Which one of the following energy systems can extract energy from both fat and glucose?

• A. Glycolysis
• B. Fermentation
• C. Phosphagen system
• D. Aerobic respiration

Answer: (D)

Verified step by step guidance

1. Understand the energy systems listed: Glycolysis, Fermentation, Phosphagen system, and Aerobic respiration. Each system has distinct characteristics and substrates it uses to extract energy.
2. Recall that fats and glucose are two major energy sources in the body. Fats are broken down into fatty acids, while glucose is metabolized into pyruvate or directly used in energy pathways.
3. Identify which energy system can utilize both fats and glucose. Glycolysis primarily uses glucose, Fermentation is an anaerobic process that also relies on glucose, and the Phosphagen system uses creatine phosphate for immediate energy, not fats or glucose.
4. Aerobic respiration is the energy system that can extract energy from both fats and glucose. It occurs in the mitochondria and requires oxygen. Fats are metabolized through β-oxidation, producing acetyl-CoA, which enters the citric acid cycle. Glucose is metabolized into pyruvate, which also enters the citric acid cycle under aerobic conditions.
5. Conclude that aerobic respiration is the correct answer because it is the only system capable of utilizing both fats and glucose efficiently to produce ATP.