Mention the stages of respiration.

Explanation

During the process of respiration, oxygen is utilised and carbon dioxide, water and energy are relaxed as products. The combustion reaction requires oxygen.
But some cells live where oxygen may or may not be available.
The first cells on this plants lived in atmosphere that lacked oxygen.
Even among present day-living organisms, several are adapted to anaerobic conditions.
Some of these organisms are facultative anaerobes , while in others the requirement for anaerobic condition is obligate.
In any case, all living organisms retain the enzymatic machinery to partially oxidise glucose without the help of oxygen . This breakdown of glucose to pyruvic acid is called glycolysis