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PCB 4233 Quiz 1-12/ Exam MC questions well answered
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- PCB 4233
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- University Of Central Florida
PCB 4233 Quiz 1-12/ Exam MC questions well answered
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PCB 4233 Quiz 1-12/ Exam MC8. Yersinia pestis, the causative agent of the bubonic plague, has multiple mechanisms of immune
evasion. This Gram-negative bacterium is transmitted from fleas (body temperature 26 deg C) to humans
(body temperature 37 deg C) by flea bites. Studies have shown that the lipopolysaccharide (LPS)
produced by Y. pestis grown at 37 deg C is about 10-fold less potent at stimulating TLR4 signaling than is
the Y. pestis LPS from bacteria grown at 26 deg C. When these two forms of Y. pestis LPS are compared
for their abilities to induce responses from human macrophages, one would expect that the 26 deg C Y.
pestis LPS would result in:
A. Increased production of antimicrobial peptides
B. Increased production of TNF-a and IL-6
C. Reduced production of IL-10
D. Increased activation of the inflammasome
E.Reduced production of Type 1 interferons - correct answer ✔✔B. Increased production of TNF-a and
IL-6
1. An infant with recurrent bacterial and fungal infections is suspected to have an
immunodeficiency disease. Within two days after exposure to a pathogen, the organisms have
proliferated to dangerous levels requiring immediate systemic antibiotic treatment. It is
unlikely that this infant has a defect in B or T lymphocyte responses to the infection because:
A. Systemic infections of bacteria and fungi are usually cleared by the spleen.
B. Bacteria and fungi do not require B cell or T cell responses for their clearance.
C. Bacteria and fungi are not efficiently transported to draining lymph nodes to initiate adaptive
immune responses.
D. The defective immune response occurs too rapidly following infection to be due to a defect
in B or T lymphocytes responses.
E. Adaptive immune responses require dendritic cells to take up and degrade pathogens. - correct
answer ✔✔D. The defective immune response occurs too rapidly following infection to be due to a
defect
in B or T lymphocytes responses.
,2. In patients with lymphomas, the cancer cells invade the bone marrow and destroy the
environment required for normal hematopoiesis. This leads to bone marrow failure, which
disrupts the production of hematopoietic cell lineages. All of the following cell types would be
affected by this EXCEPT:
A. Red blood cells
B. Endothelial cells
C. Lymphocytes
D. Dendritic cells
E. Neutrophils - correct answer ✔✔B. Endothelial cells
3. Epithelial surfaces provide the first line of defense against infection by the use of several types
of mechanisms. What is a chemical way to fend off pathogens?
A. Secretion of antimicrobial peptides by epithelial cells
B. Joining of epithelial cells by tight junctions
C. Production of mucus, tears, or saliva in the nose, eyes, and oral cavity
D. Movement of mucus by cilia
E. Peristalsis in the gastrointestinal tract - correct answer ✔✔A. Secretion of antimicrobial peptides by
epithelial cells
4. Neutrophil secret defensins, which are:
A. Enzymes
B. Glycolipids
C. Short amphipathic peptides
D. Carbohydrates
E. Reactive oxygen species (ROS) - correct answer ✔✔C. Short amphipathic peptides
5. Which of the following statements is TRUE of lysozyme?
A. Lysozyme is a cytoplasmic organelle
B. Lysozyme activates complement
,C. Lysozyme is a protease
D. Lysozyme splits peptidoglycan
E. Lysozyme is released by mast cells - correct answer ✔✔D. Lysozyme splits peptidoglycan
6. True or False: The classical and lectin pathways of complement activation converge at the step
of C3 activation. Moreover, the initiating steps of each pathway use protein components and
enzymatic mechanisms that share high similarity with each other. - correct answer ✔✔TRUE
7. Which one of the following is NEITHER a C3 convertase NOR a C5 convertase?
A. C4b2a3b
B. C3bBb
C. C4b2a
D. C3(H2O)Bb
E. C1q, C1r and C1s - correct answer ✔✔E. C1q, C1r and C1s
8. The membrane attack complex consists of
A. C4b2a
B. (C3b)2Bb
C. C5b, 6, 7, 8, 9
D. C3a or C5a
E. MASP-1, -2, and -3 - correct answer ✔✔C. C5b, 6, 7, 8, 9
9. True or False: The C3 convertase of the alternative complement pathway amplifies the overall
magnitude of complement activation regardless of which of the three pathways initiated the
complement activation initially.
A. This statement is true.
B. This statement is false. - correct answer ✔✔TRUE
10. The Toll-like receptor 3 (TLR3) pattern recognition receptor recognizes:
, A. Bacterial lipopeptides
B. Flagellin
C. Lipopolysaccharide (LPS) from Gram negative bacteria
D. Double-stranded RNA (dsRNA)
E. Double-stranded DNA (dsDNA) - correct answer ✔✔D. Double-stranded RNA (dsRNA)
11. The formation of the C3 convertase is a key step in complement activation that occurs in all
three complement pathways. This enzyme cleaves C3 in blood plasma, leading to a
conformational change in the C3b fragment that exposes its reactive thioester group. The
activated C3b is potentially harmful to the host, if it becomes covalently attached to a host cell,
rather than to the surface of a pathogen. This deleterious outcome is largely avoided by:
A. The inability of active C3b to diffuse away in the blood plasma.
B. The inability of active C3b to covalently attach to the membranes of eukaryotic cells.
C. The rapid hydrolysis of active C3b in solution, rendering it inactive.
D. The tight binding of active C3b to the C3 convertase.
E. The ability of active C3b to recruit phagocytic cells. - correct answer ✔✔C. The rapid hydrolysis of
active C3b in solution, rendering it inactive.
12. Which of the following does not occur during an inflammatory response?
A. Local blood clotting
B. Endothelial cell activation
C. Decreased vascular permeability
D. Extravasation of leukocytes into inflamed tissue - correct answer ✔✔C. Decreased vascular
permeability
1.Activation of which pattern recognition receptor (PRR) does NOT lead to activation of transcription
factors (e.g. NF-κB, IRF3)?
A.TLR4
B.RIG-I
C.NLRP3
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