MCQs Immunology (31-40): Complement System with Answers

31. Complement component C3 is cleaved by:
A. C3b
B. C3bBb
C. Factor B
D. Factor D
E. Factor H  

32. The membrane attack complex  in the complement pathway consists of:
A. C3b3b,Bb
B. C5b,6,7,8,9
C. Colicins
D. OH.
E. Properdin  

33. Complement component C3b:
A.      directly injures bacteria.
B.      is an anaphylatoxin.
C.      is chemotactic.
D.      is the inactive form of C3.
E.      opsonizes bacteria.  

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34. A complement component that is strongly chemotactic for neutrophils is:
A.      C3
B.      C3b
C.      C5a
D.      C5b
E.       C9  

35. The initial complement component that is bound by complement-fixing antibodies is:
A.      C1q
B.      C1s
C.      C3b
D.      C5a
E.       C9  

36. Several of the complement components are:
A.      Antibodies
B.      Cytokines
C.      Enzymes
D.      Glycolipids
E.       Hormones

37. The classical and alternative pathways meet at complement component:
A.   C3
B.   C4
C.  C4b
D.  C5
E.  Factor D

38. One principal function of complement is to:
A.    bind antibodies attached to cell surfaces and to lyse these cells
B.    cross-link allergens
C.    inactivate perforins
D.    mediate the release of histamine
E.    phagocytize antigens  

39. The major role of the complement system is to work in conjunction with
A.    antibodies to lyse cells via the C8 and C9 components
B.    antibodies to lyse cells via the perforin molecules
C.    antibodies to opsonize cells
D.    the major histocompatibility complex for cell recognition
E.    the T-cell receptor for production of lymphokines  

40. Complement fixation:
A.   can be modified by the cholera toxin
B.    has intrinsic guanylate cyclase activity
C.    can be desensitized by phosphorylation
D.    is an effector function of IgG and IgM following antigen binding  

Answers key of the above MCQs in Immunology are
31. B (C3bBb)
32. B (C5b,6,7,8,9)
33. E (Opsonizes bacteria.)
34. C (C5a)
35.A (C1q)
36. C (Enzymes)
37. A. (C3)
38. A. (Bind antibodies attached to cell surfaces and to lyse these cells)
39. A. (antibodies to lyse cells via the C8 and C9 components)
40. B and D (is an effector function of IgG and IgM following antigen binding)

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