In Precipitation Tests, Maximum Precipitation Takes Place When

Question

In precipitation tests, maximum precipitation takes place when
A) the amount of the antibody exceeds the amount of the antigen.
B) the amount of the antigen exceeds the amount of the antibody.
C) the amount of the antibody and the amount of the antigen are at optimal proportions.
D) a toxin is present.
E) a complex solution of many antibodies is used.

Accepted Answer

Maximum precipitation takes place when the amount of the antigen and the amount of the antibody are at optimal proportions. In this situation, there is an equivalence zone where antigen and antibody combine to form precipitation complexes at a maximum rate. Outside of this range, there is either an antigen or antibody excess, leading to incomplete precipitation. The presence of a toxin or using a complex solution of many antibodies would not affect the optimal proportions of antigen and antibody for precipitation.