Question

Assume that the genes for tan body and bare wings are 15 map units apart on chromosome II in Drosophila.

Assume also that a tan-bodied, bare-winged female was mated to a wild-type male and that the resulting F1
phenotypically wild-type females were mated to tan-bodied, bare-winged males. Of 1000 offspring, what
would be the expected of wild-type offspring, and in what numbers would they be expected?
A) 75 B) 425 C) 50 D) 350 E) 8

Answer 1

The expected number of wild-type offspring in the F2 generation is 150 out of 1000.

Step-by-step explanation:

In this case, the genes for tan body and bare wings are 15 map units apart on chromosome II in Drosophila. When a tan-bodied, bare-winged female was mated to a wild-type male, the resulting F1 generation had phenotypically wild-type females. These F1 females were then mated to tan-bodied, bare-winged males to produce the F2 generation.

Since the genes for body color and wing size are 15 map units apart, there is a 15% chance of recombination occurring between these genes. Recombination can result in wild-type offspring. Therefore, out of 1000 offspring, we can expect 15% to be wild-type, which equals 0.15 * 1000 = 150 wild-type offspring.