# A student tests two food samples, X and Y, using the iodine test and Benedict's test. Sample X turns blue-black with iodine solution and remains blue after heating with Benedict's solution. Sample Y remains brown with iodine solution and turns brick-red after heating with Benedict's solution. Explain what these results tell the student about the biological molecules present in each sample.

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

## Mark scheme (4 marks)

1. Sample X contains starch
2. Sample X does not contain a reducing sugar / glucose
3. Sample Y does not contain starch
4. Sample Y contains a reducing sugar / glucose

## Key terms

- [iodine test](https://www.gradenine.co.uk/glossary/iodine-test)
- [Benedict's test](https://www.gradenine.co.uk/glossary/benedict-s-test)

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](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-tests-two-food-samples-6ab65fb9) · Published by Druglandscape Ltd.