What two main processes make up cellular respiration?

Cellular respiration consists of two primary processes: glycolysis and the pathways associated with aerobic or anaerobic respiration. Glycolysis is the initial step that breaks down glucose into pyruvate, producing a small amount of ATP and NADH in the process.

Following glycolysis, the distinction arises between aerobic and anaerobic respiration. Aerobic respiration occurs in the presence of oxygen and includes the citric acid cycle (Krebs cycle) and oxidative phosphorylation, leading to the production of a substantial amount of ATP. Anaerobic respiration, on the other hand, occurs in the absence of oxygen and leads to fermentation processes, which yield less ATP compared to aerobic pathways.

Selecting aerobic respiration and glycolysis recognizes these two components as integral to cellular respiration—glycolysis initiates the process, and aerobic respiration maximizes energy extraction when oxygen is available. Thus, this pairing accurately reflects the major processes involved in cellular respiration.