Question

In mice, brown fur is the dominant trait, and the recessive trait is white fur. In a cross between two heterozygous mice, how many offspring will be white if 24 mice result from the cross?

Answer 1

6 offsprings with white fur

Step-by-step explanation:

The gene involved here codes for fur colour in mice where the allele for brown fur (B) is dominant over the allele for white fur (b) i.e. the B allele will mask the expression of b allele in an heterozygous state (Bb).

Since allele B is dominant, in an heterozygous state (Bb), the mice will be brown-furred. Hence in a cross between two Bb parents, a phenotypic ratio of 1:2:1 will be produced where;

1 is BB (homozygous brown fur), 2 is Bb (heterozygotic brown fur) and 1 is bb (homozygous white fur).

Hence, 1/4 × 100= 25% offsprings will be white furred. If 24 mice result, 25/100 × 24 = 6 offsprings will be white.