Question

Two pure-breeding mutant dogs were crossed: The male had small ears (wild-type ears are large) and the female had purple fur (wild-type fur color is brown). All F1 dogs (male and female) had small ears and brown fur. Assuming independent assortment, what proportion of the F2 individuals are expected to be phenotypically wild type for both traits?

Answer 1

Small ears = L; Large ears = l

Purple fur = B; Brown fur =

Based on the information, samll ear trait is dominant over large ear trait and brown fur trait is dominant over purple fur trait.

LLBB (male) x (female) llbb --Parents

LlBb (small, purple)-----------F1

LlBb x LlBb --F1 selfcrossing

Ll x Ll = L_ (3/4) & ll (1/4)

Bb x Bb = B_ (3/4) & bb (1/4)

The proportion of the F2 individuals are expected to be phenotypically wild type for both traits = large ears, brown fur = llB_ = 1/4 *3/4 = 3/16