A couple have been trying to conceive a child for over two years without success. A doctor diagnoses one partner with infertility and recommends in vitro fertilisation (IVF) as a treatment. Explain how IVF works and describe the role of hormones in this process.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
In vitro fertilisation (IVF) is a fertility treatment used when natural conception has not occurred. It involves the use of hormones and laboratory procedures to achieve fertilisation.
Model answer (5 marks)
IVF is a fertility treatment that fertilises an egg with sperm outside the body and then implants the resulting embryo in the uterus.
1. The woman receives FSH injections to stimulate the ovaries to produce and mature several eggs.
2. LH (or a synthetic analogue) is given to trigger the final maturation and release of the egg(s) – ovulation.
3. The mature eggs are collected from the ovaries and mixed with sperm in a laboratory dish.
4. Fertilised eggs develop into embryos over a few days.
5. One or more embryos are then transferred into the uterus, where implantation can occur.
IVF is used when a couple has difficulty conceiving and is a recognised treatment for infertility.
1. The woman receives FSH injections to stimulate the ovaries to produce and mature several eggs.
2. LH (or a synthetic analogue) is given to trigger the final maturation and release of the egg(s) – ovulation.
3. The mature eggs are collected from the ovaries and mixed with sperm in a laboratory dish.
4. Fertilised eggs develop into embryos over a few days.
5. One or more embryos are then transferred into the uterus, where implantation can occur.
IVF is used when a couple has difficulty conceiving and is a recognised treatment for infertility.
Examiner tips
- Use the exact sequence: FSH → LH → fertilisation → implantation
- Mention that eggs are collected and fertilised in vitro
- Show that IVF is a treatment for infertility
Common mistakes
- Confusing in vitro fertilisation with natural fertilisation
- Omitting the role of LH in triggering ovulation
- Failing to state that embryos are implanted into the uterus
Mark scheme (5 marks)
- IVF involves fertilisation of an egg by sperm outside the body
- FSH is given to stimulate/cause the maturation of eggs in the ovary
- LH is given to stimulate the release/ovulation of the mature egg(s)
- The fertilised egg(s) / embryo(s) are then implanted into the uterus
- IVF is used when a couple are having difficulty conceiving / is a treatment for infertility
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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