Final answer:
The G1 checkpoint checks cell size and DNA damage. The G2 checkpoint checks DNA duplication and repair. The M checkpoint checks chromosome attachment.
Step-by-step explanation:
The G1 checkpoint checks whether the cell is ready to divide. It assesses cell size and DNA damage. If conditions are favorable, the cell can proceed to the next phase of the cell cycle. The G2 checkpoint checks whether DNA has doubled and repairs any damage. Finally, the M checkpoint checks whether microtubules have attached to the centromeres of the chromosomes, ensuring proper chromosome separation during cell division.