In a species of snail, shell pattern is controlled by a single gene. The allele for a striped shell (S) is dominant to the allele for an unstriped shell (s). A striped snail was crossed with an unstriped snail. Their offspring had these shell patterns:
| Shell pattern | Number of offspring |
|---|---|
| Striped | 12 |
| Unstriped | 12 |
Explain what these results suggest about the genotypes of the two parent snails and the probability that their next offspring will have an unstriped shell. Use a genetic diagram in your answer.
186 exam-style questions on OCR GCSE Biology 5.1 Inheritance, covering 5.1.1 The genome, 5.1.2 Environment and phenotype, 5.1.3 Variants and mutations, 5.1.4 How genetic variants influence phenotype, 5.1.5 Asexual and sexual reproduction, 5.1.6 Haploid and diploid, 5.1.7 Meiotic cell division, 5.1.8 Single gene inheritance, 5.1.9 Predicting single gene crosses, 5.1.10 Sex determination, 5.1.11 Multiple gene inheritance, and 5.1.12 Development of our understanding of genetics. Each one has a worked solution and a mark scheme showing where the marks go.