Human reproduction and the menstrual cycle – IGCSE Biology exam questions with mark scheme

1Grade 1–35 marks

The diagram shows the female reproductive system.

(a) Name the parts labelled A and D. [2]

(b) Give the letter of the part where fertilisation normally takes place. [1]

(d) Which structure in the male reproductive system carries sperm from the testis towards the urethra? Choose one answer from: bladder prostate gland scrotum sperm duct [1]

A: ovary (ignore left / right)(1)
D: cervix (do not accept vagina or uterus)(1)
B (oviduct)(1)
C (uterus lining / endometrium); accept the word uterus if letter is C(1)
sperm duct (allow vas deferens)(1)
Answer: (a) A ovary, D cervix (b) B (c) C (d) sperm duct
Examiner tip: Students often label the cervix as the vagina — the cervix is the narrow neck at the bottom of the uterus, the vagina is the tube below it.

2Grade 4–56 marks

The table shows some structures in the male reproductive system.

Structure	Function
testis	(i) ............
glands (e.g. prostate gland)	(ii) ............
urethra	(iii) ............

(a) Complete the table by giving the function of each structure. [3]

(b) The testes are held in the scrotum, outside the main body cavity. Explain why. [1]

(i) produces sperm / male gametes (accept produces testosterone)(1)
(ii) add / secrete fluid to sperm to make semen (allow provides nutrients / allows sperm to swim)(1)
(iii) carries semen / sperm (and urine) out of the body (through the penis)(1)
temperature in the scrotum is (slightly) lower than body temperature, which is better / optimum for sperm production (ignore 'to keep them cool' alone)(1)
sugar / glucose is used in (aerobic) respiration (by sperm / by mitochondria in sperm)(1)
to release energy for the tail to move / for sperm to swim (do not accept 'make energy' / 'produce energy')(1)
Answer: (a) testis makes sperm; glands add fluid (semen); urethra carries semen out (b) lower temperature for sperm production (c) sugar respired to release energy for swimming
Examiner tip: Never write that respiration 'makes' or 'produces' energy — Edexcel only credits 'releases energy'.

3Grade 4–56 marks

The female reproductive system has several features that adapt it for its functions.

Explain how each feature helps the female reproductive system to carry out its function.

(a) The oviduct is lined with cells that have cilia. [2]

(b) The lining of the uterus becomes thick and develops many blood vessels. [2]

(d) The cervix is a ring of muscle that stays tightly closed during pregnancy. [1]

(a) cilia beat / wave / sweep (ignore 'move' alone unless direction given)(1)
(a) to move the egg (or zygote / embryo) along the oviduct towards the uterus(1)
(b) ready for (an embryo to) implant(1)
(b) blood vessels supply oxygen / nutrients (e.g. glucose) to the embryo / allow the placenta to form(1)
(c) contracts (strongly) to push the baby out during birth / labour(1)
(d) keeps the baby / fetus in the uterus (until birth) / prevents entry of microorganisms(1)
Answer: (a) cilia beat to move egg to uterus (b) for implantation; blood supplies oxygen and nutrients (c) contracts in birth (d) keeps fetus in uterus
Examiner tip: 'Explain' needs the feature linked to a purpose — 'cilia move the egg' scores 1, 'cilia beat to sweep the egg towards the uterus' scores 2.

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4Grade 1–34 marks

A developing fetus gets its food from its mother through the placenta.

(a) Name two nutrients that pass from the mother's blood to the fetus across the placenta. [2]

(b) Name the structure that connects the fetus to the placenta. [1]

any one from: glucose / amino acids / fatty acids / glycerol / vitamins / minerals (named ions, e.g. iron, calcium) / water(1)
a second from the list (do not accept 'food', 'protein', 'starch' or 'fat' — these are too large to cross; ignore oxygen as it is not a nutrient)(1)
umbilical cord(1)
carbon dioxide / urea (ignore 'urine')(1)
Answer: (a) e.g. glucose and amino acids (b) umbilical cord (c) carbon dioxide or urea
Examiner tip: Name small soluble molecules: 'protein' and 'starch' cannot cross the placenta, so give 'amino acids' and 'glucose'.

5Grade 6–76 marks

The table shows the total surface area of the placenta villi and the mass of the fetus at two stages of pregnancy.

Week of pregnancy	Surface area of villi / m²	Mass of fetus / kg
20	5.0	0.30
40	12.5	3.40

(a) Calculate the percentage increase in surface area of the villi from week 20 to week 40. [2]

(b) Explain why the surface area of the villi needs to increase between week 20 and week 40. Use information from the table. [2]

(c) The concentration of glucose in the mother's blood in the placenta is higher than in the fetus's blood. Explain how glucose moves into the fetus's blood. [1]

(d) Give one other feature of the placenta that makes the exchange of nutrients efficient. [1]

$\frac{12.5-5.0}{5.0}\times 100$ / $\frac{7.5}{5.0}\times100$(1)
150 (%) (correct answer scores 2 marks; 250 scores 1 mark)(1)
the mass of the fetus increases (about 11 times / from 0.30 to 3.40 kg) so it needs more nutrients / glucose / amino acids / oxygen(1)
a larger surface area allows more / faster diffusion / exchange (of nutrients) across the placenta(1)
by diffusion, down the concentration gradient / from higher to lower concentration (accept facilitated diffusion; reject active transport as glucose is moving down its gradient)(1)
any one from: thin barrier / short diffusion distance between mother's and fetus's blood; good blood supply / many capillaries (in the villi) maintaining a concentration gradient; mother's blood flows (in spaces) close to the fetal capillaries(1)
Answer: (a) 150% (b) fetus mass increases so needs more nutrients; larger area gives faster diffusion (c) diffusion from high to low concentration (d) e.g. thin barrier / rich blood supply
Examiner tip: For percentage increase divide the change by the ORIGINAL value (5.0), not the final one — 7.5/12.5 gives 60% and loses the accuracy mark.

6Grade 4–56 marks

The table shows the volume of amniotic fluid around a fetus at different stages of pregnancy.

Week of pregnancy	10	20	34	40
Volume of amniotic fluid / cm³	30	350	980	800

(a) Describe how the volume of amniotic fluid changes between week 10 and week 40. [2]

(b) Calculate the percentage decrease in the volume of amniotic fluid from week 34 to week 40. Give your answer to 3 significant figures. [2]

volume increases (rapidly) up to week 34 / to a maximum of 980 cm³(1)
then decreases (to 800 cm³) from week 34 to week 40 (accept quoted figures)(1)
$\frac{980-800}{980}\times100$ / $\frac{180}{980}\times100$(1)
18.4 (%) (accept 18.37 for 1 mark if not rounded; correct answer scores 2 marks)(1)
any two from: acts as a shock absorber / cushions the fetus against bumps / pressure / mechanical damage; maintains a constant / stable temperature around the fetus; supports the fetus / allows it to move (so limbs and muscles develop); (fluid in the amniotic sac) is a barrier to infection / microorganisms(1)
second way from the list(1)
Answer: (a) increases to a peak of 980 cm³ at week 34, then falls to 800 cm³ (b) 18.4% (c) any two: shock absorber; stable temperature; support/allows movement; barrier to infection
Examiner tip: In 'describe' questions, give both the trend AND the turning point with a figure — just 'it goes up then down' rarely gets both marks.

7Grade 6–76 marks

The graph shows how the thickness of the lining of the uterus changed during one menstrual cycle.

(a) Give the days during which menstruation (bleeding) took place. [1]

(b) Calculate the mean rate of increase in thickness of the uterus lining between day 5 and day 14. Give your answer in mm per day to 2 significant figures. [2]

(c) Explain the roles of oestrogen and progesterone in causing the changes in the uterus lining between day 5 and day 28. [3]

day 0 / day 1 to day 5 (accept days 1–5; reject any range ending after day 6)(1)
(4.0 − 1.0) ÷ 9 / 3.0 ÷ 9(1)
0.33 (mm per day) (correct answer scores 2 marks)(1)
oestrogen (concentration rises from day 5 to 14 and) causes the lining to repair / grow / thicken(1)
progesterone (from about day 14) maintains the lining / keeps it thick / makes it thicker(1)
so it is ready for implantation of an embryo / so the lining has a good blood supply for an embryo(1)
Answer: (a) days 0–5 (b) 0.33 mm per day (c) oestrogen repairs and thickens lining; progesterone maintains it for implantation
Examiner tip: Read the graph to the nearest small square: the lining is 1.0 mm at day 5 and 4.0 mm at day 14, so the change is 3.0 mm over 9 days, not 14 days.

8Grade 8–9Triple only5 marks

The combined contraceptive pill contains the hormones oestrogen and progesterone. A woman takes one pill every day.

(a) Explain how taking the pill prevents the woman from becoming pregnant. Refer to the hormones FSH and LH in your answer. [4]

(b) Some packs contain 7 pills with no hormones, taken after 21 hormone pills. Suggest why the woman has a menstrual bleed during the 7 days she takes the pills with no hormones. [1]

oestrogen / progesterone (from the pill) inhibits / stops the release of FSH (from the pituitary gland)(1)
so no follicle / egg matures in the ovary(1)
oestrogen / progesterone inhibits the release of LH / no LH surge(1)
so ovulation does not happen / no egg is released (so no egg can be fertilised)(1)
progesterone (and oestrogen) concentration in the blood falls, so the uterus lining is no longer maintained / breaks down(1)
Answer: (a) Pill hormones inhibit FSH so no egg matures, and inhibit LH so there is no ovulation, so there is no egg to fertilise (b) progesterone level falls so lining breaks down
Examiner tip: Link each hormone to its effect — 'stops FSH' needs the consequence 'so no egg matures'; 'stops LH' needs 'so no ovulation'.

9Grade 6–76 marks

Sperm are made in the testes. The sperm must travel to meet an egg released from an ovary, and the fertilised egg must then develop in the female body.

Explain how the structures of the male and female reproductive systems are adapted to allow fertilisation to take place and the resulting embryo to develop. [6]

testes produce (large numbers of) sperm; held in scrotum at a lower temperature, better for sperm production(1)
sperm ducts carry sperm from the testes to the urethra(1)
glands (prostate gland / seminal vesicles) add fluid containing nutrients / sugar so sperm can swim / respire(1)
urethra / penis delivers semen into the vagina (near the cervix) during sexual intercourse(1)
sperm swim through the cervix and uterus into the oviduct(1)
ovaries release (usually one) egg each month / ovulation(1)
oviduct is lined with cilia that move the egg towards the uterus; fertilisation takes place in the oviduct(1)
uterus lining is thick with many blood vessels, so the embryo can implant(1)
placenta develops in the uterus lining to supply the embryo with oxygen / nutrients(1)
uterus wall is muscular, allowing it to stretch as the fetus grows and to contract at birth; cervix keeps the fetus in the uterus(1)

Level	Marks	What it looks like
Level 3	5–6	Covers both the male and female systems in a logical sequence, from sperm production to implantation, with most structures clearly linked to how they help fertilisation or development of the embryo.
Level 2	3–4	Describes several structures from both systems with some correct functions; some links to fertilisation or the embryo are made, but the sequence may be incomplete or one system is underdeveloped.
Level 1	1–2	Names a few structures or gives isolated functions (e.g. testes make sperm) with little explanation or sequence.
Level 0	0	No rewardable content.

Answer: Testes in scrotum make sperm; sperm ducts and glands add nutrient fluid; penis deposits semen in vagina; sperm swim to oviduct where cilia move the egg; fertilisation in oviduct; embryo implants in thick, well-supplied uterus lining where the placenta forms.
Examiner tip: Level 3 answers follow the journey in order — testis to oviduct, then implantation — and give a reason for each structure, not just a list of names.

10Grade 6–76 marks

Scientists measured the mean concentration of testosterone in the blood of boys of different ages.

Age / years	9	11	13	15	17
Mean testosterone concentration / nmol per dm³	0.3	1.5	8.0	15.0	18.0

(a) Calculate how many times greater the mean testosterone concentration is at age 15 than at age 9. [2]

(b) A 15-year-old boy has a testosterone concentration of 0.5 nmol per dm³. A doctor treats him with testosterone injections. Suggest two changes the doctor would expect to see in the boy during the following year. [2]

(c) In girls, the hormone oestrogen rises during puberty. Give two secondary sexual characteristics that oestrogen causes to develop in girls. [2]

15.0 ÷ 0.3(1)
50 (times) (correct answer scores 2 marks)(1)
any one from: voice deepens / breaks; growth of facial / body / pubic / underarm hair; penis / testes grow; (muscle) growth / more muscular / growth spurt / broader shoulders; testes start producing sperm(1)
a second change from the list(1)
any one from: breasts develop; hips widen; menstrual cycle / periods begin; growth of pubic / underarm hair (accept as oestrogen-linked at this level)(1)
a second characteristic from the list (do not accept two hair answers for 2 marks)(1)
Answer: (a) 50 times (b) e.g. voice deepens, facial hair grows (c) e.g. breasts develop, hips widen
Examiner tip: Secondary sexual characteristics develop at puberty — do not give the testes or ovaries themselves, which are present from birth.

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