31. Which of the following statements concerning the spleen is true? 
A. Splenic arteries enter the organ at the periarterial sheath.
B. The spleen can act as a blood reservoir.
C. The white pulp is associated with the venous supply.
D. The red pulp has trabeculae.
E. Humans can not survive without a spleen.

32.  The white pulp of the spleen  
A.  contains lymphocytes that can stimulate an immune response. 
B.  filters lymph as it flows through the spleen.
C.  destroys defective red blood cells.
D.  stimulates immune responses, filter lymph, and destroys defective red blood cells.

33. Which of the following statements accurately describes the thymus gland? 
A. The thymus gland lacks a capsule.
B. The thymus gland contains many reticular fibers.
C. The thymus gland decreases in size after age 60.
D. Lymphocytes are found only in the medulla of the thymus gland.
E. The thymus increases in size with aging.

34.  What is the function of thymosin?  
A.  destroys damaged red blood cells
B.  destroys damaged white blood cells
C.  activates lymphocytes in lymph nodes
D.  maturation of T-cells

35.  When innate immunity is activated,  
A.  each exposure is very specific.
B.  previous exposures are remembered.
C.  each exposure produces the same response.
D.  each exposure increases the strength of the immune response.
E.  the second exposure does not produce a response.

36.  Which of the following is true of adaptive immunity?  
A.  It is present at birth.
B.  Previous encounters with the foreign substance does not change the response.
C.  The second response is faster and stronger than the first response.
D.  Responses are general, not specific.

37.  Which of the following is NOT a characteristic of adaptive immunity?  
A.  It has memory.

B.  You are born with it.
C.  It has specificity.
D.  Acquired throughout your lifetime.

38.  Which of the following characteristics is/are most consistent with adaptive immunity?  
A.  constant response to each exposure
B.  specificity
C.  memory
D.  increased response to second and subsequent exposures
E.  specificity, memory and increased response to second and subsequent exposures

39.  Which of the following would be classified as an innate physical barrier?  
A.  activation of complement
B.  phagocytosis of invading organisms
C.  washing action of tears and saliva
D.  inflammation
E.  release of histamine

40.  Complement proteins  
A.  can form holes in the plasma membrane of target cells.
B.  are on the surface of macrophages.
C.  are hormones found in the blood.
D.  may cause the release of interferon.
E.  do not attract neutrophils, monocytes, macrophages, or eosinophils.