44 Year 2: Cellular Immunology exam questions on Immunology Quiz for medical students. Includes MCQs, answers, explanations and written questions. Sample: Phago
This MCQ set contains 44 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 – 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: 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: 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: 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: 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: 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. ---
Correct answer: C – IgE
IgE-mediated allergic reactions to antibiotics (like penicillin) can prevent patients from taking necessary antimicrobial treatments, complicating the management of bacterial infections. ---
Correct answer: C – FACS (fluorescence-activated cell sorting)
FACS uses fluorescent antibodies to label cells and then sorts them based on their fluorescence properties using laser excitation and electrical charges to separate different cell populations. ---
Correct answer: A – ELISA (Enzyme-linked immunosorbent assay)
ELISA uses enzyme-linked antibodies to detect antigens or antibody-antigen complexes. The enzyme catalyzes a color reaction that can be quantified, making it highly sensitive and widely used for diagnostic purposes. ---
Correct answer: D – Western blotting (immunoblotting)
Western blotting separates proteins by gel electrophoresis and then uses specific antibodies to identify and characterize individual antigens within complex protein mixtures. ---
Correct answer: B – Fluorescent antibody (fluorochromes)
Fluorescent antibody techniques use fluorochromes that are excited by UV light and emit visible light, allowing visualization of antigen-antibody binding under fluorescence microscopy. ---
Correct answer: B – IgD & IgM
Mature naive B cells co-express IgD and IgM on their surface through alternative RNA splicing of the same primary transcript. Both have identical variable regions and antigen specificity. ---