# Life Sciences Paper 1, November 2024, question 3.4.3

> The diagram below shows how the level of thyroxin in the blood of a healthy... Marked mark by mark. Q3.4.3, Life Sciences Paper 1 November 2024, 4 marks.

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Last updated: 2026-11-12

Subject: Life Sciences. Source: Based on Nov 2024 · Paper 1 · Q3.4.3. Marks: 4. Not yet checked by a teacher.

## Question 3.4.3 (4 marks)

The diagram below shows how the level of thyroxin in the blood of a healthy person is kept steady. A low thyroxin level at point X is detected by the body. Explain how the pituitary gland helps to bring thyroxin back to its normal level.

Figure: Flow diagram with GLAND Y on the left and PITUITARY GLAND on the right. A dashed upper loop: an arrow from Gland Y to the pituitary labelled Level of thyroxin (X), the low level, and a return arc over the top labelled Less TSH. A solid lower loop: an arrow from Gland Y to the pituitary labelled Level of thyroxin (Z), the high level, and a return arc underneath labelled More TSH.

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[Answer this question](https://sharpkop.co.za/life-sciences/2024-nov-p1/q3-4-3/) and see it marked mark by mark, with the reason for every lost mark.

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