The primary purpose of cellular respiration in organisms is to convert the energy stored in glucose and other nutrients into usable energy, specifically in the form of ATP (adenosine triphosphate). This biochemical process occurs in the presence of oxygen (aerobic respiration) or in its absence (anaerobic respiration). Cellular respiration involves a series of metabolic pathways, notably glycolysis, the Krebs cycle, and the electron transport chain. The energy released through respiration powers vital cellular functions, including growth, repair, and maintenance of biological processes, ensuring the survival of the organism.