59 Year 2: Cellular Immunology exam questions on Immunology Quiz for medical students. Includes MCQs, answers, explanations and written questions. Sample: The i
This MCQ set contains 59 questions on Immunology Quiz in the Year 2: Cellular Immunology unit. Each question includes the correct answer and a detailed explanation for active recall and exam preparation.
Correct answer: C – Innate; Phagocytes; Adaptive; Lymphocytes
The innate immune system primarily uses phagocytes (like macrophages and neutrophils) along with complement components for immediate defense. The adaptive immune system uses lymphocytes (T and B cells) along with specific antigen recognition molecules like antibodies and T cell receptors. ---
Correct answer: C – Minutes
Phagocytic cells like neutrophils and macrophages respond to tissue damage and infection within minutes through chemotactic signals. This rapid response is characteristic of the innate immune system's immediate defense mechanism. ---
Correct answer: E – Interferons
Interferons are proteins produced by virus-infected cells that provide immediate antiviral protection by inhibiting viral replication in neighboring cells. They are a key component of the innate immune response to viral infections. ---
Correct answer: D – Cytokines
Cytokines are signaling molecules that facilitate communication between different immune cells and coordinate both innate and adaptive immune responses. They act as messengers that bridge these two immune systems. ---
Correct answer: A – Phagocyte
Phagocytes recognize general pathogen-associated molecular patterns (PAMPs) rather than specific epitopes. T cells, B cells, antibodies, and NK cells all have mechanisms for recognizing specific molecular structures or epitopes. ---
Correct answer: B – Major histocompatibility complexes (MHCs)
The MHC is a large gene complex found in most vertebrates that encodes proteins essential for adaptive immunity, including antigen presentation to T cells. HLAs are the human version of MHC, but MHC is the broader term applicable to all vertebrates. ---
Correct answer: D – Bone marrow; Thymus
All blood cells, including T cell precursors, originate in the bone marrow. T cells then migrate to the thymus where they undergo selection and maturation processes to become functional T lymphocytes. ---
Correct answer: B – Cluster of differentiation 8 (CD8+)
CD8+ T cells are cytotoxic T lymphocytes (CTLs) that express the CD8 co-receptor, which binds to MHC class I molecules. These cells are responsible for killing infected or abnormal cells. ---
Correct answer: C – Plasma cells (activated B cells)
Plasma cells are differentiated B cells that specialize in producing and secreting large amounts of antibodies. They develop from B cells following activation by antigens and helper T cells (CD4+). ---
Correct answer: A – Cluster of differentiation 4 (CD4+)
CD4 is expressed on helper T cells, regulatory T cells, and various antigen-presenting cells. It serves as a co-receptor that binds to MHC class II molecules during antigen presentation. ---
Correct answer: C – Effector phase
The effector phase is when activated immune cells perform their functions. Plasma cells with extensive ER actively synthesize and secrete antibodies during this phase, which is the functional output of the adaptive immune response. ---
Correct answer: B – Dendritic cell
Dendritic cells are the most potent antigen-presenting cells and are critical for initiating adaptive immune responses. They efficiently capture, process, and present antigens to naive T cells in secondary lymphoid organs. ---
Correct answer: C – B cell
B cells express membrane-bound immunoglobulins (antibodies) as their antigen receptors. When these receptors bind specific antigens, the antigen-antibody complex is internalized, processed, and presented on MHC class II molecules to T helper cells. ---
Correct answer: A – Macrophage
Macrophages are particularly effective at phagocytosing and degrading particulate antigens, pathogens, and cellular debris. They then present processed antigens to T cells via MHC molecules. ---
Correct answer: C – They attract phagocytes to both foreign material and self-cells
Complement components attract phagocytes to foreign material and pathogens, but they should NOT attract phagocytes to healthy self-cells. The complement system is designed to distinguish self from non-self. ---
Correct answer: B – C3
C3 is the central component where all three complement activation pathways (classical, alternative, and lectin) converge. Its cleavage is essential for all complement functions. ---
Correct answer: E – BCRs, TCRs, & MHCs
The immunoglobulin fold is a common structural motif found in the immunoglobulin superfamily, which includes B cell receptors (BCRs), T cell receptors (TCRs), and MHC molecules. ---
Correct answer: A – BCRs
Only B cell receptors (antibodies) undergo somatic hypermutation in germinal centers to improve antigen binding affinity. TCRs and MHCs do not undergo this process. ---
Correct answer: C – MHCs
MHC genes are the most polymorphic genes in the human genome, with hundreds of allelic variants. This diversity allows populations to present a wide variety of pathogenic peptides. ---
Correct answer: C – The cells are cultured in a selective medium allowing fused and non-fused cells to survive
The selective medium (HAT medium) is designed to kill unfused cells and allow only successfully fused hybridoma cells to survive. Non-fused cells should NOT survive in this medium. ---
Correct answer: D – 2; 2
A typical antibody molecule has a Y-shaped structure consisting of 2 identical heavy chains and 2 identical light chains, connected by disulfide bonds. ---
Correct answer: A – IgA
IgA is the predominant antibody in mucosal secretions and provides the first line of defense at mucosal surfaces. It exists as secretory IgA (sIgA) in these locations. ---
Correct answer: C – IgE
IgE binds to high-affinity Fc receptors (FcεRI) on mast cells and basophils. Cross-linking of bound IgE by allergens triggers degranulation and allergic reactions. ---
Correct answer: B – IgD
IgD is primarily found on the surface of mature, naive B cells along with IgM. It serves as a B cell receptor and plays a role in B cell activation and tolerance. ---
Correct answer: E – Peptide bonds
Antigen-antibody interactions involve non-covalent forces like electrostatic interactions, hydrophobic interactions, Van der Waals forces, and hydrogen bonds. Peptide bonds are covalent bonds within protein structures, not between antigen and antibody. ---