# Explain how a lipid-soluble hormone produces a response in a target cell, including the role of the hormone–receptor complex.

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

## Mark scheme (4 marks)

1. Lipid-soluble hormones can diffuse directly across the phospholipid bilayer of the plasma membrane (because they are non-polar / hydrophobic).
2. The hormone binds to a specific receptor protein located in the cytoplasm or nucleus of the target cell, forming a hormone–receptor complex.
3. The hormone–receptor complex moves into (or acts within) the nucleus and functions as a transcription factor, binding to specific regions of DNA (response elements / promoter regions).
4. Binding of the hormone–receptor complex to DNA alters the rate of transcription of specific genes, leading to changes in protein synthesis and hence a cellular response.

## Key terms

- [lipid-soluble hormone](https://www.gradenine.co.uk/glossary/lipid-soluble-hormone)
- [hormone–receptor complex](https://www.gradenine.co.uk/glossary/hormone-receptor-complex)
- [target cell](https://www.gradenine.co.uk/glossary/target-cell)

## 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)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-a-lipid-soluble-hormone-produces-57d433b8) · Published by Druglandscape Ltd.