Question

Match List-I with List-II:

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

Hint:

Down syndrome is the most common human trisomy (chromosome 21).

Answer 1

The Correct Option is A

Chromosomal variations:
Nullisomy: 2n
2 (missing one chromosome pair) (A
IV)
Trisomy: 2n+1 (extra chromosome) (B
II)
Monosomy: 2n
1 (missing one chromosome) (C
III)
Tetrasomy: 2n+2 (extra chromosome pair) (D
I)

Answer 2

Formula-based approach:
Each chromosomal numerical variation can be identified from its deviation formula relative to the normal diploid number, \(2n\). A loss of an entire homologous pair gives \(2n-2\), the condition called nullisomy. The gain of a single extra chromosome gives \(2n+1\), termed trisomy. The loss of a single chromosome from one pair gives \(2n-1\), termed monosomy. The gain of an entire extra homologous pair gives \(2n+2\), termed tetrasomy.
Matching each formula to its name gives Nullisomy \(2n-2\), Trisomy \(2n+1\), Monosomy \(2n-1\), Tetrasomy \(2n+2\), which corresponds to the pairing A-IV, B-II, C-III, D-I in this list.