Final answer:
Cleavage of pyrophosphate during ATP hydrolysis produces inorganic phosphate (Pi), which releases free energy that is used to power cellular processes.
Step-by-step explanation:
The cleavage of pyrophosphate during the hydrolysis of ATP produces inorganic phosphate (Pi) that helps to drive the reaction. Hydrolysis of ATP into ADP (adenosine diphosphate) and Pi is an exergonic reaction, meaning it releases energy. This energy comes from breaking the high-energy phosphoanhydride bonds between the phosphate groups in ATP. The products of the reaction, ADP and Pi, have considerably lower free energy than the reactants, creating a free energy release which is used to power various cellular processes.