keep blood flowing.
oxygen, exercising muscles need more 9 (a) Produced by lymphocytes, formed in lymph
oxygen, more glucose, and produce carbon nodes, antibodies make bacteria clump together,
dioxide (or lactic acid) which needs to be so that phagocytes can digest them. They also
removed. neutralise toxins produced by bacteria, and
(v) Rate starts higher than 60 bpm, reaches a remain in blood to provide long-term
higher peak, takes longer to return to normal. protection.
(vi) Keeps heart muscle in good tone, results in (b) Phagocytes can move out of capillaries, to the
the heart being more efficient in maintaining site of an infection; they engulf pathogens, and
blood pressure. kill them by digestion.
(c) Any three of the following answers (you must 10 Donor organ used is of similar tissue type to that of
give the cause and the preventive measure for the patient, ref. to use of immunosuppressive drugs,
each mark): keep patient in isolation during recovery.
11
11 Returns tissue fluid (in the form of lymph) to blood/ (b) (i) diffusion
ANSWERS
prevents build-up of fluid in the tissues, produces (ii) thin, moist, large surface area, has a
lymphocytes, absorbs fatty acids and glycerol from concentration gradient
the small intestine. 4 (a) the volume of air breathed in/out during normal,
relaxed breathing
(b) the maximum amount of air that can be inhaled/
Exam focus exhaled in one breath
1 C 5 cancer, emphysema, lungs, carcinogen, carbon
2 B monoxide, tar, bronchitis, nicotine, tobacco, filter
3 (a) A aorta B pulmonary vein 6 intercostal muscles contract
C left atrium D semilunar valve ribcage moves up and out
E bicuspid valve F tendon diaphragm muscle contracts
G left ventricle H right ventricle diaphragm moves down
J tricuspid value K right atrium volume in the lungs increases
L vena cava M pulmonary artery air pressure in the lungs decreases
(b) (i) right atrium air moves in to fill the lungs
(ii) pulmonary vein
(iii) semilunar valve
(iv) left ventricle Exam focus
(v) tendons 1 D
(vi) vena cava 2 (a) A spinal cord B left lung C heart
(vii)aorta (b) (i) lung
(viii)tricuspid valve (ii) Any four from: contains many alveoli,
4 (a) Blood passes through the heart twice, for each contains many blood capillaries, for gas
complete circulation of the body. exchange, ref. to oxygen and carbon dioxide,
(b) (artery) Any two from: thick and tough wall, ref. to diffusion.
narrow lumen, valves absent. (c) Any six from: intercostal muscles contract, ribs
(vein) Any two from: thin wall, large lumen, move upwards and outwards, diaphragm muscle
valves present. contracts, diaphragm moves down, volume of
(capillary) Any two from: permeable wall, wall thorax increases, air pressure in thoracic cavity
one cell thick, lumen one red blood cell wide, decreases, to become lower than atmospheric
valves absent. pressure, so air moves into the lungs.
5 (a) (i) transport of dissolved substances to cells/ 3 (a) Volume of air per breath increases, from
removal of wastes from cells normal tidal volume, e.g. from 0.5 litres, rate of
(ii) transport of oxygen breathing increases, from 12 to over 20 breaths
(iii) produces antibodies to fight disease per minute.
(iv) engulfs bacteria to fight disease (b) Any three named chemicals and their effects from:
(v) forms blood clots Carbon monoxide any two from: poisonous
(b) (i) biconcave disc shape/no nucleus/contains gas, combines with haemoglobin to produce
haemoglobin (pink colour) carboxyhaemoglobin, preventing red blood
(ii) large nucleus cells from carrying oxygen, smoker gets out of
(iii) lobed nucleus/cell can change shape breath easily, increases risk of atherosclerosis,
thrombosis, coronary heart disease.
15 Respiration Nicotine any two points from: addictive,

resulting in prolonged exposure of lungs to other
harmful chemicals, raises blood pressure, risk of
1 (a) glucose + oxygen water + carbon
stroke, stimulates brain, can reduce birth weight
dioxide + energy
of baby if mother smokes during pregnancy.
(b) ATP (adenosine triphosphate)
Smoke particles any two points from: irritates
(c) (i) lactate/lactic acid
air passages in lungs, causes inflammation,
(ii) Lactic acid causes muscle cramp (muscle
increased mucus production, causes chronic
fatigue), which will stop the athlete running.
bronchitis, emphysema.
An oxygen debt builds up, which needs to be
Tar any two points from: ref. to carcinogen,
repaid.
increases risk of lung cancer, paralyses cilia in air
2
passages, can cause bronchitis.
Product Food manufacturing process 4 (a) (i) respiration
1 carbon dioxide breadmaking/brewing (ii) carbon dioxide
2 ethanol/alcohol brewing (iii) turns from colourless to milky
(iv) ethanol/alcohol
3 (a) (b) Any five from:
Respiration of yeast is very slow at low
mouth trachea bronchus bronchiole temperatures, as molecules have little kinetic
energy so few collisions.
red blood alveolus/ 30C is optimum temperature for yeast
cell air sac respiration, as molecules have lots of kinetic
energy to collide.
12
Enzymes in yeast begin to denature at 45C, so (c) Any two from: expensive to buy/maintain, very
ANSWERS
respiration slows down. tiring for the user, may require frequent hospital
All yeast enzymes denatured at 100C, so no visits.
respiration.
17 Reactions to
16 Excretion in humans
1 blood, water, glucose, reabsorbed, ADH, more,
stimuli by plants and
concentrated, osmosis, diffusion, active transport
2 (a) The removal of toxic materials, the waste invertebrates
products of metabolism and substances in excess 1 (a) a plant response to gravity
of requirements from organisms. (b) (i) Root. Advantage: access to water/access to
(b) renal minerals/better anchorage.
aorta capillary nephron
artery
(ii) Shoot. Advantage: access to light.
2 (a) taxic responses/taxes
urethra bladder ureter (b) (i) avoid predators/protection from UV light
(ii) prevents dehydration/source of food
3 (a) Surplus amino acids are removed from the blood (c) They move faster in unfavourable conditions, so
by the liver and broken down into urea by the will tend to move out of them, but move slower
process of deamination. in favourable conditions, so tend to stay there.
(b) Any three from: breakdown of poisons/alcohol, 3 (a) auxin
breakdown/removal of drugs, breakdown of (b) (i) The shoot bends/grows towards the light.
hormones, storage of vitamins, storage of iron, (ii) When a shoot is exposed to one-sided light,
controlling levels of glucose in the blood, making bile. auxins produced by the tip move towards
4 Any two advantages from: the shaded side of the shoot/auxins are
The patient can return to a normal lifestyle dialysis destroyed on the light side, causing an
may require a lengthy session in hospital, three times a unequal distribution. Cells on the shaded side
week, leaving the patient very tired after each session. are stimulated to absorb more water than
A dialysis machine is available for other patients to use. those on the light side, making them bigger.
Dialysis machines are expensive to buy and maintain. The unequal growth causes the stem to bend
Any two disadvantages from: towards the light.
Transplants require a suitable donor with a good (c) (i) weedkiller/chemical which kills weeds
tissue match. (ii) They are sprayed onto plants, causing rapid,
The operation is very expensive. uncontrolled growth and respiration that
There is a risk of rejection of the donated kidney/ results in the death of the plant.
immunosuppressive drugs have to be used.
Transplants are not accepted by some religions. Exam focus
Exam focus 1 (a) (i) mean numbers: A 3.2 B 0.8 C 5.4 D 20.6
(ii) A dark and dry
1 (a) (i) A renal vein B left kidney C ureter B light and dry
D bladder E urethra C light and damp
(ii) (in part A) amino acids present, glucose D dark and damp
present, more salts (iii) 1 dark and damp 2 dry and light
(iii) Any three from: smaller volume, more (iv) taxic response/taxis
concentrated, urea more concentrated, salts (v) Any two from: less risk of dehydration, less
more concentrated. likely to be found by predators, could be
(b) Vena cava (X) has a thinner wall, larger lumen, a good food source (due to presence of
contains valves. decaying materials/bacteria).
2 (a) (i) a method of removing one or more components (b) (i) increases reliability of results/helps to identify
from a solution using the process of diffusion anomalous results
(ii) (pump) keeps blood flowing through the (ii) to give them more time to acclimatise to the
machine conditions/more time to explore the options
(dialysis fluid) receives wastes/toxins from the available
blood by diffusion (iii) to prevent contact with the drying agent/
(bubble trap) removes any air bubbles before drying agent could be toxic/prevent drowning
the blood is returned to the patients vein
(partially permeable membrane) allows small
molecules in higher concentrations to pass 18 Coordination
out of the blood, but prevents loss of blood
cells, large molecules from blood
(b) (i) Visking tubing/cellulose
and response
(ii) provides a large surface area, for efficient 1 (a) Central nervous system: made up of brain and
diffusion spinal cord, which have the role of coordination.
(iii) Any two from: to maintain a concentration Peripheral nervous system: made up of nerves,
gradient, concentrations of removed which connect all parts of the body to the central
substances build up, so diffusion slows down. nervous system.
13
(b) (i) a group of receptor cells responding to a 5 (a) A ciliary muscles contract
ANSWERS
specific stimulus, e.g. light, sound, touch, B suspensory ligaments slacken

temperature, chemicals C lens thickens
(ii) (b) (i),(ii) D circular muscles contracted
Sense organ Stimulus detected E radial muscles relaxed
F pupil constricted
1 ear sound/body movement
6 (a) the maintenance of a constant internal
2 eye light environment
3 nose chemicals/smell (b) (i) 37C
4 tongue chemicals (taste) (ii) Increase in sweating sweat is secreted
5 skin temperature, pressure, touch, pain onto the skin surface. Water from sweat
evaporates, taking heat from the skin surface.
2 (a) Any three from: sensory neurone has dendron Vasodilation arterioles dilate to allow more
present/very long, sensory neurone has no axon / blood to flow near the skin surface, so more
very short axon, cell body is near the end of the heat is lost through radiation.
sensory neurone, dendrites are present at the 7 (a) (i) Automatic action, generally a reflex, which
end of the sensory neurone. cannot be overridden.
(b) 1 acts as electrical insulation/stops impulse (ii) faster
leaking out/makes transmission of impulse (iii) Any two examples from: heart beat,
more efficient peristalsis, uterine contractions during birth.
2 makes connections with other neurones (b) The drop in glucose is detected by the pancreas.
3 transmits the impulse along the neurone It secretes glucagon. This is transported to the
4 coordinates the cell/contains DNA liver in the blood. In the liver, glucagon converts
3 (a) A chemical secreted by an endocrine gland. It is glycogen to glucose.
transported in the bloodstream and usually has a
long-term effect on a target organ.
(b) Any three from: causes heart rate to increase,
blood supplies muscles with oxygen and glucose
Exam focus
1 C
more quickly, blood supply to skin reduced,
2 (a) Any three from: used to treat disease, reduce
blood supply to digestive organs is reduced,
sensation of pain, help to calm the patient down,
blood is diverted to vital organs, liver is
used as anaesthetic, to cause unconsciousness.
stimulated to convert glycogen to glucose.
(b) (i)
(c)
Drug Effects on the Dangers to the
Feature Nervous Hormonal
body person using the
(endocrine)
drug
form of electrical chemical/
alcohol small amounts increases reaction
transmission impulses hormones
relaxes the body, times, so driving and
transmission nerves blood vessels large amounts handling machinery
pathway acts as a depres- is impaired, can lead
speed of fast slow sant, slows down to criminal activity,
transmission reactions, coordi- promiscuity, alcohol-
duration of effect short term long term nation impaired, ism, financial prob-
4 (a) (i), (ii), (iii) creates mood lems, liver disease,
swings, can trigger etc.
relay neurone B ganglion
pain receptors violence
spinal cord heroin has narcotic addictive, tolerance to
effect, increases drug increases, so risk
relaxation, reduces of overdosing, risk of
pain infection from using
unsterilised needles
A sensory neurone can lead to criminal
motor neurone C activity, promiscuity,
alcoholism, financial
problems, etc.
D biceps muscle nicotine raises blood pres- addictive, other
(in sure, heart rate chemicals in the
tobacco) cigarette can lead
to cancer, risk of
atherosclerosis,
thrombosis, coronary
heart disease, etc.
(b) it contracts (ii) Any three from: ref. to criminal activity, sexual
(c) (i) synapse promiscuity, financial problems for family, dangers
(ii) acetylcholine for unborn children.
14
3 Any eight from: 2
ANSWERS
Homeostasis means maintaining a constant internal
environment. anther protects the flower while in bud
Pancreas acts as a sensor in negative feedback and
acts as an effector by secreting hormones.
If glucose levels rise above normal, change is sensed often large and coloured to
ovary
by the pancreas. attract insects
Insulin is secreted by the pancreas and passed into
bloodstream.
Insulin instructs the liver to remove excess glucose produces pollen grains
from the blood. petal
containing male sex cells
Glucose is converted to glycogen and stored.
Rate of respiration in the liver is increased to use up
glucose.
Glucose levels return to normal. sticky, to receive pollen grains
sepal
If glucose levels fall below normal the pancreas stops during pollination
secreting insulin and starts to secrete glucagon.
Glucagon instructs the liver to convert glycogen to
contains ovules, the female sex
glucose. stigma
cells
Glucose is passed into the blood, returning glucose
levels to normal.
4 (a) (i) A scapula 3 (i) A stigma
B humerus B style
C biceps C ovary
D radius D ovule (accept seed)
E ulna E filament
F triceps F anther
(ii) tendon (ii) 1 carpel
(b) (i) (effector) a muscle or gland which responds 2 stamen
when it receives an impulse from a motor (iii) 1 Ref. to feathery/with a larger surface area/
neurone. hanging outside the flower to increase the
(antagonistic muscle) pairs of muscles which chance of trapping pollen grains.
oppose each other when they contract. 2 Ref. to larger numbers of pollen grains/
(ii) Triceps muscle contracts, pulling on the ulna. pollen grains lighter to increase chances of
(iii) Biceps relaxes. pollination/to be more easily carried by the
wind.
19 Reproduction, growth
4 (a) Growth an increase in dry mass of an organism,
as a result of cell growth and division.
Development an increase in complexity
and development in through the differentiation of cells.
(b) (i) Named seed any one from the following or
plants any other suitable example:
e.g. dandelion has a group of fine hairs
1 (a) the formation of a new organism, without the called a pappus, which catches the wind and
involvement of gametes or fertilisation acts like a parachute.
(b) (i) Ref. to binary fission. Inside each bacterium e.g. sycamore has a wing with a large
the DNA replicates, then the cell divides into surface area. It spins and falls slowly.
two, with each daughter cell containing (ii) Named seed any one from the following or
identical DNA. The daughter cells grow any other suitable example:
before dividing again. Blackberry is a succulent fruit that attracts
(ii) Ref. to spore production. Spores may be animals because it is brightly coloured/
produced in a sporangium, which bursts when juicy/nutritious. When eaten, the seeds pass
ripe, allowing spore dispersal. The spores through the animals gut without being
germinate and grow into new individuals. digested and are deposited with the animals
(iii) Ref. to stem tubers. The parent plant faeces.
photosynthesises and the food produced is Bur has hooked seeds, which catch onto
stored in underground stems. These swell an animals fur as it brushes past the parent
with starch, forming tubers. Connections with plant. Eventually, the seeds drop off or are
the parent plant die. The tuber has buds that removed as the animal grooms itself.
can produce new stems and roots, forming a (c) (i) Oxygen is needed for respiration to provide
new plant. energy for the growing seedling.
(ii) Warm temperatures activate/speed up
enzymes to release soluble nutrients for the
germinating seed.
15
(iii) Water activates enzymes and allows stored 2 (a) (type of pollination) wind
ANSWERS
foods to be broken down/digested/dissolved (explanation) any six from:

for transport. A = stigma, which is feathery, hangs outside the
(d) (i) Stored food in the cotyledon is used for flower, has large surface area.
respiration. B = filament, which is long to expose the anther
(ii) Photosynthesis starts, producing food to the wind.
that can be stored or built up into new C = anther, which hangs outside the flower,
tissues. exposed to the wind, contains large amounts of
5 (a) Any two advantages from: light, smooth pollen grains.
Variation in offspring is produced. (b) Any six from: mature anthers burst, releasing
New varieties of plant can be created. pollen grains into air, wind carries pollen grains,
Seeds are formed, which allow dispersal away some are trapped by feathery stigmas, hanging
from the parent plant. outside flowers, or other flowers of the same
Two disadvantages: species.
Two parents are usually needed.
Growth of a new plant tends to be slow.
(b) 20 Reproduction, growth
Definition Advantage Disadvan-
tage and development in
self- The
pollination transfer
Smaller Reduces the
numbers of variation animals
of pollen pollen in the
from the grains offspring/ 1 Across 2 prostate gland 5 seminal vesicle 6 testis
anther need to be less likely to 7 sperm duct 8 penis
to the produced/ cope with Down 1 urethra 3 epididymis 4 scrotum
stigma of there is a adapting 2 (a) Sperm released from the testes pass through
the same greater to environ- the sperm duct, into the urethra through the
flower, or chance of mental penis. They are ejaculated into the vagina, swim
to another successful change. through the cervix and uterus and into the
flower of pollination. oviduct.
the same (b) An ovum passes down the oviduct. A single
plant. sperm penetrates the membrane of the ovum
by secreting a protease enzyme. The sperm
cross- The Increases Reduces the
nucleus fuses with the ovum nucleus to form a
pollination transfer variation/ chance of
zygote.
of pollen the ability fertilisation.
3 A The lining of the uterus is starting to build up,
from the to adapt
under the influence of oestrogen.
anther of to environ
B Ovulation occurs the wall of an ovary ruptures,
a flower to mental
releasing an egg. This is due to secretion of LH
the stigma change.
(luteinizing hormone).
of a flower
C The lining of the uterus is maintained, due to
on a
high levels of progesterone, produced by the
different
corpus luteum.
plant of
D Menstruation occurs the lining of the
the same
uterus breaks down, due to a drop in
species.
progesterone.
4 (a) placenta
Exam focus (b) 1cervix
1 (a) (i) arrows from pollen grain down through the 2vagina
stigma (A), style (B) around either side of the (c) zygote
ovary wall (C), into micropyle (D) to the ovule (d) Any two from: oxygen, glucose, amino acids.
(ii) Any six from: pollen grain germinates, pollen (e) carbon dioxide, urea
tube grows, pollen tube contains the male (f) amniotic fluid
nucleus, grows down through the stigma (A), (g) menstruation
through the style (B), through the ovary wall (h) ejaculation
(C), into micropyle (D) to the ovule, male (i) oviduct (Fallopian tube)
nucleus fuses with nucleus of ovule. (j) mitosis
(b) (i) Any one from: pollen grain would be lighter/ 5 (a) 1A rubber sheath placed over the penis to stop
have a larger surface area/no spikes on sperm entering the vagina.
surface/smooth surface. 2The sperm ducts are tied or cut, so no sperm
(ii) Stigma would be feathery, hangs outside the can leave the testes.
flower.
16
3Contains progesterone and oestrogen, which
21 Inheritance
ANSWERS
prevent ovulation, or progesterone only
which prevents implantation of a blastula.
1
4A plastic-coated copper coil surgically inserted
into the wall of the uterus which prevents
implantation of a blastula. a section of DNA, coding for a
allele
(b) condom specific protein
(c) Any two from: abstinence from sexual
intercourse, screening of blood used for blood
transfusions, use of sterilised needles for drug
injections, feeding a baby with bottled milk chromosome having a pair of identical
when the mother has HIV, use of sterilised alleles
surgical instruments.
6 (a) progesterone, oestrogen
(b) (i) FSH and LH treatment causes multiple release
of ova (eggs). The ova are collected. Some dominant a thread of DNA, made up of
of them are fertilised in a Petri dish using
genes
the male partners sperm. The early embryos
produced are then inserted into the uterus to
achieve pregnancy.
(ii) (advantage) Any one from: increases the gene
chance of pregnancy, can result in pregnancy a gene that always shows in
of a woman with blocked oviducts, fertilised the phenotype
eggs can be screened for genetic diseases,
(disadvantage) Any one from: expensive,
quite a low success rate. genotype
the characteristics visible in an
Exam focus organism
1 D
2 A
3 (a) Testis is the male gonad, producing sperm; testa homozygous
is the seed coat, which is waterproof/protects an alternative form
seed from microbes. of a gene
(b) Urethra is the tube carrying urine from the
bladder, passes through the penis in males;
ureter is the tube carrying urine from the the genetic make-up of an
kidneys, to the bladder. phenotype
organism
(c) Ovary is the female gonad, producing ova in
animals, ovules in plants; ovule contains the 2
female sex cell.
Parent phenotype male female
(d) Fertilisation is the fusion of the male and female
sex cells, to form a diploid zygote; implantation Parent genotype XY x XX
is the embedding of an embryo, into the uterus
Gametes (sex cells) X Y x X X
lining.
4 (a) (AIDS) virus, (Gonorrhoea) bacterium
(b) AIDS
(c) Ref. to may not use condom during sex when
under the influence of the drug. First filial
Drug may be injected using an infected needle/ generation (F1) XX XX XY XY
ref. to sharing needles. female female male male
Phenotype
5 (a) A ovary B oviduct (Fallopian tube) C uterus
(wall) Dcervix E vagina The ratio is 1 female: 1 male.
(b) Ref. to oviducts closed/blocked, so eggs cannot
pass down/sperm cannot reach egg. 3 (a) Any two differences from:
(c) (i) in vitro fertilisation Mitosis produces cells with the same number
(ii) X placed on lining of uterus of chromosomes as the parent cell/the diploid
(iii) Ref. to being expensive, ref. to low success number of chromosomes is maintained.
rate. Meiosis produces cells with half the number of
(d) Any three from: ref. to maintaining healthy chromosomes/haploid cells produced.
diet, ref. to eating more protein/iron/calcium/ Mitosis produces identical cells. Meiosis results in
vitamin C/energy-containing foods than normal, variation.
avoid alcohol, avoid drugs, avoid contact with Mitosis involves body cells/somatic cells. Meiosis
rubella. happens in the gonads/ovaries and testes.
17
Mitosis results in growth or replacement of old 2 (a) (i) rat B
ANSWERS
rat C
or damaged cells. Meiosis makes sex cells.
X X X Y
(b) leg muscle cell 8
sperm cell 4 (ii) 50%
zygote 8 (iii) sperm cell, the Y chromosome determines
skin cell 8 male, absence of Y in the zygote results in
(c) (i) female
(b) (i) an alternative form of a gene, pairs of
Parent phenotype grey black
alleles occupy the same relative positions on
Parent genotype GG x gg chromosome pairs
(ii) 1 C 2 B
Gametes (sex cells) G G x g g (c) Rat E has genotype Gg, where G = grey fur,
g = white fur.

(rat B) (rat E)
F1 generation Gg Gg Gg Gg
Parent phenotype grey grey
Phenotype grey grey grey grey
Parent genotype Gg x Gg
(ii) (a Punnett square is acceptable)
Parent phenotype grey grey Gametes (sex cells) G g x G g
Parent genotype Gg x Gg
Gametes (sex cells) G g x G g

First filial
generation (F1) GG Gg Gg gg
Phenotype grey grey grey white

F2 generation GG Gg Gg gg
3 (a) A gene is a section of DNA that codes for a
Phenotype grey grey grey black protein, an allele is an alternative form of a gene.
Ratio 3 grey: 1 black (b) A diploid nucleus contains pairs of chromosomes,
e.g. in body cells. A haploid nucleus contains a
4 (a) The term describes a pair of alleles, neither of single set of unpaired chromosomes, e.g. sex cells.
which is dominant over the other. Both can (c) Phenotype describes the characteristics visible
have an effect on the phenotype when they are in an organism, genotype describes the genetic
present together in the genotype. The result is make-up of an organism.
that there can be three different phenotypes. (d) Homozygous refers to chromosomes that
(b) (i) have a pair of matching alleles controlling the
Parent phenotype red
same characteristic, heterozygous refers to
white
chromosomes that have a pair of dissimilar alleles
Parent genotype CRCR for a characteristic.
x CWCW
(e) A dominant gene is a one that always shows in
Gametes (sex cells) CR CR x CW CW the phenotype, a recessive only has an effect on
the phenotype if the genotype is homozygous.
22 Variation
F2 generation CRCW CRCW CRCW CRCW
1 (a) (i) a spontaneous change in a gene or a
Phenotype pink pink pink pink chromosome
(ii) Any two from: faulty copying of DNA, faulty
(ii) 1 red:2 pink:1 white
separation of chromosomes during cell
Exam focus division, exposure to radiation, exposure to
some chemicals.
1 (a) (i) Blood clotting can occur, due to reaction
(b) (i) During ova formation in the ovaries in
between antibodies and antigens, leading to
the division process (meiosis), one of the
death of the patient.
chromosomes (number 21) sticks to its
(ii) Ref. to possible transmission of HIV.
partner. This results in one ovum with 24
(b)
chromosomes and one with only 22. The
Parent phenotype blood group A blood group B ovum with 24 chromosomes is still viable.
If it is fertilised, the fetus formed has 47
Parent genotype IAIo x IBIo
chromosomes instead of 46.
Gametes (sex cells) IA Io x IB Io (ii) Any three from: lowered life expectancy,
mental retardation, early puberty, a
distinctive round face/short neck.
2 (a) Continuous variation shows a complete range
F2 generation IAIB IAIo IBIo IoIo of a characteristic within a population. It is
Phenotype AB A B O caused by both genes (often a number of
18
different genes) and the environment. When the More of the next generation carry the
ANSWERS
frequency is plotted on a graph, a smooth curve advantageous genes, resulting in a stronger
is produced, with the majority of the population population, better adapted to a changing
sample grouped together and only small environment. Gradually, over a long period of
numbers at the extremes of the graph. time, the whole species becomes stronger.
e.g. height, body mass, intelligence, hand span, 5 (a) Any three symptoms from: episodes of pain,
shoe size. younger children may develop painful swelling
Discontinuous variation is where there are in their hands or feet, older children can be
obvious, distinct categories for a feature. There affected in their ribs/long bones/spine, increase
are no intermediates between categories. It is in vulnerability to other diseases, jaundice,
caused by a single gene or a small number of increased risk of leg ulcers, delayed growth in
genes, with no environmental influence. When children, progressive organ damage.
the frequencies are plotted on a graph, bars are (b) (i) (ii)
produced that cannot be linked with a smooth Parents man woman
curve, e.g. blood group, ability to tongue-roll,
ear lobe shape. Parent genotype HNHn HNHn
x
(b) Continuous variation graph, e.g.
height in a class Gametes (sex cells) HN Hn x HN Hn
12
10
number of students
8 genotype of
first filial HNHN HNHn HNHn HnHn
6 generation (F1)
4 Phenotype normal some some abnormal

haemoglobin, abnormal abnormal haemoglobin,
no anaemia haemoglobin, haemoglobin, sickle cell
2 sickle cell trait sickle cell trait anaemia
0
120 130 140 150 160 170
129 139 149 159 169 179 Exam focus
height / cm 1 (a) (i) discontinuous variation
Discontinuous variation graph, e.g. (ii) (example) any example of continuous
45
variation, e.g. height, body weight, hand
percentage frequency
40 span, intelligence
35 (explanation) ref. to influence of genes, and
30 environment
25 (b) (i) The malarial parasite is unable to invade and
20
reproduce in the sickle cells.
15
10 (ii) Any two from: they have sickle cell anaemia
5 so red blood cells deform and become sickle-
0 shaped, when blood oxygen levels get low, so
A B AB O cells become stuck in capillaries, e.g. in lungs.
blood group 2 (a) Involves transfer of pollen from the anther of a
flower to the stigma of a flower on a different
3 O
ne named example of an animal, e.g. cow:
plant of the same species, so there is mixing of
Select one variety of cattle with a higher than
genetic material leading to variation.
average milk yield.
(b) Tubers form at the tips of underground stems of
Select another variety that has a very high meat
the parent plant, so the tuber cells will have the
yield.
same DNA as the parent.
Cross-breed the two varieties to form a new breed
3 (a) (i) bacterium
with the benefits of both parental varieties, e.g.
(ii) Any three from: presence of cell wall,
high milk production in females, high meat yield in
presence of slime capsule, presence of single
males.
strand of DNA, presence of flagellae, ref. to
4 (a) the passing on of genes by the best adapted
small size.
organisms
(b) binary fission (accept asexual reproduction)
(b) Named example, e.g. lion:
(c) Any two from: ref. to mutation, during cell
Variation within a lion population gives some
division, variation has provided resistance to the
individuals an advantage over others, e.g. bigger
antibiotic.
muscles in the legs of some lions enable them to
(d) Any three from: some of the bacteria will
run faster/get food more successfully.
have survived but have been exposed to the
If there is a food shortage, the lions with the
antibiotic so mutations are possible, which can
biggest leg muscles are most likely to survive to
result in a resistant strain forming so future
being an adult and pass on the advantageous
use of antibiotic will be ineffective, bacteria
genes to their offspring.
in the patient will breed again causing disease
The weaker individuals die before having the
symptoms to return.
chance to breed.
19
23 Energy flow, food 4 (a) The producer may be a single large plant, e.g. a
ANSWERS
tree.
The top consumers may be parasites, which are
chains and food webs small but many feed on the previous level.
(b) There is a reduced amount of energy at each
1 (a) A list of organisms that shows the feeding successive level.
relationship between them. Arrows link the (c) The organisms have to be killed and burned to
organisms to represent the direction of flow of measure their energy content.
energy.
(b) (i) (ii)
clover
snail thrush sparrow hawk Exam focus
primary secondary tertiary 1 (a) (i) an organisms position in a food chain, food
producer
consumer consumer consumer
web or food pyramid
(c) (i) The thrush population would decrease/thrushes (ii) e.g. maize locust lizard snake
die because they have fewer snails to eat. (iii) e.g.
(ii) The sparrow hawk population would
decrease/sparrow hawks die because they snake
have fewer thrushes to eat.
lizard
(d) Snails use less energy because they move less/
more slowly/dont hunt. locust
Snails are cold blooded, so less energy used maize
maintaining a constant body temperature.
2 (a) (i) photosynthesis (b) (i) 35%
(ii) sunlight (ii) (waxy) cuticle
(iii) Any three from: light is reflected off shiny (iii) Any two from: ref. to presence of large
leaves, light is the wrong wavelength for numbers of chloroplasts, ref. to closely packed
chlorophyll to trap, light passes through nature of palisade cells, ref. to position
the leaves without passing through any near upper surface of leaf, ref. to ability of
chloroplasts, light does not fall on the leaves. chloroplasts to migrate to top of cells.
(b) (i) Energy is lost at each level in a food chain. So, (c) (i) 90%
very little of the energy entering the chain (ii) Any two from: movement, e.g. to find
through the producer is available to the top food or a mate, maintaining constant body
carnivores. temperature, some heat lost in urine or
(ii) Fewer levels to lose energy from. faeces, not all of the food organism is
90% of the energy is lost at each level/a eaten by the consumer/some parts are
smaller percentage of the energy trapped by indigestible.
the producers is lost in a short food chain. 2 (a) (i) (grass)(cow) (humans)
3 (a) producer primary secondary
consumerconsumer
leopard
(ii) Ref. to leaves, capture light energy, and
convert it into carbohydrates/stored food.
baboon (iii) Any three from: movement, e.g. to find
tertiary
consumer
food or a mate, maintaining constant body
temperature, building up proteins/muscles,
some heat lost in urine or faeces.
scorpion impala primary
secondary
consumer
consumer/ (b) (i) 200 100 = 0.2%
herbivore 100000
(ii) Ref. to fewer trophic levels, so less energy
lost/more energy conserved for top
primary locust consumer.
consumer/
(c) (i) Ref. to greater range of vitamins and minerals
herbivore
grass available in a mixed diet, meat contains a
producer
greater range of amino acids.
(ii)
(b) When feeding on impala it is a secondary humans
consumer, but when feeding on baboons it is a
quaternary/fourth consumer.
(c) Any three from: over-predation or hunting,
disease, pollution, use of pesticides, lack of food cows
(or other resources).
(d) They represent the direction of flow of energy/
point towards the consumer of the previous
organism. grass maize
20
24 Nutrient cycles 25 Population size
ANSWERS
1 photosynthesis, respiration, combustion, 1 (a) (i) (ii)
decomposition
2 A evaporation
B condensation
C transpiration
stationary phase
D precipitation (rain)
number of organisms
E osmosis
3 (a) (i) Present in soil/(leguminous plant) root
nodules. Convert nitrogen into compounds of log phase
death phase
ammonia.
(ii) Convert compounds of ammonia into nitrates.
(iii) Present in waterlogged soil. Break down
nitrites into nitrogen.
(iv) Energy from the lightning converts gaseous
lag phase
nitrogen into nitrogen oxides, which dissolve
in rain to form nitrates.
(b) adding artificial fertilisers time
adding manure/compost
growing leguminous plants, then ploughing the (b) Any three factors from: food supply, predation/
roots (with their nodules) into the soil hunting, disease, use of contraceptives (for
4 (a) photosynthesis, respiration human growth).
(b) Any two from: cutting down forests/ (c) (i) Ref. to no stationary or death phase, the log
deforestation, combustion of fossil fuels, phase will continue upwards instead of the
increasing numbers of animals/increasing the line levelling off.
human population. (ii) Any four from: greater pressures on the
(c) Any three from: environment, more land needed for housing,
ref. to melting of polar ice caps, causing flooding more land needed for growing crops, more
of low lying land land needed for road building, deforestation
ref. to a change in weather conditions in some due to increased demand for wood for fuel/
countries, increasing flooding housing, more pollution due to increased
ref. to reducing rainfall changing arable (farm) industry/vehicle use, greater demands on
land to desert education, greater demands on health care.
ref. to causing the extinction of some species 2 Lag phase the new population takes time to settle
that cannot survive in increased temperatures. and mature, before breeding begins. When this
happens, a doubling of small numbers does not have
Exam focus a big impact on the total population size, so the line
1 (a) (i) (root) nodule of the graph only rises slowly with time.
(ii) bacteria Log (exponential) phase there are no limiting
(iii) Any four from: ref. to nitrogen fixing factors. Rapid breeding in an increasing population
bacteria, in the root nodules, take in gaseous causes a significant increase in numbers. A steady
nitrogen from air spaces in the soil, convert doubling in numbers per unit of time produces a
it to compounds of ammonia, which are straight line.
changed to nitrates, then used to make Stationary phase limiting factors such as shortage
protein, for plant growth. of food causes the rate of reproduction to slow
(iv) Any two from: add manure/compost, add down and there are more deaths in the population.
artificial fertilisers, use crop rotation, with When the birth rate and death rate are equal, the
leguminous plants in the cycle. line of the graph becomes horizontal.
(b) Any two from: Death phase there are more deaths than births,
Feature Maize Bean due to factors, e.g. famine/disease/war/mass use of
contraceptives.
leaf shape long and narrow broad
leaf veins parallel branching Exam focus
cotyledons one two
1 (a) (i)
1 lag phase label at start of graph
groupings of in threes in fives 2 log phase label as the line rises steeply
flower parts (ii) (lag phase) any one from: the yeast
2 Any eight from: ref. to osmosis, water passes population takes time to settle/acclimatise
through xylem, into leaves, evaporates into air to new conditions/takes time to mature,
spaces, in spongy mesophyll, present in higher doubling of small numbers does not have big
concentration than in atmosphere, so diffuses, impact on total population size.
through stomata, ref. to transpiration, forms clouds, (log phase) any one from: there are no limiting
ref. to precipitation/rain, returns to soil, drains into factors, e.g. food or predators or disease/ref.
river, runs down to sea to rapid breeding in an increasing population
causes significant increase in numbers.
21
(b) (i) line flattens off, then falls Ref. to a build-up of the chemical because they
ANSWERS
(ii) flattened line labelled as stationary phase, cannot excrete it.

dropping line labelled as death phase Animals at the top of the food chain eat many
(iii) lack of food, presence of predators, presence fish accumulating high concentrations of the
of disease chemical, which is toxic at these levels.
(c) alcohol/ethanol (b) (i) combustion of coal/oil, volcanoes
(ii) Any three from: damage to plant leaves,
26 Human influences on eventually killing the plants, acidification of
lakes, destroying fish stocks, increasing the
the ecosystem risk of asthma attacks/bronchitis in humans,
corrosion of stonework on buildings, release
1 Any four points from the following (note: this list is of soluble aluminium ions in soil toxic to
not exhaustive): fish when washed into lakes.
The development/use of chemical fertilisers on 5 Any five from:
farm land boosting levels of nutrients in the soil, Large objects, e.g. sticks, are screened out of the raw
increasing crop yields. sewage.
The development/use of pesticides these kill pests Suspended grit is allowed to settle out by gravity in
that feed on or damage crops, so crop yields are a grit settling tank.
increased. Organic matter is allowed to settle out by gravity in
The development/use of herbicides these kill a sludge settling tank.
weeds that compete with crops for nutrients/light/ The sludge is digested in a sludge digester.
water/space, so crop yields are increased. Digested sludge can be used as fertiliser on
The development of biological control methods for farmland.
pest control as an alternative to pesticides some Methane gas can be generated, for use a fuel.
pesticides are non-selective. The remaining liquid is sprinkled onto the top of an
The use of tractors/combine harvesters to enable aeration tank containing stones.
land and crops to be managed more efficiently. Microorganisms on the surface of the stones digest
Artificial selection to produce plant varieties that are any remaining organic matter.
suited to particular climates/soil types, or breeds of Ref. to chlorination of water to kill any bacteria, so
animals for specific purposes, e.g. optimum meat/ it is safe to drink.
milk/wool production.
2 (a) deforestation
Exam focus
(b) Any three from: provide land for farming, 1 (a) Any four from: named species, e.g. tiger,
provide land for roads, provide timber for extinction would result in genes being lost,
building/furniture, ref. to fuel source. which may be important for genetic engineering,
(c) Any four from: to produce chemicals such as medicines, species
Reduction of habitats/food sources for animals, may be important in food chain, so its loss could
which can result in their extinction. endanger other species.
Animal and plant diversity is reduced, so food (b) (i) description of habitat of organism named in
chains are disrupted. (a), e.g. forest, in mountains
The loss of plant species and their genes (ii) Any three from: use laws to protect habitat,
may be important for medical use/genetic use wardens to protect habitat, control public
engineering in the future. access, maintain species features of habitat,
The removal of trees, so no roots to hold soil, e.g. by controlling water drainage or number
resulting in soil erosion and leaching of minerals. of prey animals or top carnivores.
Desertification can eventually occur. 2 (a) (farming) any four from:
Lack of roots, leading to flooding/mudslides/lakes Pesticides applied to land may leach into river,
can become silted up. and kill aquatic animals.
Leaching of nutrients into lakes and rivers Ref. to bioaccumulation of chemicals, e.g. DDT,
leading to eutrophication. in food chain, killing top carnivores.
Less carbon dioxide is absorbed from the Herbicides applied to plant crops may leach into
atmosphere, increasing the greenhouse effect. river, and kill aquatic plants.
Less oxygen produced, so atmospheric oxygen Fertilisers leach into river, cause rapid growth of
levels can drop. river plants, plants die, bacteria feed on dead
Less transpiration can lead to reduced rainfall. plants, use up oxygen in respiration, so fish die.
3 Water extracted from river for agriculture, so
organisms in river die.
C G A E B F D (b) (power station) any four from:
Waste water from power station is at high
4 (a) Any four from: temperature, so river organisms die/population
Ref. to bioaccumulation. species change.
Occurs if the chemicals enter a food chain. Radiation from power station leaks into river,
Plankton absorb the chemical but cannot excrete it. causes mutations, ref. to bioaccumulation in
Animals, e.g. small fish, feed on large numbers of food chains, makes fish unsafe to eat, causes
plankton. cancer in top carnivores.
22
(c) (town) any four from: or:
ANSWERS
Sewage enters the river, causes rapid growth of ref. to finding shade or darkness
river plants, plants die, bacteria feed on dead to avoid predators/very bright light may
plants, use up oxygen in respiration, so fish die, damage chlorophyll or enzymes or
chemicals from factories enter river, killing river cytoplasm. [2]
organisms, water becomes unfit to drink. 4 (a) C iliated tissue moves dust and bacteria up from
bronchi.
Past exam questions Root hair tissue absorbs water and minerals
from soil.
1 [4] Xylem tissue transports water and minerals
through the stem.
Feature Fish Amphibia Rep- Birds Mam- Muscle tissue contracts to cause movement. [4]
tiles mals (b) A leaf contains different types of cells or tissues/a
mammary tissue contains one type.
glands At least two named examples of tissues or cells
fur/hair in a leaf, e.g. xylem, phloem, palisade mesophyll,
spongy mesophyll, etc.
scales/ (ex-
A leaf/organ carries out a number of functions. [3]
scaly skin cept 5 (a) (i) [4]
feet
and
Tube Colour of indicator Colour of indicator
legs)
at start after 6 hours
external
A pinky red yellow
ears
B pinky red yellow
feathers
C pinky red yellow
2 1 mark for each row (ticks and name) [5] D pinky red purple
1 1 2 2 3 3 4 4 5 5 Name of (ii) Tube A
(a) (b) (a) (b) (a) (b) (a) (b) (a) (b) arthropod 1 respiration occurs
A Pediculus 2 carbon dioxide produced/added to water
B Anopheles 3 becomes acidic/more acidic/pH falls
C Ornithodorus Tube D
4 photosynthesis occurs
D Pulex
5 carbon dioxide removed from water
E Musca 6 becomes alkaline/less acidic/pH rises [4]
F Periplaneta (b) Tube E
3 (a) Any three from: growth, movement, 1 colour stays pinky red/does not change
reproduction, respiration. [3] 2 respiration and photosynthesis balance out
(b) 1 mark for each horizontal line [4] 3carbon dioxide amount in water/pH does not
change
Feature Animal cell Plant cell Bacterial cell OR
1 colour goes purple
chloroplast
2 photosynthesis more than respiration
cytoplasm 3 carbon dioxide amount in water drops/pH rises
membrane OR
nucleus 1 colour goes yellow
2 respiration more than photosynthesis
(c) Any three from: ref. to gradient/gradient 3 carbon dioxide amount in water rises/pH falls
described for water, so water will move in Any one prediction 3 marks. [3]
(to the cell), by osmosis/diffusion, cell will 6 (a) (i) heat [1]
become turgid/swell up/increase in size, (ii) condensation/cooling of water vapour [1]
resulting in bursting/contractile vacuole (b) (i) transpiration/evapo-transpiration [1]
prevents bursting. [3] (ii) humidity
(d) Any two from: temperature
(i) ref. to movement towards light/away from wind/air movement
light light/sunlight
using flagellum/reference to eye spot detects Any three 1 mark each. [3]
bright light or a change in light intensity/ (c) (i) reduced transpiration (in forest area)
eye spot contracts in response to light leading to less water vapour (moving
ref. to taxis. [2] inland)/less clouds form
(ii) Depending on response to (d)(i): thus less/no rainfall/less humid (inland)
either: Any two 1 mark each. [2]
light (energy) needed for photosynthesis (ii) more surface runoff of rain water/flooding
to make food/glucose/sugar/starch/ increased surface wind speed
carbohydrate can result in greater erosion of soil/silting
up of streams/rivers/landslides
23
desertification (d) (feature) presence of valves
ANSWERS
destruction of habitats/disrupt food chains (explanation) prevents backflow of blood/

possible extinction of animal/plant species blood flows in one direction
more carbon dioxide/less oxygen in (feature) ref. to wide lumen
atmosphere (explanation) allows blood to flow with
Any two 1 mark each. [2] minimum resistance/flows more
7 (a) osmosis easily
water diffuses/moves down water potential (feature) ref. to tough wall/collagen
gradient present
through partially permeable membrane/sugars/ (explanation) to prevent bursting
solutes in root hair cell (to lower water (feature) thin/elastic walls
potential) [3] (explanation) makes it easier for body muscle
(b) 20.0 [1] contractions to cause blood to
(c) (rate of water) uptake increases move forward [4]
positive correlation/exponential/not linear 9 (a) (i) oxygen/dust/particles [1]
e.g. 0.4mmmin1 at 0ms1/no wind, 20mmmin1 (ii) carbon dioxide; water (vapour) [2]
at 8ms1 [2] (iii) lower [1]
(d) Any two from: temperature, humidity, light (b) mix air with/bubble through lime water; which
intensity. [2] goes cloudy/white/milky [2]
(e) (raw material for) photosynthesis/forming (c) (diffusion is) random movement of particles/
glucose or carbohydrate molecules/ions from their high concentration to
turgidity/support their lower concentration/down concentration
transport of: solutes/named solute/food gradient
substances Any two 1 mark each [2]
forming vacuoles/growth/(cell) expansion 10 (a) because they are toxic/poisonous [1]
taking part in chemical reaction(s); e.g. (b) (i) ureter [1]
hydrolysis/breaking down food substance (ii) (urinary) bladder [1]
medium for chemical reactions (iii) renal vein [1]
Any two 1 mark each. [2] (c) filter (from the blood)/ultrafiltration
(f) loss of water (vapour) through stomata (in leaves) plasma /soluble/dissolved substances/named
evaporation from surfaces of (mesophyll) cells/ examples
into air spaces (in leaf) reabsorption
loss of water from leaf (cells) lowers water of useful substances/named example
potential remainder becomes/forms urine
water moves into leaf (from xylem) Any three points 1 mark each. [3]
(this) pulls on/creates tension (in water column in (d) (i) liver [1]
xylem) (ii) urea [1]
cohesion of water molecules [4] 11 (a) (i) 184 [1]
(g) (Note question says structural adaptations.) (ii) liver [1]
leaves, small/reduced to spines/are needles (iii) line meets/cuts horizontal axis at 4pm [1]
no leaves (iv) 9am (approx.) [1]
curled/rolled leaves (b) (i) slows down nerve impulses/crossing
hairs on the leaves/stems synapses
thick (waxy) cuticle responses/reactions take longer
sunken stomata interferes with judgements
few stomata Any two points 1 mark each. [2]
fleshy/succulent leaves/stems (ii) liver causes cirrhosis/cancer/kills/destroys
small surface area: volume ratio cells
deep roots brain damages/kills/destroys cells
long/extensive shallow roots stomach irritates/damages wall/lining of/
ignore stomata close during the day cause ulcers
Any three 1 mark each [3] kidney can cause damage to cells
8 (a) (i) Any two from: oxygen, glucose, accept other heart increased risk of coronary disease
valid substances such as water, amino acids, Any two points 1 mark each. [2]
etc. [2] (iii) aggressive behaviour/fighting
(ii) carbon dioxide/lactic acid [1] family break up/loss of friends
(b) (i) (cardiac) muscle [1] inability to concentrate/poor time keeping
(ii) Ref. to contraction/shortening. [1] loss of job
(iii) Any three from: pressure will increase, the financial problems/money spent on alcohol
blood will be forced out from the heart, into lack of personal care/hygiene
the aorta, the volume of blood decreases. [2] problems with law/theft
(c) (i) Any two from: high fat diet/cholesterol, drunk driving/higher risk of accidents/lose
smoking, stress, lack of exercise, obesity, licence
genetic influence. [2] homelessness
(ii) all parts of the artery below point B Any two points 1 mark each. [2]
shaded [1]
24
12 (a) (i) label G clearly indicating testis [1] (c) conditions not favourable:
ANSWERS
(ii) label S clearly indicating sperm duct [1] cannot compete with S. thermophilus (or reverse
(iii) label T clearly indicating testis [1] argument)
(iv) label U clearly indicating urethra [1] cannot increase until pH falls/changes (or reverse
(b) (stimulate) production of sperm argument)
growth/development of pubic/axillary hair cannot increase until oxygen concentration
growth/development of facial/body hair decreases (or reverse argument)
breaking of the voice grows slower than S. thermophilus
widening of shoulder (girdle) takes longer to adapt/feed
development of more muscle/more muscular fewer L. bulgaricus to start with
increased aggressive behaviour idea that substance/condition provided by
growth of penis/testes S. thermophilus [2]
Any two points 1 mark each. [2] 15 (a) (i) Any one from: NOx/oxides of nitrogen,
(c) meiosis; four; haploid; half [4] vehicle/car, exhausts/fumes/emissions/gases,
13 (a) blue because no white flowers in offspring/in burning fossil fuels in houses/burning forests,
presence of inherited blue allele [1] volcanic eruptions/snow melt. [1]
(b) (i) blue BB; white bb [2] (ii) Any two from:
(ii) offspring Bb [1] Leaves/trees/producers/vegetation/plants
(iii) parents Bbbb harmed/damaged/killed.
gametes B b b b Trees more likely to get diseased.
offspring genotypes Bb Bb bb bb Bark is damaged.
phenotypes blue, blue, white, white Roots killed.
ratio 2 : 2 or 1 : 1 (Sensitive species of) lichens killed.
Any four 1 mark each. [4] (Named) microorganisms killed e.g. bacteria/
(c) (i) shows extremes and all intermediates fungi.
(of cob length) [1] Soil pH decreases/soil becomes more acidic.
(ii) (amount of) light Aluminium ions become mobile.
(amount of) minerals Nutrients/named example(s) leached.
(amount of) water Food chains/food webs disrupted.
temperature Loss of habitat/less biodiversity/extinction of
Any three 1 mark each. [3] species. [2]
(iii) flower colour only blue or white/no (b) Any two from:
intermediate colours (thus is discontinuous Use alternative/renewable/green energy sources
variation) [1] (e.g. nuclear power/wind power/wave power/
14 (a) (i) high temperatures denature enzymes solar power/hydrogen power).
kill bacteria Use low-sulfur fuels.
to give optimum temperature (for, enzymes/ Reduce use of coal.
bacteria) [2] Flue gas desulfurisation/use scrubbers/chimney
(ii) respiration is anaerobic; lactic acid electrostatic precipitators/neutralise waste gases
produced [2] with lime.
(iii) named example of a food additive: Catalytic converters.
colouring; preservative/stabiliser/emulsifier/ Provide/use more public transport.
antioxidant; flavouring/(artificial) sweetener; Car sharing/car pools/reduce use of cars/hybrid
thickening agent [1] cars/electric cars/use biofuels.
(b) (description) Walking/cycling.
sigmoid (growth curve) or lag phase + Reduce food miles. [2]
exponential/log + stationary phase (c) (look for positive features, not absent ones
little/no growth, rapid growth, no apart from unsegmented)
growth/levelling off unsegmented/not segmented/shell/(muscular)
(explanation) foot [1]
lag phase: (d) (i) frogs/black-fly larvae [1]
small number of bacteria (ii) clams/snails/molluscs [1]
produce proteins/enzymes/DNA (iii) Any two from:
exponential phase: enzymes do not function (well)
binary fission/asexual reproduction acid damages shells/scales/skin
no limiting factors/no competition/plenty of calcium ions not available for shells/difficult
food/plenty of resources to make shells
stationary phase: aluminium in solution is toxic to fish/fish die
death rate = birth rate acid/low pH kills fish
resources/food used up fish produce (lots of) mucus
pH not favourable/optimum [5] blocks gills [2]
25

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Cambridge

1 Characteristic Definition Exam focus

this involves feeding

until it reaches the xylem. Water moves up the xylem 0.0

(ii) The concentration of sugar in the potato as the bread is baked.

fastest here taking place

(b) (i) The reaction would speed up because the

12 Digestion and pieces

absorption 4 (a) Physical digestion involves breaking large pieces

absorption of the products of

14 Transport in humans lumen, much narrower

100 rest of body

40 Stretch and challenge

15 Respiration Nicotine any two points from: addictive,

specific stimulus, e.g. light, sound, touch, B suspensory ligaments slacken

foods to be broken down/digested/dissolved (explanation) any six from:

Gametes (sex cells) G g x G g

Phenotype grey grey grey white

4 Phenotype normal some some abnormal

(ii) flattened line labelled as stationary phase, cannot excrete it.

destruction of habitats/disrupt food chains (explanation) prevents backflow of blood/

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(ii) The concentration of sugar in the potato as the bread is baked.

(b) (i) The reaction would speed up because the

absorption 4 (a) Physical digestion involves breaking large pieces

15 Respiration Nicotine any two points from: addictive,

(ii) flattened line labelled as stationary phase, cannot excrete it.

destruction of habitats/disrupt food chains (explanation) prevents backflow of blood/