Question

What chromosome were the genes located on that were used by Morgan in his dihybrid cross?

(a) X chromosome

(b) Y chromosome

(c) W chromosome

(d) Z chromosome

This question was posed to me in class test.

Question is taken from Inheritance Principles topic in section Principles of Inheritance and Variation of Biology – Class 12

Answer 1

The correct option is (a) X chromosome

To explain I would say: The genes were located on X-chromosome. These are called sex-linked genes because their expression depends on the sex of the fly. The X chromosome is present in copies of two in females, but the males have only one copy of X. Thus, a recessive mutant might remain suppressed in females, but the males will always exhibit the phenotype.