What does the 1st law of thermodynamics state?

The first law of thermodynamics, also known as the law of energy conservation, states that energy cannot be created or destroyed in an isolated system. Instead, energy can only change forms or be transferred from one system to another. This principle underscores the conservation of energy in biological and physical processes, meaning that the total amount of energy remains constant.

For example, in cellular respiration, the chemical energy stored in glucose is transformed into ATP, the energy currency of cells, illustrating how energy is converted from one form to another rather than being created or eliminated. Understanding this law is crucial for analyzing energy transfer in biological systems, as it provides the foundation for how organisms obtain and utilize energy from their environments.