Pathways of cellular respiration that require oxygen are described as?

• A. Aerobic
• B. Anaerobic
• C. Fermentative
• D. Glycolytic

Answer: (A)

Oxygen is required for the electron transport chain to accept electrons, which makes aerobic respiration possible. When oxygen is present, electrons flow through the chain and NADH and FADH2 are oxidized, driving ATP production by oxidative phosphorylation; oxygen serves as the final electron acceptor to form water. Because this dependence on oxygen defines the main ATP-generating steps, the pathways that rely on it are described as aerobic. Without oxygen, the electron transport chain stalls and cells switch to anaerobic methods, yielding far less ATP. The term anaerobic describes those no-oxygen pathways, while glycolysis can occur without oxygen but is not itself the oxygen-dependent path.