Question

$F_2$ ratio in chicken came out to be 9 rose comb blacks, 1 single comb white, 3 rose comb whites and 3 single comb blacks. Which are the recessives?

• A. Single comb, white plumage
• B. Rose comb, white plumage
• C. Single comb, black plumage
• D. Rose comb, black plumage

Answer 1

The correct option is A Single comb, white plumage

Two or more genes, interact together, specifying the phenotype of specific trait are called Collaborative genes. In chickens a single dominant gene specifies one type of Comb . When the two pairs of dominant genes together, new phenotype appear. PP alleles is for pea comb, RR alleles for Rose comb. When P and R together Walnut comb appear. When a pea comb chicken is crossed to Rose comb chicken, in the F2 generation 9Walnut comb, 3 rose comb 3 pea comb 1 single comb chickens are formed.

So, the correct option is ‘single comb, white plumage’