Variation in rates of cell division is regulated by a cell-cycle control system, which is a group of molecules, mostly proteins, within a cell that coordinates the events of the cell cycle. This control system functions through a system of checkpoints. Which assessment occurs at the G1/S checkpoint?

Interphase

Explanation:

When a cell is in any phase of the cell cycle, it is referred to as *Interphase *.The cell cycle consist of three phases;G1, S, and G2.

*At G1 phase,a cell grows*.

*At S phase,the cell continues to grow as it duplicates it's chromosome ( i.e,chromosomes are replicated only during S phase*.

At G2, the cell grows more and prepares for mitosis.

DNA is checked if there is any damage prior to commencement of  cell division.

Explanation:

The G1/S check point also known as restriction point is  checkpoint stage of G1 phase. It is the phase which prepare the cell  for the long journey of cell cycle.It  is  independent of any external stimulus or command  to  increase  number  and mass of cells.

The mechanisms at the G1/S checkpoints involved the activation of certain protein complexes and phosphorylation of  the protein  for DNA replications,centromere duplication and other events needed for events of cell cycle, so that any anomaly is checked for before cell cycle commences.