You Are Mapping the Location of Two Genes in Drosophila

Multiple Choice

You are mapping the location of two genes in Drosophila, listless l and blind b. (l+ l+ b+ b+) and (l+ l- b+ b-) flies are normal, but ( l- l- b- b-) flies don't move around very much and cannot detect the location of a light source. You perform a testcross and get the following results: listless, sighted 100 listless, blind 400 normal activity, sighted 400 normal activity, blind 100 What is the distance between these two genes on the chromosome?

A) They are on different chromosomes.
B) They are 10 map units apart.
C) They are 20 map units apart.
D) They are 40 map units apart.
E) They are 80 map units apart.