Question

Result of a cross between a normal homozygous female and a haemophilic male would be

• A. normal males and normal females
• B. haemophilic males and normal females
• C. normal males and carrier females
• D. haemophilic males and carrier females.

Answer 1

Answer: (C)

Haemophilia is a common hereditary coagulation blood disorder. It occurs due to the deficiency or reduced activity of clotting factor VIII or IX. In this disease, the blood clotting process will slow down. This disorder is an X-linked recessive disorder which is generally transmitted by females who are carriers to males (affected) and affected males (father) to females. When the normal homozygous female (XX) crosses with an haemophilic male ( $X^{h}X$ ) then the progeny is obtained is $X{X}^h,XY,X{X}^h,XY$ . Here the daughters will be carriers and sons will be normal.