Answer – Energy is released from ATP molecules when they are hydrolyzed and a phosphoanhydride bond is broken.

Explanation:

For a cell to carry out the various functions required for its continued survival, it is the site of reactions that are taking place constantly. Some of these reactions are energetically favorable (release energy as a product, or ‘exogenic’), while others are energetically unfavorable (consume energy in order to take place, or ‘endergonic’). To keep these reactions running and through them, the cell alive, energy is a constant requirement. Even exogenic reactions need a small amount of activation energy.

ATP or adenosine triphosphate is a molecule that provides energy to cells when they need them for energetically unfavorable reactions. It is a sort of energy currency that the cells rely upon for their energy requirements. 

An ATP molecule is made up of a five-carbon sugar called ribose attached to a nitrogenous base called adenine and a chain of three phosphates. The phosphates are attached to one another by “phosphoanhydride” bonds that are unstable. 

ATP releases energy when it is hydrolyzed (broken down by water). 

ATP + H₂O ↔  ADP + P_i + energy

One phosphate group (P_i) is removed, and ATP becomes ADP (adenosine diphosphate). The energy is then utilized to perform the various reactions essential for the cell. 

The reaction is a reversible one, and ADP can easily be converted back to ATP, ready to be used when more energy is needed. Thus, it acts as a rechargeable battery.