An incompletely dominant gene controls the color of chickens so that BB produces black,?

Question

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?

1. 9/16

2. 3/8

3. 3/16

4. 1/8

5. 1/16

Answer 1

You are given a cross: pure-breeding black chicken with a rose comb (BBRR) crossed with splashed white chicken with a single comb (bbrr), which gives an F1 generation of:

BbRr

Self the F1 to get the F2: BbRr x BbRr. The desired phenotype is produced by BBRR or BBRr. Of the 16 offspring produced, 3 have the correct genotypes, so the answer is 3 (3/16).