biology

The two main forms of energy that power living systems are chemical energy and mechanical energy. Chemical energy is the energy stored in bonds between atoms, driven by the attraction of oppositely charged particles. Examples of chemical energy include food sources such as carbohydrates, lipids, proteins and ATP molecules. Mechanical energy is the energy that is stored in motion or in the form of sound and light. Examples of mechanical energy include muscular contraction, nerve impulses and sound waves.