Equal masses of thyroid tissue were placed in three dishes of culture solution. A different hormone was added to two of the dishes. All other conditions were controlled.
| Hormone added | Thyroxine released by the tissue in arbitrary units |
|---|---|
| none | 6 |
| TSH | 19 |
| insulin | 6 |
Which conclusion is supported by these results?
Thyroid tissue responds to TSH but does not respond to insulin.
Insulin lowers the amount of thyroxine released by thyroid tissue.
Thyroid tissue responds to TSH and also responds to insulin.
Thyroid tissue makes thyroxine by converting the added TSH.
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.