Immunoglobulins are glycoproteins made up of four polypeptide chains (linked by disulphide bonds) - TWO heavy (h) (440 AMINO ACIDS) and two light (L) (220 amino acids). Light and heavy chains are subdivided into variable and constant regions. They are mainly of five types as given below.☢ Types of Immunoglobulins :Most abudant and predominant antibody in the secondary response.Only antibody to cross the placenta.Opsonizes i.e., enhance phagocytosis and fixes complement.Secondary immunoglobulinFound in body secretions including saliva and tears.Does not fix complement.Available in colostrum and mother's milk.Fight against invading micro-organisms even before sensitized.MacroimmunoglobulinProduced early in the primary response.Most efficient in aggutination, complement fixation.Does not cross placenta.Antigen receptor on the SURFACE of B cells.Umcertain.Functions as antigen receptor.Activates B-cells.Concentrated in mucous membranes, SKIN and lungs.Mediate immediate hypersensitivity.Does not fix complement.Main host defence against helminths infection.____________________________Correct Answer (1) :(A) (iii)(B) (ii) (C) (iv)