# Explain how increasing temperature affects the rate of an enzyme-controlled reaction, both below and above the enzyme's optimum temperature.

> Eduqas A-Level Biology — 1.4 Biological reactions and enzymes · Explain · 5 marks

> Enzymes are biological catalysts that speed up metabolic reactions in living cells. The rate at which an enzyme works is affected by temperature.

## Mark scheme (5 marks)

1. Below the optimum, increasing temperature increases the rate of reaction
2. Because molecules have more kinetic energy so move faster / collide more frequently
3. More enzyme-substrate complexes form (below/at the optimum)
4. Above the optimum temperature the enzyme becomes denatured
5. Because the shape of the active site changes permanently, so the substrate can no longer fit / no enzyme-substrate complexes can form, decreasing the rate of reaction

## Key terms

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

## Related

- [Revision notes for Eduqas A-Level Biology](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-increasing-temperature-affects-the-e676d3b1) · Published by Druglandscape Ltd.