Which metabolic process releases stored energy by breaking down glucose in the presence of oxygen, producing carbon dioxide and water?

Which metabolic process releases stored energy by breaking down glucose in the presence of oxygen, producing carbon dioxide and water?

• A. Fermentation
• B. Photosynthesis
• C. Respiration
• D. Digestion

Answer: (C)

Aerobic respiration uses oxygen to fully oxidize glucose, releasing energy captured as ATP while producing carbon dioxide and water. In this pathway, glucose is first broken down in the cytoplasm (glycolysis) to produce a small amount of ATP and NADH, then pyruvate is processed in the mitochondria to enter the citric acid cycle and, finally, electrons are transferred through the electron transport chain to drive most of the ATP production. Oxygen acts as the final electron acceptor, combining with protons to form water. This yields far more ATP per glucose than anaerobic processes, making it the primary energy-releasing route when oxygen is available. Fermentation occurs without oxygen and yields far less ATP, along with lactate or ethanol and CO2. Photosynthesis builds glucose using light energy and does not release energy from glucose. Digestion is the breakdown of food in the digestive system and is not the process that releases energy from glucose with oxygen.

Aerobic respiration uses oxygen to fully oxidize glucose, releasing energy captured as ATP while producing carbon dioxide and water. In this pathway, glucose is first broken down in the cytoplasm (glycolysis) to produce a small amount of ATP and NADH, then pyruvate is processed in the mitochondria to enter the citric acid cycle and, finally, electrons are transferred through the electron transport chain to drive most of the ATP production. Oxygen acts as the final electron acceptor, combining with protons to form water. This yields far more ATP per glucose than anaerobic processes, making it the primary energy-releasing route when oxygen is available.

Fermentation occurs without oxygen and yields far less ATP, along with lactate or ethanol and CO2. Photosynthesis builds glucose using light energy and does not release energy from glucose. Digestion is the breakdown of food in the digestive system and is not the process that releases energy from glucose with oxygen.