Define the term dominant allele

A dominant allele is a gene variant that expresses its phenotypic trait even when only one copy is present in the genotype. This means that if an individual inherits one dominant allele and one recessive allele for a specific gene, the trait associated with the dominant allele will be observed.

For example, in pea plants, the allele for purple flowers (P) is dominant over the allele for white flowers (p). A plant with the genotype Pp will have purple flowers because the dominant P allele masks the effect of the recessive p allele.