# A student is investigating the effect of temperature on the rate of enzyme activity using a colorimeter. Explain how the student could ensure that the results obtained from this investigation are reliable.

> OCR A-Level Biology A (H420) — 1.2 Practical skills assessed in the practical endorsement · Explain · 4 marks

> A student sets up an investigation using catalase extracted from potato tissue to break down hydrogen peroxide at five different temperatures: 10 °C, 20 °C, 30 °C, 40 °C and 50 °C. Absorbance readings are taken using a colorimeter at regular intervals.

## Mark scheme (4 marks)

1. Repeat readings at each temperature and calculate a mean
2. Identify and exclude anomalous results from the mean calculation
3. Control all other variables that could affect enzyme activity
4. Calibrate the colorimeter before use with a blank (cuvette containing distilled water or reaction mixture without enzyme/substrate)

## Key terms

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

## Related

- [Revision notes for OCR A-Level Biology A (H420)](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)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-is-investigating-the-effect-4efdb40f) · Published by Druglandscape Ltd.