Question

Sons of a colour blind woman are always colour blind but not the daughters. This suggests that

• A. Fewer sex chromosomes are transferred to the daughter.
• B. Sex chromosomes are transferred only from mother to son.
• C. Sex is determined by the mother.
• D. Sex linked characters find immediate expression in man.

Answer 1

The correct option is D Sex linked characters find immediate expression in man.

One example of an X-linked trait is red-green colorblindness. Let (Xc) represent the recessive allele that causes colorblindness and (X${}^{+}$) represent the normal dominant allele. Females that are X${}^{+}$X${}^{+}$ or X${}^{+}$X${}^c$ have normal color vision, while X${}^c$X${}^c$ females are colorblind. Males that are X${}^{+}$Y have normal color vision, while X${}^c$Y males are colorblind. Thus, the correct answer is option D.