Question

Concerning comb shape in chickens, which of the following is true? Multiple Choice

The R gene is dominant to the P gene.
The R and P must both be present to produce a walnut comb.
R is recessive to r and produces a rose comb.
P is recessive to p and produces a single comb.

Answer 1

The R and P must both be present to produce a walnut comb.

Step-by-step explanation:

Comb shape in chickens is an example of intergenic interaction. Two genes R and P come together to determine the type of comb.

• If R is present in dominant form and p in recessive form ( R_pp ) : Rose comb
• If P is present in dominant form and r in recessive form ( rrP_ ) : Pea comb
• If both R and P are present in dominant form ( R_P_ ) : Walnut comb
• If both r and p are present in recessive form ( rrpp ) : Single comb

Hence, it is clear that both R and P must be present to produce a walnut comb.