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.”
Identify the correct statement with regard to
G1 phase (Gap 1) of interphase.
AI-generated explanation. Check against your textbook.
Explanation:
During G1 (the first gap phase) of interphase, the cell is metabolically active and grows in size. It does not replicate its DNA; DNA replication occurs in the S phase. G1 prepares the cell for DNA synthesis by producing RNA and proteins required for DNA replication and by increasing cytoplasmic components. Therefore, the correct statement is 3: “Cell is metabolically active, grows but does not replicate its DNA.”
🧠 Did You Know?
G1 is followed by S phase, then G2; together these phases constitute interphase, before mitosis (M phase).
💡 NCERT Memory Line:
“In G1, the cell grows and carries out normal metabolic activities; DNA replication occurs later in S phase.”