Question

Consider a cross in which a trait is inherited by incomplete dominance. What percentage of the F₂ from the mating of homozygous dominant and homozygous recessive individuals will possess the dominant phenotype?

Options

• 0 per cent

• 25 per cent

• 50 per cent

• 75 per cent

Answer 1

25 per cent

Explanation:

In incomplete dominance, the heterozygotes show an intermediate phenotype, not the dominant phenotype, so they are not counted as having the dominant phenotype. Only the homozygous dominant genotype shows the dominant phenotype, which is 25% in the F₂ generation. This is consistent with the phenotypic ratio of 1:2:1 seen in incomplete dominance crosses.