Question

A breed of chicken shows codominance for feather color. One allele codes for black feathers, another codes for white feathers. The feathers of heterozygous chickens of this breed will be

Answer 1

Generally the relationship between alleles of a gene is that of dominant and recessive ie in the presence of a dominant allele the recessive allele doesn't express. However in co-dominance both the alleles express and the dominant - recessive relationship disappears. So in this case heterozygous chickens will have both white and black feathers.
have a look at the uploaded image to get a clear idea .