Which of the following types of molecules can be used as metabolic fuel to produce ATP during cellular respiration?

• A. Only carbohydrates
• B. Only nucleic acids
• C. Only lipids
• D. Carbohydrates, lipids, and proteins

Answer: (D)

Verified step by step guidance

1. Understand the concept of cellular respiration: Cellular respiration is the process by which cells convert biochemical energy from nutrients into ATP, the energy currency of the cell. This process involves breaking down molecules to release energy.
2. Identify the types of molecules that can serve as metabolic fuel: Carbohydrates, lipids, and proteins are the primary macromolecules that can be broken down during cellular respiration to produce ATP. Nucleic acids are not typically used as metabolic fuel.
3. Explain how carbohydrates are used: Carbohydrates, such as glucose, are the primary and most efficient source of energy. Glucose undergoes glycolysis, the citric acid cycle, and oxidative phosphorylation to produce ATP.
4. Explain how lipids are used: Lipids, particularly triglycerides, are broken down into glycerol and fatty acids. Fatty acids undergo beta-oxidation to produce acetyl-CoA, which enters the citric acid cycle to generate ATP.
5. Explain how proteins are used: Proteins are broken down into amino acids. The amino acids can be deaminated, and their carbon skeletons can enter the citric acid cycle or be converted into glucose through gluconeogenesis to produce ATP.