[Campbell Biology P.295] For many cells, the G₁ checkpoint is considered the most important.... | Practice Question

For many cells, the G₁ checkpoint is considered the most important. What happens if a cell does not receive a go-ahead signal at this checkpoint?

  • A: It proceeds directly to the S phase without a delay.
  • B: It enters a nondividing state called the G₀ phase.
  • C: It initiates apoptosis (programmed cell death).
  • D: It immediately doubles its DNA content and prepares for division.

Explanation

The text states that if a cell does not receive a go-ahead signal at the G₁ checkpoint, it may exit the cycle and enter the G₀ phase, a nondividing state. This is a critical regulatory point controlling whether cells commit to division or enter a quiescent state.