Which energy system uses oxygen to produce 30+ ATP and occurs in the mitochondria?

Which energy system uses oxygen to produce 30+ ATP and occurs in the mitochondria?

• A. Anaerobic glycolysis
• B. Creatinine phosphate system
• C. Aerobic respiration
• D. Lactic acid fermentation

Answer: (C)

The energy system that uses oxygen, occurs in the mitochondria, and yields about 30 or more ATP per glucose is aerobic respiration. Here’s how it works: glycolysis happens in the cytosol and produces a small amount of ATP and pyruvate. When oxygen is present, pyruvate enters the mitochondria and is fully oxidized through the citric acid cycle and the electron transport chain. The NADH and FADH2 generated during these steps drive oxidative phosphorylation, where most of the ATP is created. Because this process relies on oxygen as the final electron acceptor in the mitochondria, it is efficient and produces a large energy payoff—roughly 30 to 32 ATP per glucose. This makes it the primary source of ATP during longer, endurance activities, even though it takes longer to kick in than the immediate bursts from other systems. In contrast, anaerobic glycolysis does not require oxygen and yields only about 2 ATP per glucose in the cytosol, the creatine phosphate system provides a quick but limited supply of ATP without using glucose, and lactic acid fermentation occurs when oxygen is limited and also occurs outside the mitochondria.

The energy system that uses oxygen, occurs in the mitochondria, and yields about 30 or more ATP per glucose is aerobic respiration. Here’s how it works: glycolysis happens in the cytosol and produces a small amount of ATP and pyruvate. When oxygen is present, pyruvate enters the mitochondria and is fully oxidized through the citric acid cycle and the electron transport chain. The NADH and FADH2 generated during these steps drive oxidative phosphorylation, where most of the ATP is created. Because this process relies on oxygen as the final electron acceptor in the mitochondria, it is efficient and produces a large energy payoff—roughly 30 to 32 ATP per glucose. This makes it the primary source of ATP during longer, endurance activities, even though it takes longer to kick in than the immediate bursts from other systems. In contrast, anaerobic glycolysis does not require oxygen and yields only about 2 ATP per glucose in the cytosol, the creatine phosphate system provides a quick but limited supply of ATP without using glucose, and lactic acid fermentation occurs when oxygen is limited and also occurs outside the mitochondria.