Question

Incomplete Dominance Problem... In Andalusian fowls the heterozygous condition of the factors for black plumage and white plumage is blue. What offspring will a blue Andalusian fowl have if bred to birds of the following plumage colors: (a) black, (b) blue, (C) white. Do you think it possible to breed Andalusians true for blue? Why?

Answer 1

The first thing to remember is the random assortment of alleles: a blue fowl will give gametes that are either black or white, so when bred with a black one that can only have black alleles you'll get either balck or blue:

With blue, the Punnett square will look like this:

so you will get one black fowl, 2 blue and a white in every four offspring.

With white, the offspring will be only white and blue. I'll let you draw your own conclusions about the last question - get back to me if you have trouble.