What happens to the energy released in metabolism?

• A. It is released as heat only
• B. It is released as kinetic energy that cells use to do work
• C. It is stored as chemical potential energy
• D. It disappears

Answer: (B)

Metabolic energy is meant to power what the cell needs to do. When nutrients are broken down, the released energy is captured and used to perform work inside the cell—things like moving molecules across membranes, powering chemical reactions, and driving muscle contraction. Some of that energy is stored temporarily in ATP, which acts as a handy chemical energy reservoir, ready to release energy as needed. A byproduct of metabolism is heat, which helps maintain body temperature, but the energy isn’t simply dumped as heat or lost; it’s transformed into work and stored in usable forms. So the energy released in metabolism is utilized to drive cellular processes (the movement and activity inside the cell), with heat generation as a byproduct.