Final answer:
The correct sequence for glucose catabolism in the presence of oxygen is a. Glycolysis, followed by the Krebs cycle, and ending with the Electron transport chain, culminating in ATP production.
Step-by-step explanation:
The correct order of events that occur during the catabolism of glucose in the presence of O₂ is Glycolysis → Krebs cycle → Electron transport chain. In the first stage, glucose is broken down into pyruvate through glycolysis, which occurs in the cytoplasm. Then, pyruvate is transported into the mitochondria where it is decarboxylated and enters the Krebs cycle (also known as the citric acid cycle), during which high-energy electrons and carbon dioxide are produced. These electrons are then used in the electron transport chain that occurs in the inner membrane of the mitochondria, leading to the synthesis of ATP via chemiosmosis. This series of reactions is critical in cellular respiration because it produces the ATP needed for cellular functions.
In the Krebs cycle, the pyruvate produced during glycolysis is fully oxidized into carbon dioxide. This pathway occurs in the mitochondria and generates NADH and FADH₂, which are electron carriers. The electrons from NADH and FADH₂ are then used in the electron transport chain to pump protons and produce ATP through chemiosmosis.