Which of the following most appropriately describes hemophilia?
Answer: (B) X – linked recessive gene disorder. Answer: (B) X – linked recessive gene disorder Solution: Haemophilia is a sex-linked recessive disease in which a single clotting-cascade protein is defective, so a simple cut causes non-stop bleeding.
- A.Recessive gene disorder
- B.X – linked recessive gene disorder✓
- C.Chromosomal disorder
- D.Dominant gene disorder
Correct Answer
(B) X – linked recessive gene disorder
Solution & Explanation
Answer: (B) X – linked recessive gene disorder Solution: Haemophilia is a sex-linked recessive disease in which a single clotting-cascade protein is defective, so a simple cut causes non-stop bleeding. Because the gene is on the X chromosome and is recessive, a heterozygous (carrier) female transmits it to some of her sons. It is a single-gene (Mendelian) disorder, not a chromosomal one. NCERT Reference: NCERT Class XII, Ch 4, p.74, lines 8-13: "Haemophilia : This sex linked recessive disease, which shows its transmission from unaffected carrier female to some of the male progeny has been widely studied. In this disease, a single protein that is a part of the cascade of proteins involved in the clotting of blood is affected."