# Explain how the sodium-potassium pump maintains the resting membrane potential of a neuron.

> IB DP Biology Standard Level (2023 syllabus) — B2.1 Membranes and membrane transport · Explain · 4 marks

## Mark scheme (4 marks)

1. The sodium-potassium pump is a carrier protein / intrinsic protein embedded in the plasma membrane that uses ATP (active transport) to move ions against their concentration gradients.
2. Three sodium ions are pumped out of the cell for every two potassium ions pumped in, creating an unequal charge distribution.
3. The inside of the cell becomes negatively charged relative to the outside, establishing the resting membrane potential (approximately −70 mV in neurons).
4. The low intracellular Na⁺ concentration and high intracellular K⁺ concentration are maintained, which are essential for the cell to be able to generate an action potential.

## Key terms

- [sodium-potassium pump](https://www.gradenine.co.uk/glossary/sodium-potassium-pump)
- [resting membrane potential](https://www.gradenine.co.uk/glossary/resting-membrane-potential)

## 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-sodium-potassium-pump-maintains-e85f1472) · Published by Druglandscape Ltd.