(embryology) A reaction that manifests during fertilization, when the sperm cell coalesces with the egg's plasma membrane; this prevents entry of a second sperm

The occurrence of proteolytic enzymes specific for foreign proteins introduced via parents.

(organic chemistry) Any reaction that produces an azo compound. / (pathology) A red discolouration of the urine on addition of diazobenzenesulfonic acid - an indication of typhoid fever.

(inorganic chemistry) An exothermic redox reaction between a metal and metal oxide as reactants, such as aluminium and iron oxide.

(chemistry) Any reversible reaction in which a product is continuously removed by precipitation, driving the reaction in one direction

(chemistry) The amount of heat evolved or absorbed in the production of one mole of a reaction product

(organic chemistry) The disproportionation of an aldehyde into an alcohol and a carboxylic acid.

(organic chemistry) An organic reaction which condenses aldehydes (or ketones) with α-halo esters, using a metallic zinc to form β-hydroxy-esters.

(organic chemistry) A class of reaction in which a bond (typically a double bond) is broken and a small molecule (such as carbon monoxide) is inserted in its place

(immunology) A hypersensitivity reaction involving the in situ formation of antigen/antibody complexes after the intradermal injection of an antigen.