Is the Krebs cycle aerobic or anaerobic?

The Krebs cycle is an aerobic pathway because its operation depends on the presence of oxygen, although it does not directly use molecular oxygen (O₂) in its enzymatic reactions. The high-energy electron carriers (NADH and FADH₂) produced during the cycle donate electrons to the electron transport chain, where oxygen serves as the final electron acceptor. Without oxygen, the electron transport chain halts, leading to an accumulation of reduced cofactors (NADH, FADH₂) and cessation of the Krebs cycle.