# Explain why increasing the temperature from 10 °C to the optimum temperature increases the rate of an enzyme-controlled reaction, and what happens to the rate of reaction when the temperature is raised well above the optimum.

> Cambridge International IGCSE Biology (0610) — 5.1 Enzymes · Explain · 4 marks

## Mark scheme (4 marks)

1. Increasing temperature increases the kinetic energy of molecules
2. More frequent / successful collisions between enzyme and substrate, so more enzyme-substrate complexes form
3. Above the optimum temperature the enzyme becomes denatured
4. Denaturation causes a permanent change in the shape of the active site, so the substrate can no longer bind and the rate of reaction decreases

## Key terms

- [optimum temperature](https://www.gradenine.co.uk/glossary/optimum-temperature)
- [rate of reaction](https://www.gradenine.co.uk/glossary/rate-of-reaction)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-increasing-the-temperature-from-b5af7af5) · Published by Druglandscape Ltd.