Which statement about catabolic metabolic pathways is true?

Which statement about catabolic metabolic pathways is true?

• A. Catabolic pathways store energy by building molecules.
• B. Catabolic pathways release energy by breaking down molecules.
• C. Catabolic pathways increase entropy only.
• D. Catabolic pathways convert energy to heat with no chemical changes.

Answer: (B)

Catabolic pathways break down large, complex molecules into smaller ones, and in doing so they release the chemical energy stored in bonds. That energy becomes available as usable forms like ATP and NADH to power other cellular processes. Because these reactions involve bond breaking and energy transfer, they are exergonic and release energy overall. Building molecules to store energy is the job of anabolic pathways, which use energy to synthesize larger structures. While entropy tends to increase as large molecules are broken apart, catabolic processes involve actual chemical changes and energy transfer, not just a rise in disorder. Some energy is released as heat, but there is also purposeful energy captured in carriers, so the key idea is the release of energy by breaking down molecules.

Catabolic pathways break down large, complex molecules into smaller ones, and in doing so they release the chemical energy stored in bonds. That energy becomes available as usable forms like ATP and NADH to power other cellular processes. Because these reactions involve bond breaking and energy transfer, they are exergonic and release energy overall. Building molecules to store energy is the job of anabolic pathways, which use energy to synthesize larger structures. While entropy tends to increase as large molecules are broken apart, catabolic processes involve actual chemical changes and energy transfer, not just a rise in disorder. Some energy is released as heat, but there is also purposeful energy captured in carriers, so the key idea is the release of energy by breaking down molecules.