Question

Crosses between F₁ individuals resulting from the cross AABB × aabb lead to F₂ phenotypic ratio close to ______.

Options

• 1 : 1 : 1 : 1

• 3 : 1

• 9 : 3 : 3 : 1

• 1 : 2 : 1

Answer 1

Crosses between F₁ individuals resulting from the cross AABB × aabb lead to F₂ phenotypic ratio close to 9 : 3 : 3 : 1.

Explanation:

Crosses between F₁ individuals resulting from the cross AABB × aabb produce F₁ heterozygotes (AaBb). When these F₁ individuals are crossed (AaBb × AaBb), the F₂ generation exhibits a classic dihybrid Mendelian phenotypic ratio of 9 : 3 : 3 : 1 for the traits controlled by the two gene pairs. This ratio reflects the independent assortment of two pairs of alleles, giving nine offspring with both dominant traits, three with the first dominant and second recessive trait, three with the first recessive and second dominant trait, and one with both recessive traits.