Which type of reaction uses energy to build larger molecules from smaller ones?

• A. Catabolic reactions
• B. Photosynthesis
• C. Anabolic reactions
• D. Immobilised enzyme

Answer: (C)

Anabolic reactions are the building-up side of metabolism. They use energy to join small molecules into larger, more complex ones, forming bonds that create macromolecules like proteins from amino acids or starch from glucose. Because energy is required to drive these bond-forming steps, anabolic pathways consume energy (often via ATP) to build up structure and function in the cell.

Photosynthesis is an example of a process that builds sugars using light energy, but the term that describes the general type of reaction for building larger molecules from smaller ones is anabolic reactions. An immobilised enzyme isn’t a type of reaction; it’s a way of fixing an enzyme to a support for practical use.