Which molecule is a product of cellular respiration and used for energy transfer in cells?

• A. ATP
• B. DNA
• C. RNA
• D. Glucose

Answer: (A)

Energy transfer in cells relies on a molecule that acts like a rechargeable battery: ATP is produced by cellular respiration and used to power most cellular work. During respiration, the energy stored in glucose is captured and stored in the high-energy phosphate bonds of ATP through glycolysis, the citric acid cycle, and oxidative phosphorylation in the mitochondria. When the cell needs energy, ATP is converted to ADP and inorganic phosphate, releasing energy to drive processes such as muscle contraction, active transport, and synthesis of molecules. DNA and RNA store and relay genetic information, not immediate energy for cellular activities. Glucose is a fuel that can be broken down to make ATP, but the energy is delivered through ATP itself. Therefore, ATP fits both parts of the question: it’s produced by cellular respiration and it serves as the primary molecule for energy transfer in cells.