Which statement accurately describes anabolism?

• A. Energy-releasing reactions that break down molecules
• B. Energy-requiring reactions that build larger molecules
• C. Reactions that occur only in mitochondria
• D. Reactions that convert nutrients into energy without steps

Answer: (B)

Anabolism is the set of biosynthetic processes that use energy to build larger, more complex molecules from smaller ones. These reactions require input of energy (often in the form of ATP) to form new chemical bonds, enabling things like protein synthesis, glycogen formation, and lipid synthesis. That’s why the best description is energy-requiring reactions that build larger molecules. In contrast, catabolic pathways break down molecules to release energy, and energy production in cells happens through regulated, stepwise processes—not “without steps.” While mitochondria are important for energy production and some biosynthetic steps, anabolic reactions are not confined to a single organelle.