Question

What caused the amount of oxygen in the atmosphere to stabilize to the extent that it is today?

A. Oxygen was toxic to many of the organisms living at the time.
B. Carbon dioxide dissolved into the oceans, eventually forming carbonate rocks.
C. Carbon dioxide dissolved into the oceans and was eventually used in the formation of sea creatures' shells.
D. The amount of oxygen consumed by respiratory organisms balanced the amount of oxygen produced by plants undergoing photosynthesis.

Answer 1

D. The amount of oxygen consumed by respiratory organisms balanced the amount of oxygen produced by plants undergoing photosynthesis.


Autrophs are the organisms that have the capacity to form their own food from inorganic substances like the carbon dioxide.
Heterotrophs are the organisms that cannot produce their own food but depends on other animals or plants for their nutritional needs.

Photosynthesis is a process wherein light energy is converted into chemical energy.