The process that describes the transformation of food into energy in living organisms is known as cellular respiration. This critical metabolic pathway involves breaking down glucose molecules in the presence of oxygen, producing adenosine triphosphate (ATP), which is the energy currency of cells. Cellular respiration occurs in various stages, including glycolysis, the citric acid cycle, and the electron transport chain. This process is vital for maintaining cellular functions and supporting life by providing the necessary energy for growth, repair, and other metabolic activities.