In a species of bird, a head crest is controlled by one gene. The allele C C\,C is dominant and produces a head crest. The allele c c\,c is recessive and produces no head crest.
A geneticist records these genotypes:
| Bird | Genotype recorded |
|---|---|
| X | CcCcCc |
| Y | cccccc |
State whether bird X is homozygous or heterozygous, and state the phenotype shown by bird Y.
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.