Life is a constant battle against entropy. All living things are well-ordered structures with low entropy (degree of disorder) and the second law of thermodynamics demands that entropy levels are always trying to increase. Animals fight this tendency by eating low entropy plants (or other animals), breaking them down to release entropy, thus satisfying the second law, and retaining low entropy components, i.e. highly-ordered and high energy molecules such as glucose. If we stop eating, our bodies start to disintegrate and we die – entropy wins as the molecules of bodies are dispersed.
Plants use sunlight to fight the entropic battle. In photosynthesis, low entropy solar energy converts carbon dioxide and water to oxygen and glucose with the creation of entropy in the form of dispersed heat.