# Explain how the structure of the vacuole in plant cells is related to its functions.

> IB DP Biology Standard Level (2023 syllabus) — B2.2 Organelles and compartmentalisation · Explain · 4 marks

## Mark scheme (4 marks)

1. The vacuole is enclosed by a single membrane called the tonoplast, which controls the movement of substances into and out of the vacuole.
2. The large central vacuole occupies most of the cell volume, storing water and dissolved solutes (sugars, ions, pigments, or waste products).
3. The vacuole contains cell sap at high solute concentration, generating osmotic pressure that draws water in by osmosis, creating turgor pressure that supports the cell.
4. The compartmentalisation provided by the tonoplast isolates stored substances (e.g. toxins, pigments, or acids) from the cytoplasm, protecting metabolic reactions and/or deterring herbivores.

## Key terms

- [vacuole](https://www.gradenine.co.uk/glossary/vacuole)

## Related

- [Revision notes for IB DP Biology Standard Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-structure-of-the-37269f38) · Published by Druglandscape Ltd.