IMMUNOLOGY

Detailed explanation-1: -As more antigen is added, the amount of protein precipitated increases until the antigen/antibody molecules are at an optimal ratio. This is known as the zone of equivalence or equivalence point. When the amount of antigen in solution exceeds the amount of antibody, the amount of precipitation will decrease.

Detailed explanation-2: -The range of optimal concentrations, at which the greatest amount of precipitation is generated, is called the equivalent zone. Based upon this principle, the presence of specific antigens in a mixture and the relative concentration of antigens can be detected using antibodies.

Detailed explanation-3: -Zone of Equivalence-optimal amounts of both antibody and antigen (results in agglutination) Postzone-excess antigen to the available antibody (no agglutination is a result)