Oxidation-reduction reactions are an important type of reaction in biochemistry that involve the transfer of electrons. Oxidation involves the loss of electrons and reduction involves the gain of electrons. These two processes must occur simultaneously. Thermodynamics is the study of energy and is important for understanding biochemistry. The first law of thermodynamics states that energy is conserved, while the second law states that spontaneous reactions result in an increase in the randomness or entropy of the universe. For a reaction to be spontaneous, the change in entropy of the universe must be positive.