Doubling of the number of chromosomes can be achieved by disrupting mitotic cell division soon after
Answer: (B) Metaphase. Answer: Metaphase Solution: At metaphase the duplicated chromosomes (each with two sister chromatids) are aligned on the metaphase plate; disrupting division right after metaphase prevents the cell from dividing while the centromeres still split at anaphase, so all sister chromatids end up in a single undivided cell, doubling the chromosome number.
- A.Prophase
- B.Metaphase✓
- C.Anaphase
- D.Telophase
Correct Answer
(B) Metaphase
Solution & Explanation
Answer: Metaphase Solution: At metaphase the duplicated chromosomes (each with two sister chromatids) are aligned on the metaphase plate; disrupting division right after metaphase prevents the cell from dividing while the centromeres still split at anaphase, so all sister chromatids end up in a single undivided cell, doubling the chromosome number. Disruption after anaphase or telophase would occur after the cell has already begun/completed segregation, and prophase precedes alignment, so they do not give a clean doubling. NCERT Reference: Ch 10, p.124, line 5 — "Centromeres split and chromatids separate"