Question

Two black female mice are coupled with a brown male mouse. If female A produces 4 black and 3 brown children and female B in its litter produces 10 black children, what is the genotype of A, B and male mouse respectively?

(a) BB Bb and bb

(b) Bb Bb and Bb

(c) Bb BB and bb

(d) bb Bb and BB

The question was asked during an interview.

This interesting question is from Numerical Problems in section Mendelian Genetics of Cytogenetics

Answer 1

Right option is (c) Bb BB and bb

The explanation: Brown mouse is homozygous recessive so this is sort of a test cross for the female mice. As mouse A has both black and brown progeny, it must be heterozygous. And within his litter size, we can say that B is expected to be homozygous BB.