Which statement accurately describes anabolic and catabolic reactions?

• A. Anabolism releases energy; catabolism consumes energy.
• B. Both processes consume energy.
• C. Both processes produce energy.
• D. Anabolism requires energy to build; catabolism breaks down releasing energy.

Answer: (D)

In metabolism, building larger molecules from smaller ones (anabolism) uses energy to form bonds, while breaking those molecules down (catabolism) releases energy as bonds are broken. That energy released can be captured in ATP and electron carriers to power other cellular work, which is why anabolism requires energy to build and catabolism releases energy. The other statements mix up the direction of energy flow: anabolic processes don’t release energy, and catabolic processes don’t universally produce energy in every step. The overall pattern is energy input for building and energy release from breaking down.