Question

With independent assortment, the ratio of phenotypes in the F2 generation of a cross between true-breeding strains (AA bb x aa BB) can be described as 9:3:3:1 when A and B are dominant over a and b. To what phenotype does the "9" in the ratio refer?

a. recessive for both traits
b. dominant for one trait and recessive for the other
c.dominant for the A trait and recessive for the B trait
d. dominant for both traits

Answer 1

Answer:

B. Dominant for one trait and recessive for the other

Explanation:

using the Punnetts square for the question above, the 9 in the ration refers to a dominant for both traits such as AABB, AaBb.

while the 3: 3 refers to a dominant for a single trait and recessive for one such as AAbb, Aabb, aaBB, aaBb

and the 1 refers to recessive for both traits such as aabb.