Answer : Electron transport
Cellular respiration is a process by which respiratory substrate such as glucose gets oxidized and releases energy. On the basis of the availability of oxygen, the oxidation of substrate depends. In presence of oxygen, cellular respiration is called aerobic respiration and in absence of oxygen it is called anaerobic respiration. Glycolysis is common process for both type of respiration. In absence of oxygen, incomplete oxidation of respiratory substrate occurs which does not involves electron transport.
