Antigen-antibody binding occurs at-

Ans. is 'a' i.e., SurfaceGeneral features of antigen antibody reactiono The reaction is specific, an antigen combines with only its homologous antibody and vice versa, the specificity however is not absolute.o Antigen-Antibody reaction requires the presence of electrolytes at a specific pH and temperatureo Bonds involved in Antigen-Antibody reaction are - Van der waal's bond, Ionic bonds, and Hydrogen bondingo Covalent bonds are not involvedo There is no denaturation of the antigen or antibody during the reactiono Entire molecule of the antigen and antibody reactso The combination occurs at the surface. Therefore it is surface antigens that are immunologically relevanto The combination is firm and reversibleo Both antigen and antibody participate in the formation of agglutinates or precipitates.