[Campbell Biology P.294] Which statement accurately describes a key aspect of the cell cycle... | Practice Question

Which statement accurately describes a key aspect of the cell cycle control system and its checkpoints as presented in the text?

  • A: The cell cycle control system operates like a washing machine's internal clock, making it completely independent of external signals.
  • B: Checkpoints are control points in the cell cycle where stop and go-ahead signals can regulate the cycle.
  • C: The three important checkpoints are located only in the S, G2, and M phases.
  • D: The cell cycle control system is entirely dependent on external signals for its progression.

Explanation

The text defines a checkpoint as 'a control point where stop and go-ahead signals can regulate the cycle,' which matches option B. It also clarifies that the system has a 'built-in clock' but is also subject to internal and external regulation, contradicting options A and D. The checkpoints are in G1, G2, and M phases, not S, making C incorrect.