5 Steps to a 5 AP Biology, 2014-2015 Edition

AP Biology Practice Exam 2 ❮ 305

1. Immune system question (here, the student can
   obtain 4 points from two of the answers; if
   4 points are awarded for an answer, a maximum
   of 3 points can be obtained for each of the
   remaining answers)
   A. (maximum 4 points)
   
   
   • Definition of an antigen as a molecule
     foreign to the body. (1 ⁄ 2 point)
   
   
   • Mentioning that the primary immune
     response is an example of humoral immu-
     nity. (1 ⁄ 2 point)
   
   
   • Description of a B cell and how each B
     cell has a specific antigen recognition site
     on its surface that will match up with
     onlyoneantigen. (1 point)
   
   
   • When B cells meet and attach to the
     appropriate antigen, they become acti-
     vated and undergo mitosis and differenti-
     ation into two types of cell. (1 point)
   
   
   • The two types of cell are the memory cells
     and plasma cells. (1 ⁄ 2 point)
   
   
   • Definition of plasma cells as the cells
     that produce the specific antibodies.
     (1 ⁄ 2 point)
   
   
   • Definition of memory cells as the cells
     that head up the secondary immune
     response. (1 ⁄ 2 point)
   
   
   • Description of how an antibody recog-
     nizes a particular antigen, including the
     fact that antibodies have two functional
     regions: Fab, which binds to the antigen;
     and Fc, which binds to the effector cells,
     and later comes in and cleans up the trash
     left behind. (1 point)
   
   
   • Mentioning that complement is the one
     that binds to the antigen–antibody com-
     plex and aids in the quicker removal of
     the complex from the body. (1 ⁄ 2 point)
     B. (maximum 3 points)
   
   
   • Mentioning that this portion of the
     immune system is known as cell-mediated
     immunity. (1 ⁄ 2 point)
   
   
   • Mentioning that the major player involved
     here is the cytotoxic T cell. (1 point)
     
     
     • Mentioning that the cells infected by a
       virus are forced to produce viral antigens,
       some of which show up on the surface of
       the cell, and that it is these antigens that
       cytotoxic T cells recognize and attack.
       (1 point)
     
     
     • Mentioning that all cells of the human
       body (except red blood cells) have class I
       histocompatibility antigens (MHC I) on
       their surfaces. (1 point)
     
     
     • Further discussion of MHC—mentioning
       that MHC I antigens are slightly different
       for each person and the immune system
       accepts any cell that has the identical
       MHC I as friendly, and any cell that has
       a different form of MHC on its surface as
       an enemy. (1 point)
       C. (maximum 4 points)
     
     
     
     
   
   
   
   

• Definition of nonspecific immunity as the
  nonspecific prevention of the entrance of
  invaders into the human body. (1 point)


• Examples (each example is worth 1 point)
  a. Lysozyme in the saliva can kill germs
  before they have the chance to take hold.
  b. The skin covering the body is a major
  form of nonspecific protection against
  invasion.
  c. The mucous membrane lining the tra-
  chea and lungs prevent bacteria from
  entering cells and actually assist in the
  expulsion of bacteria by ushering them
  up and out with a cough.
  d. The low pH of the stomach (acidity) is
  a nonspecific defense mechanism
  because it is able to kill a lot of bacteria
  that enter the body that cannot handle
  such an acidic environment.
  D. (maximum 4 points)


• Definition of a vaccination as something
  given to an individual in an effort to
  prime the immune system to be prepared
  to fight a specific sickness if confronted
  again in the future. (1 point)

❯ Free-Response Grading Outline

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