A student is investigating the menstrual cycle. Explain how the hormones oestrogen and LH work together to bring about ovulation, and describe what happens to the uterus lining in the days before ovulation occurs.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
The menstrual cycle is controlled by hormones released from the pituitary gland and the ovaries. The cycle involves a series of coordinated hormonal events that prepare the body for potential pregnancy each month.
Model answer (5 marks)
1. FSH from the pituitary stimulates the maturation of a follicle in the ovary.
2. The developing follicle produces oestrogen, causing a rise in oestrogen levels.
3. High oestrogen levels trigger a surge in LH from the pituitary.
4. The LH surge causes ovulation – the release of the mature egg.
5. In the days before ovulation, the rising oestrogen thickens the uterine lining (endometrium) in preparation for a possible embryo.
2. The developing follicle produces oestrogen, causing a rise in oestrogen levels.
3. High oestrogen levels trigger a surge in LH from the pituitary.
4. The LH surge causes ovulation – the release of the mature egg.
5. In the days before ovulation, the rising oestrogen thickens the uterine lining (endometrium) in preparation for a possible embryo.
Examiner tips
- Use the sequence FSH→follicle→oestrogen→LH surge→ovulation to structure the answer.
- Mention the effect on the uterus lining explicitly – thickening of the endometrium.
- Keep the answer concise and use the exact terminology (oestrogen, LH, follicle, endometrium).
Common mistakes
- Confusing the order of hormone release (e.g., stating LH before oestrogen).
- Failing to mention the thickening of the uterine lining or using vague terms like "prepare the uterus" instead of "thickening of the endometrium."
Mark scheme (5 marks)
- FSH stimulates the maturation of an egg in the ovary
- Oestrogen levels rise / oestrogen is produced by the developing follicle
- High levels of oestrogen trigger / stimulate a surge in LH
- The surge in LH stimulates / causes ovulation (release of the egg)
- In the days before ovulation, oestrogen causes the uterus lining to thicken / repair / build up
Key terms in this question
oestrogen · ovulation · uterus lining · menstrual cycle
Related
- All OCR A-Level Biology B — Advancing Biology (H422) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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