21. Structures of anti-PCP antibody shows that the tight binding of PCP to the antibody is primarily due to
A. hydrophobic forces
B. electrostatic forces.
C. Van der Waals forces.
D. none of these
22. Antigenic determinants bind to which portions of an antibody?
A. Variable regions
B. Constant regions
C. Only light chains
D. Only heavy chains
23. The humoral immune response relies on the production of soluble proteins called
A. antibodies
B. macromolecules
C. lymphocytes
D. none of these
24. The human IgG class of antibodies is divided into
A. five IgG classes
B. two IgG classes
C. three IgG classes
D. four IgG classes