Which statement about anabolic vs catabolic is true?

• A. Anabolic builds molecules, requiring energy; Catabolic breaks down molecules, releasing energy
• B. Anabolic releases energy; Catabolic consumes energy
• C. Both are identical
• D. Only catabolic processes require energy

Answer: (A)

In metabolism, energy flow distinguishes anabolic from catabolic processes: anabolic reactions synthesize larger, more complex molecules and require input of energy to build bonds, while catabolic reactions break down molecules and release energy that can be captured to power cellular work. This makes the statement that anabolic builds molecules and needs energy, while catabolic breaks down molecules and releases energy, the correct one. The other ideas don’t fit because they either flip the energy direction (anabolism releasing energy), claim the processes are identical, or say only catabolic processes require energy—none of which aligns with how cells typically harvest and use energy.