What is Oxidation-Reduction?


An oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between two species. An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron. Redox reactions are common and vital to some of the basic functions of life, including photosynthesis, respiration, combustion, and corrosion or rusting[1].



Fig.1 The illustration of oxidation-reduction (redox) reaction(The figure from https://tuitiontube.com/)


Oxidation-Reduction in Biology


In biology, photosynthesis and respiration of plants are typical oxidation-reduction reactions. Photosynthesis in plants provides the material basis for respiration, and respiration provides energy and raw materials for photosynthesis; they are two processes that are mutually opposed, interdependent and restricted.



Fig.2 The process of photosynthesis(The figure from http://bglarochelle.pbworks.com/)


In humans and animals, respiration oxidizes glucose to carbon dioxide and water. Through respiration, energy stored in food molecules is transformed into chemical energy of high-energy phosphoric acid bonds existing in adenosine triphosphate (ATP). This chemical energy is then supplied to humans and animals for mechanical movement, maintenance of body temperature, anabolism, active transport of cells, etc.



Fig.3 Respiration(The figure from https://www.thinglink.com/)






[1] Petrucci, et al. General Chemistry: Principles & Modern Applications. 9th ed. Upper Saddle River, New Jersey: Pearson/Prentice Hall, 2007.

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