Question

Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). The genes for the two traits are non-linked. What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?

Answer 1

Answer: One half of the progeny would have black fur and long tail.

Explanation: Given P1 BbTt x BBtt

Gametes according to segregation law are 1/2 BB, 1/2 Bb and 1/2 Tt, 1/2 tt

The F1 then: 1/4 BBTt, 1/4 BBtt, 1/4BbTt, 1/4 Bbtt.

So finally we obtain the result for the phenotype. The 50% of the mice are black and have long tails.