# Homeostasis is the maintenance of a constant internal environment. Explain why it is important for the body to maintain a constant internal temperature and a constant blood glucose concentration.

> Pearson Edexcel A-Level Biology A (9BI0) — 4.6 Homeostasis · Explain · 5 marks

> During exercise, a student notices they begin to sweat and feel hungry shortly afterwards.

## Mark scheme (5 marks)

1. Enzymes work best at an optimum temperature / enzymes are denatured if temperature is too high
2. If body temperature is not maintained, metabolic reactions / enzyme-controlled reactions in cells will slow down or stop
3. Glucose is needed as a source of energy / for respiration
4. If blood glucose concentration is too low, cells cannot respire adequately / not enough energy is released for cellular processes
5. If blood glucose concentration is too high, water moves out of cells by osmosis, causing cells to shrink / become dehydrated

## Key terms

- [homeostasis](https://www.gradenine.co.uk/glossary/homeostasis)
- [internal environment](https://www.gradenine.co.uk/glossary/internal-environment)
- [blood glucose concentration](https://www.gradenine.co.uk/glossary/blood-glucose-concentration)

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](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/homeostasis-is-the-maintenance-of-a-99acf887) · Published by Druglandscape Ltd.