Which of the following correctly represents the main stages of cellular respiration in the order they occur?

• A. Electron transport chain → Glycolysis → Krebs cycle
• B. Krebs cycle → Glycolysis → Electron transport chain
• C. Glycolysis → Krebs cycle → Electron transport chain
• D. Glycolysis → Electron transport chain → Krebs cycle

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the process of cellular respiration, which is the metabolic pathway that converts glucose into energy (ATP) in cells. It consists of three main stages: Glycolysis, Krebs cycle (Citric Acid Cycle), and Electron Transport Chain.
2. Step 2: Glycolysis is the first stage of cellular respiration. It occurs in the cytoplasm and breaks down one molecule of glucose into two molecules of pyruvate, producing a small amount of ATP and NADH. This step does not require oxygen.
3. Step 3: The Krebs cycle (Citric Acid Cycle) is the second stage. It occurs in the mitochondria and processes the pyruvate from glycolysis into carbon dioxide while generating high-energy electron carriers (NADH and FADH2) and a small amount of ATP.
4. Step 4: The Electron Transport Chain is the final stage. It occurs in the inner mitochondrial membrane, where the high-energy electrons from NADH and FADH2 are used to create a proton gradient that drives the synthesis of ATP through oxidative phosphorylation.
5. Step 5: Based on the sequence of these processes, the correct order of the main stages of cellular respiration is: Glycolysis → Krebs cycle → Electron Transport Chain.