# Explain why two organisms of the same species can have different characteristics even though they share the same genome.

> Eduqas GCSE Biology — 7.1 The genome and gene expression · Explain · 4 marks

> Scientists have found that identical twins, who have the same DNA sequence, can sometimes develop different physical characteristics as they grow older.

## Mark scheme (4 marks)

1. Gene expression can differ between individuals / not all genes are expressed in every cell or at every time
2. The environment can influence which genes are expressed / environmental factors affect gene expression
3. Proteins are produced as a result of gene expression, and it is proteins that determine characteristics
4. If different genes are expressed, different proteins are made, leading to different characteristics / phenotype differs despite same genotype

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Biology](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/explain-why-two-organisms-of-the-7c79cda6) · Published by Druglandscape Ltd.