Answer: DNA is correctly replicated and chromosomes properly aligned before proceeding.
- A Cell division proceeds continuously at the fastest possible rate without pause
- B DNA is correctly replicated and chromosomes properly aligned before proceeding
- C Cell division is permanently and irreversibly halted in every body tissue
- D Only the G<sub>1</sub> restriction point is monitored, with all later phases unchecked
Correct answer: B. DNA is correctly replicated and chromosomes properly aligned before proceeding
Explanation: Cell cycle checkpoints (G<sub>1</sub>, S, G<sub>2</sub>/M, spindle) monitor DNA integrity and proper chromosome attachment. Damaged cells don't proceed.
The cell cycle: G1 (growth and preparation), S (DNA replication, chromosome number stays 2n but DNA content doubles), G2 (final checks before division), and M (mitosis itself) - together, G1+S+G2 make up interphase.
Concept context
Mitosis and meiosis: how cells divide for growth, repair, and reproduction.