Question

Human skin colour is controlled by several gene pairs. Let us assume here that there are just three gene pairs on different chromosomes and that for each pair there are two alleles, an incompletely dominant one that codes for melanin deposition. If a very dark skinned person marries a very light skinned woman, what will be the chance that their offspring will have very dark skin?

• A. 0
• B. 1/4
• C. 5/8
• D. 6/64
• E. 3/64

Answer 1

Answer: (A)

0

Human skin colour is a polygenic inheritance in which three pairs of polygenes A,B and C produces melanin pigment that causes human skin colour.

Very dark skin AABBCC X very light skin aabbcc

Gametes ABC abc

F${}_1$ AaBbCc (intermediate colour i.e., mulatto)

Thus, the correct answer is option A.