MCQs In Immunology and Answers: Complement system (31-40)

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.

34.   A complement component which 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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About Acharya Tankeshwar 452 Articles
Hello, thank you for visiting my blog. I am Tankeshwar Acharya. Blogging is my passion. I am working as an Asst. Professor and Microbiologist at Department of Microbiology and Immunology, Patan Academy of Health Sciences, Nepal. If you want me to write about any posts that you found confusing/difficult, please mention in the comments below.


  1. Complement protine are present in blood plasma in healthy people…. Why does complement only become activated in the presence of infection

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