Question

An incompletely dominant gene controls the color off chickens so that BB produces black, Bb produces a slate-gray color called blue, and bb produces splashed white. A second gene controls comb shape, with the dominant gene R producing a rose comb and r producing a single comb. If a pure-breeding black chicken with a rose comb is mated to a splashed white chicken with a single comb in the F2 generation, what fraction of the offspring will be black with rose comb?

Answer 1

Approximately 56.25% of the offspring will be black with a rose comb.

Step-by-step explanation:

When a pure-breeding black chicken with a rose comb (BBRR) is mated to a splashed white chicken with a single comb (bbrr), the F1 generation will be all black with a rose comb (BbRr) due to incomplete dominance and the dominant nature of the rose comb gene. The F1 generation will then be heterozygous for both traits. When the F1 generation is crossed in the F2 generation, the offspring will exhibit a 9:3:3:1 phenotypic ratio. Therefore, 9/16 or approximately 56.25% of the offspring will be black with a rose comb.