Question

In flies, thorax color (green versus purple, controlled by the p gene such that p+/- is green, p/p is purple) and puparium color (brown versus black, controlled by the b gene such that b+/- is brown, b/b is black) are monogenic traits on the same chromosome. What are the expected phenotype ratios in a testcross in (a) coupling configuration (cis), and in (b) repulsion configuration (trans), if the two genes are unlinked and segregating independently?

Answer 1

So, phenotypic ratio will be 1:1:1:1 in both cases.