Question

Given below are two statements:
Statement I: Failure of segregation of chromatids during cell cycle resulting in the gain or loss of whole set of chromosome in an organism is known as aneuploidy.
Statement II: Failure of cytokinesis after anaphase stage of cell division results in the gain or loss of a chromosome is called polyploidy.
In the light of the above statements, choose the correct answer from the options given below:

• A. Statement I is true but Statement II is false
• B. Statement I is false but Statement II is true
• C. Both Statement I and Statement II are true
• D. Both Statement I and Statement II are false

Answer 1

The Correct Option is D

To solve the given question, we need to evaluate each statement based on the definitions and concepts of aneuploidy and polyploidy in cell biology.

1. Statement I: "Failure of segregation of chromatids during cell cycle resulting in the gain or loss of whole set of chromosome in an organism is known as aneuploidy."
   • Aneuploidy: This term refers to the presence of an abnormal number of chromosomes in a cell, such as having 45 or 47 chromosomes in humans instead of the usual 46. It arises due to the failure of separation of chromosomes or chromatids during cell division, but it does not involve the gain or loss of a whole set. Thus, the effect is on individual chromosomes, not the complete set.
   • Conclusion: The statement incorrectly describes aneuploidy, as it does not involve whole sets of chromosomes.
2. Statement II: "Failure of cytokinesis after anaphase stage of cell division results in the gain or loss of a chromosome is called polyploidy."
   • Polyploidy: This refers to cells having more than two paired (homologous) sets of chromosomes. This condition typically results from failure of the entire mitotic or meiotic division (or cytokinesis), leading to an organism or cell with extra sets of chromosomes. It does not involve individual chromosomes but entire sets.
   • Conclusion: The statement incorrectly describes polyploidy, as polyploidy involves entire sets of chromosomes, not single chromosomes, and is more commonly associated with overall set expansion due to complete cytokinesis failure, not gain or loss of one chromosome.

After comparing both statements with the established definitions:

• Statement I is false because aneuploidy involves individual chromosomes, not whole chromosome sets.
• Statement II is false because polyploidy involves whole sets of chromosomes, not individual chromosomes.

Answer: Both Statement I and Statement II are false.