Question

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

Options

• 75 per cent

• 50 per cent

• 25 per cent

• 0 per cent

Answer 1

50 per cent

Explanation:

Starting with AA crossed with aa gives all heterozygous Aa in F₁. When these F₁ heterozygotes interbreed, their offspring in F₂ follow a 1:2:1 genotypic ratio, meaning half are Aa (heterozygous), one quarter AA, and one quarter aa. This 1:2:1 ratio results from the random segregation of alleles during gamete formation under complete dominance inheritance.