Which energy system requires oxygen and is known as the oxidative system?

• A. aerobic
• B. glycolysis
• C. oxidative system
• D. anaerobic

Answer: (C)

The energy system that requires oxygen and is described as the oxidative system is the one that fuels activity through aerobic metabolism. It relies on oxygen to drive the Krebs cycle and the electron transport chain in the mitochondria, allowing fats and carbohydrates to be converted into ATP. This system supports longer, steady-state exercise because it can sustain energy production for extended periods, though it takes a bit longer to ramp up compared to anaerobic pathways.

In contrast, pathways that don’t require oxygen—such as the immediate, phosphagen system and anaerobic glycolysis—provide quick bursts of ATP but are limited in duration. The term oxidative (often aligned with the aerobic label) specifically captures the oxygen-using, long-duration energy source, which is why it’s the best choice for this question.