Question

Cell division can not be stopped in .......... phase of the cell cycle.

• A. G${}_1$ phase
• B. G${}_2$ phase
• C. S phase
• D. Prophase

Answer 1

Answer: (C)

S phase

The interphase comprises of G${}_1$, S and G${}_2$ phase. In G${}_1$ phase the cell has three options:

(a) Continue cell cycle and enter S phase,

(b) Stop cell cycle and enter quiescent stage or G${}_0$ phase

(c) Stop cell cycle and undergo differentiation.

The S phase is known as a synthetic phase in which DNA undergoes replication. Because the DNA has replicated in S phase and the DNA content has become two times the normal content. The S phase must necessarily follow the mitotic phase. Thus, the S phase is the point of no return for a cell cycle and the cell must compulsorily divide in the M phase of cell cycle.

So, the correct answer is option C.