In rats, the gene for the pigment (P) is dominant to no pigment (p). The gene for black (B) is dominant to the gene for cream (b). If a pigment gene (P) is absent, genes B and b are inoperative. Predict the genotypes and phenotypes of the F1 of a cross between a homozygous black rat and an albino homozygous for cream.

PpBb, albino

Explanation:

In this case, the pigment gene (P) is present, since the cross is between the homozygous black rate and an albino homozygous for cream. Hence a cross between these two rats would produce offspring with the genotype PpBb, while the phenotype would be that of albino, as long as the criteria If a pigment gene (P) is absent, genes B and b are inoperative is taken into consideration.