1.1. Figure 1 below shows a representation of the events that take place during the cell cycle. 

Figure 1

Name the stage of the cell cycle that contains G1, S and G2.

1.2. State three cellular processes that take place during G1 of the cell cycle.

1.3. Before the cell progresses from G1 into S phase, it needs to pass through a stage called the G1/S checkpoint, which prevents the cell cycle from proceeding if certain conditions are not met. Suggest one reason why the cell might not progress through the G1/S checkpoint. 

1.4. The M phase of the cell cycle in Figure 1 involves cell division by mitosis. The frequency of mitosis depends on the length of time that the cell spends completing each cell cycle. 

A human cell takes 12 hours to complete one cell cycle. Calculate how many cells will be present if the cell cycle proceeds at a constant rate for 4 days.