(ASU Online) BIO 420 Immunology(Molecular and Cellular Foundations) Comprehensive Midterm, Exams of Biochemistry

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BIO 420

Immunology: Molecular

and Cellular Foundations

Comprehensive Midterm Exam

1. Which of the following cell types is primarily responsible for antibody production? A. T lymphocytes B. B lymphocytes C. Macrophages D. Dendritic cells

Correct Answer: B. B lymphocytes

Rationale: B lymphocytes, or B cells, are the cells that differentiate into plasma cells that produce antibodies, which are crucial for the humoral immune response.

2. The process by which antibodies facilitate the destruction of pathogens by immune cells is known as: A. Neutralization B. Opsonization C. Agglutination D. Complement activation

Correct Answer: B. Opsonization

Rationale: Opsonization is the process where antibodies bind to the surface of pathogens and enhance their ingestion and destruction by phagocytes.

3. Which molecule is a primary signaler in the inflammatory response and is produced by activated macrophages?

A. Interleukin-1 (IL-1) B. Interleukin-2 (IL-2) C. Interferon-gamma (IFN-γ) D. Tumor necrosis factor (TNF)

Correct Answer: A. Interleukin-1 (IL-1)

Rationale: IL-1 is a pro-inflammatory cytokine produced by activated macrophages and is a key mediator in the inflammatory response.

4. The major histocompatibility complex (MHC) class I molecules present antigenic peptides to: A. CD4+ T cells B. CD8+ T cells C. B cells D. Natural Killer cells

Correct Answer: B. CD8+ T cells

Rationale: MHC class I molecules present endogenously synthesized peptides to CD8+ T cells, which are cytotoxic T cells.

5. In the context of immunology, what does 'clonal selection' refer to? A. The process of generating diverse B cell receptors B. The removal of self-reactive B cells C. The proliferation of B cells in response to antigen binding D. The differentiation of B cells into plasma cells and memory cells

Correct Answer: C. The proliferation of B cells in response to antigen

binding Rationale: Clonal selection is the process by which an antigen selectively binds to and activates B or T cells with specific receptors, leading to their proliferation.

6. Which type of hypersensitivity reaction is mediated by IgE antibodies? A. Type I B. Type II C. Type III D. Type IV

Correct Answer: A. Type I

Rationale: Type I hypersensitivity reactions are immediate allergic reactions mediated by IgE antibodies, such as in the case of asthma or anaphylaxis.

7. The complement system can be activated by which of the following pathways? A. Classical pathway B. Lectin pathway C. Alternative pathway D. All of the above

Correct Answer: D. All of the above

Rationale: The complement system can be activated through three pathways: classical, lectin, and alternative, all of which lead to the destruction of pathogens.

8. Which cytokine is essential for the differentiation of naive T cells into Th1 cells? A. IL- 4 B. IL- 12 C. IL- 17 D. TGF-β

Correct Answer: B. IL- 12

Rationale: IL-12, produced by dendritic cells and macrophages, is crucial for the differentiation of naive T cells into Th1 cells, which are involved in cell-mediated immunity.

9. What is the primary function of regulatory T cells (Treg)? A. To enhance the immune response B. To suppress the immune response C. To remember past infections D. To directly kill infected cells

Correct Answer: B. To suppress the immune response

Rationale: Treg cells play a critical role in maintaining immune tolerance by suppressing the immune response and preventing autoimmunity.

10. The presence of double-stranded DNA (dsDNA) antibodies is most commonly associated with which autoimmune disease? A. Rheumatoid arthritis B. Systemic lupus erythematosus C. Multiple sclerosis D. Type 1 diabetes

Correct Answer: B. Systemic lupus erythematosus

Rationale: dsDNA antibodies are a hallmark of systemic lupus erythematosus and are used as a diagnostic criterion for the disease.

11. Which of the following is a characteristic feature of the adaptive immune system? A. Immediate response B. Non-specificity C. Memory D. Involvement of physical barriers

Correct Answer: C. Memory

Rationale: The adaptive immune system is characterized by its ability to remember specific pathogens, leading to an enhanced response upon subsequent exposures.

12. The variable regions of antibodies are responsible for: A. Binding to antigens B. Complement activation

C. Crossing the placenta D. Binding to Fc receptors

Correct Answer: A. Binding to antigens

Rationale: The variable regions of antibodies contain the antigen-binding sites, allowing for the specific recognition and binding of antigens.

13. Which cell type is the primary target of HIV infection? A. B cells B. Macrophages C. CD4+ T cells D. CD8+ T cells

Correct Answer: C. CD4+ T cells

Rationale: HIV primarily targets CD4+ T cells, which are essential for orchestrating the immune response, leading to immunodeficiency.

14. The process by which a B cell receptor is modified to increase its affinity for antigen is known as: A. Isotype switching B. Somatic hypermutation C. Clonal expansion D. Affinity maturation

Correct Answer: B. Somatic hypermutation

Rationale: Somatic hypermutation involves the mutation of B cell receptor genes, resulting in an increased affinity for the antigen during the immune response.

15. What role do dendritic cells play in the immune response? A. They produce antibodies B. They directly kill infected cells C. They act as antigen-presenting cells D. They suppress the immune response

Correct Answer: C. They act as antigen-presenting cells

Rationale: Dendritic cells are crucial for initiating the adaptive immune response by capturing antigens and presenting them to T cells. Question: Which of the following cell types is responsible for presenting antigens to T cells? A) B cells B) Macrophages C) Natural killer cells D) Neutrophils

Correct Answer: B) Macrophages

Rationale: Macrophages play a crucial role in antigen presentation to T cells through major histocompatibility complex (MHC) molecules.

Question: What is the primary function of cytotoxic T cells in the immune response? A) Phagocytosis of pathogens B) Secretion of antibodies C) Killing of infected cells D) Activation of B cells

Correct Answer: C) Killing of infected cells

Rationale: Cytotoxic T cells are specialized in identifying and eliminating virus-infected or cancerous cells through the release of cytotoxic molecules. Question: Which of the following is a hallmark of adaptive immunity? A) Rapid response upon reinfection B) Limited specificity C) Non-specific cellular responses D) Lack of memory

Correct Answer: A) Rapid response upon reinfection

Rationale: Adaptive immunity provides a swift and targeted response upon re-exposure to a pathogen due to the presence of memory cells. Question: What is the role of cytokines in immune regulation? A) Direct killing of pathogens B) Activation of complement system C) Communication between immune cells

D) Antigen presentation to T cells

Correct Answer: C) Communication between immune cells

Rationale: Cytokines act as signaling molecules that facilitate communication and coordination between different immune cells. Question: Which type of hypersensitivity reaction is mediated by IgE antibodies? A) Type I B) Type II C) Type III D) Type IV

Correct Answer: A) Type I

Rationale: Type I hypersensitivity reactions involve the release of histamine and other mediators by mast cells and basophils triggered by IgE antibodies. Question: What is the primary function of regulatory T cells in the immune system? A) Phagocytosis of pathogens B) Suppression of immune responses C) Production of antibodies D) Activation of cytotoxic T cells

Correct Answer: B) Suppression of immune responses

Rationale: Regulatory T cells play a crucial role in maintaining immune tolerance and preventing autoimmune reactions by suppressing excessive immune responses. Question: Which of the following cell types is responsible for antibody production? A) T cells B) Natural killer cells C) B cells D) Dendritic cells

Correct Answer: C) B cells

Rationale: B cells are specialized in producing antibodies in response to specific antigens encountered by the immune system. Question: What is the main function of MHC class II molecules? A) Presentation of endogenous antigens B) Presentation of exogenous antigens C) Recognition of self-antigens D) Activation of cytotoxic T cells

Correct Answer: B) Presentation of exogenous antigens

Rationale: MHC class II molecules present antigens derived from extracellular pathogens to CD4+ T helper cells.

Question: Which of the following cells is responsible for antibody class switching? A) Plasma cells B) Memory B cells C) Follicular dendritic cells D) T helper cells

Correct Answer: D) T helper cells

Rationale: T helper cells play a crucial role in guiding B cells to undergo class switching and produce different classes of antibodies. Question: What is the primary function of natural killer cells in the immune response? A) Phagocytosis of pathogens B) Antibody production C) Killing of virus-infected cells D) Antigen presentation to T cells

Correct Answer: C) Killing of virus-infected cells

Rationale: Natural killer cells are adept at recognizing and eliminating virus-infected or cancerous cells without prior sensitization. Question: Which of the following cytokines is involved in promoting inflammation and fever during infection? A) Interleukin- 4 B) Tumor necrosis factor-alpha

C) Interferon-gamma D) Transforming growth factor-beta

Correct Answer: B) Tumor necrosis factor-alpha

Rationale: Tumor necrosis factor-alpha is a pro-inflammatory cytokine that plays a key role in initiating immune responses and promoting inflammation. Question: What is the primary function of dendritic cells in the immune system? A) Antibody production B) Phagocytosis of pathogens C) Antigen presentation to T cells D) Killing of infected cells

Correct Answer: C) Antigen presentation to T cells

Rationale: Dendritic cells are professional antigen-presenting cells that play a crucial role in initiating adaptive immune responses by presenting antigens to T cells. Question: Which of the following is a characteristic feature of memory B cells? A) Short lifespan B) Ability to produce antibodies C) Immediate response upon reinfection D) Lack of specificity

Correct Answer: C) Immediate response upon reinfection

Rationale: Memory B cells exhibit a rapid and enhanced response upon re-exposure to a pathogen due to their ability to quickly differentiate into plasma cells. Question: What is the primary role of complement proteins in the immune system? A) Phagocytosis of pathogens B) Direct killing of infected cells C) Opsonization and lysis of pathogens D) Antibody production

Correct Answer: C) Opsonization and lysis of pathogens

Rationale: Complement proteins enhance the immune response by promoting opsonization of pathogens and facilitating their lysis. Question: Which of the following is a characteristic feature of the adaptive immune response? A) Non-specific recognition of pathogens B) Lack of memory C) Specificity for particular antigens D) Rapid response upon primary exposure

Correct Answer: C) Specificity for particular antigens

Rationale: The adaptive immune response is characterized by its specificity for unique antigens, allowing targeted and precise immune reactions.

1. Which of the following enzymes is responsible for the activation of naïve T cells? A) Interleukin- 2 B) Protein kinase C C) Phospholipase C D) Calcineurin

Answer: D) Calcineurin

Rationale: Calcineurin is a calcium-dependent phosphatase that plays a crucial role in the T cell activation pathway by dephosphorylating the nuclear factor of activated T cells (NFAT), allowing its translocation to the nucleus.

2. Which of the following cell types is responsible for antigen presentation to T cells? A) B cells B) Macrophages C) Dendritic cells D) Natural killer cells

Answer: C) Dendritic cells

Rationale: Dendritic cells are professional antigen-presenting cells that capture, process, and present antigens to T cells, initiating the adaptive immune response.

3. What is the function of Toll-like receptors in the immune system? A) Antigen presentation B) Cytokine production C) Pattern recognition D) Antibody production

Answer: C) Pattern recognition

Rationale: Toll-like receptors recognize specific molecular patterns associated with pathogens and initiate signaling cascades that lead to the production of cytokines and activation of immune responses.

4. Which of the following cytokines is primarily involved in promoting the differentiation of naïve T cells into Th1 cells? A) IL- 4 B) IL- 12 C) IL- 10 D) TGF-β

Answer: B) IL- 12

Rationale: IL-12 is crucial for the differentiation of naïve T cells into Th cells, which are important in cell-mediated immunity against intracellular pathogens.

5. Which of the following processes is critical for the generation of diversity in the antigen receptor repertoire of lymphocytes? A) Somatic recombination

B) Phagocytosis C) Complement activation D) Apoptosis

Answer: A) Somatic recombination

Rationale: Somatic recombination is a process by which different gene segments encoding antigen receptors are rearranged, leading to the generation of a diverse repertoire of receptors on lymphocytes.

6. What is the primary function of cytotoxic T lymphocytes (CTLs) in the immune system? A) Antibody production B) Phagocytosis of pathogens C) Killing of infected cells D) Activation of macrophages

Answer: C) Killing of infected cells

Rationale: CTLs recognize and kill infected or abnormal cells by inducing apoptosis, thereby eliminating the source of antigens in the body.

7. Which of the following molecules is critical for the formation of the immunological synapse between a T cell and an antigen-presenting cell? A) CD B) MHC class II C) ICAM- 1 D) TCR

Answer: C) ICAM- 1

Rationale: ICAM-1 (Intercellular Adhesion Molecule-1) plays a key role in stabilizing the interaction between T cells and antigen-presenting cells, facilitating signal transduction and T cell activation.

8. Which of the following is a characteristic feature of regulatory T cells (Tregs)? A) Production of pro-inflammatory cytokines B) Suppression of immune responses C) Participation in antigen presentation D) Direct killing of infected cells

Answer: B) Suppression of immune responses

Rationale: Tregs play a crucial role in immune tolerance by suppressing excessive immune responses, maintaining self-tolerance, and preventing autoimmunity.

9. What is the role of complement proteins in the immune system? A) Phagocytosis of pathogens B) Activation of T cells C) Opsonization and lysis of pathogens D) Antigen presentation

Answer: C) Opsonization and lysis of pathogens

Rationale: Complement proteins participate in the opsonization and lysis of pathogens, enhancing their recognition and elimination by phagocytes and promoting inflammation.

10. Which of the following cell types is responsible for the production of antibodies? A) T cells B) B cells C) NK cells D) Mast cells

Answer: B) B cells

Rationale: B cells are specialized lymphocytes that produce antibodies in response to specific antigens, mediating humoral immune responses.

11. In the context of immunology, what is the function of the major histocompatibility complex (MHC)? A) Antigen recognition B) Cytokine secretion C) Tissue repair D) Costimulation of T cells

Answer: A) Antigen recognition

Rationale: The MHC molecules present antigens to T cells and play a crucial role in antigen recognition and activation of immune responses.

12. Which of the following cell types is involved in the process of antibody class switching? A) Plasma cells

B) Memory B cells C) Follicular dendritic cells D) T helper cells

Answer: D) T helper cells

Rationale: T helper cells provide signals to B cells, inducing class switching and the production of different antibody isotypes to tailor immune responses to specific pathogens.

13. Which of the following effector functions is associated with the activation of mast cells in the context of allergy? A) Antibody production B) Release of histamine C) Phagocytosis D) Cytotoxicity

Answer: B) Release of histamine

Rationale: Mast cells release histamine and other inflammatory mediators in response to allergens, contributing to the symptoms of allergic reactions.

14. What is the consequence of central tolerance in the development of the immune system? A) Generation of self-reactive lymphocytes B) Elimination of self-reactive lymphocytes C) Induction of immune memory D) Activation of innate immunity

Answer: B) Elimination of self-reactive lymphocytes

Rationale: Central tolerance mechanisms eliminate self-reactive lymphocytes during development to prevent autoimmune responses and maintain self-tolerance.

15. Which of the following molecules functions as a co-stimulatory signal for T cell activation? A) PD- 1 B) CTLA- 4 C) CD28 D) B7

Answer: C) CD28

Rationale: CD28 on T cells interacts with B7 molecules on antigen- presenting cells, providing a co-stimulatory signal necessary for T cell activation and proliferation.

16. In the context of immunological memory, which cell type is responsible for mounting a rapid and robust secondary response to a previously encountered antigen? A) Naïve B cells B) Memory B cells C) T regulatory cells D) Plasmacytoid dendritic cells

Answer: B) Memory B cells

Rationale: Memory B cells retain the ability to rapidly differentiate into plasma cells and produce specific antibodies upon re-exposure to an antigen, contributing to the secondary immune response.

17. Which of the following mechanisms is involved in the process of peripheral tolerance in the immune system? A) Immune surveillance B) Anergy induction C) Self-antigen recognition D) Tissue repair

Answer: B) Anergy induction

Rationale: Peripheral tolerance mechanisms induce T cell anergy or deletion of self-reactive lymphocytes outside the central lymphoid organs to prevent autoimmunity.

18. What is the role of natural killer (NK) cells in the immune system? A) Phagocytosis of pathogens B) Antibody production C) Cytotoxic killing of infected cells D) Antigen presentation to T cells

Answer: C) Cytotoxic killing of infected cells

Rationale: NK cells are part of the innate immune system and function by recognizing and killing virus-infected cells or tumor cells without prior sensitization.

19. Which of the following is a characteristic feature of an immune response mediated by B lymphocytes? A) Cytokine secretion B) Cell-mediated killing C) Phagocytosis of pathogens D) Antibody production

Answer: D) Antibody production

Rationale: B lymphocytes produce antibodies that can neutralize pathogens, facilitate their clearance by phagocytes, or activate the complement system to eliminate pathogens.

20. What is the function of the proteasome in the context of antigen presentation to T cells? A) Protein synthesis B) Antigen processing C) RNA splicing D) Lipid modification

Answer: B) Antigen processing

Rationale: The proteasome degrades intracellular proteins into peptide fragments that can be loaded onto MHC class I molecules for presentation to CD8+ T cells.

21. Which of the following cytokines is primarily involved in promoting the differentiation of naïve T cells into Th2 cells? A) IL- 12

B) IL- 4

C) IL- 10

D) IFN-γ

Answer: B) IL- 4

Rationale: IL-4 is crucial for the differentiation of naïve T cells into Th2 cells, which are important for antibody-mediated immune responses and allergic reactions.

22. What is the function of the Fc region of an antibody molecule? A) Antigen binding B) Cell-mediated killing C) Complement activation D) Receptor binding

Answer: C) Complement activation

Rationale: The Fc region of an antibody can bind complement proteins, initiating the classical complement cascade and promoting the lysis of pathogens.

23. Which of the following cells is primarily responsible for the production of pro-inflammatory cytokines in response to infection? A) T regulatory cells B) Th2 cells C) Macrophages D) Memory B cells

Answer: C) Macrophages

Rationale: Macrophages are key immune cells that produce pro- inflammatory cytokines such as TNF-α and IL-1 in response to infection, promoting inflammation.

24. What is the mechanism by which cytotoxic T lymphocytes (CTLs) recognize infected target cells? A) Antibody binding B) TLR signaling C) TCR-MHC interaction D) Complement activation

Answer: C) TCR-MHC interaction

Rationale: CTLs recognize antigenic peptides presented by MHC class I molecules on infected cells through the T cell receptor (TCR), leading to target cell killing.

25. Which of the following pathways is involved in the activation of the NF- κB transcription factor in immune cells? A) JAK-STAT pathway B) MAP kinase pathway C) TLR signaling pathway D) PI3K-Akt pathway

Answer: C) TLR signaling pathway