Two cycle records show hormone concentrations on days 23 and 26. No pregnancy occurs in either cycle.
| Cycle record | Day | Oestrogen concentration (relative units) | Progesterone concentration (relative units) |
|---|---|---|---|
| A | 23 | 14 | 20 |
| A | 26 | 13 | 19 |
| B | 23 | 15 | 21 |
| B | 26 | 5 | 4 |
Explain which cycle record is more likely to be followed soon by menstruation.
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.