A person had their thyroid gland removed. The person now takes thyroxine tablets every day.
Doctors use the concentration of TSH in the blood to check whether the dose of thyroxine is correct.
Explain why the person needs to take thyroxine tablets for the rest of their life.
Explain why a high concentration of TSH shows that the dose of thyroxine is too low.
The doctor increases the dose of thyroxine.
Predict the effect on the concentration of TSH in the blood.
Give a reason for your answer.
42 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.