A progesterone contraceptive injection is given at week 0. The table shows the mean FSH concentration in the blood of a group of women before the injection and 12 weeks after the injection.
| Time | Mean FSH concentration in arbitrary units |
|---|---|
| Before the injection | 8.0 |
| 12 weeks after the injection | 2.0 |
Calculate the percentage decrease in the mean FSH concentration 12 weeks after the injection.
Explain how the injection caused the change in FSH concentration and how this change helps to prevent pregnancy.
85 exam-style questions on AQA GCSE Biology 5.3 Hormonal coordination in humans, covering 5.3.1 Human endocrine system, 5.3.2 Control of blood glucose concentration, 5.3.3 Maintaining water and nitrogen balance in the body, 5.3.4 Hormones in human reproduction, 5.3.5 Contraception, 5.3.6 The use of hormones to treat infertility (HT only), and 5.3.7 Negative feedback (HT only). Each one has a worked solution and a mark scheme showing where the marks go.