1. A brown mink crossed with a silver-blue mink produced all brown offspring. When these F1 were crossed among themselves, they produced forty-seven brown animals and fifteen silver-blue animals. What are the genotypes of the parentals and the F1s

The correct answer is -

Parental - BB and bb

F1

Genotypes: 100% Bb  

F2

Genotypes: ¼ BB, ½ Bb, ¼ bb

Explanation:

It is given that a cross between a brown and a silver-blue mink produces all brown offspring and it is only possible if brown is dominant over silver blue in true breed cross, assume brown trait is represented by B and silver-blue is b then parents will be

BB and bb

   B    B

b  Bb   Bb

b  Bb   Bb

Cross between F1 individuals: Bb cross Bb

gametes : B, b and B, b

   B     b

B  BB   Bb

b   Bb    bb

the genotype of F2 : 1:2:1 = ¼ BB, ½ Bb, ¼ bb

the answer is sex-linked recessive.