The release of energy in living thins is known as cellular respiration.
In the process of cellular respiration, oxygen combines with sugar and thereby releasing energy in form of ATP(Adenosine Triphosphate) and carbon dioxide. ATP is the store house energy in the cells and during respiration, this compound is synthesized.
The sugar is produced in the process of photosynthesis in plants using carbon dioxide and water in the presence of sunlight.
