# Describe how temperature affects the rate of an enzyme-controlled reaction, including what happens both below and above the enzyme's optimum temperature.

> Eduqas A-Level Biology — 1.1 Chemical elements and biological molecules · Describe · 5 marks

## Mark scheme (5 marks)

1. As temperature increases up to the optimum, the rate of reaction increases
2. Because molecules have more kinetic energy so move faster, leading to more successful collisions between enzyme and substrate
3. More enzyme-substrate complexes form (at or below the optimum)
4. Above the optimum temperature, the enzyme becomes denatured / the active site changes shape
5. The substrate can no longer fit into the active site, so the rate of reaction decreases

## Key terms

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

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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-temperature-affects-the-rate-e45d66a2) · Published by Druglandscape Ltd.