# A baker adds yeast to dough in a warm, enclosed container. Over time, the dough rises and a distinctive smell develops. Explain how the process of anaerobic respiration in yeast is responsible for these observations.

> Cambridge International IGCSE Biology (0610) — 12.3 Anaerobic respiration · Explain · 4 marks

## Mark scheme (4 marks)

1. Yeast respires anaerobically, breaking down glucose to produce carbon dioxide (and alcohol).
2. The carbon dioxide gas produced causes the dough to rise.
3. Alcohol (ethanol) is also produced during anaerobic respiration in yeast.
4. The distinctive smell is due to the alcohol (ethanol) produced.

## Key terms

- [anaerobic respiration](https://www.gradenine.co.uk/glossary/anaerobic-respiration)
- [yeast](https://www.gradenine.co.uk/glossary/yeast)

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](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/a-baker-adds-yeast-to-dough-f76f5f78) · Published by Druglandscape Ltd.