Cross two heterozygous black mice and tell the possible phenotypes and genotypes in their offspring.

The correct answer is -

Phenotype: 3:1 (dominant black mice: recessive brown allele)

genotype: 1:2:1 (purebred dominant : heterozygous: purebred recessive)

Explanation:

In the given question there is a cross that takes place between two heterozygous black mice. LEt assumes B is black which is the dominant allele and b is the recessive allele or brown. As it is given in heterozygous condition black mice are present which means the B is dominant over b.

Now cross:

Gametes: B and b for each mice

      B        b

B     BB      Bb

b    Bb       bb

By the cross, there are two phenotypic offspring that produce 3 black mice out of four and 1 brown or recessive allele out of four

And, genotypically three offspring in the ratio of 1:2:1 (purebred dominant : heterozygous: purebred recessive)

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