Matching Chromosomal Aberrations with Chromosome Number

This question requires matching different types of chromosomal aberrations with their corresponding changes in the diploid chromosome number, typically represented as $2n$. Let's analyze each term from LIST-I:

1. Nullisomic (A)

Definition: Nullisomy refers to the condition where a pair of homologous chromosomes is lost from a diploid set. Chromosome Number: The chromosome number is reduced by two chromosomes, represented as $2n - 2$. Match: This corresponds to option III ($2n - 2$) in LIST-II.

2. Monosomic (B)

Definition: Monosomy is the condition where only one chromosome of a homologous pair is present. Chromosome Number: The chromosome number is reduced by one chromosome, represented as $2n - 1$. Match: This corresponds to option IV ($2n - 1$) in LIST-II.

3. Trisomic (C)

Definition: Trisomy occurs when there is an extra copy of one chromosome in a diploid set. Chromosome Number: The chromosome number is increased by one chromosome, represented as $2n + 1$. Match: This corresponds to option I ($2n + 1$) in LIST-II.

4. Tetrasomic (D)

Definition: Tetrasomy is the condition where a pair of homologous chromosomes is added to a diploid set. Chromosome Number: The chromosome number is increased by two chromosomes, represented as $2n + 2$. Match: This corresponds to option II ($2n + 2$) in LIST-II.

Final Matching Summary

Based on the analysis above, the correct matching is:

• A. Nullisomic - III ($2n - 2$)
• B. Monosomic - IV ($2n - 1$)
• C. Trisomic - I ($2n + 1$)
• D. Tetrasomic - II ($2n + 2$)

Therefore, the correct option is A-III, B-IV, C-I, D-II.