Regarding Meiosis, which of the statements is incorrect?
AI-generated explanation. Check against your textbook.
Explanation:
The incorrect statement is 1. DNA replication occurs in S phase before Meiosis I, i.e., during the interphase preceding meiosis, not during Meiosis-II. Thus DNA replication occurs once, prior to Meiosis I. In Meiosis II there is no S-phase replication.
🧠 Did You Know?
NCERT states that DNA replication happens in the interphase (S phase) before meiosis, so that each chromosome has two sister chromatids for the first division.
💡 NCERT Memory Line:
DNA replication occurs in the interphase (S phase) before meiosis I.
The fruit fly has 8 chromosomes (2n) in each cell.
During interphase of Mitosis if the number of
chromosomes at G1 phase is 8, what would be the number of chromosomes after S phase?
Attachment of spindle fibers to kinetochores of
chromosomes becomes evident in:
AI-generated explanation. Check against your textbook.
Explanation:
In mitosis, the kinetochores on chromosomes attach to spindle microtubules as the chromosomes align. This attachment becomes evident when the chromosomes align at the middle of the cell, i.e., in metaphase, with kinetochores held on by spindle fibers from opposite poles. Thus, the visible connection between kinetochores and spindle fibers is most evident during metaphase of cell division, as per NCERT description.
🧠 Did You Know?
Metaphase is characterized by chromosomes lining up at the equator, with kinetochores attached to microtubules from both poles.
💡 NCERT Memory Line:
“Chromosomes move to the equator and become arranged at metaphase plate; spindle fibers attach to kinetochores.”