Question

A cross was made with true-breeding AABB flies and true-breeding aabb flies. The resulting F1 generation was then crossed with true-breeding aabb flies. Based on the linkage map, which of the following F2 generation genotype ratios is most likely to be observed?
A) Number Observed: AaBb (46), Aabb (4), aaBb (4), Aabb (46)
B) Number Observed: AaBb (4), Aabb (46), aaBb (46), Aabb (4)
C) Number Observed: AaBb (25), Aabb (25), aaBb (25), Aabb (25)
D) Number Observed: AaBb (50), Aabb (0), aaBb (0), Aabb (50)

Answer 1

C is the answer.

Number observed: AaBb (25), Aabb (25), aaBb( 25), aabb (25).

Explanation:

when true-breeding aabb is crossed with the F1 AaBb, in F2 generation

the genotype ratio will be 1:1:1:1

AaBb (25), Aabb (25), aaBb( 25), aabb (25).

The resultant offspring will have 25 percent probability of the appearance of the two genes whether heterozygous dominant or recessive or homozygous recessive.