Allele

How this is marked

Do not use 'gene' and 'allele' interchangeably in genetics answers. Mark schemes check. A gene codes for a characteristic; alleles are its versions. Genetic cross questions are marked on correct allele notation (R and r, defined in your answer).

In an exam answer

In a genetics answer: 'The gene for seed shape has two alleles, a round allele (R) and a wrinkled allele (r), found at the same position on the chromosome.'

Full topic guide: Inheritance