Question

Match List-I with List-II

List-I (Chromosomal situation in human being) & List-II (Chromosome number)
(A) Monosomy & (I) 69
(B) Triploidy & (II) 48
(C) Tetraploidy & (III) 45
(D) Tetrasomy & (IV) 92

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

Hint:

Always distinguish between aneuploidy (ends in "-somy", e.g., monosomy $2n-1$, tetrasomy $2n+2$) and euploidy/polyploidy (ends in "-ploidy", e.g., triploidy $3n$, tetraploidy $4n$). This distinction prevents common calculation errors.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Numerical chromosomal aberrations are classified into aneuploidy (gain or loss of one or more individual chromosomes, e.g., monosomy, trisomy, tetrasomy) and euploidy (gain of one or more complete sets of chromosomes, e.g., triploidy, tetraploidy).
In humans, the normal diploid chromosome number is $2n = 46$, where the haploid set is $n = 23$.

Step 2: Detailed Explanation:
Let us calculate the chromosome numbers for each condition:
- (A) Monosomy $\rightarrow$ (III) 45:
Monosomy refers to the loss of a single chromosome from the diploid set ($2n - 1$).
In humans, this results in:
\[ 46 - 1 = 45 \text{ chromosomes} \]
- (B) Triploidy $\rightarrow$ (I) 69:
Triploidy is a type of polyploidy where the cell contains three complete sets of chromosomes ($3n$).
In humans, this results in:
\[ 3 \times 23 = 69 \text{ chromosomes} \]
- (C) Tetraploidy $\rightarrow$ (IV) 92:
Tetraploidy is a polyploid condition where the cell has four complete sets of chromosomes ($4n$).
In humans, this results in:
\[ 4 \times 23 = 92 \text{ chromosomes} \]
- (D) Tetrasomy $\rightarrow$ (II) 48:
Tetrasomy is an aneuploid condition characterized by the gain of an extra pair of homologous chromosomes ($2n + 2$).
In humans, this results in:
\[ 46 + 2 = 48 \text{ chromosomes} \]
Matching these values gives the sequence: (A)-(III), (B)-(I), (C)-(IV), (D)-(II).

Step 3: Final Answer:
The correct matching sequence is (A) - (III), (B) - (I), (C) - (IV), (D) - (II).