Question

In mice, the allele for black fur is dominant to the allele for brown fur. A male homozygous black mouse is crossed with a female brown mouse, and the F1 offspring are allowed to breed. What percentage of F2 offsprings do you predict will be homozygous black mice?

Answer 1

The male homozygous black mouse would have the genotype BB (assuming the letter representing black fur is B), so the female brown mouse would have to have the genotype bb. This means that 100% of their offspring would have the genotype Bb, making them heterozygous black. If these mice bred, it would have the following results based on their partner's genotype:
Bb+BB= 50% homozygous black
Bb+Bb=25% homozygous black
Bb+bb=0% homozygous black

Answer 2

Answer:

25%

Explanation:

Given that the allele for black fur is dominant to the allele for brown fur. A male homozygous black mouse (BB) is crossed with a female brown mouse (bb). The F1 progeny would have black fur with heterozygous dominant genotype (Bb).

Self crossing of F1 progeny would obtain the F2 progeny in following genotype ratio= 1/4 BB (homozygous black): 1/2 Bb (heterozygous black): 1/4 bb (homozygous brown).

Hence, 25% of the F2 progeny would be homozygous black.