Exam Success Guide Biology
Answers
Unit 1: Characteristics and classification of
living organisms
Apply 1
D
Apply 2
(a) protease (b) amino acid (c) fungi (d) hypha (accept mycelium);
(e) oxygen concentration (%) on x-axis/rate of uptake (arbitrary units)
on y-axis, units added, accuracy of plot (f) uptake depends on oxygen
concentration up to 16%, then some other limiting factor becomes
significant (g) temperature/pH (h) might try to maintain temperature,
perhaps with dark-coloured plastic cover.
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(a) F (b) T (c) T (d) F (e) F (f) F (g) T (h) T (i) T (j) T
Apply 4
(a) (i)mammal (ii) fungus (iii) reptile (iv) insect (v) bacterium;
(vi) virus
(b) (i)
(vii) bird
respiration
(ii) excretion (iii) sensitivity
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(a) Ophiophagus hannah; scaly skin
Apply Crossword
Across: 2. key; 3. fungi; 5. plant; 6. energy; 8. protoctist; 9. gene; 10. movement;
13. respiration; 16. nutrition; 18. sensitivity; 19. Homosapiens; 20. animal;
21. development; 22. reproduction
Down: 1. species; 2. kingdom; 4. growth; 7. excretion; 8. prokaryote;
11. taxonomy; 12. binomial; 14. organisation; 17. Linnaeus
1
Exam Success Guide Biology
Answers
Unit 2: Organisation of the organism
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1.
Structure
nucleus
cell membrane
chloroplast
mitochondrion
rough endoplasmic
reticulum
vacuole
Function
Contains chlorophyll to
absorb light for photosynthesis
The site of energy release by
aerobic respiration
A surface for the synthesis of
proteins in a cell
Contains genetic information,
as DNA on chromosomes
A fluid filled space, which may
be permanent or temporary
Controls the entry and exit of
materials from a cell
Apply 2
(a) cell wall – A; cytoplasm – B; vacuole – E (b) nucleus; two from:
presence of cell wall/large permanent vacuole/chloroplasts in plant cell
(d) nucleus (e) no cell membrane shown/no obvious organelles
Apply 3
(a) From left to right, top to bottom: 1-2-3-cell C; 1-2-3-cell B;
1-4-5-6-7-cell F; 1-4-5-8-cell I; 1-4-5-6-cell E (b) lymphocyte – production
of antibodies; red blood cell – transport of oxygen; phagocyte – engulfing
and digesting ‘foreign’ particles, such as bacteria
Apply 4
(a) From left to right: Carries oxygen around the body of mammals; Moves
dust and bacteria up the bronchi of a mammal; Absorbs water and
minerals from soil for the plant; Transports water and minerals through
the stem of a plant; Contracts to cause movement within animals;
(b) heart contains several different tissues (muscle/nerve/blood) working
together to carry out one function more effectively
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Exam Success Guide Biology
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(a) cells, tissues, blood, organ, systems, excretory system;
(b) specialised, red blood cell, division of labour, endocrine/nervous,
nervous/endocrine;
(c) palisade cell, chloroplasts, leaf, epidermis, xylem
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(a) 10 (b) 1000
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(a) A – cell (surface) membrane, B – cytoplasm, C – nucleus;
(b) nucleus;
(c) Any two from: chloroplasts/cell wall/vacuole;
(d) length of scale line = 300 mm = 300 × 1000 = 300 000 μm
magnification =
3
measured length of scale line
actual length of scale line
=
300 000
25
= 12 000
Exam Success Guide Biology
Answers
Unit 3: Movement in and out of cells
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cytoplasm; membrane; diffusion; random; concentration gradient; temperature;
oxygen; respiration; diffusion
Apply 2
(a) correct quantities AND units on axes/accuracy of plot, especially
‘crossover’ between C and D (b) 0.25M (c) at this concentration water
uptake and loss are balanced, so mass is unchanged (d) so that a mean
value for mass can be obtained (e) to eliminate the effect of excess
(surface) water (f) 8 g
4
Exam Success Guide Biology
Answers
Unit 4: Biological molecules
Apply 1
Molecule
glucose
glycogen
starch
cellulose
lipid
Function
An insoluble storage
carbohydrate in animal cells
A structural component of plant
cell walls
A soluble source of energy
for cells
A component of cell membranes
An insoluble storage
carbohydrate in plant cells
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(a) A, F, G, H (b) dissolve sample in water / add equal volume of
Benedict’s reagent / heat in a boiling water bath / wear eye protection
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(a) 1: iodine solution/starch; 2: Benedict’s reagent/glucose (simple sugar);
3: alcohol/lipid; 4: Biuret reagent/protein (b) Test 1 – straw yellow, Test 2 –
blue, Test 4 – blue (c) (i) cheese/butter/full-fat milk (ii) meat/fish/eggs
Apply 4
B
Apply 5
D
Apply 6
D
5
Exam Success Guide Biology
Answers
Unit 5: Enzymes
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proteins, pathways, catalysts, specific
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(a) temperature (b) Any two from: pH (use a buffer solution)/enzyme
concentration(fixed mass of potato discs)/substrate concentration (fixed
volume and concentration of hydrogen peroxide solution) (c) rate of
breakdown of hydrogen peroxide (oxygen production in measured amount
of time) (d) repeat with boiled potato/without any potato (e) able
to demonstrate that results are repeatable, reduces errors from single
measurements
6
Exam Success Guide Biology
Answers
Unit 6: Plant nutrition
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(a) by moving the lamp closer to or further from the plant (b) carry out
without the water plant (c) temperature, carbon dioxide concentration
(d) (i) check axes, labelled with quantities and units, light intensity on x-axis,
rate of photosynthesis (ii) 27 (iii) To begin with an increase in light
intensity increases the rate of photosynthesis – light intensity is the limiting
factor (up to about 60 units). At higher light intensity, rate of photosynthesis
does not increase – there is some other limiting factor, such as carbon
dioxide concentration or temperature (iv) higher oxygen concentration/
no nitrogen present (v) repeat readings and calculate means
Apply 2
(a) carbon dioxide + water
light
chlorophyll
glucose + oxygen (b) photosynthesis
(c)sugar is sometimes used faster than it is produced/variable light intensity
– no photosynthesis in the dark; lower light intensity/lower temperature
(e) combustion releases heat and carbon dioxide
Apply 3
(a) (i) A – purple, B – red/purple, C – yellow (ii) A – photosynthesis
exceeds respiration so carbon dioxide removed more quickly than it is
released, B – less chlorophyll, so less photosynthesis, but still more than
respiration, C – respiration exceeds photosynthesis, so more carbon dioxide
is released (b) leaf is boiled in alcohol to remove chlorophyll (never on
open flame – alcohol is flammable), then covered with iodine solution. If
starch is present, iodine solution will turn blue-black; ii. shaded area all over
leaf A and in chlorophyll-containing areas of leaf B, no shading on leaf C
Apply 4
(a) (i) A – upper epidermis, B – palisade (mesophyll) cell, C – spongy
mesophyll, D – guard cell, e – xylem vessel (b) sucrose (c) (i) starch
(ii) Add iodine solution to a sample of the tissue. If starch is present iodine
solution will turn blue-black (iii) Can be respired to release energy, can
be built into other molecules, such as cellulose (d) scale line is 0.5 cm
thickness of leaf is 7.5 cm so actual thickness = 7.5/0.5 × 0.1 mm = 1.5 mm;
length of palisade cell is 2 cm so actual length = 2.0/0.5 × 0.1 mm = 0.4 mm
7
Exam Success Guide Biology
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(a) starting size of plant/light intensity/temperature (b) (i) reduced
growth – nitrate is required for production of protein needed for growth
(ii) plant leaves would be pale/yellow – magnesium is required for
production of chlorophyll (c) (i) taken up by plant/washed out of soil
(leaching) (ii) add inorganic fertiliser (NPK), add organic matter and allow
microbes to decay proteins to nitrate
Apply 6
A–4, B–10, C–15, D–1, E–13, F–8; G–5, H–14; I–12, J–6; K–2, L–9, M–11,
N–7; O–3
8
Exam Success Guide Biology
Answers
Unit 7: Human nutrition
Apply 1
(a) boy is growing/has greater mass of muscle (b) girl is menstruating, so
losing blood/iron required for production of haemoglobin (c) pregnant
woman has developing fetus/fetus requires calcium for development of
bones and teeth
Apply 2
Disease/condition
Type of malnutrition
obesity
Lack of dietary fibre
constipation
Excess fat and/or salt
starvation
Deficiency of vitamin C
coronary heart
disease
scurvy
Much greater energy intake
than energy use
A shortage of all nutrients,
especially carbohydrate or fat
Apply 3
(a) 0.05% (b) brand C (c) boiling reduces vitamin C content
(d) prevents scurvy/helps strengthen gums (e) potato/fresh citrus fruit
Apply 4
(a) (i) X – molar, Y – canine, Z – incisor; X – crushing food, Z – biting off
pieces of food (b) calcium/phosphate, vitamin D
Apply 5
(a) tongue (b) A mixes food with saliva from B (c) peristalsis – show
contraction of circular muscle (d) (i) along the pancreatic duct
(ii) amylase – starch to maltose OR trypsin – protein to amino acids OR
lipase – fat to fatty acids and glycerol (e) E – absorption of water, F –
storage of faeces before defaecation
9
Exam Success Guide Biology
Apply 6
(a) lipase (b) fatty acids (c) (i) 1.0 units of pH over 4 min = 0.25 units
per min (ii) bile emulsifies fats so increases the surface area for the action
of lipase
Apply 7
(a) A – blue-black, B – straw-yellow (b) A – boiled amylase cannot
break down starch so starch can react with the iodine solution, B –
amylase has digested starch to maltose so no starch remains to react
with iodine (c) (i) epithelium, capillary, lacteal (ii) ileum/small
intestine (iii) X (iv) transports digested fats away from intestine
Apply 8
(a) A – 12, B – 22, C – 21, D – 17, E – 3, F – 13, G – 19, H – 1, I – 20; J – 18,
K – 2, L – 14, M – 9, N – 16, O – 6, P – 8, Q – 7, R – 5, S – 4, T – 15,
U – 11, V – 10
10
Exam Success Guide Biology
Answers
Unit 8: Transport in plants
Apply 1
Term
Definition
phloem
Transport of water and mineral
ions from root to leaf
Large surface area for uptake
of water and ions
Transport of sucrose through
the plant
Made up of phloem, xylem,
and cambium
Tiny pores on leaf surface
needed for carbon dioxide
absorption.
Main site of water loss from
the plant
xylem
leaf
root hair
vascular bundle
stomata
Apply 2
(a)
Time taken for
bubble to move
10 cm / min
Rate of bubble
movement / cm
per minute
5
16
1
17
25
2
0.7
10
0.6
0.4
Bar chart – bars must not touch/each bar same width/bars correctly labelled
(b) high light intensity – open stomata to aid photosynthesis – more
water lost
(c) 2 – low water potential gradient – low water loss, 5 – dark – stomata
closed – low water loss
(d) 3 – high water loss as atmosphere ‘dried’ by wind, 4 – lower water loss
since low light intensity means stomata are closed
Apply 3
(a) (i) lower surface – compare B and C (ii) yes – compare D with B
and C (b) (i) X – stomatal pore, Y – guard cell (ii) water lost mainly
through stomata/stomata only on lower surface
11
Exam Success Guide Biology
Answers
Unit 9: Transport systems in animals
Apply 1
(a) (i) 0.8s (ii) 1 min = 60s, 60/0.8 = 75 bpm (b) (i) max in left
ventricle = 130 mm mercury, so max in right ventricle = 130/5 = 26 mm
mercury (ii) muscular wall of left ventricle is much thicker than wall
of right ventricle (c) at 0.3 s pressure in left ventricle exceeds pressure
in aorta, so blood is forced through the semilunar/aortic valve into the
aorta (d) X – left atrioventricular valve closes to prevent backflow from
ventricle to atrium, Y – left seminar valve closes to prevent backflow from
aorta into left ventricle
Apply 2
(a) 120 000 (b) 240 000 (c) 12012000/540 000 = 22%; pie chart –
largest segment to begin from vertical position. Pie chart is easier to see what
proportion of total is due to each of the conditions.
Apply 3
(a) A – c, d, ;B – e, f, g, h, i; C – a, b, j
Apply 4
(a) (i) hepatic portal vein – hepatic vein – vena cava – right atrium – right
ventricle – pulmonary artery – pulmonary vein (ii) pulmonary vein – left
atrium – left ventricle – aorta – hepatic artery – hepatic vein – vena cava –
right atrium – right ventricle (b) (i) Any two from: low intake of fats/salt,
exercise/non-sedentary lifestyle, not smoking (ii) opposite of any two above
Apply 5
(a) Sample 1 – more red blood cells as oxygen concentration lower at high
altitude (b) Sample 1 – white cells needed to fight infection (c) Sample
3 – platelets involved in blood clotting (d) Sample 3 – iron needed for
haemoglobin in red blood cells (e) age and gender could be variables that
might affect the numbers of different blood cells
12
Exam Success Guide Chemistry
Answers
Unit 10: Diseases and immunity
Apply 1
(a) phagocyte (b) phagocytosis (c) by antigens/proteins on the surface
of the bacterium (d) digestive enzymes are added (e) e.g. cholera/
tuberculosis/food poisoning (g) a course of antibiotics
Apply 2
(a) A – larynx, B – trachea, C – bronchus, D – lung, E – pleural membrane,
F – alveolus/air sac, G – diaphragm;
Term
pathogen
antibody
lymphocyte
antigen
passive
phagocyte
active
memory cell
13
Definition
Protein which is displayed on the surface of
a pathogen
Form of immunity in which a person
receives ready-made antibodies
Activated lymphocyte which remains in the
body after infection
Disease-causing organism
Form of immunity in which a person
produces their own antibodies
Cell which produces antibodies
Y-shaped protein that can recognise a
pathogen
Cell which destroys pathogens labelled by
antibodies
Lorem
Success
ipsum
Guide Biology
4 Exam
Answers
Unit 11: Gas exchange in humans
Apply 1
nasal cavity – pharynx (throat) – trachea – bronchus – bronchiole – alveolus/
air sac
Apply 2
(a) A – larynx, B – trachea, C – bronchus, D – lung, E – pleural membrane,
F – alveolus/air sac, G – diaphragm;
(a) (i) – G (ii) – C (iii) – A (iv) – B (v) – F (vii) – D
Apply 3
(a) before – 10, after – 13/14 (b) 0.8 (c) recovery – the extra oxygen
is needed to pay off the oxygen debt (to oxidise lactic acid formed during
anaerobic respiration)
14
Exam Success Guide Biology
Answers
Unit 12: Respiration
Apply 1
(a) bar chart – bars not touching/correct labels on axes/bars same width/
bars labelled (b) 450 + 1000 + 1100 + 2600 = 4150 kJ (c) to maintain
body temperature/nervous activity/breathing movements (d) water is
denser so harder to move through (also probably colder so some energy
consumed to maintain temperature as heat conducted away from body)
Apply 2
(a) (i) carbon dioxide (ii) respiration (iii) growth/movement/
active transport/impulse conduction (b) passing gas through sodium or
potassium hydroxide (c) so that there is the same mass of respiring tissue,
for reliable comparison of results (d) glucose contains radioactive C and
is consumed by the mice – absorbed from gut – carried in blood to respiring
cells – respired to release carbon dioxide – carbon dioxide carried in blood
to lungs – exhaled – trapped in limewater (calcium carbonate forms) –
filtered onto filter paper.
Apply 3
TRUE: b, d, e, f, (g), h, i, j, k; FALSE a, c (g). For statement g: fat can also be
respired, but you do not need the equation for this.
15
Exam Success Guide Biology
Answers
Unit 13: Excretion in humans
Apply 1
Urea
Product of
respiration
Carbon
dioxide
Water loss
Needed to
dissolve
soluble
wastes
Formed
from excess
amino acids
May
dehydrate
cells
Alters blood
pH
Can
denature
enzymes
Apply 2
(a) (i) protein molecules are too large to cross the filtration membrane
(ii) most glucose is reabsorbed from the filtrate back into the blood
(b) sweating lowers the blood volume, so less water is lost in the filtrate and
more is reabsorbed before it can enter the urine.
16
Exam Success Guide Biology
Answers
Unit 14: Coordination and response
Apply 1
(a) (i) 73, 75, 79, 79, 83, 89 (ii) bar or line graph suitable
(iii) yes (iv) same volume of coffee drunk in each cup/same
concentration of caffeine/people with same body mass (b) compare birth
mass of children with heroin usage – ethically impossible to make women
take heroin and then deliver babies.
Apply 2
A – 5; B – 9; C – 1; D – 10; E – 2; F – 8; G – 4; H – 3; I – 6; J – 7
Apply 3
(a) A – ciliary body/muscle, B – controls amount of light which enters eye/
controls size of pupil (b) (i) voluntary – contraction is controlled by the
person/non-reflex, antagonistic – have opposing/balanced actions (ii) eye
turns to right (iii) C would relax and D would contract (c) cornea –
aqueous humour – pupil – lens – vitreous humour (d) rods – low intensity/
around outer edges, cones – colour (red/green/blue)/at centre of retina
Apply 4
(a) (i) convert light to electrical impulse (ii) rods – low intensity, cones –
colour (red/green/blue) (b) neurone – links receptor cell to nerve fibre to
brain (c) cornea – aqueous humour – lens – vitreous humour
Apply 5
A – 5; B – 1; C – 8; D – 6; E – 2; F – 7; G – 3; H – 4
Apply 6
(a) (i) insulin is needed to remove glucose from the blood (ii) insulin
increases uptake of glucose by muscle and liver (iii) sugar will be used in
increased respiration (b) sugar is in soluble form, starch would have to be
digested, which would take time (c) glycogen is converted to glucose and
glucose is released from cells under the influence of the hormone glucagon
(and adrenaline) (d) negative feedback means that a change from the
norm (such as an increase in blood glucose) sets off a process to cancel out
the change (the release of insulin)
17
Exam Success Guide Biology
Apply 7
Option C – the tip receives the light stimulus which sets off the auxin
secretion
Apply 8
(a) auxin is secreted – diffuses back down both sides of stem – stimulates
cell growth – shoot increases in length (b) (i) auxin diffuses to shaded
side of shoot (ii) R (c) Any two from: production of seedless
fruits/co-ordination of fruiting/weedkillers
18
Exam Success Guide Biology
Answers
Unit 15: Drugs
Apply 1
C
Apply 2
Disease
AIDS
cholera
influenza
tuberculosis
COVID-19
malaria
19
Pathogen (virus, bacteria
or neither of these)
virus
bacterium
virus
bacterium
virus
neither of these
Exam Success Guide Biology
Answers
Unit 16: Plant and human reproduction
Review p141
sepals – petals – stamens – anther – carpels – stigma/ovary – ovary/stigma –
Pollen – anther – stigma
Apply 1
(a) (i) pollination (ii) bee visits flower A – pollen brushes on body
from anther – bee flies to flower B – pollen brushed off body onto
stigma (b) (i) fertilisation (ii) ovary (c) similar because they contain
same genes, but different because they contain different alleles of these
genes. Each pollen grain is different to all others, and each ovule in the ovary
is different to others. Many new combinations are possible.
Review p142
Across: 4. stigma; 7. fruit; 9. hermaphrodite; 10. wind; 12. seed; 13. anther;
15. nectary; 17. ovary; 18.dispersal; 19. pollination; 20. insect; 22; variation;
23. filament; 24. tuber
Down: 1. egg; 2. competition; 3. sepal; 5. asexual; 6. fertilisation; 78. runner;
11. petal; 14. germination; 16. pollen; 21. Style
Apply 2
(a) A – testa, B – cotyledon, C – radicle/root, D – plumule/shoot,
E – embryo;
(b) use crushed seed in water: Iodine test for starch – blue-black colour if
present; emulsion test for lipid – cloudy emulsion if present
Apply 3
(a) A – sperm duct/vas deferens, B – urethra, C – testis, D – scrotal
sac/scrotum, E – penis (b) C (c) F (d) C (e) B
Review p147
T; F, fertilisation requires ovulation (the release of an egg from the ovary) to
have taken place; T; F, a zygote implants in the wall of the uterus; T
20
Exam Success Guide Biology
Apply 4
(a) (i) carbon dioxide/urea (ii) large surface area for exchange/good
blood circulation to deliver/remove solutes (iii) any two from: lungs –
exchange of gases, intestines – absorption of food, kidneys – removal of
nitrogenous waste
Apply 5
H; H; A; H; A; H
Apply 6
STI
Sexually transmitted
infection
HIV
Acquired immune
deficiency syndrome
AIDS Acquired immune
deficiency syndrome
IVF
In vitro fertilisation
FSH
Follicle stimulating
hormone
Al
Artificial
insemination
Luteinising hormone
LH
21
A group of diseases resulting
from a weakening of the
immune system
Stimulates ovulation
Delivery of sperm to the
vagina through a plastic tube
Hormone which stimulates
the development of an ovum
An infection transmitted
through body fluids through
sexual contact
A pathogen transmitted by
transfer of body fluids
Mixing of eggs and sperm in
a laboratory dish
Exam Success Guide Biology
Answers
Unit 17: Inheritance
Apply 1
(a) a thread-like structure of DNA carrying genetic information in the form
of genes (b) (i) 46 (ii) 23 (iii) 0 (iv) 0 (c) meiosis (d) mitosis
Apply 2
(a) 46 – 23 – 23 – 46 – 46 (b) suggests that sperm and egg come from the
same adult/suggests that meiosis occurs in body cells (c) ovary (female)
and testis (male) (d) to half the chromosome number ready for fertilisation
Apply 3
(a) phenotype (b) allele (c) Mendel (d) gene (e) genotype
(f) heterozygote (g) dominant
Apply 4
(a) Rr × Rr
Gametes R
r Rr
Zygotes RR
Rr
Rr
rr
A – RR normal, B – Rr carrier, C – Rr carrier, D – dd with cystic fibrosis;
(b)1 in 4 (25%) (c) white blood cell – red blood cell has no nucleus so
could not provide the DNA sample
Apply 5
(a) IA and IB (b) I° (c) parents would be heterozygotes (IAI° × IBI°) so
each would provide I°, so group O individual would be homozygous I°
(ii) 50% probability that child will be a girl and 25% probability that child be
group B so 0.5 × 0.25 = 12.5%
22
Exam Success Guide Biology
Apply 6
(a) (i)colour blind male (ii) carrier female (normal colour vision);
(b) Parents
XCY
Male: not
colour blind
Gametes
XC
XCXc
×
Female:
carrier
XC
Y
Xc
F1 generation
XCY
XcY
XCXC
XCXc
Colourblind male
Carrier Female
(c) for father to be normal colour vision he must provide dominant allele
from his X chromosome, XX individual (female) cannot be colour blind
23
Exam Success Guide Biology
Answers
Unit 18: Variation and selection
Apply 1
(a) 110 (10 in A and 100 in B) (b) B – greater sample size so less influence
of ‘rogue’ result (c) B – higher proportion of limpets with greater diameter
foot (d) continuous (e) body mass/body length
Apply 2
A – desert/dry area, B – water (b) (i) A (ii) B (c) A – 4, B – 2, C – 6,
D – 1, E – 5, F – 3
Apply 3
Artificial (A) – 1, 2, 3, 8 Natural (N) – 4, 5, 6, 7
24
Exam Success Guide Biology
Answers
Unit 19: Organisms and their environment
Apply 1
(a) level 1: oak tree; level 2: oak eggar caterpillar, winter moth larva, field
mouse; level 3: willow warbler, great tit, beetle; level 4: tawny owl (b) level
1: 1, level 2: 100, level 3: 14, level 4: 2 (c) check accuracy (d) seems too
small to support tawny owls, but tawny can fly from one tree to another
Apply 2
(a) secrete digestive enzymes/name enzymes/example of complex to simple
conversion (b) (i) 1025 (ii) movement/maintaining body temperature/
other examples (c) (i) 1.8/ 5950 + 50 = 0.03% (ii) easier to maintain
temperature/no competition for food (iii) cost of energy input from fossil
fuel/production of large amounts of waste matter
Apply 3
respiration/combustion of fossil fuels
Apply 4
(a) nitrogen (b) X – nitrogen fixation, Y – denitrification, Z – nitrification
(c) (ammonium) nitrate (d) amino acids/proteins (e) urea
25
Exam Success Guide Biology
Answers
Unit 20: Human influences on ecosystems
Apply 1
(a) (i) potatoes – fallow – sprouts – peas (ii) altering crop grown/in a
certain order/to reduce depletion of soil nutrients/improve soil condition
(b) (i) bar should be same width – not touching – labelled (ii) total
with sprouts = 54 + 44 + 52 = 150 total with peas = 82 + 88 + 80 = 250.
Percentage increase = (250 – 150)/150 × 100/1 = 67%
Apply 2
Action
Example of species
Harmful effect
Removal of top
predator
Buffalo in North
America
Carnivores start to kill
farm animals
Killing of
herbivores
Tigers in India
Sea urchins almost
destroyed giant
seaweeds
Overfishing
Sea otters in
California
Explosion in
population of natural
prey can cause more
damage to crops
Hunting for fur
Great reduction in
shoals of cod
Fisheries start to
process other species
of fish
Apply 3
(a) 23%, bars not touching/same width/labelled (b) can be broken down
by natural means/decomposers, e.g. waste vegetables (c) methane
(d) 32 + 24 = 56, as a percentage of (excluding other) total this is
(32 + 24)/77 × 100/1 = 73%
26
Exam Success Guide Biology
Apply 4
Term
resource
sustainable
resource
non-renewable
resource
sustainable
development
recycled resource
fossil fuel
Definition
a resource that can be renewed by
natural processes as rapidly as it is
removed
development that provides for
the needs of an increasing human
population without harming the
environment for future generations
a substance or organism taken
from the environment
a non-renewable resource that
releases energy by combustion
resources that cannot be replaced and
so, once removed, are gone forever
a product of one human activity that
can be treated to be reused in another
process
Apply 5
(a) fur/mammary glands (b) destruction of its (forest) habitat (c) poor
breeding rate/limited genetic variation/non-development of survival
skills (d) protected from predators/cannot be poached/veterinary care
available (e) controls the trade in endangered species or their products,
such as skins (f) if we save an attractive species – easier to raise funds
which will also protect other species in the same habitat
27
Exam Success Guide Biology
Answers
Unit 21: Biotechnology and genetic engineering
Apply 1
(a) this represents the optimum temperature for the microbial culture
– high enough for rapid metabolism but not so high that enzymes are
denatured. (b) to mix the contents – keep microbes and substrates in
close contact (c) (i) check axes (quantities and units) and accuracy of
plot (ii) the maximum yield is 3.5 kg; 90% of 3.5 is 3.15 kg, reached after
22–23 hours
Apply 2
(a) (i) with oxygen (ii) as a substrate for respiration/to release
energy (iii) when dry and crystalline it is easier to store/transport
(b) penicillin (others acceptable, but penicillin most likely) (c) (i) mitosis/
cell division (ii) selection (d) an antibiotic kills bacteria within the body,
an antiseptic kills bacteria on a surface (including the skin)
Apply 3
(a) the same restriction enzyme must be used to give complementary
‘sticky ends’ (b) DNA ligase ‘stitches’ the gene into the opened
plasmid (c) temperatures outside this range would not be the optimum
for action of the enzymes involved.
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