Question

When cell has stalled DNA replication fork, which checkpoint should be predominantly activated?

• A. Both $G_2/M$ and $M$
• B. $G_1/S$
• C. $G_2/M$
• D. $M$

Answer 1

The correct option is B $G_1/S$

G1 is an intermediate phase occupying the time between the end of cell division in mitosis and the beginning of DNA replication during S phase. During this time, the cell grows in preparation for DNA replication, and certain intracellular components, such as the centrosomes undergo replication. So this would be checkpoint that would be activated by stalled DNA replication fork.
G2 and M phase are check points after DNA synthesis.