Which of the following is the final metabolic pathway for all energy-yielding nutrients in cellular respiration?

• A. Citric acid cycle (Krebs cycle)
• B. Fermentation
• C. Electron transport chain
• D. Glycolysis

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the context of cellular respiration, which is the process by which cells convert energy-yielding nutrients (like carbohydrates, fats, and proteins) into usable energy in the form of ATP.
2. Step 2: Review the major stages of cellular respiration: Glycolysis, Citric Acid Cycle (Krebs Cycle), and Electron Transport Chain (ETC). Each stage plays a specific role in energy production.
3. Step 3: Glycolysis occurs in the cytoplasm and breaks down glucose into pyruvate, producing a small amount of ATP and NADH. It is the first step but not the final pathway.
4. Step 4: The Citric Acid Cycle (Krebs Cycle) occurs in the mitochondria and processes acetyl-CoA to produce NADH and FADH2, which are electron carriers. This is an intermediate step, not the final pathway.
5. Step 5: The Electron Transport Chain (ETC) is the final metabolic pathway in cellular respiration. It occurs in the inner mitochondrial membrane, where electrons from NADH and FADH2 are transferred through protein complexes, driving the production of ATP via oxidative phosphorylation.