# Explain why a cell with a higher surface area to volume ratio absorbs dissolved substances by diffusion more quickly than a cell with a lower surface area to volume ratio.

> Pearson Edexcel International GCSE Biology (4BI1) — 2.4 Movement of substances into and out of cells · Explain · 4 marks

> Some unicellular organisms are very small, whilst some specialised animal cells are much larger. The rate at which substances move into a cell by diffusion depends on several factors, including the surface area to volume ratio of the cell.

## Mark scheme (4 marks)

1. A higher surface area to volume ratio means more cell membrane is available relative to the volume of the cell / more membrane is exposed to the surrounding solution
2. More substances can enter the cell across the membrane per unit time / diffusion occurs across a greater area simultaneously
3. The concentration gradient between the outside of the cell and the inside is maintained / substances do not accumulate inside the cell as quickly relative to its volume
4. Therefore the overall rate of diffusion into the cell is faster / substances reach all parts of the cell more quickly

## Key terms

- [surface area to volume ratio](https://www.gradenine.co.uk/glossary/surface-area-to-volume-ratio)
- [diffusion](https://www.gradenine.co.uk/glossary/diffusion)

## Related

- [Revision notes for Pearson Edexcel International GCSE Biology (4BI1)](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-why-a-cell-with-a-d8806656) · Published by Druglandscape Ltd.