Question

In cocker spaniels, black color (b) is dominant over red (b), and solid color (S) is dominant over spotted (s).

If the genes are linked and the offspring of BBss and bbss individuals are mated with each other, what fraction of their offspring will be black and spotted?

a) 1/16 b) 9/16 c) 1/9 d) 3/16 e) 3/4

Answer 1

e) 3/4

Explanation:

As given;

Black (B) is dominant over red (b), so B is dominant over b.

Solid (S) is dominant over spotted color(s), so S is dominant over s.

Offspring of BBss and bbss individuals are:

Gametes of parent BBss are Bs, Bs and gamete of bbss are bs, bs

offspring are : all Bbss

Cross between these offspring is; Bbss×Bbss

Gametes of parent Bbss are: Bs and bs as given that the genes are linked.

Bs, bs × Bb, bs

Offspring are = BBss, Bbss, Bbss, bbss

Black spotted (B_ss) = 3/4