Question

5.  Kevin has X-linked dominant skin-scaliness. What is the likely scenario for the disease in Kevin's family? Explain (2pts)

         (a) He can pass it only to his sons

         (b) The disease will skip a generation

         (c) His daughter cannot get the disease unless her mother has the disease.

         (d) His son can get the disease even if his mother is healthy.

         (e) His daughter can get the disease even if her mother is healthy.

(c) How do you know?

(d) Explain why this disorder is seen only in boys and never in girls.

Answer 1

Ans:

5.

(a) He cannot pass it to his son because he gives Y chromosome to his son, not the X chromosome.

(b) The disease cannot skip a generation because it is X-linked dominant disease. The disease skips generation if it is recessive.

(c) His daughter can get the disease even her mother is healthy because it is dominant disease.

(d) His son cannot get the disease if his mother is healthy because the son gets healthy X-chromosome from his mother.

(e) His daughter can get the disease even her mother is healthy.

(c) It is because the trait is dominant. So, the affected X-chromosome of Kevin passes to his daughter and forms disease.

(d) This disorder is more common girls than boys beacuse girls are affected if either of the parents (fathers and mothers) are affects but boys can only affects if his mother is affected.