The document discusses biological oxidation and the respiratory chain. It defines oxidation as the addition of oxygen or removal of hydrogen, and reduction as the addition of hydrogen. Redox reactions occur together in cells and liberate energy necessary for cellular functions. The respiratory chain is a series of carriers that transfer electrons from lower to higher redox potentials, ultimately reaching oxygen. This process of oxidative phosphorylation occurs in the inner mitochondrial membrane and uses the energy released to produce ATP from ADP and phosphate. Inhibitors of the respiratory chain, such as cyanides and carbon monoxide, inhibit oxidation and therefore ATP production. Uncouplers of oxidative phosphorylation allow oxidation but prevent phosphorylation, so energy is lost as heat.