Answer:
When ATP is broken down to ADP
Step-by-step explanation:
Energy is released from a molecule of ATP when the substance is broken down to ADP
ATP is the energy currency of a cell. It is called Adenosine Triphosphate
When a phosphate is removed, it become ADP - Adenosine Disphosphate.
In like manner, the breaking down releases inherent chemical energy and converts it to other forms of energy.
This is how the body system derives sufficient amount of energy for every of its activities.
When an organism undergoes cellular respiration, this is the process that is in play to release energy needed for the body to function