Question

Match the disorders in List I with their causes in List II and choose the correct option.

List I	List II
(A) Thalassemia.	(I) non-disjunction of sex chromosomes.
(B) Sickle-cell anaemia.	(II) non-disjunction of 21st pair of chromosomes.
(C) Turner's Syndrome.	(III) Synthesising few globin molecules.
(D) Down's Syndrome.	(IV) synthesising an incorrectly functional globin.

• (A) - (I), (B) - (II), (C) - (III), (D) - (IV).
• (A) - (II), (B) - (IV), (C) - (I), (D) - (III).
• (A) - (I), (B) - (II), (C) - (IV), (D) - (III).
• (A) - (III), (B) - (IV), (C) - (I), (D) - (II).

Hint:

Thalassemia and sickle-cell anaemia are globin defects, while Turner's and Down's syndromes are non-disjunction disorders.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept
Some disorders come from gene defects and others from chromosomal non-disjunction.

Step 2: Match each disorder
(A) Thalassemia: too few globin molecules are made - (III).
(B) Sickle-cell anaemia: an incorrectly functioning globin is made - (IV).
(C) Turner's syndrome (XO): non-disjunction of sex chromosomes - (I).
(D) Down's syndrome: non-disjunction of 21st pair - (II).

Step 3: Conclusion
The pairs are (A)-(III), (B)-(IV), (C)-(I), (D)-(II).

Final Answer:
The matching is (A)-(III), (B)-(IV), (C)-(I), (D)-(II). \[ \boxed{\text{(D) }\text{(A) - (III), (B) - (IV), (C) - (I), (D) - (II).}} \]