# A student investigates the effect of temperature on the activity of amylase. As the temperature is increased from 10°C to 40°C, the rate at which amylase breaks down starch increases. Above 40°C, the rate of reaction decreases until amylase no longer functions. Explain these observations.

> WJEC A-Level Biology (Wales) — 1.2 Cell structure and organisation · Explain · 5 marks

## Mark scheme (5 marks)

1. Between 10°C and 40°C, molecules have more kinetic energy as temperature increases
2. More successful collisions occur between the substrate and the active site of the enzyme
3. More enzyme-substrate complexes form, so the rate of reaction increases
4. Above 40°C, the active site of the amylase changes shape / the enzyme is denatured
5. The substrate can no longer fit into the active site, so no enzyme-substrate complexes can form and the reaction stops

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Biology (Wales)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-investigates-the-effect-of-2d8c67b0) · Published by Druglandscape Ltd.