# Explain why two organisms of the same species can show different phenotypes for the same characteristic, such as eye colour.

> Eduqas GCSE Biology — 2.4.1 Variation · Explain · 4 marks

## Mark scheme (4 marks)

1. Genes can exist in different forms called alleles / variants
2. Different alleles have slightly different DNA base sequences
3. Different alleles code for different proteins / amino acid sequences, producing different physical characteristics
4. The phenotype is also influenced by the environment / the genotype interacts with the environment to produce the phenotype

## Key terms

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

## 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)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-two-organisms-of-the-db7d5314) · Published by Druglandscape Ltd.