When do changes and
Interactions occur In The
Great Oxygenation event?

Stage 1 (3.85–2.45 Ga): Practically no O2 in the atmosphere. ... Stage 2 (2.45–1.85 Ga): O2 produced, rising to values of 0.02 and 0.04 atm, but absorbed in oceans and seabed rock. Stage 3 (1.85–0.85 Ga): O2 starts to gas out of the oceans, but is absorbed by land surfaces. No significant change in oxygen level.

Explanation:

Sorry if it is confusing, but that is how my Biology teacher described it to me, if you don't understand, welp, neither do I, LOL.

1)

i))the process of preparing food by green plants in the presence of sunlight is called photosynthesis.

ii) leaf is the site for photosynthesis.

iii) it takes place as,

6h2o+6co2=c6h12o6+602