11. Fab fragment has

A. one antigen binding site
B. two antigen binding site
C. one antibody binding site
D. two antibody binding site

12. The main function of antibodies is to

A. kill all the foreign bodies
B. generate antigens, thus conferring immunization
C. protect the circulatory system
D. chemically combine with the antigen which induces it, inactivate the antigen and protect the body from disease

13. Alum is an effective adjuvant because it

A. disaggregates the antigen.
B. is immunogenic for stem cells
C. is immunogenic for T cells
D. slows the release of antigen

14. A secondary antibody is an antibody that

A. has been used in prior experiments
B. is synthetically produced
C. binds to another antibody
D. is produced in boostered animals

15. The immunoglobulin fold is

A. found only in IgG molecules
B. a β-barrel composed of a three- and a four-stranded antiparallel β-sheet
C. both (a) and (b)
D. found six times in the IgG molecule