Question 1
Paper 4 short-answer style1 markName the hormone that controls the development of male secondary sexual characteristics. (1 mark)
Model answer
Testosterone.
Why this scores
One mark for 'testosterone'.
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Detailed notes on Reproduction for Cambridge IGCSE Biology, covering key concepts, explanations, examples, and exam-focused revision points.
Hormones that drive puberty, the menstrual cycle and pregnancy. Three to know: testosterone, oestrogen, progesterone.
Mapped to the Cambridge IGCSE 0610 syllabus (2026-2028).
Testosterone (males) and oestrogen (females) drive the changes around age 10-14.
Puberty = the transition from child to adult, ~10-14 years old.
In males.
In females.
Both sexes:
Worked qualitative. Why do voices deepen for boys?
Cambridge tip. Memorise 3-4 changes for each sex. Don't forget: BOTH have small amounts of the OTHER hormone (just in different proportions).
28 days. Four stages: menstruation, repair, ovulation, lining maintained.
Why a cycle? Each month, the uterus prepares for a possible pregnancy. If no fertilisation occurs, the prepared lining is shed and rebuilt for next time.
The four stages (~28-day cycle):
Days 1-5 — MENSTRUATION.
Days 6-13 — REPAIR/PROLIFERATION.
Day 14 — OVULATION.
Days 15-28 — SECRETORY PHASE.
If no fertilisation:
If fertilisation:
Worked qualitative. Why are hormonal CONTRACEPTIVE PILLS designed to mimic pregnancy hormones?
Cambridge tip. Memorise the FOUR stages and which hormone dominates each. Cambridge graphs the cycle and asks 'what's happening on day 14?' or 'which hormone is at peak?'.
Each has a specific job at a specific time.
FSH (follicle-stimulating hormone) — from PITUITARY.
Oestrogen — from OVARY (developing follicle).
LH (luteinising hormone) — from PITUITARY.
Progesterone — from OVARY (corpus luteum).
Worked qualitative. Why do women on hormonal contraception still have 'periods'?
Cambridge tip. Cambridge often shows hormone levels graph. Memorise: oestrogen rises in days 6-14, progesterone rises in days 15-28.
Verbatim phrases and definitions Cambridge mark schemes credit.
Sexual hormones appear Paper 4 (5-10 marks: identify hormone, describe cycle, hormone graphs). Examiner reports flag students confusing oestrogen with progesterone roles, and missing day 14 ovulation.
Sources: Cambridge IGCSE Biology 0610 syllabus 2026-2028 (16.5); 0610/42 Oct/Nov 2024 — Q15 (sex hormones); 0610 Examiner Reports 2022-2024. Last reviewed 2026-05-07.
Step-by-step solutions to past-paper-style questions on sexual hormones in humans, written exactly the way a tutor would explain them at the board.
Question
Name the sex hormones that drive puberty in males and females, and give two secondary sexual characteristics for each.
Step-by-step solution
Step 1
In males, the hormone is testosterone (from the testes).
Step 2
Its effects include: a deeper voice, growth of facial and body hair, and increased muscle development.
Step 3
In females, the hormone is oestrogen (from the ovaries).
Step 4
Its effects include: development of the breasts, widening of the hips, and the start of the menstrual cycle.
Answer
Males: testosterone → deeper voice, facial/body hair, more muscle. Females: oestrogen → breasts develop, hips widen, periods begin.
Question
Name the hormone responsible for: (a) male secondary sexual characteristics; (b) repairing and thickening the uterus lining; (c) maintaining the uterus lining after ovulation.
Step-by-step solution
Step 1
(a) Male characteristics → testosterone.
Step 2
(b) Repairing/thickening the uterus lining → oestrogen.
Step 3
(c) Maintaining the lining after ovulation → progesterone.
Answer
(a) Testosterone; (b) oestrogen; (c) progesterone.
Examiner tip
Oestrogen builds the lining; progesterone maintains it. Don't swap these two.
Question
Describe the main events of the menstrual cycle (about 28 days).
Step-by-step solution
Step 1
Days 1–5: the lining of the uterus breaks down and is lost (menstruation, a 'period').
Step 2
Days 6–13: the lining is repaired and thickens again.
Step 3
About day 14: an egg is released from an ovary — ovulation.
Step 4
Days 15–28: the thick lining is maintained, ready to receive a fertilised egg. If no fertilisation occurs, the lining breaks down again and the cycle repeats.
Answer
Days 1–5: menstruation (lining lost). Days 6–13: lining repairs/thickens. Day 14: ovulation. Days 15–28: lining maintained; if no fertilisation, it breaks down and the cycle restarts.
Question
Describe the roles of oestrogen and progesterone in the menstrual cycle.
Step-by-step solution
Step 1
Oestrogen (from the ovary) causes the lining of the uterus to repair and thicken after menstruation.
Step 2
A rise in oestrogen also helps to trigger ovulation (around day 14).
Step 3
Progesterone (from the ovary after ovulation) maintains the thick uterus lining, ready for a fertilised egg.
Step 4
If there is no pregnancy, the progesterone level falls, so the lining can no longer be maintained and breaks down — menstruation begins.
Answer
Oestrogen repairs and thickens the uterus lining (and helps trigger ovulation). Progesterone maintains the lining after ovulation; when it falls, the lining breaks down.
Examiner tip
Oestrogen BUILDS the lining; progesterone MAINTAINS it. The fall in progesterone causes menstruation.
Question
On a graph of the menstrual cycle, oestrogen rises to a peak just before day 14, and progesterone rises after day 14 and then falls towards day 28. Explain what these changes bring about.
Step-by-step solution
Step 1
The rise in oestrogen up to its peak causes the uterus lining to repair and thicken after menstruation.
Step 2
The peak of oestrogen just before day 14 helps to trigger ovulation.
Step 3
After ovulation, the rise in progesterone maintains the thick lining, ready for a fertilised egg.
Step 4
The fall in progesterone towards day 28 (when there is no pregnancy) means the lining can no longer be maintained, so it breaks down and menstruation begins on day 1 of the next cycle.
Answer
Rising oestrogen thickens the lining and its peak triggers ovulation. Rising progesterone after day 14 maintains the lining; its fall towards day 28 causes the lining to break down (menstruation).
Examiner tip
Match each hormone change to its effect on the uterus lining or to ovulation.
Question
Describe the roles of the hormones FSH and LH in the menstrual cycle.
Step-by-step solution
Step 1
FSH (follicle-stimulating hormone), from the pituitary gland, causes an egg to mature in the ovary and stimulates the ovary to produce oestrogen.
Step 2
The rising oestrogen then stimulates the release of LH (and inhibits FSH).
Step 3
LH (luteinising hormone), also from the pituitary, causes ovulation (the release of the egg) around day 14.
Step 4
LH also stimulates the ovary to produce progesterone, which maintains the lining.
Answer
FSH matures an egg and stimulates oestrogen production; rising oestrogen triggers LH; LH causes ovulation and stimulates progesterone production.
Examiner tip
FSH and LH are Supplement content. FSH → egg matures + oestrogen; LH → ovulation + progesterone.
High-scoring sample answers for sexual hormones in humans on the Cambridge IGCSE 0610 paper, with examiner-style notes mapping each response to the mark scheme and assessment objectives.
Name the hormone that controls the development of male secondary sexual characteristics. (1 mark)
Model answer
Testosterone.
Why this scores
One mark for 'testosterone'.
State two secondary sexual characteristics that develop in females at puberty. (2 marks)
Model answer
The breasts develop and the hips widen (other answers: growth of body/pubic hair; the start of the menstrual cycle).
Why this scores
Two distinct female secondary sexual characteristics.
Describe the role of oestrogen in the menstrual cycle. (3 marks)
Model answer
Oestrogen is produced by the ovary and causes the lining of the uterus to repair and thicken after menstruation. A rise in oestrogen also helps to trigger ovulation (the release of an egg) at about day 14. (It also stimulates the release of LH.)
Why this scores
Three marks: repairs/thickens the uterus lining; rise in oestrogen triggers ovulation; (stimulates LH).
Describe the main events of the menstrual cycle over about 28 days. (4 marks)
Model answer
On about days 1 to 5, the lining of the uterus breaks down and is lost (menstruation). From about days 6 to 13, the uterus lining is repaired and thickens again. At about day 14, an egg is released from an ovary (ovulation). From about days 15 to 28, the thickened lining is maintained, ready to receive a fertilised egg; if no fertilisation occurs, the lining breaks down again and the cycle repeats.
Why this scores
Four marks: menstruation (days 1–5); lining repairs/thickens; ovulation around day 14; lining maintained / breaks down if no fertilisation.
Explain how oestrogen and progesterone control the lining of the uterus during the menstrual cycle. (5 marks)
Model answer
After menstruation, oestrogen produced by the ovary causes the lining of the uterus to repair and thicken again. As the oestrogen level rises, it also helps to trigger ovulation at about day 14. After ovulation, progesterone is produced, and this maintains the thick lining of the uterus, keeping it ready to receive a fertilised egg. If the egg is not fertilised, the level of progesterone falls, so the lining can no longer be maintained and it breaks down, causing menstruation and starting the next cycle.
Why this scores
Five marks: oestrogen repairs/thickens lining; oestrogen rise triggers ovulation; progesterone maintains the lining; fall in progesterone if no fertilisation; lining breaks down (menstruation).
Explain the roles of FSH, LH, oestrogen and progesterone in controlling the menstrual cycle. (6 marks)
Model answer
At the start of the cycle, FSH is secreted by the pituitary gland. FSH causes an egg to mature in the ovary and stimulates the ovary to produce oestrogen. The oestrogen causes the lining of the uterus to repair and thicken, and as its level rises it stimulates the release of LH (while inhibiting further FSH). The surge of LH from the pituitary causes ovulation — the release of the mature egg — at about day 14, and it also stimulates the ovary to produce progesterone. Progesterone then maintains the thick uterus lining, ready for a fertilised egg, and inhibits FSH and LH so no new egg matures. If the egg is not fertilised, the progesterone level falls, the lining breaks down (menstruation), and the fall in progesterone allows FSH to rise again, starting the next cycle.
Why this scores
Up to 6 marks: FSH matures the egg/stimulates oestrogen; oestrogen thickens the lining; oestrogen stimulates LH; LH causes ovulation; LH stimulates progesterone; progesterone maintains the lining; fall in progesterone → menstruation/new cycle. (Supplement content.)
Definitions to memorise and the exact keywords mark schemes credit for sexual hormones in humans answers — sharpened from recent examiner reports for the 2026 0610 sitting.
The male sex hormone, from the testes. Controls male puberty (deeper voice, body hair, muscle) and sperm production.
A female sex hormone from the ovaries. Controls female puberty; repairs and thickens the uterus lining and helps trigger ovulation.
A hormone from the ovary, produced after ovulation. Maintains the thick uterus lining; its fall causes menstruation.
Hormones from the pituitary gland. FSH matures an egg and stimulates oestrogen; LH causes ovulation and stimulates progesterone.
The release of a mature egg from an ovary, at about day 14 of a 28-day cycle.
The breakdown and loss of the uterus lining at the start of the cycle (days 1–5), seen as a period.
The traps other students keep falling into on sexual hormones in humans questions — taken from recent Cambridge IGCSE 0610 examiner reports and mark schemes — and how to avoid them.
Why it happens
Both have small amounts of each.
How to avoid it
Males have mainly testosterone; females have mainly oestrogen. The dominant hormone shapes the secondary sexual characteristics.
Why it happens
Both are events in the cycle.
How to avoid it
Menstruation is around days 1–5; ovulation is around day 14. They are about two weeks apart.
Why it happens
Both hormones affect the lining.
How to avoid it
OESTROGEN builds/thickens the lining; PROGESTERONE maintains it after ovulation.
The things students keep getting wrong in this sub-topic, answered.