Which of the following statements concerning B cell receptors (BCRs) is FALSE?
◦ They are bound to the surface of B lymphocytes and have two antigen-binding sites.
◦ They are complementary in shape to a specific antigenic determinant that they may or may not encounter.
◦ Each B lymphocyte is randomly generated with antibody variable regions that determine its BCR.
◦ They are formed in response to an encounter with an antigen.
◦ Scientists estimate that each person forms at least 1011 different types of B lymphocytes with distinct BCRs.