Final answer:
With the alleles BB, a mouse has black fur; with bb, it has white fur; and with Bb, it also has black fur. These outcomes follow simple Mendelian inheritance where black is dominant to white. However, in some cases like epistasis, other genes can affect the expression of these traits.
Step-by-step explanation:
In mice, black fur is dominant to white fur. The fur colour a mouse would have with the following allele combinations would be:
- a. BB: Black fur because both alleles are for the dominant black fur.
- b. bb: White fur because both alleles are for the recessive white fur trait.
- c. Bb: Black fur because the presence of one dominant allele for black fur is enough to express the trait.
It is important to note that while this question only considers one gene, in reality, coat color in mice and other organisms might involve multiple genes and can sometimes show more complex inheritance patterns such as epistasis, where the expression of one gene can be affected by another gene. For example, a mouse that is homozygous for the recessive allele responsible for pigment production (cc) will be albino, regardless of the genotype at a different locus that determines coat color. Thus, the detailed phenotypic ratios for a cross considering both the coat color and pigment production might yield results of agouti, solid color, and albino mice depending on their genotypes for both genes.