Cambridge IGCSE Biology 0610: Sex hormones in humans and sexually transmitted infections (by subtopic) – Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – examination boards hold copyright in their own papers. Use these alongside the official past papers from your board or school.

These questions follow the Cambridge IGCSE Biology 0610 syllabus for examination in 2026, 2027 and 2028, topic 16, outcome by outcome: section 16.5 Sex hormones in humans (outcomes 1 to 4) and section 16.6 Sexually transmitted infections (outcomes 1 to 5, Core only). Unlabelled questions use Core content; questions marked “(Extended)” use Supplement outcomes 16.5.3 and 16.5.4. Each question is tagged with its outcomes.

The topic-level Reproduction practice questions do not cover these sections. Learn it first: Reproduction study guide · Recall: Reproduction revision notes · Course hub: Cambridge IGCSE Biology · Checklist: 0610 printable checklist · Diagnostics: Core and Extended.

Questions

1. (16.5.1) The list shows four changes that happen during puberty.

• the voice becomes deeper
• the breasts develop
• the hips widen
• hair grows on the face

(a) For each change, state whether it is caused mainly by testosterone or by oestrogen. [2] (b) Name the organ that produces testosterone and the organ that produces oestrogen. [2]

2. (16.6.1, 16.6.2, 16.6.3)

(a) Describe what is meant by a sexually transmitted infection. [1] (b) HIV is a pathogen that causes a sexually transmitted infection. State what the letters HIV stand for. [1] (c) State the condition that HIV infection may lead to. [1]

3. (16.5.2) Ultrasound scans measured the thickness of a woman’s uterus lining during a regular 28-day cycle. Day 1 is the first day of menstruation.

Day of cycle	1	5	7	14	21	28
Thickness of lining / mm	11	3	3	10	13	12

(a) Describe the changes in the lining between day 1 and day 7. [2] (b) Calculate the mean rate at which the lining thickened between day 7 and day 14. Give the unit. (calculator allowed) [2] (c) State what happens in the ovary at about day 14. [1] (d) Explain why the lining stays thick between day 14 and day 28. [1]

4. (16.5.2) A woman’s menstrual cycles are regular and 32 days long. Her menstruation starts on 5 May, which is day 1 of the cycle. In this question, assume that ovulation happens 14 days before the next menstruation starts.

(a) Calculate the day of the cycle on which she ovulates, and give the date. [2] (b) State the date on which her next menstruation is expected to start. [1] (c) No egg is fertilised in this cycle. Describe the changes in her uterus lining between ovulation and the start of the next cycle. [2]

5. (16.6.4)

(a) For each situation, state whether HIV could be transmitted from an infected person to another person.

(i) sharing a hypodermic needle [1] (ii) drinking from the same cup [1] (iii) receiving a transfusion of unscreened blood from an infected donor [1] (iv) a baby being breastfed by an infected mother [1]

(b) Explain how sharing a needle can pass HIV from one person to another. [1]

6. (16.6.5) Explain how each of these measures reduces the spread of HIV.

(a) testing all donated blood before it is used [2] (b) giving people who inject drugs free sterile needles [2] (c) having fewer sexual partners [2]

7. (Extended) (16.5.3, 16.5.4)

(a) Copy and complete the table to show where each hormone is produced.

Hormone	Site of production during the menstrual cycle	Site of production later in pregnancy
oestrogen
progesterone

[4] (b) Name the gland that secretes FSH and LH. [1]

8. (Extended) (16.5.4) The table shows the concentration of LH in the blood of a woman during one 28-day cycle. The units are arbitrary.

Day of cycle	2	6	10	12	13	14	15	18	24
LH concentration	5	6	8	15	45	60	20	6	4

(a) State the day on which ovulation is most likely to happen, and give a reason from the data. [2] (b) Calculate how many times greater the LH concentration is on day 14 than on day 2. (calculator allowed) [1] (c) Explain what causes the LH concentration to rise sharply on days 12 to 14. [2] (d) State one effect of LH in the ovary, other than causing ovulation. [1]

9. (Extended) (16.5.4) A woman takes a tablet every day that contains a synthetic hormone with the same effects as progesterone. Explain why she does not ovulate. [3]

10. (Extended) (16.5.3, 16.5.4) Explain how the hormones FSH, LH, oestrogen and progesterone control what happens:

• at the end of a menstrual cycle in which no pregnancy occurs, and
• during a pregnancy, so that the lining is kept and no further cycles happen. [10]

11. (16.6.2, 16.6.4, 16.6.5) The table shows new HIV diagnoses in one region (illustrative figures). At the start of year 3 the region began a programme of free condoms, free HIV testing and school education about STIs.

Year	1	2	3	4	5
New HIV diagnoses	2400	2300	2250	1900	1620

(a) Calculate the percentage decrease in new HIV diagnoses from year 3 to year 5. (calculator allowed) [2] (b) Suggest how each part of the programme could have reduced the number of new infections. [3] (c) Suggest one reason why these data alone do not prove that the programme caused the decrease. [1] (d) Another STI, gonorrhoea, is caused by a bacterium and can be cured with antibiotics. Explain why antibiotics do not cure HIV infection. [2]

Answers

1. (a) Testosterone: voice deepens and facial hair – both needed [1]. Oestrogen: breasts develop and hips widen – both needed [1]. (b) Testosterone: the testes [1]. Oestrogen: the ovaries [1].

Examiner insight: Where one mark covers two answers, both must be right, so one slip in part (a) costs a whole mark.

2. (a) An infection that is transmitted through sexual contact [1]. (b) Human immunodeficiency virus [1]. (c) AIDS [1].

Examiner insight: “A disease of the reproductive organs” is not credited: the definition is about how the infection is passed on.

3. (a) Between day 1 and day 5 the lining breaks down and is lost from the body (menstruation), falling from 11 mm to 3 mm [1]; it then stays thin at 3 mm until day 7 [1]. (b) (10 − 3) ÷ (14 − 7) = 7 ÷ 7 [1] = 1.0 mm per day [1]. (c) Ovulation: an egg is released from the ovary [1]. (d) The lining is kept thick so that an embryo can implant in it if fertilisation happens [1].

Examiner insight: In (b) the accuracy mark needs the unit “mm per day”; a bare “1” or “1 mm” loses it.

4. (a) Ovulation is on day 32 − 14 = day 18 [1], which is 22 May [1]. (b) The next cycle’s day 1 is day 33 of this one: 6 June [1]. (c) The lining stays thick after ovulation [1]; as no embryo implants, it breaks down and is lost at the next menstruation [1].

Examiner insight: Day 1 is 5 May, so day 18 is 17 days later, not 18; write the day number first so the method mark is safe if the date slips.

5. (a) (i) Yes [1]. (ii) No [1]. (iii) Yes [1]. (iv) Yes [1]. (b) Infected blood left in or on the needle is injected directly into the bloodstream of the next user [1].

Examiner insight: In (b) the answer must name infected blood entering the body; “germs on the needle” is too vague.

6. (a) Infected blood is detected and not used [1], so HIV is not passed to the person who receives the transfusion [1]. (b) People who inject drugs do not need to share needles [1], so infected blood is not transferred from one user to another [1]. (c) Body fluids are exchanged with fewer people [1], so there is a lower chance of having sex with an infected person [1].

Examiner insight: Each part has a “what the measure does” mark and a “so the virus cannot pass” mark; restating the measure earns nothing.

7. (Extended) (a)

Hormone	During the menstrual cycle	Later in pregnancy
oestrogen	ovary (developing follicle) [1]	placenta [1]
progesterone	corpus luteum in the ovary [1]	placenta [1]

(b) The pituitary gland [1].

Examiner insight: For progesterone during the cycle, name the corpus luteum; “uterus” is where the hormones act, not where they are made.

8. (Extended) (a) Day 14 (accept 14 to 15) [1]; LH peaks then, and the LH surge triggers ovulation [1]. (b) 60 ÷ 5 = 12 times [1]. (c) The developing follicle releases oestrogen, which rises in the first half of the cycle [1]; high oestrogen stimulates the pituitary gland to release a surge of LH [1]. (d) It causes the empty follicle to develop into the corpus luteum [1].

Examiner insight: In (c) the second mark needs the link “high oestrogen → pituitary → LH”; “oestrogen turns into LH” scores zero.

9. (Extended) The progesterone-like hormone inhibits the release of FSH from the pituitary gland [1], so no follicle develops and no egg matures [1]. It also inhibits LH, so there is no LH surge to trigger ovulation [1].

Examiner insight: “Stops the hormones” is not enough; name FSH or LH and its effect in the ovary.

10. (Extended)

No pregnancy:

• No embryo implants, so the corpus luteum breaks down [1].
• Progesterone concentration falls [1].
• The lining is no longer maintained: menstruation [1].
• Low progesterone no longer inhibits FSH, so FSH rises [1].
• FSH makes a new follicle develop; its oestrogen rebuilds the lining [1].

Pregnancy:

• The corpus luteum keeps secreting progesterone in early pregnancy [1].
• Later the placenta secretes progesterone and oestrogen [1].
• Progesterone maintains the lining, so no menstruation [1].
• Progesterone inhibits FSH and LH release from the pituitary [1].
• So no follicle develops and no ovulation happens [1].

Examiner insight: An answer covering only one half can reach at most half the marks, so plan both; it is the fall in progesterone that leads to menstruation.

11. (a) Decrease = 2250 − 1620 = 630 [1]; (630 ÷ 2250) × 100 = 28% [1]. (b) Condoms: a barrier, so body fluids are not exchanged during sex [1]. Testing: infected people find out and can avoid passing HIV on; their partners can be tested [1]. Education: people learn how HIV spreads, so use condoms and avoid sharing needles [1]. (c) Any one: other factors may have changed at the same time; more testing changes the number diagnosed, not only the number infected; data from one region over a short time [1]. (d) HIV is a virus [1]; antibiotics kill bacteria but do not affect viruses [1].

Examiner insight: In (a) showing 630 earns the method mark even if the division slips; in (b) each mark must be tied to a different part of the programme.

Where marks are usually lost

• Writing “the uterus breaks down” instead of “the lining breaks down”.
• Giving a rate without a unit.
• Saying FSH or LH is made in the ovary. Both come from the pituitary gland.
• Forgetting the corpus luteum, or that the placenta makes the hormones later in pregnancy.
• Saying progesterone “causes” menstruation, when it is the fall in progesterone that does.
• Writing “stops hormones” without naming FSH or LH.
• Naming an STI control measure without explaining how it stops body fluids passing between people.
• Treating HIV and AIDS as the same thing, or saying antibiotics treat HIV.

Next steps

• Reproduction revision notes and study guide (sections 16.5 and 16.6).
• Reproduction practice questions for the rest of topic 16.
• Course hub and printable checklist.
• All free 10-minute diagnostics.
• Book a free trial class.

Official syllabus

Cambridge IGCSE Biology 0610 syllabus for examination in 2026, 2027 and 2028 (Version 3), Cambridge Assessment International Education, part of Cambridge University Press & Assessment. Topic 16 Reproduction, sections 16.5 Sex hormones in humans and 16.6 Sexually transmitted infections.