# Explain why the products of fermentation by yeast can eventually stop the fermentation process from continuing.

> Cambridge International IGCSE Biology (0610) — 12.1 Respiration · Explain · 4 marks

> Yeast is used in brewing to produce alcoholic drinks. During brewing, yeast breaks down glucose anaerobically in a process called fermentation. Over time, the fermentation process slows and eventually stops.

## Mark scheme (4 marks)

1. Fermentation produces alcohol (ethanol) as a product
2. Alcohol accumulates / builds up in the surroundings of the yeast
3. High concentrations of alcohol denature the enzymes responsible for (catalysing) fermentation / respiration
4. Denatured enzymes can no longer catalyse / speed up the breakdown of glucose, so fermentation stops

## Key terms

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

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](https://www.gradenine.co.uk/learn)
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