The process by which living organisms convert food into usable energy is known as cellular respiration. This biophysical process occurs primarily in the mitochondria of cells, where glucose and oxygen are transformed into ATP (adenosine triphosphate), the energy currency of the cell. During cellular respiration, glucose undergoes glycolysis, followed by the Krebs cycle and the electron transport chain, resulting in energy release. Oxygen serves as the final electron acceptor, producing water as a byproduct. This process is essential for maintaining cellular functions, enabling organisms to perform activities essential for life, such as growth, reproduction, and maintaining homeostasis.