# Explain why glucose is described as the primary source of energy for cells, and describe how cells release energy from glucose.

> AQA A-Level Biology (7402) — 3.1.2 Carbohydrates · Explain · 5 marks

## Mark scheme (5 marks)

1. Glucose is broken down (in respiration) to release energy
2. Glucose is used in aerobic respiration, which requires oxygen
3. Products of aerobic respiration are carbon dioxide and water
4. When oxygen is not available, anaerobic respiration occurs (in animals, producing lactic acid; in yeast/plants, producing ethanol and carbon dioxide)
5. Glucose is the monomer / building block of polysaccharides (such as starch and glycogen), meaning it is readily available from digestion of these storage carbohydrates

## Key terms

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

## Related

- [Revision notes for AQA A-Level Biology (7402)](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-why-glucose-is-described-as-9313e925) · Published by Druglandscape Ltd.