2024 May/June · Paper 22 · Q311 markPregnancy, placenta & fetal development
2024 May/June · Paper 23 · Q271 markPregnancy, placenta & fetal development
2024 May/June · Paper 31 · Q5 (a(i), a(ii))4 marksOfficial paper ↗Fertilisation, seeds & germination
2024 May/June · Paper 32 · Q84 marksFlowers & pollination
2024 May/June · Paper 42 · Q3 (a(ii), b)3 marksAsexual vs sexual reproduction
2024 May/June · Paper 42 · Q5 (b, c, d(i), d(ii))13 marksAsexual vs sexual reproduction · Human reproductive systems & gametes · Pregnancy, placenta & fetal development
2024 May/June · Paper 43 · Q2 (a(ii), b(i), b(ii), c, d)12 marksAsexual vs sexual reproduction · Fertilisation, seeds & germination · Flowers & pollination
2022 May/June · Paper 33 · Q3 (a(i), a(ii), b, c)13 marksPregnancy, placenta & fetal development · Sex hormones & menstrual cycle
2022 May/June · Paper 33 · Q7 (c(i))5 marksHuman reproductive systems & gametes
2022 May/June · Paper 41 · Q6 (a, b(i), b(ii), c)15 marksHuman reproductive systems & gametes · Pregnancy, placenta & fetal development
2022 May/June · Paper 43 · Q2 (e)4 marksAsexual vs sexual reproduction
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References only, not question text. Open Official paper ↗ where Cambridge publishes the paper,
or see the official Cambridge past-papers page; for other papers, ask your
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.
Q1Human reproductive systems & gametes · Core · Paper 4 style · 5 marks
(a)Name the structure in the human reproductive systems that:(i) produces sperm(ii) carries sperm from the testis to the urethra(iii) secretes fluid containing nutrients for sperm (name one gland)(iv) releases eggs(v) is where the fetus develops[5]
Q2Human reproductive systems & gametes · Standard · Paper 2 style · 1 mark
(a)Where does fertilisation normally take place in humans?[1]
Show answer
(a) C oviduct
Sperm meet the egg in the oviduct (fallopian tube); the embryo then moves to the uterus to implant. D is the main distractor: the uterus is where implantation, not fertilisation, occurs.
Q3Human reproductive systems & gametes · Standard · Paper 4 style · 5 marks
(a)Describe how a sperm cell is adapted for its function.[3]
(b)Describe two ways an egg cell is adapted for its function.[2]
Show answer
(a) Flagellum for swimming; many mitochondria to release energy (by respiration) for movement; acrosome containing enzymes to digest through the jelly coat of the egg; haploid nucleus.
1 mark each for any three features with function.
(b) Energy stores (cytoplasm with nutrients) for the early embryo; jelly coat that changes after fertilisation so only one sperm can enter; haploid nucleus.
1 mark each for any two.
Q4Human reproductive systems & gametes · Standard · Paper 4 style · 4 marks
(a)List, in order, the structures that sperm pass through from where they are made to where fertilisation takes place.[3]
3 marks for all in correct order; 2 marks for one error; 1 mark for two errors.
(b) It dilates / widens to let the baby pass from the uterus into the vagina.
B1 dilates / widens.
Q5Human reproductive systems & gametes · Challenge · Paper 4 style · 5 marks
A human egg cell has a diameter of 0.12 mm. The head of a human sperm cell is 5 µm long.
(a)Convert the egg diameter into micrometres (µm).[1]
(b)Calculate how many times greater the diameter of the egg is than the length of the sperm head.[1]
(c)Suggest why an egg is so much larger than a sperm, and why millions of sperm are released but only one egg each month.[3]
Show answer
(a) 120 µm
0.12 × 1000 = 120 µm (B1).
(b) 24 times
120 ÷ 5 = 24 (B1).
(c) The egg contains energy stores / nutrients for the zygote and early embryo; sperm are small so they can swim; most sperm die or do not reach the oviduct, so many are needed to make it likely that one fertilises the egg.
1 mark each: egg stores food / energy for embryo; sperm small and mobile; many sperm lost / long journey, so large numbers increase chance of fertilisation.
Q6Flowers & pollination · Core · Paper 2 style · 1 mark
(a)Which part of a flower produces pollen grains?[1]
Show answer
(a) A anther
Pollen (containing the male gametes) is made in the anthers. The stigma (D) receives pollen; it does not produce it.
Q7Flowers & pollination · Core · Paper 4 style · 5 marks
(a)Name the part of an insect-pollinated flower that has each function.(i) sticky surface that receives pollen(ii) contains the ovules(iii) brightly coloured to attract insects(iv) stalk that holds the anther up(v) protects the flower while it is a bud[5]
Q8Flowers & pollination · Standard · Paper 4 style · 5 marks
(a)Wheat is wind-pollinated and mustard is insect-pollinated. Describe four ways in which a wheat flower differs from a mustard flower.[4]
(b)Explain why a wind-pollinated plant produces far more pollen than an insect-pollinated plant.[1]
Show answer
(a) Wheat: small, dull / green petals or none (mustard: large, bright yellow petals); no scent or nectar (mustard has scent and nectar); anthers hang outside the flower on long filaments (mustard: anthers inside); large feathery stigmas outside the flower (mustard: small sticky stigma inside); large amounts of small, light, smooth pollen (mustard: less pollen, larger / sticky or spiky grains).
1 mark each for any four comparative differences; each must refer to both flowers or be clearly comparative.
(b) Pollen transfer by wind is random / much pollen does not land on a stigma, so more is needed to make pollination likely.
B1 wind transfer is random / wasteful.
Q9Flowers & pollination · Standard · Paper 6 style · 7 marks
Pollen grains grow a pollen tube when they germinate. A student placed pollen from a single flower species in drops of sucrose solution on microscope slides. After 2 hours, she examined 50 grains in each drop and counted how many had grown a pollen tube.sucrose concentration / %: 0, 5, 10, 15, 20, 30number of grains germinated (out of 50): 3, 14, 31, 38, 22, 6
(a)Calculate the percentage of pollen grains that germinated in 15 % and in 30 % sucrose solution.[2]
(b)Describe the effect of sucrose concentration on pollen germination shown by these results.[2]
(c)State two variables that should be controlled.[2]
(d)Suggest why the student counted 50 grains in each solution instead of 5.[1]
(b) Germination increases from 0 % to 15 % sucrose, is highest at 15 %, and decreases from 15 % to 30 %.
B1 increase to a maximum at 15 %; B1 decrease above 15 %.
(c) Any two: temperature; time before counting; species / source of pollen; volume of sucrose solution; number of grains counted.
1 mark each.
(d) A larger sample is more representative / reduces the effect of a few unusual grains.
B1 representative sample.
Q10Flowers & pollination · Standard · Paper 2 style · 1 mark
(a)Which row shows features of a typical wind-pollinated flower?[1]
Show answer
(a) A stigma: feathery, outside flower; petals: small and green; nectar: absent
Wind-pollinated flowers have large feathery stigmas that catch pollen from the air and no need to attract insects. B describes an insect-pollinated flower.
Q11Flowers & pollination · Challenge · Paper 4 style · 6 marks
(a)Distinguish between self-pollination and cross-pollination.[2]
(b)Explain one advantage and one disadvantage, to a species, of cross-pollination compared with self-pollination.[2]
(c)Mango farmers in Multan have reported fewer flies and bees visiting their trees after heavy insecticide spraying. Suggest how this could affect the mango harvest.[2]
Show answer
(a) Self-pollination: transfer of pollen from the anther to the stigma of the same flower or another flower on the same plant. Cross-pollination: transfer of pollen from the anther of a flower to the stigma of a flower on a different plant of the same species.
B1 self – same flower / same plant; B1 cross – different plant of same species.
(b) Advantage: more genetic variation in offspring, so the species is more likely to adapt to environmental change / disease. Disadvantage: depends on pollinators or wind, so pollination may fail if pollinators are scarce or plants are far apart.
B1 advantage with reason (variation → adaptation); B1 disadvantage with reason (relies on external agent / plants close together).
(c) Fewer insects → less pollination of flowers; fewer ovules fertilised, so fewer fruits / lower yield.
B1 less pollination; B1 fewer fruits / seeds formed (lower yield).
Q12Sex hormones & menstrual cycle · Core · Paper 4 style · 5 marks
(a)Name the main sex hormone secreted by:(i) the testes(ii) the ovaries (name two)[3]
(b)State two secondary sexual characteristics that develop in boys at puberty.[2]
Show answer
(a) (i) testosterone; (ii) oestrogen and progesterone
1 mark for (i); 1 mark each for oestrogen and progesterone.
(b) Any two: growth of facial / body / pubic hair; deepening of the voice; growth of muscles; growth of penis and testes; sperm production starts.
1 mark each.
Q13Sex hormones & menstrual cycle · Standard · Paper 2 style · 1 mark
(a)Which hormone maintains the thickened lining of the uterus in the second half of the menstrual cycle?[1]
Show answer
(a) D progesterone
Progesterone maintains the uterine lining after ovulation. Oestrogen (C) is the main distractor: it causes the lining to build up / repair in the first half of the cycle.
Q14Sex hormones & menstrual cycle · Standard · Paper 4 style · 5 marks
The concentrations of hormones in a woman's blood were measured during one 28-day menstrual cycle.FSH: rises from day 1, peaks at day 13, then falls.Oestrogen: low during menstruation (days 1–5), rises to a peak on day 12, then falls.LH: low except for a sharp peak on days 13–14.Progesterone: low until day 14, rises to a peak on day 21, then falls to a low level by day 28.
(a)State the day on which ovulation is most likely to have happened. Give a reason.[2]
(b)Describe the roles of FSH and oestrogen in the first half of the cycle.[3]
Show answer
(a) Day 14; LH concentration peaks on day 13–14 and a surge of LH causes ovulation.
(b) FSH (from the pituitary gland) stimulates a follicle / egg to develop in the ovary and stimulates oestrogen secretion; oestrogen causes the uterus lining to thicken / repair.
1 mark each: FSH – follicle / egg development; FSH stimulates oestrogen production; oestrogen – builds up uterus lining (also: high oestrogen triggers LH surge).
Q15Sex hormones & menstrual cycle · Challenge · Paper 4 style · 5 marks
(a)Explain why menstruation begins at the end of a cycle in which the egg is not fertilised.[2]
(b)Explain why menstruation does not occur during pregnancy.[2]
(c)Describe the role of LH in the menstrual cycle.[1]
Show answer
(a) Progesterone concentration falls; the uterus lining is no longer maintained, so it breaks down and is lost.
B1 progesterone falls; B1 lining not maintained / breaks down.
(b) Progesterone stays high; it is secreted (first by the ovary and later) by the placenta, so the lining is maintained.
(c) It causes ovulation (release of an egg from the ovary).
B1 triggers ovulation.
Q16Sex hormones & menstrual cycle · Challenge · Paper 4 style · 3 marks
A woman recorded the length of five of her menstrual cycles: 27, 29, 28, 30 and 26 days. Assume ovulation happens 14 days before the start of the next menstruation.
(a)Calculate the mean cycle length.[1]
(b)Another woman has a regular cycle of 31 days. Using the information given, calculate on which day of her cycle ovulation is likely to occur.[1]
(c)Suggest why cycle lengths vary from month to month.[1]
Show answer
(a) 28 days
(27 + 29 + 28 + 30 + 26) ÷ 5 = 28 days (B1).
(b) Day 17
31 − 14 = day 17 (B1).
(c) Hormone concentrations vary / affected by stress, illness, diet or exercise.
Any one sensible suggestion.
Q17Fertilisation, seeds & germination · Core · Paper 4 style · 4 marks
(a)Describe what happens after a pollen grain lands on the stigma, up to the formation of a seed.[4]
Show answer
(a) A pollen tube grows out of the pollen grain, down through the style to the ovary; it enters an ovule; the male nucleus fuses with the female nucleus in the ovule (fertilisation); the ovule develops into a seed (and the ovary into a fruit).
1 mark each: pollen tube grows; down the style; enters ovule / reaches ovary; nuclei fuse (fertilisation); ovule becomes seed / ovary becomes fruit (any four).
Q18Fertilisation, seeds & germination · Standard · Paper 6 style · 6 marks
A student set up four tubes, each with 30 moong (mung bean) seeds, and left them for 5 days.A: damp cotton wool, air, 25 °C — 27 seeds germinatedB: dry cotton wool, air, 25 °C — 0 germinatedC: seeds under boiled and cooled water covered by oil, 25 °C — 0 germinatedD: damp cotton wool, air, 4 °C in a refrigerator — 2 germinated
(a)Calculate the percentage germination in tube A and in tube D. Give your answer for tube D to 1 decimal place.[2]
(b)State the three conditions needed for germination that are shown by these results. Use the tubes to explain your answer.[3]
(c)Explain why the water in tube C was boiled and then covered with a layer of oil.[1]
(b) Water – compare A with B (no water, no germination); oxygen – compare A with C (no oxygen, no germination); suitable / warm temperature – compare A with D (cold, very little germination).
1 mark each condition with the correct comparison.
(c) Boiling removes dissolved oxygen; oil stops oxygen from the air dissolving back in.
B1 both ideas.
Q19Fertilisation, seeds & germination · Challenge · Paper 6 style · 6 marks
(a)Plan an investigation to find the effect of temperature on the germination of radish seeds.[6]
Show answer
(a) Place equal numbers (e.g. 20) of radish seeds on damp cotton wool in Petri dishes; keep dishes at five temperatures (e.g. 10, 15, 20, 25, 30 °C) in incubators; same volume of water, same seed type/age, same light; count the number germinated (radicle visible) after a fixed time (e.g. 3 days) and calculate %; repeat with three dishes per temperature and find mean; wash hands after handling seeds.
1 mark each, max 6: 1. at least five temperatures; 2. how temperature is controlled (incubators / thermostatically controlled); 3. same number of seeds per dish (≥ 10); 4. how germination is judged (radicle emerges) and measured (count / % after fixed time); 5. two controlled variables with method (same volume of water, same seed variety / age, same light, same time); 6. repeats and means; 7. keep cotton wool damp / supply oxygen (lid with air gap); 8. relevant safety (seeds may be treated with fungicide – wear gloves / wash hands).
Q20Asexual vs sexual reproduction · Core · Paper 2 style · 1 mark
(a)Which is an example of asexual reproduction?[1]
Show answer
(a) B a potato plant growing new plants from tubers
Tubers grow into new plants that are genetically identical to the parent, without gametes. A, C and D all involve gametes (sexual reproduction).
Q21Asexual vs sexual reproduction · Core · Paper 4 style · 4 marks
(a)Define asexual reproduction.[2]
(b)Give one advantage and one disadvantage of asexual reproduction to a plant species.[2]
Show answer
(a) A process resulting in the production of genetically identical offspring from one parent (no gametes / no fertilisation).
B1 one parent; B1 genetically identical offspring.
(b) Advantage: fast / no pollinator or mate needed / all offspring suited to the same environment. Disadvantage: no genetic variation, so all may be killed by a disease or change in environment; overcrowding / competition near parent.
1 mark each.
Q22Asexual vs sexual reproduction · Standard · Paper 4 style · 5 marks
A farmer grows bananas from suckers, which are new shoots that grow from the base of one parent plant. All the banana plants on the farm came from one original plant.
(a)Explain why all the banana plants in the plantation are genetically identical.[2]
(b)Explain why a fungal disease could destroy the whole plantation.[2]
(c)Suggest one way the farmer could reduce this risk.[1]
Show answer
(a) They are produced asexually from one parent (by mitosis), so there is no fusion of gametes and no variation.
B1 asexual / from one parent; B1 mitosis / no gametes, so same genes / alleles.
(b) No genetic variation, so if one plant is susceptible all are; no plant has resistance alleles, so the disease spreads to every plant.
B1 no variation / all have same alleles; B1 none resistant, so all infected.
(c) Grow several different varieties / grow plants from seed (sexual reproduction) / mix with other crops.
Any one sensible.
Q23Asexual vs sexual reproduction · Standard · Paper 2 style · 1 mark
(a)Which statements describe sexual reproduction?1 The offspring are genetically identical to the parent.2 The nuclei of two gametes fuse.3 The zygote has a haploid nucleus.4 The offspring show genetic variation.[1]
Show answer
(a) C 2 and 4
Sexual reproduction involves fusion of two haploid gamete nuclei to form a diploid zygote, giving variation. Statement 3 is false (the zygote is diploid), so B and D are wrong.
Q24Asexual vs sexual reproduction · Challenge · Paper 4 style · 6 marks
In summer, female aphids reproduce asexually. Assume that each aphid produces 4 daughters every week and that no aphids die, so the population is multiplied by 5 every week. A cotton plant starts with 1 aphid.
(a)Calculate the number of aphids after 3 weeks and after 4 weeks.[2]
(b)Suggest why asexual reproduction is an advantage to aphids in summer.[2]
(c)Suggest why aphids reproduce sexually in autumn.[2]
Show answer
(a) 3 weeks: 125; 4 weeks: 625
1 × 5 × 5 × 5 = 125 (B1); 125 × 5 = 625 (B1).
(b) Plenty of food and good conditions; asexual reproduction is fast (no mate needed), so the population can grow quickly and exploit the food; offspring suited to the same conditions as the parent.
1 mark each for any two.
(c) Sexual reproduction produces genetic variation; some offspring (eggs) may survive the changing / cold winter conditions or new diseases.
B1 variation; B1 better chance of some surviving changing conditions.
Q25Pregnancy, placenta & fetal development · Core · Paper 4 style · 4 marks
(a)State the function of the amniotic fluid.[1]
(b)State the function of the umbilical cord.[2]
(c)Name the structure in which a fertilised egg implants.[1]
Show answer
(a) Protects the fetus from mechanical shock / bumps (cushioning).
B1.
(b) It contains blood vessels (umbilical artery and vein) that carry blood between the fetus and the placenta.
B1 contains blood vessels; B1 links fetus to placenta / carries blood both ways.
(c) Uterus (lining)
B1.
Q26Pregnancy, placenta & fetal development · Standard · Paper 4 style · 6 marks
(a)Name three substances that pass from the mother's blood to the fetus across the placenta.[3]
(b)Name two waste substances that pass from the fetus to the mother.[2]
(c)Some harmful substances and pathogens can also cross the placenta. Give one example.[1]
(c) Any one: nicotine; alcohol; some drugs; rubella virus; HIV.
Any one.
Q27Pregnancy, placenta & fetal development · Standard · Paper 4 style · 5 marks
A study compared the birth mass of babies born to mothers who smoked during pregnancy with those born to mothers who did not.mean birth mass, non-smokers: 3.42 kgmean birth mass, smokers: 3.15 kg
(a)Calculate the percentage by which the mean birth mass of babies of smokers is lower than that of babies of non-smokers. Give your answer to 1 decimal place.[2]
(b)Suggest how smoking during pregnancy could cause lower birth mass.[3]
Show answer
(a) 7.9 %
(3.42 − 3.15) ÷ 3.42 × 100 (M1) = 7.9 % (A1).
(b) Carbon monoxide combines with haemoglobin, so the mother's blood carries less oxygen; less oxygen crosses the placenta to the fetus; less aerobic respiration / energy for growth; nicotine crosses the placenta (and narrows blood vessels).
1 mark each, max 3: carbon monoxide; binds haemoglobin / less oxygen carried; less oxygen to fetus; less respiration for growth; nicotine / toxins cross placenta.
Q28Pregnancy, placenta & fetal development · Challenge · Paper 4 style · 6 marks
A fetus had a mass of 1.2 kg at week 28 of pregnancy and 3.3 kg at birth in week 40.
(a)Calculate the mean increase in mass of the fetus per week between week 28 and week 40, in grams per week.[2]
(b)Explain how the structure of the placenta is adapted for efficient exchange of substances.[3]
(c)Suggest why it is important that the blood of the mother and the fetus do not mix.[1]
Show answer
(a) 175 g per week
(3.3 − 1.2) = 2.1 kg = 2100 g (M1); 2100 ÷ 12 = 175 g per week (A1).
(b) Large surface area (villi); thin barrier between the blood of mother and fetus so short diffusion distance; rich blood supply on both sides keeps concentration gradients high.
1 mark each for three features linked to function.
(c) Mother's higher blood pressure could damage fetal vessels / the blood groups may be different and could clump / protects fetus from some toxins and pathogens.
Any one.
Q29STIs & HIV · Core · Paper 4 style · 5 marks
(a)HIV is a sexually transmitted infection. State what is meant by a sexually transmitted infection.[1]
(b)State two ways, other than sexual contact, in which HIV can be transmitted.[2]
(c)Suggest two ways of controlling the spread of HIV.[2]
Show answer
(a) An infection that is passed on through sexual contact.
B1.
(b) Any two: sharing needles (e.g. drug users); transfusion of infected blood; from mother to baby across the placenta, at birth or in breast milk.
1 mark each.
(c) Any two: use condoms; screen blood donations; do not share needles / use sterile needles; HIV testing and treatment; education.
1 mark each.
Q30STIs & HIV · Challenge · Paper 4 style · 5 marks
The number of lymphocytes in the blood of a person infected with HIV was measured when the infection was first diagnosed and again six years later, before treatment began.at diagnosis: 1050 lymphocytes per mm³six years later: 340 lymphocytes per mm³
(a)Calculate the percentage decrease in the lymphocyte count. Give your answer to 2 significant figures.[2]
(b)Explain why a person with a very low lymphocyte count often suffers from other infections, such as tuberculosis.[3]
(b) HIV infects and destroys lymphocytes; fewer lymphocytes means fewer antibodies are produced; so the body cannot fight pathogens and other infections develop (AIDS).
1 mark each: HIV destroys lymphocytes; fewer antibodies made; immune system weakened / pathogens not destroyed, so opportunistic infections.
Similar questions
Questions that test the same subtopic in different years, grouped so you can work on one skill at a time.
References only: find each question in its paper (official link where available, otherwise through your school).
Human reproductive systems & gametesBanker46 questions · 9/9 sessions
