5.23 Treating infertility
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Name the two hormones in a fertility drug and describe their effect.
Mark scheme
- FSH (1)
- LH (1)
- stimulate eggs to mature and be released / ovulation (1)
Model answer
FSH and LH. They stimulate eggs to mature in the ovaries and then be released.
Describe the main steps in IVF treatment.
Mark scheme
- mother given FSH and LH (1)
- to stimulate maturation of several eggs (1)
- eggs collected (from the ovaries) (1)
- fertilised by sperm in the laboratory (1)
- fertilised eggs develop into embryos / balls of cells (1)
- one or two embryos inserted into the uterus (1)
Max 5
Model answer
The mother is given FSH and LH so that several eggs mature. The eggs are collected from her ovaries and fertilised by the father's sperm in the laboratory. The fertilised eggs develop into embryos, and when they are tiny balls of cells, one or two embryos are inserted into the mother's uterus.
Evaluate the use of IVF to treat infertility.
Mark scheme
- advantage: allows an infertile couple to have their own child (1)
- disadvantage: emotionally / physically stressful (1)
- disadvantage: low success rate (1)
- disadvantage: multiple births, risk to mother and babies (1)
- disadvantage: expensive / ethical issue of unused embryos (1)
- a justified conclusion (1)
Max 4; must include an advantage and a disadvantage
Model answer
IVF gives an infertile couple the chance to have a baby of their own. However, success rates are low, so several expensive cycles may be needed; it is emotionally and physically stressful; and if more than one embryo is implanted it can lead to multiple births, which are risky for the mother and babies. Unused embryos may be destroyed, which some people object to. It is worth offering, but couples need to understand the low chance of success, and transferring one embryo at a time reduces the risks.
Explain how clomifene therapy can help a woman who does not ovulate.
Mark scheme
- clomifene stops / blocks the (negative feedback) effect of oestrogen on the pituitary (1)
- so more FSH and LH are released (1)
- (which) stimulate egg maturation and ovulation (1)
Model answer
Clomifene blocks oestrogen's inhibition of the pituitary gland, so the pituitary releases more FSH and LH. These stimulate an egg to mature and be released, so the woman ovulates and may become pregnant naturally.
Explain why doctors often transfer only one embryo during IVF.
Mark scheme
- to reduce the chance of multiple births (1)
- which are risky for the mother and babies / babies more likely premature or low birth weight (1)
Model answer
Transferring one embryo reduces the chance of twins or triplets, and multiple births carry greater risks for the mother and the babies, such as premature birth.
Suggest one ethical issue raised by IVF.
Mark scheme
any one: unused embryos are destroyed / embryos have a right to life / embryo screening could lead to designer babies / who should pay or have access
Model answer
Spare embryos are often destroyed, and some people believe embryos have a right to life.
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