# Explain why two pea plants with the same phenotype for seed texture can have different genotypes.

> OCR GCSE Biology A: Gateway Science (J247) — B5.1 Inheritance · Explain · 4 marks

> Pea plants can produce either wrinkled seeds or round seeds. Round seed texture is controlled by a dominant allele (R) and wrinkled seed texture is controlled by a recessive allele (r). A scientist grows several pea plants and observes that some plants producing round seeds have different genotypes to one another.

## Mark scheme (4 marks)

1. The dominant allele (R) is always expressed when present
2. A homozygous dominant plant (RR) has two dominant alleles and produces round seeds
3. A heterozygous plant (Rr) also produces round seeds because the recessive allele is not expressed
4. Therefore RR and Rr have the same phenotype (round seeds) but different genotypes

## Key terms

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

## Related

- [Revision notes for OCR GCSE Biology A: Gateway Science (J247)](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-pea-plants-with-2b74f49c) · Published by Druglandscape Ltd.