# Explain how down-regulation of receptors allows a target cell to reduce its sensitivity to a hormone signal.

> IB DP Biology Higher Level (2023 syllabus) — C2.1 Chemical signalling (HL only) · Explain · 4 marks

## Mark scheme (4 marks)

1. Down-regulation involves a reduction in the number of receptors present on the surface of (or within) the target cell
2. Receptors are internalised (endocytosed) into the cell when hormone–receptor complexes form, removing them from the cell surface
3. With fewer receptors available, less hormone can bind, so the magnitude/intensity of the cellular response is reduced
4. Down-regulation is a form of negative feedback that prevents over-stimulation of / desensitises the target cell to sustained or excessive hormone levels

## Key terms

- [down-regulation](https://www.gradenine.co.uk/glossary/down-regulation)

## Related

- [Revision notes for IB DP Biology Higher Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-down-regulation-of-receptors-allows-5c281c5f) · Published by Druglandscape Ltd.