Hello!
You have three checkpoints here. One at the end of G1, one at the end of G2, and one in the middle of the Mitotic stage.
Let's go through these individually.
The G1 checkpoint determines whether or not a cell should begin cell replication. It checks to see whether the cell has grown to an appropriate stage. This checkpoint is seen as the most important. Therefore, this matches with "checks for cell size and DNA damage".
The G2 checkpoint determines if a cell is ready for mitosis. This checkpoint checks whether or not replicated DNA is correct. Therefore, this one matches with "checks whether DNA has doubled and repairs it if damaged".
The M checkpoint occurs at the end of metaphase. This makes sure the chromosomes have aligned properly at the metaphase plate and makes sure the sister chromatids are correctly attached to the spindle microtubules. Therefore, this one corresponds with "checks whether the microtubules have attached to the centromeres of the chromosomes".
Hope this helps!
The cell theory follows :
Cells are the basic unit of life
All living things are composed of cells
All cells are reproduced from other cells
Hope this helps:)
~ His Cookie Monster
