Oxidation-Reduction Reaction - Biological Processes

Photosynthesis consists of a series of oxidation-reduction reactions which begin when carbon in carbon dioxide is reduced and electrons are passed to molecules in the plant. When living things break down molecules of food to produce energy, carbon dioxide, and water, oxidation-reduction has taken place in the form of cellular respiration. As in photosynthesis, a series of chemical reactions are necessary to complete cellular respiration. Another important biological process, the nitrogen cycle, is composed of a series of oxidation and reduction reactions. Bacteria take nitrogen from the air and reduce it to ammonia and nitrates, nutrients that plants use to make proteins, nucleic acids, and other nitrogen-containing molecules needed for their metabolism. Other bacteria in soil convert nitrates back into nitrogen gas. Many of the oxidation-reduction reactions that occur in living organisms are regulated by enzymes.