If the offspring of a cross between a brown mouse (bb) and a black mouse (BB) are allowed to interbreed, how many different genotypes would result?

Answer Details

If the offspring of a cross between a brown mouse (bb) and a black mouse (BB) are allowed to interbreed, four different genotypes would result.
When the brown mouse (bb) and black mouse (BB) are crossed, their offspring are all heterozygous (Bb) and have a black coat due to the dominant black allele. If these offspring are allowed to interbreed, their offspring can have any of the four possible combinations of alleles from their parents: BB, Bb, bB, or bb. The BB and bb genotypes will produce black and brown coat colors respectively, while the Bb and bB genotypes will produce a black coat, as the black allele is dominant. Therefore, the four possible genotypes that can result from the interbreeding of the offspring are BB, Bb, bB, and bb.