# Explain how the hydrogen bonding between water molecules is responsible for the high specific heat capacity of water, and outline the significance of this property for aquatic organisms.

> IB DP Biology Higher Level (2023 syllabus) — A1.1 Water · Explain · 4 marks

## Mark scheme (4 marks)

1. Water molecules form hydrogen bonds with neighbouring water molecules due to the partial charges on oxygen (δ−) and hydrogen (δ+) atoms.
2. A large amount of energy (heat) is required to break the many hydrogen bonds before the kinetic energy / temperature of the water increases, giving water a high specific heat capacity.
3. The high specific heat capacity means aquatic environments resist rapid changes in temperature / remain thermally stable.
4. Thermal stability of the aquatic environment is significant for aquatic organisms because enzymes / metabolic reactions / homeostasis function optimally within a narrow temperature range.

## Key terms

- [hydrogen bonding](https://www.gradenine.co.uk/glossary/hydrogen-bonding)
- [specific heat capacity](https://www.gradenine.co.uk/glossary/specific-heat-capacity)

## 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-the-hydrogen-bonding-between-c7444106) · Published by Druglandscape Ltd.