# Describe how the biuret test is carried out on a food sample and explain what each possible result indicates.

> Cambridge International IGCSE Biology (0610) — 4.1 Biological molecules · Describe · 4 marks

## Mark scheme (4 marks)

1. Add sodium hydroxide solution to the sample (in a test tube)
2. Add a few drops of dilute copper(II) sulphate solution
3. A purple colour indicates that protein is present in the sample
4. If the solution remains blue, no protein is present in the sample

## Key terms

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

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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-the-biuret-test-is-f1ff0374) · Published by Druglandscape Ltd.