Question

Given below is a pedigree chart with symbols for sex-linked trait in humans. The trait of the pedigree chart is?

• A. Recessive Y-linked
• B. Recessive X-linked
• C. Dominant Y-linked
• D. Dominant X-linked

Answer 1

The correct option is D Dominant X-linked

The trait traced in the given pedigree is dominant X-linked. As seen in the figure (given in the question), in first generation male is affected, but female is not affected i.e. female carries normal chromosomes but in generation 2 both females are affected, but none of the male are affected. Fig. shows that inspite of carrying single X linked trait, they are affected, i.e. the trait is dominant. Likewise in the third generation when X linked trait are again crossed with a normal male, then, both male and female offspring carrying single X linked trait are affected. Thus we can say that the trait is dominant X-linked.

So, the correct answer is 'Dominant X-linked'.