5005 Blue Notes Practice Test

The concept here is chemical energy—the energy stored in chemical bonds that is released during chemical reactions. Food contains nutrients with bonds that store energy, and the body unlocks that energy through digestion and metabolism to power growth, maintenance, and activity. So food is a source of chemical energy for living organisms. In contrast, heat from a heater is thermal energy, not stored in chemical bonds for biological use. Light is radiant energy carried by photons, and movement is kinetic energy of motion; neither are chemical energy stored in molecules to be released by digestion. Therefore, food best provides chemical energy.