Question

In mice, the allele for black coat color (B) is dominant over the brown allele (b). Two heterozygous mice are mated, and produce the following offspring:

20 black
4 brown

What is the EXPECTED FREQUENCY of black and brown mice in the offspring from this cross?

a. 5 black: 1 brown
b. 3 black: 1 brown
c. 2 black: 1 brown
d. 1 black: 3 brown

Answer 1

a. 5 black: 1 brown

Step-by-step explanation:

This question involves a gene coding for coat color in mice. The allele for black coat color (B) is dominant over the brown allele (b). This means a mouse that is heterozygous for the Gene will have a black coat color.

According to this question, two heterozygous mice are mated i.e. Bb × Bb to produce the following offspring: 20 black mice and 4 brown mice.

Based on this result, the EXPECTED FREQUENCY of black and brown mice in the offsprings can be calculated;

20 black ÷ 4 = 5

4 brown ÷ 4 = 1

The expected frequency of black to brown is 5:1.