# Explain how the properties of water are important to organisms that live in rocky intertidal zones, where they are exposed to air and direct sunlight at low tide.

> AQA A-Level Biology (7402) — 3.1.7 Water · Explain · 5 marks

> Rocky intertidal organisms such as limpets and seaweeds are regularly exposed to air and high temperatures when the tide goes out. They must survive until the tide returns.

## Mark scheme (5 marks)

1. Water has a high specific heat capacity, so large amounts of heat energy are needed to raise its temperature
2. This prevents the body fluids / cells of organisms from overheating / experiencing large temperature fluctuations when exposed to sunlight
3. Water has a high latent heat of evaporation / vaporisation, so a large amount of energy is needed to evaporate it
4. This slows water loss / desiccation from the organism's body when exposed to air and sun, helping prevent dehydration
5. Water is a solvent / metabolic reactions require water as a reactant or medium, so retaining water allows chemical reactions / metabolism to continue

## Related

- [Revision notes for AQA A-Level Biology (7402)](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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