Question

What phenotypic ratio in test cross offspring indicates that the dominant parent is heterozygous (Tt)?

Options

• All recessive phenotypes

• 1:1 ratio of dominant to recessive traits

• 3:1 ratio of dominant to recessive traits

• All dominant phenotypes

Answer 1

A 1:1 ratio of dominant to recessive offspring indicates the dominant parent is heterozygous (Tt). This occurs because Tt × tt produces Tt and tt offspring in equal proportions, expressing both dominant and recessive phenotypes.