A researcher uses a computer simulation of the control of thyroxine concentration. In the simulation, one of the two inhibitory effects of thyroxine does not occur. The simulation starts with normal hormone concentrations.
| Time in hours | TRH concentration (% of normal) | TSH concentration (% of normal) | Thyroxine concentration (% of normal) |
|---|---|---|---|
| 0 | 100 | 100 | 100 |
| 12 | 60 | 170 | 160 |
Use the data to explain which inhibitory effect of thyroxine does not occur and how this affects the metabolic rate at 12 hours.
89 exam-style questions on Edexcel GCSE Biology 7.1 Hormones and coordination, covering 7.1.1 Endocrine glands and hormone transport, 7.1.2 Adrenalin and fight or flight, and 7.1.3 Thyroxine and negative feedback. Each one has a worked solution and a mark scheme showing where the marks go.