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school. “Paper 42” means Paper 4, variant 2.
Practice questions
Original questions written by HomiLabs in the style of the exam, with answers and mark schemes. They are not
Cambridge past paper questions and have not been reviewed by Cambridge. Try each one before opening the answer.
Q1Fertilisation, seeds & germination · Core · Paper 1 style · 1 mark
(a)Which conditions are needed for the germination of most seeds?[1]
Show answer
(a) B water, oxygen and a suitable temperature
Seeds need water, oxygen (for aerobic respiration) and a suitable temperature (for enzymes). Light (A) is not needed because the seed uses stored food.
Q2Fertilisation, seeds & germination · Core · Paper 2 style · 4 marks
A tomato plant in a kitchen garden in Quetta has been pollinated and fertilised.
(a)After fertilisation, state what each of these structures develops into.(i) ovule(ii) ovary[2]
(b)State what happens to the petals after fertilisation.[1]
(c)State the name of the cell formed when a male nucleus fuses with a female nucleus.[1]
Show answer
(a) (i) seed; (ii) fruit
B1 each.
(b) They wither and fall off.
B1
(c) zygote
B1
Q3Fertilisation, seeds & germination · Core · Paper 4 style · 4 marks
Crushed maize grains were tested on the day they were soaked and after 4 days of germination.Day 0: iodine test – blue-black; Benedict's test – blueDay 4: iodine test – brown with a few black spots; Benedict's test – orange
(a)Describe how the results change from day 0 to day 4.[2]
(b)Name the enzyme responsible for these changes.[1]
(c)Suggest what the germinating grain uses the sugar for.[1]
Show answer
(a) Starch decreases (iodine less blue-black) and reducing sugar increases (Benedict's changes from blue to orange).
B1 less starch; B1 more reducing sugar.
(b) amylase
B1
(c) Respiration to release energy for growth (or to build cellulose for new cells).
B1
Q4Fertilisation, seeds & germination · Core · Paper 1 style · 1 mark
(a)After fertilisation, what does the wall of the ovule (the integuments) develop into?[1]
Show answer
(a) A the testa (seed coat)
The integuments of the ovule harden to form the testa, which protects the seed. B is wrong because the fruit wall develops from the ovary wall, not the ovule.
Q5Fertilisation, seeds & germination · Standard · Paper 4 style · 7 marks
Twenty radish seeds were placed in each of four tubes and left for 5 days.A: dry cotton wool, 25 °C – 0 germinatedB: moist cotton wool, 25 °C – 18 germinatedC: seeds under boiled and cooled water with a layer of oil on top, 25 °C – 0 germinatedD: moist cotton wool, in a refrigerator at 4 °C – 3 germinated
(a)Calculate the percentage germination in each tube.[2]
(b)State which condition was missing in tube C and explain why it is needed for germination.[2]
(c)Explain why a few seeds in tube D germinated but many fewer than in tube B.[2]
(d)State the control tube.[1]
Show answer
(a) A 0 %; B 90 %; C 0 %; D 15 %
B2 all correct; B1 two or three correct (n ÷ 20 × 100).
(b) Oxygen (boiling removed dissolved oxygen and the oil stops more dissolving); needed for aerobic respiration to release energy for growth.
B1 oxygen; B1 aerobic respiration / energy for growth.
(c) At 4 °C the enzymes in the seeds work very slowly (low kinetic energy), so germination is slow; it is not stopped completely.
Q6Fertilisation, seeds & germination · Standard · Paper 2 style · 4 marks
(a)Describe the events that take place from the moment a pollen grain lands on a stigma until fertilisation.[4]
Show answer
(a) A pollen tube grows from the pollen grain down through the style; it enters the ovary and passes through the micropyle into an ovule; the male nucleus travels down the tube; it fuses with the female nucleus (egg cell) in the ovule.
1 mark each, max 4: pollen tube grows; down style; through micropyle into ovule; male nucleus moves down tube; fuses with female nucleus/egg nucleus = fertilisation.
Q7Fertilisation, seeds & germination · Standard · Paper 4 style · 5 marks
Thirty mung bean seeds were placed on moist paper in each of four dishes at different temperatures. The number that had germinated after 4 days was counted.Temperature / °C: 10 | 20 | 30 | 40Number germinated: 6 | 21 | 28 | 12
(a)Calculate the percentage germination at each temperature. Give each answer to the nearest whole number.[2]
(b)Five seedlings at 30 °C had radicle lengths of 18, 22, 20, 25 and 15 mm. Calculate the mean radicle length.[1]
(c)Suggest why fewer seeds germinated at 40 °C than at 30 °C.[2]
Show answer
(a) 10 °C 20 %; 20 °C 70 %; 30 °C 93 %; 40 °C 40 %
B2 all correct; B1 two or three correct.
(b) 20.0 mm
100 ÷ 5 = 20.0 mm. B1
(c) 40 °C is above the optimum for the seeds' enzymes; some enzymes are denatured, so less stored food is broken down and respiration is slower.
B1 above optimum / enzymes start to denature; B1 less food broken down / less energy for growth.
Q8Fertilisation, seeds & germination · Standard · Paper 2 style · 5 marks
(a)Explain why seeds need water to germinate.[2]
(b)Explain why seeds need oxygen to germinate.[2]
(c)Farmers in Punjab sow wheat seeds in moist, loose soil rather than in waterlogged soil. Suggest why.[1]
Show answer
(a) Water activates enzymes / allows stored food to be broken down and transported in solution; it makes cells swell so the testa splits.
1 mark each, max 2.
(b) For aerobic respiration, which releases energy for cell division and growth of the embryo.
B1 aerobic respiration; B1 energy for growth.
(c) Waterlogged soil has little air, so the seeds would not get enough oxygen.
B1
Q9Fertilisation, seeds & germination · Challenge · Paper 4 style · 6 marks
A student split open a soaked broad bean seed and made a large drawing. The length of the bean on the drawing was 84 mm. The actual length of the bean was 21 mm. She labelled the testa, cotyledons, plumule and radicle.
(a)Calculate the magnification of the drawing.[2]
(b)State the function of: (i) the testa; (ii) the cotyledons; (iii) the radicle.[3]
(c)The student measured the bean after soaking it overnight. Suggest why the soaked bean was larger than a dry bean.[1]
Show answer
(a) × 4.0
M1 84 ÷ 21; A1 × 4.0.
(b) (i) protects the seed (embryo); (ii) store food for the embryo during germination; (iii) grows into the root.
B1 each.
(c) It absorbed water (by osmosis), so its cells swelled.
B1
Q10Fertilisation, seeds & germination · Challenge · Paper 4 style · 7 marks
A student soaked mung bean seeds for different times before placing 20 seeds of each group on moist cotton wool at 25 °C. After 3 days she counted the germinated seeds and measured the radicle lengths of five seedlings from each group.Soaking time / h: 0 | 4 | 8 | 12 | 24Number germinated (out of 20): 9 | 14 | 18 | 19 | 11Radicle lengths for 8 h / mm: 12, 15, 11, 14, 13
(a)Calculate the percentage germination after 8 hours of soaking and after 24 hours of soaking.[2]
(b)Calculate the mean radicle length for the seeds soaked for 8 hours. Give your answer to 1 decimal place.[1]
(c)Explain why soaking the seeds for up to 12 hours increased the number that germinated.[2]
(d)Suggest why fewer seeds germinated after 24 hours of soaking.[1]
(e)Suggest one way to make the results more reliable.[1]
(c) The seeds absorb water, which activates their enzymes so stored food (starch) is broken down and transported to the embryo; it also makes the seed swell and the testa split.
B1 water absorbed / enzymes activated; B1 stored food broken down and transported for growth / testa splits.
(d) Seeds kept under water for a long time get too little oxygen, so aerobic respiration cannot release enough energy (some embryos may die).
B1 lack of oxygen when submerged / less aerobic respiration.
(e) Repeat with more dishes (or more seeds) for each soaking time and calculate means.
B1 repeats / larger sample and mean.
Q11Fertilisation, seeds & germination · Challenge · Paper 4 style · 6 marks
You are given mung bean seeds, Petri dishes, cotton wool, water, incubators that can be set to different temperatures, and a refrigerator.
(a)Plan an investigation to find the effect of temperature on the germination of mung bean seeds.[6]
Show answer
(a) A plan with a range of temperatures, controlled variables, a measured outcome, repeats and a conclusion method.
1 mark each, max 6: at least 4 temperatures (e.g. 10, 20, 30, 40 °C) using incubators/refrigerator/water baths; same number of seeds (e.g. 20) per dish, same type and age; same volume of water / moist cotton wool kept moist; same time (e.g. 4 days); same light conditions; count number germinated (radicle visible) and calculate percentage; repeat with three dishes per temperature and find mean; plot percentage against temperature.
Q12Flower structure & pollination · Core · Paper 1 style · 1 mark
(a)What is the function of the anther?[1]
Show answer
(a) A to make pollen grains
Anthers produce pollen. The stigma (B) receives pollen.
Q13Flower structure & pollination · Core · Paper 2 style · 4 marks
A student looked at a hibiscus flower from her garden in Hyderabad.
(a)State the function of each part of a flower.(i) sepal(ii) petal(iii) stigma(iv) ovary[4]
Show answer
(a) (i) protects the flower in bud; (ii) attracts insects (pollinators); (iii) receives pollen; (iv) contains ovules / develops into the fruit.
B1 each.
Q14Flower structure & pollination · Standard · Paper 2 style · 5 marks
(a)Describe four ways in which a wind-pollinated flower such as wheat differs from an insect-pollinated flower such as mustard.[4]
(b)Explain why wind-pollinated plants produce large amounts of pollen.[1]
Show answer
(a) Wind: small/dull or no petals (insect: large, brightly coloured); no scent or nectar (insect: scent and nectar); anthers hang outside the flower on long filaments (insect: inside); large feathery stigmas outside (insect: small sticky stigma inside); large amounts of small, light, smooth pollen (insect: less, larger, sticky/spiky pollen).
1 mark for each comparative point, max 4.
(b) Pollen is carried randomly by wind, so most is wasted and never reaches a stigma.
B1
Q15Flower structure & pollination · Standard · Paper 4 style · 5 marks
A student removed the parts of a flower and counted them: 5 sepals, 5 petals, 10 stamens and 1 carpel. In a photograph taken through a microscope, a pollen grain from this flower is 18 mm across. Its actual diameter is 0.03 mm.
(a)State whether this flower is from a monocotyledon or a dicotyledon. Give a reason.[1]
(b)Calculate the magnification of the pollen grain photograph.[2]
(c)The pollen grains are large with spiky surfaces. Suggest how this flower is pollinated. Give a reason.[2]
Show answer
(a) Dicotyledon – the flower parts are in multiples of five.
B1 dicot with reason.
(b) × 600
M1 18 ÷ 0.03 (same units, mm); A1 × 600.
(c) By insects – spiky pollen sticks to the insect's body.
B1 insects; B1 spiky/sticky pollen attaches to insects.
Q16Flower structure & pollination · Challenge · Paper 2 style · 5 marks
(a)Define cross-pollination.[1]
(b)In some flowers the anthers release pollen several days before the stigma of the same flower is ready. Suggest the advantage of this to the plant.[2]
(c)Explain why genetic variation can help a population of plants survive if the climate changes.[2]
Show answer
(a) Transfer of pollen from the anther of a flower to the stigma of a flower on a different plant of the same species.
B1 different plant of same species.
(b) It prevents self-pollination, so cross-pollination happens; this increases genetic variation in the offspring.
B1 prevents self-pollination / promotes cross-pollination; B1 more variation.
(c) Some individuals may have features better suited to the new conditions; they survive and reproduce, passing on these features.
B1 some better adapted; B1 survive and reproduce / pass on alleles.
Q17Asexual vs sexual · Core · Paper 1 style · 1 mark
(a) B One parent produces offspring that are genetically identical to it.
Asexual reproduction involves one parent and no gametes, giving genetically identical offspring. C describes sexual reproduction (fertilisation).
Q18Asexual vs sexual · Standard · Paper 2 style · 4 marks
Farmers in Sindh grow new sugarcane plants by planting pieces of stem cut from a high-yielding crop.
(a)State two advantages to the farmer of growing sugarcane from stem cuttings rather than from seeds.[2]
(b)State one disadvantage of this method.[1]
(c)Name the type of cell division that produces the cells of the new plants.[1]
Show answer
(a) All plants identical to a high-yielding parent; faster growth/quicker crop; no pollination or seed needed; uniform crop ripens at the same time.
1 mark each for any two.
(b) No variation, so all plants could be killed by the same disease or change in conditions.
B1
(c) mitosis
B1
Q19Asexual vs sexual · Challenge · Paper 2 style · 5 marks
Most bananas grown for sale are produced asexually from suckers, so all the plants in a large plantation are genetically identical.
(a)Explain why a fungal disease can destroy a whole plantation of bananas grown asexually.[3]
(b)Explain how sexual reproduction could help produce bananas resistant to the disease.[2]
Show answer
(a) The plants are genetically identical (clones); if one is not resistant, none are; so the disease can spread to and kill every plant.
B1 genetically identical / no variation; B1 none has resistance; B1 disease spreads through all.
(b) It produces offspring with genetic variation; some may be resistant, and these can be selected and bred.
B1 variation; B1 resistant individuals selected.
Q20Menstrual cycle & hormones · Core · Paper 2 style · 4 marks
(a)In a 28-day menstrual cycle, state the days on which menstruation (bleeding) usually happens.[1]
(b)State on which day ovulation usually happens.[1]
(c)Name the hormone made by the ovary that causes the lining of the uterus to thicken (repair) after menstruation.[1]
(d)Name the hormone that keeps the uterus lining thick after ovulation.[1]
Show answer
(a) days 1–5
B1 days 1 to about 5.
(b) about day 14
B1
(c) oestrogen
B1
(d) progesterone
B1
Q21Menstrual cycle & hormones · Standard · Paper 1 style · 1 mark
(a)Which hormone causes ovulation to take place?[1]
Show answer
(a) C LH (luteinising hormone)
A surge of LH from the pituitary gland triggers the release of an egg. Oestrogen (A) rises before ovulation but does not itself release the egg.
Q22Menstrual cycle & hormones · Challenge · Paper 2 style · 7 marks
A woman recorded the lengths of five of her menstrual cycles: 27, 29, 30, 28 and 26 days.
(a)Calculate the mean length of the five cycles.[1]
(b)Her last period started on 3 March. Use the mean cycle length to predict the date her next period will start.[1]
(c)Explain why the lining of the uterus breaks down if the egg is not fertilised.[3]
(d)Name the gland that releases FSH and state one effect of FSH.[2]
Show answer
(a) 28.0 days
140 ÷ 5 = 28.0. B1
(b) 31 March
3 + 28 = 31 → 31 March. B1
(c) The corpus luteum (yellow body) in the ovary breaks down; so less progesterone is made; progesterone no longer maintains the lining, so it breaks down (menstruation).
B1 corpus luteum breaks down; B1 progesterone falls; B1 lining no longer maintained → menstruation.
(d) Pituitary gland; FSH causes an egg (follicle) to develop in the ovary / stimulates oestrogen release.
B1 pituitary; B1 effect.
Q23Pregnancy, placenta & birth · Core · Paper 2 style · 6 marks
(a)State the function of the amniotic fluid.[1]
(b)State the function of the umbilical cord.[1]
(c)Describe what happens during birth.[3]
(d)Give one advantage of breast-feeding a baby.[1]
Show answer
(a) Protects the fetus from mechanical shock / bumps.
B1
(b) Carries blood vessels linking the fetus to the placenta.
B1
(c) Muscles of the uterus wall contract; the cervix widens (dilates); the amniotic sac breaks; the baby is pushed out through the vagina head first; the placenta is pushed out afterwards.
1 mark each, max 3.
(d) Contains antibodies / right balance of nutrients / free and sterile / bonding.
B1
Q24Pregnancy, placenta & birth · Standard · Paper 2 style · 5 marks
(a)Name two substances that pass from the mother's blood to the fetus across the placenta and one that passes from the fetus to the mother.[3]
(b)The blood of the mother and the fetus do not mix. Suggest one reason why this is important.[1]
(c)State one feature of the placenta that helps exchange of substances.[1]
Show answer
(a) To fetus: any two of oxygen, glucose, amino acids, water, mineral ions, antibodies; to mother: carbon dioxide or urea.
B1 B1 to fetus; B1 to mother.
(b) Mother's higher blood pressure could damage the fetus's vessels / blood groups may be incompatible / reduces passage of some pathogens.
B1 any one.
(c) Large surface area (villi) / thin barrier / good blood supply.
B1
Q25Pregnancy, placenta & birth · Challenge · Paper 2 style · 6 marks
A hospital survey found that the mean birth mass of babies born to mothers who did not smoke was 3.4 kg, and of babies born to mothers who smoked during pregnancy was 3.1 kg.
(a)Calculate the percentage by which the mean birth mass of babies of smokers is lower than that of non-smokers. Give your answer to 1 decimal place.[2]
(b)Explain how smoking during pregnancy can reduce the growth of the fetus.[3]
(c)Name one pathogen that can cross the placenta.[1]
Show answer
(a) 8.8 %
M1 (3.4 − 3.1) ÷ 3.4 × 100; A1 8.8 %.
(b) Carbon monoxide from smoke enters the mother's blood and combines with haemoglobin; less oxygen is carried across the placenta to the fetus; less aerobic respiration/energy for growth (nicotine also crosses the placenta).
B1 carbon monoxide binds haemoglobin; B1 less oxygen to fetus; B1 less respiration / growth (or harmful chemicals cross placenta).
(c) HIV (or rubella virus)
B1
Q26Human reproductive organs & gametes · Core · Paper 1 style · 1 mark
(a)Where are sperm cells produced in the human male?[1]
Show answer
(a) C testes
Sperm are made in the testes. The prostate gland (A) adds fluid to the sperm but does not make them.
Q27Human reproductive organs & gametes · Standard · Paper 2 style · 5 marks
(a)Describe how a sperm cell is adapted for its function.[3]
(b)Give two differences between a sperm cell and an egg cell.[2]
Show answer
(a) Flagellum (tail) to swim; many mitochondria to release energy for swimming; acrosome containing enzymes to digest the jelly coat of the egg; haploid nucleus.
1 mark each, max 3 (feature + function).
(b) Sperm smaller; sperm can move (flagellum), egg cannot; egg has large food store in cytoplasm; egg has jelly coat; many sperm produced, one egg a month.
1 mark each for any two.
Q28Human reproductive organs & gametes · Challenge · Paper 2 style · 5 marks
(a)A semen sample of 3.0 cm³ contains 6.0 × 10⁷ sperm per cm³. Calculate the total number of sperm in the sample, in standard form.[2]
(b)A human egg is about 0.1 mm across and a sperm head is about 5 µm long. Calculate how many times wider the egg is than the sperm head.[2]
(c)State the function of the prostate gland.[1]
Show answer
(a) 1.8 × 10⁸
M1 3.0 × 6.0 × 10⁷; A1 1.8 × 10⁸.
(b) 20 times
M1 0.1 mm = 100 µm; A1 100 ÷ 5 = 20.
(c) Adds fluid (containing nutrients) to the sperm so they can swim.
B1
Q29Contraception & STIs · Core · Paper 2 style · 4 marks
HIV is the virus that can lead to AIDS.
(a)State two ways in which HIV can be passed from one person to another.[2]
(b)Explain how using a condom reduces the spread of HIV.[1]
(c)State one other method of reducing the spread of HIV.[1]
Show answer
(a) Any two: unprotected sexual intercourse; sharing needles; transfusion of infected blood; from mother to baby (across placenta, at birth or in breast milk).
1 mark each.
(b) It is a barrier that stops body fluids (semen) containing the virus passing between partners.
B1
(c) Not sharing needles / screening donated blood / having fewer sexual partners / antiretroviral drugs for infected mothers.
B1
Q30Contraception & STIs · Challenge · Paper 2 style · 6 marks
A health survey gave the number of pregnancies per 100 couples in one year of typical use of each method:condom: 13contraceptive pill: 7IUD (copper coil): 0.8no method: 85
(a)Using the data, calculate how many pregnancies would be expected in one year among 2500 couples using condoms and among 2500 using an IUD.[2]
(b)Suggest why condoms have a higher failure rate than the IUD in typical use.[1]
(c)Give one advantage of condoms over the IUD and the contraceptive pill.[1]
(d)Explain how the contraceptive pill prevents pregnancy.[2]
