<prompt> Which of the following is true about IgG antibody?Produced in primary immune responseCannot cross placentaProvides local protectionProduced in secondary immune response  <response>: IgG contains 2 heavy chains and 2 light chains;heavy chains being of gamma type. It is the major antibody;it constitutes of 75 -80 of total immunglobulins in circulation. It is the antibody seen in secondary immune response. It can pass from vascular compament to interstiitial space. REFERENCE: DM VASUDEVAN TEXTBOOK SEVENTH EDITION ; PAGE NO : 688 