# Explain how the properties of water make it an effective solvent for ionic compounds and polar molecules within living cells.

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

## Mark scheme (4 marks)

1. Water molecules are polar / have an uneven distribution of charge due to the electronegativity of oxygen, creating partial negative (δ−) and partial positive (δ+) charges.
2. Water molecules orient around ions / polar solutes — the δ− oxygen faces cations and the δ+ hydrogen faces anions — forming hydration shells that keep solute particles separated in solution.
3. For polar molecules (e.g. glucose, amino acids), hydrogen bonds and dipole–dipole interactions form between the polar groups of the solute and water, dispersing the molecules throughout the solvent.
4. Being an effective solvent is essential for cell metabolism because it allows reactants and products (ions, metabolites) to move freely and interact, enabling biochemical reactions to occur in the cytoplasm / organelles.

## Key terms

- [polar molecule](https://www.gradenine.co.uk/glossary/polar-molecule)
- [solvent](https://www.gradenine.co.uk/glossary/solvent)

## 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-properties-of-water-1fb952fc) · Published by Druglandscape Ltd.