Which of the following correctly represents the sequence of major stages in cellular respiration as the body uses food to produce energy?

• A. Citric Acid Cycle → Glycolysis → Electron Transport Chain
• B. Glycolysis → Citric Acid Cycle → Electron Transport Chain
• C. Electron Transport Chain → Glycolysis → Citric Acid Cycle
• D. Glycolysis → Electron Transport Chain → Citric Acid Cycle

Answer: (B)

Verified step by step guidance

1. Understand the process of cellular respiration: Cellular respiration is the process by which cells convert glucose into energy in the form of ATP. It occurs in three major stages: Glycolysis, the Citric Acid Cycle (also known as the Krebs Cycle), and the Electron Transport Chain (ETC).
2. Step 1: Glycolysis - This is the first stage of cellular respiration and occurs in the cytoplasm. During glycolysis, one molecule of glucose (C₆H₁₂O₆) is broken down into two molecules of pyruvate, producing a small amount of ATP and NADH.
3. Step 2: Citric Acid Cycle - After glycolysis, the pyruvate molecules are transported into the mitochondria, where they are converted into Acetyl-CoA. The Citric Acid Cycle then processes Acetyl-CoA to produce more NADH, FADH₂, and a small amount of ATP.
4. Step 3: Electron Transport Chain (ETC) - The NADH and FADH₂ molecules generated in the previous stages donate electrons to the ETC, which is located in the inner mitochondrial membrane. This process drives the production of a large amount of ATP through oxidative phosphorylation.
5. Sequence of stages: Based on the above steps, the correct sequence of major stages in cellular respiration is Glycolysis → Citric Acid Cycle → Electron Transport Chain.