Over time, changes within species lead to the replacement of old species by new species, as less successful species become

g1

choices:

a. g2. b. g1. c. m

cell division has two checkpoints namely, g1

checkpoint and spindle assembly checkpoint. the checkpoint which determines if

division has properly occurred is the g1 checkpoint. at this point, is a damage

in the dna is detected or  the has not reach the optimum size, the cell is

stopped in g1 and is not allowed to proceed to further process.

source:

enzyme speed up the reactions