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.

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

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.