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Question

Biology Question on Genetics

Aneuploidy is a chromosomal disorder where chromosome number is not the exact copy of its haploid set of chromosomes, due to :
(a) Substitution
(b) Addition
(c) Deletion
(d) Translocation
(e) Inversion
Choose the most appropriate answer from the options given below

A

(c) and (d) only

B

(d) and (e) only

C

(a) and (b) only

D

(b) and (c) only

Answer

(b) and (c) only

Explanation

Solution

Aneuploidy refers to an abnormal number of chromosomes, which is not a multiple of the haploid set. This arises due to errors during chromosome segregation in meiosis.
Addition (B) and Deletion (C): These directly lead to aneuploidy. Nondisjunction, where chromosomes fail to separate correctly, can result in the addition or deletion of chromosomes in gametes.
Substitution (A): Involves replacing one nucleotide with another and does not change the chromosome number.
Translocation (D): Involves the transfer of a segment of a chromosome to a nonhomologous chromosome. While potentially causing other genetic disorders, balanced translocations do not directly cause aneuploidy because the total number of chromosomes remains the same.
Inversion (E): A segment of the chromosome is reversed end-to-end. This doesn’t change
the chromosome number.