Question

In mice, brown eyes (B) are dominant over blue (b). A homozygous brown-eyed males mouse mates with a blue-eyed female mouse and they have baby mice. What are the phenotypes and genotypes of their offspring? What are the genotypes of the parents?

Answer 1

The answers are:
Q1. Phenotype of the offspring: mice with brown eyes. Genotype of the offspring: Bb.
Q2. Genotypes of the parents: male mouse - BB, female mouse - bb.

Since allele B is dominant over allele b, only one copy of B is needed for brown eyes, so we have following genotypes and phenotypes:
genotype phenotype
BB a homozygote with brown eyes
Bb a heterozygote with brown eyes
bb a homozygote with blue eyes

A homozygous brown-eyed males (BB) mates with a blue-eyed female mouse (bb). The offspring will get one allele from the father (allele B) and one allele from the mother (b):
Parents BB x bb
Offspring Bb Bb Bb Bb

So, all of the offspring will be Bb - heterozygotes with brown eyes.