Question

Assume that two genes are 80 map units apart on chromosome II of Drosophila and that a cross is made between

a doubly heterozygous female and a homozygous recessive male. What percent recombination would be
expected in the offspring of this type of cross?
A) 30 B) 5 C) 50 D) 100 E) 80

Answer 1

In a genetic cross where two genes are 80 map units apart on Drosophila's chromosome II, the expected recombination frequency in the offspring is 50%, which corresponds to option C.

Step-by-step explanation:

The question refers to the recombination frequency between two genes on chromosome II of Drosophila in a genetic cross. If two genes are 80 map units apart, the expected percent recombination in the offspring of a cross between a doubly heterozygous female and a homozygous recessive male is 50%. This is because the maximum recombination frequency observable for two genes on the same chromosome is 50%, even if the actual physical distance corresponds to a greater frequency. This is due to the fact that multiple crossovers can 'hide' the evidence of recombination between genes that are far apart. As such, the correct answer is C) 50%.