The quantum theory of energy levels within atoms was alded by:
study of the sun's light spectrum
o emission line spectra of various elements
alpha particles
o gamma rays

Explanation:

The quantum theory of energy levels within atoms was aided by the emission spectrum. When excited with light, different elements emitted photons of different frequencies. The frequencies were different because the energy difference from excited to low energy state was different depending on the element.

Hope this helps :)

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: