# Explain how hydrogen bonding between water molecules gives water a high specific heat capacity and outline the significance of this property for organisms living in aquatic environments.

> 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 arising from the polarity of the O–H bonds.
2. A large amount of heat energy must be absorbed to break / disrupt these hydrogen bonds before the kinetic energy of molecules (and therefore temperature) increases, resulting in a high specific heat capacity.
3. The high specific heat capacity means the temperature of aquatic environments changes only slowly / remains relatively stable despite large fluctuations in air temperature.
4. This thermal stability allows aquatic organisms to maintain relatively constant internal conditions / enzyme-catalysed reactions to proceed efficiently, supporting survival and metabolic activity.

## Key terms

- [hydrogen bond](https://www.gradenine.co.uk/glossary/hydrogen-bond)
- [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-hydrogen-bonding-between-water-bd3da072) · Published by Druglandscape Ltd.