91. Antibodies 
A. play a large role in cell-mediated immunity.
B. are produced by both T and B cells.
C. are composed of four light and four heavy polypeptide chains.
D. are not specific, but act generally.
E. have a variable region that binds to a specific antigenic determinant.

92.  The immunoglobulin that is often the first antibody produced in response to an antigen is  
A.  IgD.
B.  IgA.
C.  IgM.
D.  IgE.
E.  IgG.

93.  Antibodies  
A.  activate antigens.
B.  may initiate inflammation and enhance phagocytosis.
C.  are proteins produced by T helper cells.
D.  are needed for costimulation.
E.  have memory.

94.  Which of the following is correctly matched?  
A.  IgA – found in saliva and tears
B.  IgD – can cross the placenta
C.  IgG – first to challenge the antigen
D.  IgM – antigen-binding receptor on B cells
E.  IgE – transfusion reactions

95.  Antibodies secreted in breast milk  
A.  are IgG antibodies.
B.  are IgA antibodies.
C.  provide natural active adaptive immunity.
D.  include the cytokine interleukin 2.
E.  promote inflammation.

96.  As a result of opsonization,  
A.  holes are produced in target cell membranes.
B.  organ transplant rejection occurs.
C.  antigens are more susceptible to phagocytosis.
D.  antigens clump together.
E.  inflammation, chemotaxis, and lysis occur.

97.  B-cells  
A.  are a subset of T cells.
B.  when activated become plasma cells and produce antibodies.
C.  are responsible for forming all the body’s memory cells.
D.  suppress the activity of T cells.
E.  mature in the thymus.

98.  Several days after an initial contact with an antigen, antibody blood levels increases. This is a  
A.  primer response.
B.  primary response.
C.  precipitating response.
D.  principle response.
E.  cascade response.

99.  The secondary or memory response  
A.  occurs after the primary response has activated NK cells.
B.  provides better protection than the primary response.
C.  is less effective in antibody production.
D.  produces different antibodies than those produced in the primary immune response.
E.  does not protect the body after the first exposure.

100.  The type of cell responsible for the secondary response is a  
A.  mast cell.
B.  macrophage.
C.  memory cell.
D.  red blood cell.
E.  monocyte.