# A farmer grows soybeans, which are known to be rich in proteins. Explain why proteins are essential for the growth and repair of cells in the human body, and describe the role of monomers in forming protein molecules.

> Pearson Edexcel A-Level Biology A (9BI0) — Topic 1 Biological Molecules · Explain · 5 marks

> Soybeans are a plant-based food source containing large amounts of protein. When humans digest soybeans, the proteins are broken down and the products are used to build new proteins in the body.

## Mark scheme (5 marks)

1. Proteins are made up of amino acids (monomers)
2. Amino acids are joined together to form a polymer (protein chain / polypeptide)
3. Proteins are needed for growth and repair because they are used to make new cells / cell structures / tissues
4. Proteins can also act as enzymes, which control chemical reactions in cells
5. Different sequences / combinations of amino acids produce different proteins with different functions

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](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-farmer-grows-soybeans-which-are-67413325) · Published by Druglandscape Ltd.