Question

A female Drosophila with the mutant phenotype a is crossed to a male who has the mutant phenotype b. In the resulting F1 generation all females are wild-type and all males have the a mutant phenotype. Based on these results, we can conclude that the mode of inheritance of the phenotype of interest is:
A) autosomal for a and X-Linked for b
B) dominant for a and recessive for b
C) recessive for a and dominant for b
D) recessive for both a and b
E) X-linked for a and autosomal for B

Answer 1

Answer:

The correct answer is option D.

Explanation:

This is an illustration of X-linked recessive inheritance. This is a result of the mutation of genes on X-chromosomes. As females carry two X chromosomes, one from each parent, there is less chance for a female to carry mutant copies on both the X-chromosomes.  

As males possess only one X-chromosomes, obtained from the female parent, one changed gene is adequate to result in a mutant phenotype. All the males exhibit a mutant phenotype as the male parent cannot transfer the X-linked traits to the progeny.