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

Question

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. A pure-breeding black chicken with a rose comb was mated to a splashed white chicken with a single comb, and the F2 generation was produced. What fraction of the F2 offspring will be black with rose comb?

a. 9/16
b. 3/8
c. 3/16
d. 1/8
e. 1/16

thanks in advance!

Answer 1

Parents: BBRR x bbrr
F1: all BbRr; all blue, rose
F2: gametes from each parent are BR Br bR br
Write those four at the top of the Punnett square and write a second set of those four gametes at the left side of the square.
How many of the 16 boxes contain BBRR or BBRr as those are the only two genotypes that will produce the black, rose phenotype?

You should count 1 BBRR and 2 BBRr out of the 16 boxes. The expected fraction of offspring with the black, rose phenotype is 3/16.