What's oxidation in biology

Oxidation-reduction reactions. The basic definition can be defined as: One reactant is oxidized (loses electrons), while another is reduced (gains electrons).

Definition. (1) The combination of oxygen with a substance forming oxide. (2) A chemical reaction in which there is the loss of electrons or gain (or increase in the proportion) of oxygen, hence, resulting in an increase in oxidation state by a molecule, atom or ion.