The allele for brown fur in mice (B) is dominant over the allele for white fur (b).

The fur color of one mouse is represented by Bb.

What is the genotype of this mouse?

What is the phenotype of this mouse?

Genotype is if it is dominant or recessive, and phenotype are the physical characteristics of the fur.

Genotype:

Since it has a capital letter, it is dominant, and since both letters are not the same case, it is heterozygous dominant.

Phenotype:

Since dominant traits mask recessive, it is brown fur.