Question

Match List I with List II
List I (Terminology):
A. Double monosomy
B. Trisomy
C. Nullisomy
D. Double tetrasomy
List II (Genetical formula):
I. 2N+2+2
II. 2N-2
III. 2N-1-1
IV. 2N+1
Choose the correct answer from the options given below:

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

Hint:

To distinguish "double" from standard changes: "double" indicates changes on two different chromosomes, so the modification is written as two separate digits (e.g., $-1-1$ or $+2+2$) rather than a single summed value (e.g., $-2$ or $+4$).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Aneuploidy involves changes in the chromosome number of an organism by addition or loss of individual chromosomes rather than a whole set.
The terminology reflects the number of chromosomes gained or lost and whether they are from homologous or non-homologous pairs.

Step 2: Detailed Explanation:
Let us define each chromosome aberration and its genomic formula:
A. Double monosomy: Monosomy is the loss of a single chromosome from the diploid set ($2N-1$).
Double monosomy is the loss of two different, non-homologous chromosomes. This is represented by the formula $2N-1-1$.
Therefore, A matches with III ($2N-1-1$).
B. Trisomy: Trisomy is the addition of a single chromosome to the diploid chromosome set.
The organism has three copies of one chromosome instead of the normal pair. This is represented by the formula $2N+1$.
Therefore, B matches with IV ($2N+1$).
C. Nullisomy: Nullisomy is the loss of an entire pair of homologous chromosomes.
Nullisomics are represented by the formula $2N-2$. They are usually non-viable in diploids but can survive in polyploids like bread wheat.
Therefore, C matches with II ($2N-2$).
D. Double tetrasomy: Tetrasomy is the addition of a pair of homologous chromosomes ($2N+2$).
Double tetrasomy is the addition of two different homologous chromosome pairs. This is represented by the formula $2N+2+2$.
Therefore, D matches with I ($2N+2+2$).

Step 3: Final Answer:
Matching the formulas yields: A - III, B - IV, C - II, D - I, which corresponds to Option (A).