<prompt> Which one of the following hypotheses may be sufficient to explain non precipitation in antigen-antibody system?The antigen has a multivalent determinantThe antigen has a single, non-repeated determinantThe antibody has been cleaved to divalent Fab ligandsThe antibody has been cleaved to divalent Fab2 ligands  <response>: Neither monovalent antigen nor monovalent antibody Fab: can form a precipitin lattice. An antigen molecule containing closely repeating antigen determinants e.g., a polysaccharide or a multi chained polymeric protein, can bind antibody to two determinants on a single particle; this monogamous bivalency inhibits precipitation. Fab2 divalent antibodies can precipitate antigens, though they lack Fc portions. 