A marine mammal does not feed during a long journey. Receptors detect changes in its blood glucose concentration. A coordination centre sends a signal to gland X. Gland X releases a hormone into the blood that causes the blood glucose concentration to rise.
Researchers measured the blood glucose concentration when gland X responded normally and when gland X was unable to respond.
| Time without food in hours | Blood glucose concentration when gland X responded normally in mmol/dm³ | Blood glucose concentration when gland X was unable to respond in mmol/dm³ |
|---|---|---|
| 0 | 5.0 | 5.0 |
| 2 | 4.3 | 4.3 |
| 4 | 4.8 | 3.7 |
| 6 | 5.0 | 3.2 |
Using information in the table, explain why gland X is an effector and why the blood glucose concentration after 6 hours is different when gland X is unable to respond.
76 exam-style questions on AQA GCSE Biology 5.1 Homeostasis, covering 5.1 Homeostasis. Each one has a worked solution and a mark scheme showing where the marks go.