according to the mendelian inheritance pattern, where the trait is only determined by one gene, mice where gene B codes for black fur and b codes for brown, what is the phenotype for a mouse with the genotype Bb?

Question

both black & brown hairs
fur with black hairs
fur with brown hairs
fur with yellow hairs

Answer 1

In the case of Mendelian inheritance for the mouse fur color you described, the allele B codes for black fur and the allele b codes for brown fur. Since B is dominant over b, a mouse with the genotype Bb would exhibit the dominant phenotype.

Therefore, the phenotype for a mouse with the genotype Bb would be fur with black hairs.