Does Krebs cycle require oxygen?

The Krebs cycle does not directly consume molecular oxygen (O₂) during its enzymatic steps. However, it is classified as an aerobic pathway because it depends indirectly on the availability of oxygen. The reduced cofactors NADH and FADH₂ produced during the cycle transfer electrons to the electron transport chain (ETC), where oxygen acts as the final electron acceptor. Without oxygen, the ETC ceases, causing an accumulation of NADH and FADH₂ and halting the Krebs cycle due to a shortage of oxidized cofactors (NAD⁺ and FAD).