Block 2 Immunology Sloma W Explanations
The immune system protects us from infection through various lines of defense. If the immune system is not functioning, as it should, it can result in disease. Take up these immunology practice block 2 immunology test with explanations and get to learn more about this important system in the human body.
- 1.
Which of the following statements concerning T helper cells is true?
- A.
They possess membrane-bound antibodies
- B.
They can recognize and interact with antigens in the blood.
- C.
They produce numerous cytokines
- D.
They function only in cell-mediated immunity.
- E.
Their activation depends on interferon y.
Correct Answer
C. They produce numerous cytokinesExplanation
T helper cells produce a number of cytokines that affect other cells involved in both the
cell-mediated and the humoral immune responses.
T helper cells possess antigen-specific T-cell receptors (not antibodies) on their membranes. These cells recognize and interact with antigenic determinants that are associated with class II human leukocyte antigen (HLA) molecules on the
surface of antigen-presenting cells. IL-1 is necessary for activation of T helper cells.Rate this question:
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- 2.
In which of the following sites do lymphocytes become immunocompetent?
- A.
Germinal center of secondary lymphoid nodules
- B.
White pulp of the spleen
- C.
Thymic cortex
- D.
Red pulp of the spleen
- E.
Paracortex of lymph nodes
Correct Answer
C. Thymic cortexExplanation
T lymphocytes mature and become immunocompetent in the cortex of the thymus, whereas
B lymphocytes do so in the bone marrow.
After an antigenic challenge, lymphocytes proliferate and differentiate in various lymphoid tissues.Rate this question:
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- 3.
Which of the following statements concerning the thymus is true?
- A.
Lymphoid nodules form much of the thymic cortex.
- B.
Epithelial reticular cells form Hassall corpuscles.
- C.
T cells migrate into the medulla, where they become immunologically competent.
- D.
Most T cells that enter the thymus are killed in the medulla.
- E.
Macrophages are essential components of the blood-thymus barrier.
Correct Answer
B. Epithelial reticular cells form Hassall corpuscles.Explanation
Epithelial reticular cells of the medulla congregate to form Hassall (thymic) corpuscles.Rate this question:
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- 4.
Which of the following statements concerning interferon -y is true?
- A.
It is produced by T memory cells.
- B.
It is produced by T suppressor cells.
- C.
It activates macrophages.
- D.
It inhibits macrophages.
- E.
It induces viral proliferation.
Correct Answer
C. It activates macrophages.Explanation
Interferon -y activates macrophages, as well as natural killer (NK) cells and T cytotoxic cells, enhancing their phagocytic or cytotoxic activity or both.Rate this question:
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- 5.
A patient who was given penicillin has an adverse reaction to the antibiotic. Although the reaction is due to the actions of mast cells, the response occurred because mast cells have immunoglobulin E (IgE) receptors in their cell membranes. Which of the following cells produced the IgE decorating the plasma cell's surface?
- A.
T memory cells
- B.
B memory cells
- C.
T helper cells
- D.
Plasma cells
- E.
T cytotoxic cells
Correct Answer
D. Plasma cellsExplanation
Individuals allergic to penicillin produce immunoglobulin E (IgE) antibodies.
The cells that manufacture IgE are plasma.
After an antigenic challenge, proliferation and differentiation of B cells give rise to plasma cells and B memory cells.Rate this question:
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- 6.
Antigen presenting cells are essential in contributing to the activation of T cells. How do they accomplish this?
- A.
They use MHC class I and class II molecules to present peptide antigens to T cells
- B.
They use MHC class I and class II molecules to present carbohydrate antigens to T cells
- C.
They secrete complement proteins that activate T cells
- D.
They present antigen:antibody complexes to T cells
Correct Answer
A. They use MHC class I and class II molecules to present peptide antigens to T cellsExplanation
This question is simply asking about how T cells recognize antigen and what type of antigens they can recognize.
T cells = pep-T-idesRate this question:
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- 7.
What type of pathogen would be processed and loaded into MHC class II molecules?
- A.
Antigens from a parasite that infects endothelial cells
- B.
Antigens from a virus infecting endothelial cells
- C.
Antigens from a bacterium infecting endothelial cells
- D.
Antigens from extracellular bacteria
- E.
Antigens from bacteria that infects endothelial cells
Correct Answer
D. Antigens from extracellular bacteriaExplanation
This question relies on the recognition that MHC class II molecules present exogenously‐derived antigens.
In all answer choices except D the cell is infecting a cell that does not express MHC class II.Rate this question:
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- 8.
After their maturation in the thymus and release into the circulation, T lymphocytes migrate preferentially to which of the following sites?
- A.
Paracortex of lymph nodes
- B.
Cortical lymphoid nodules of lymph nodes
- C.
Hilus of lymph nodes
- D.
Lymphoid nodules of the tonsils
- E.
Lymphoid nodules of the spleen
Correct Answer
A. Paracortex of lymph nodesExplanation
T lymphocytes are preferentially located in the paracortex of lymph nodes, whereas B lymphocytes
are found in lymphoid nodules located in lymph nodes, tonsils, and the spleen.Rate this question:
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- 9.
Which of the following cell types is thought to function in preventing immune responses against self-antigens?
- A.
Ts cells
- B.
B cells
- C.
T memory cells
- D.
TH cells
- E.
Mast cells
Correct Answer
A. Ts cellsExplanation
The immune response is decreased by T suppressor (Ts) cells. Their activity is thought to
help prevent autoimmune responses against self-antigens.Rate this question:
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- 10.
Which of the following statements concerning T cytotoxic (Ta) cells is true?
- A.
They assist macrophages in killing microorganisms
- B.
They possess antibodies on their surfacs.
- C.
They possess CD8 surface markers
- D.
They possess CD28 surface markers.
- E.
They secrete interferon -y.
Correct Answer
C. They possess CD8 surface markersExplanation
cytotoxic cells are CD8+. CD28 molecules are present on TH 1 cells. Interferon (IFN)--y is
released by TH1 cells, and they also assist macrophages in killing microorganisms.Rate this question:
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- 11.
Which of the following statements concerning Hassall corpuscles is true?
- A.
They are located in the thymic cortex of young individuals.
- B.
They are located in the thymic cortex of old individuals.
- C.
They are derived from mesoderm.
- D.
They are located in the thymic medulla.
- E.
They are derived from T memory cells.
Correct Answer
D. They are located in the thymic medulla.Explanation
Hassall corpuscles are concentrically arranged accretions of epithelial reticular cells (derived
from endoderm) found only in the medulla of the thymus.Rate this question:
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- 12.
How do macrophages play an important role in the elimination of pathogens?
- A.
Produce complement proteins that can eliminate the pathogen
- B.
Phagocytosis of pathogens followed by presentation of antigens to B cells
- C.
Phagocytosis of pathogens followed by oxygen‐dependent and oxygen‐independent killing of the pathogen
- D.
Produce antibody molecules that can mark the pathogen for destruction
- E.
Phagocytosis of pathogens followed by formation of the membrane‐attack complex that causes lysis of pathogens
Correct Answer
C. Phagocytosis of pathogens followed by oxygen‐dependent and oxygen‐independent killing of the pathogenExplanation
The membrane attack complex is formed by the activation of complement…this is a detail
about complement activation that I don’t expect you to know for now…Rate this question:
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- 13.
Your patient, a 7 month‐old boy, is suffering from repeated ear infections. In the lab, you determine that he has a defect in B cell function. What is the most likely defect?
- A.
Inability to synthesize toxic nitric oxides
- B.
Failure to produce complement components
- C.
Failure to express toll‐like receptors
- D.
Failure to express MHC class I molecules
- E.
Failure to express surface‐bound antibody molecules
Correct Answer
E. Failure to express surface‐bound antibody moleculesExplanation
Without surface‐bound antibody expression, a B cell cannot become activated. Surface‐bound
antibody molecules serve as the antigen‐recognition receptor for B cells.Rate this question:
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- 14.
Which of the following is not a direct consequence of antibody binding to antigen?
- A.
Activation of B cells
- B.
Neturalization of the antigen
- C.
Activation of complement
- D.
Phagocytosis of the antigen
- E.
Activation of T cells
Correct Answer
E. Activation of T cellsExplanation
Antibody binding to antigen can trigger all of the events described in A‐D. Recall that T cells are
activated when they encounter their specific antigen presented in MHC class I or II by antigenpresenting
cells. While the B cell may become activated when surface‐bound antibody binds its specific
antigen and then go on to present the antigen to the T cell, the activation of the T cell is a consequence
of presentation of the antigen by the B cell, not a direct consequence antigen binding to antigen.Rate this question:
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- 15.
Immunodeficienies can be caused by defects in expression of many different molecules that contribute to both adaptive and innate immune responses. Failure to express which molecule would have no effect on the immune system’s ability to eliminate an extracellular bacterium?
- A.
MHC class I
- B.
MHC class II
- C.
Surface‐bound antibody molecules
- D.
Toll‐like receptors
- E.
Complement components
Correct Answer
A. MHC class IExplanation
Without MHC class II, antigen presenting cells cannot present exogenously‐derived antigen to CD4
T cells, thus preventing a CD4 T cell response against the extracellular bacterium. Without surfacebound
antibody molecules, B cells cannot get activated and there would be no antibody production
against the antigen. Without antibody production, there would be diminished phagocytosis of the
antigen by phagocytes and no classical complement activation to eliminate the pathogen. Without Tolllike
receptors, macrophages and dendritic cells would have decreased recognition of the antigen;
consequently, there would be no killing by the macrophage and very little antigen presentation of the
antigen to CD4 T cells. Without the complement components, there would be reduced inflammation at
the site of infection, no direct killing of the pathogen via the complement pathway, and no opsonization
of the pathogen by complement components (reduced pathogen uptake by phagocytes).Rate this question:
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- 16.
Which of the following statements about immunoglobulin G (IgG) is true?
- A.
It is located in the serum and on the membrane of B cells.
- B.
It can cross the placental barrier.
- C.
It is involved in allergic reactions.
- D.
It exists as a pentamer.
- E.
It binds to antigens on the body surface and in the lumen of the gastrointestinal tract.
Correct Answer
B. It can cross the placental barrier.Explanation
Immunoglobulin G (IgG) is the most abundant immunoglobulin isotype in the serum. It
can cross the placental barrier but does not bind to the B-cell plasma membrane. It exists as a
monomer, functions to activate complement, and acts as an opsoninRate this question:
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- 17.
Which of the following is TRUE concerning Haptens
- A.
Small molecules that, on their own, are not immunogenic
- B.
Antibodies can bind, but binding is below threshold of driving an immune response
- C.
To make a hapten immunogenic, you must conjugate it to a carrier
- D.
Generally only have one epitope
- E.
All of the above
Correct Answer
E. All of the aboveExplanation
Haptens are small molecules that are not immunogenic on their own. Although antibodies can bind to haptens, the binding is usually below the threshold required to trigger an immune response. In order to make a hapten immunogenic, it must be conjugated to a carrier molecule. Additionally, haptens generally only have one epitope. Therefore, the statement "all of the above" is true as it encompasses all the given statements about haptens.Rate this question:
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- 18.
The portion of antigen that binds the antigen recognition molecule is known as
- A.
Hapten
- B.
Adjuvant
- C.
Epitope
- D.
Antibody
Correct Answer
C. EpitopeExplanation
An epitope is the Part of the antigen recognized by antibody OR a Peptide recognized by the T cell receptorRate this question:
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- 19.
A chemical substances that enhances the immune response to an antigen is known as
- A.
Hapten
- B.
Adjuvant
- C.
Epitope
- D.
Antibody
Correct Answer
B. AdjuvantExplanation
Adjuvants are Thought to: Prolong the persistence of the antigen AND Stimulate or modulate immune cells AND Enhance macrophage functionRate this question:
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- 20.
Which of the following is not a direct consequence of antibody binding to antigen?
- A.
Activation of B cells
- B.
Neturalization of the antigen
- C.
Activation of complement
- D.
Phagocytosis of the antigen
- E.
Activation of T cells
Correct Answer
E. Activation of T cellsExplanation
E : Antibody binding to antigen can trigger all of the events described in A‐D. Recall that T cells are
activated when they encounter their specific antigen presented in MHC class I or II by antigenpresenting
cells. While the B cell may become activated when surface‐bound antibody binds its specific
antigen and then go on to present the antigen to the T cell, the activation of the T cell is a consequence
of presentation of the antigen by the B cell, not a direct consequence antigen binding to antigen.Rate this question:
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Mar 20, 2023Quiz Edited by
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Dec 06, 2011Quiz Created by
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