A student is learning about in vitro fertilisation (IVF) as a treatment for infertility. Explain how IVF uses hormones to increase the chances of successful fertilisation, and describe what happens to the egg and sperm during the IVF process.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Infertility affects many couples. IVF is one method used to help couples conceive when natural conception has not been possible after 12 months or more of unprotected sex.
Model answer (5 marks)
1. FSH is injected to stimulate the growth and maturation of multiple follicles in the ovaries.
2. LH (or an LH‑mimicking drug) is given to trigger ovulation and release the mature eggs.
3. The mature eggs are then retrieved from the ovaries by a minor surgical procedure.
4. In the laboratory the eggs are mixed with sperm, allowing fertilisation to occur outside the body (in vitro).
5. The resulting fertilised egg or early embryo is then transferred into the woman’s uterus for implantation.
2. LH (or an LH‑mimicking drug) is given to trigger ovulation and release the mature eggs.
3. The mature eggs are then retrieved from the ovaries by a minor surgical procedure.
4. In the laboratory the eggs are mixed with sperm, allowing fertilisation to occur outside the body (in vitro).
5. The resulting fertilised egg or early embryo is then transferred into the woman’s uterus for implantation.
Examiner tips
- Use the exact hormone names (FSH, LH) and their roles; mention ‘multiple follicles’ to show understanding of IVF’s advantage.
- Show the sequence: stimulation → ovulation → retrieval → fertilisation → implantation.
- Include the word ‘in vitro’ to demonstrate knowledge of the laboratory setting.
- Use concise, exam‑style wording and avoid unnecessary explanation.
Common mistakes
- Confusing FSH with LH or vice versa; not specifying the trigger for ovulation.
- Omitting the step of embryo transfer into the uterus.
- Using vague terms like ‘hormones’ without naming FSH and LH.
Mark scheme (5 marks)
- FSH is given to the woman to stimulate maturation of eggs in the ovary
- LH (or a drug mimicking LH) is given to stimulate the release of the eggs / trigger ovulation
- The mature eggs are collected from the ovaries
- The eggs are fertilised with sperm outside the body (in a laboratory / in vitro)
- The fertilised egg / embryo is implanted into the woman's uterus
Key terms in this question
in vitro fertilisation (IVF) · infertility
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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