There are several points during the cell cycle when the cell will check to be sure everything is progressing normally, without mistakes, and confirm that the cell should continue to the next phase of the cycle. When do these "cell cycle checkpoints" occur?

These checkpoints occurs :

Explanation:

G1 checkpoint checks for :

Metaphase checkpoint (spinal assemply checkpoint) :

G2 Checkpoint :

there are 35 white marbles

step-by-step explanation:

y- yellow marbles

4y + 5 = 45

subtract 5 from both sides

4y = 40

divide for from both sides

y = 10

plug in 10 to get 40 yellow marbles then subtract by 5 to get 35 marbles

thus there are only 10 yellow marbles