AP Bio Study Guide

Big Idea 2.A

What are the laws of thermodynamics?

Living organisms require a constant input of energy. Biological systems constantly transform this energy in order to carry out all life functions. These energy transformations are governed by the following laws of thermodynamics:

  • Energy cannot be created or destroyed, only transformed from one form to another.
  • Each transformation causes the universe to become more disordered (i.e. it increases the universe's entropy). In addition, some energy is "lost" — it doesn't leave the system, but becomes unusable or unable to do work (e.g. heat).