A fertility clinic plans to transfer an embryo into a woman's uterus. All other factors are the same on the two possible transfer days.
| day of cycle | thickness of uterus lining in mm |
|---|---|
| 4 | 2.0 |
| 20 | 8.0 |
The embryo is transferred on day 20. Shortly after the transfer, the concentrations of progesterone and oestrogen fall.
Use the data to explain why transferring the embryo on day 20 is more likely to result in pregnancy than transferring it on day 4, and how the fall in hormone concentrations could affect this chance.
90 exam-style questions on Edexcel GCSE Biology 7.2 Reproductive hormones, covering 7.2.1 Stages of the menstrual cycle, 7.2.2 Hormonal control of the menstrual cycle, 7.2.3 Hormonal contraception, 7.2.4 Evaluating contraception methods, and 7.2.5 Hormones in Assisted Reproductive Technology. Each one has a worked solution and a mark scheme showing where the marks go.