PCB 4233 Quiz 1-12/ Exam MC Questions and
Answers with Complete Solutions | New Update
2026 | University of Central Florida
8. 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 - ANSWERS 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. - ANSWERS 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 - ANSWERS 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 - ANSWERS 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) - ANSWERS 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 - ANSWERS 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. - ANSWERS
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 - ANSWERS 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 - ANSWERS 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.
Answers with Complete Solutions | New Update
2026 | University of Central Florida
8. 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 - ANSWERS 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. - ANSWERS 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 - ANSWERS 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 - ANSWERS 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) - ANSWERS 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 - ANSWERS 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. - ANSWERS
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 - ANSWERS 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 - ANSWERS 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.
