Immunology Quiz | MCQ Quiz | OmpathStudy Kenya

Question 1

Phagocytic white cells (leukocytes, e.g. macrophages) congregate within when foreign organisms get through a cut in the skin. Options

Accepted Answer

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. ---

Question 2

Which of the following mediates an early response to viral infections by the innate immune system? Options

Accepted Answer

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. ---

Question 3

Which of the following is a messenger that mediates the connection between the innate and adaptive immune systems? Options

Accepted Answer

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. ---

Question 4

Which of the following immune system components would NOT recognize a macromolecule epitope (binding site)? Options

Accepted Answer

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. ---

Question 5

Which of the following is a large genomic region or gene family found in most vertebrates, playing an important role in immunity? Options

Accepted Answer

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. ---

Question 6

T cells are made in the and complete their differentiation in the . Options

Accepted Answer

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. ---

Question 7

Which of the following is a transmembrane glycoprotein that serves as a co-receptor for the T cell receptor (TCR), and is also known as a cytotoxic T cell (CTL)? Options

Accepted Answer

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. ---

Question 8

Which of the following produce large amounts of antibodies (Igs) and differentiate upon stimulation from CD4+ cells? Options

Accepted Answer

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+). ---

Question 9

Which of the following is a glycoprotein expressed on the surface of T helper cells, regulatory T cells, monocytes, macrophages, and dendritic cells? Options

Accepted Answer

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. ---

Question 10

Which of the following types of antigen presenting cells (APCs) is critical in uptake and presentation of antigen to T cells? Options

Accepted Answer

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. ---

Question 11

Which of the following types of antigen presenting cells (APCs) has immunoglobulin that functions as a receptor, then the antigen is internalized, degraded, and presented to T cells? Options

Accepted Answer

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. ---

Question 12

Which of the following types of antigen presenting cells (APCs) is specialized for degradation and presentation of particulate antigens to T cells? Options

Accepted Answer

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. ---

Question 13

Which of the following is NOT true regarding the complement system? Options

Accepted Answer

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. ---

Question 14

Which of the following has an immunoglobulin fold? Options

Accepted Answer

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. ---

Question 15

The genes encoding which of the following can undergo hypermutation to create receptors that are an even better fit for foreign antigens? Options

Accepted Answer

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. ---

Question 16

The genes encoding which of the following are extensively polymorphic (have multiple alleles or forms of the same gene)? Options

Accepted Answer

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. ---

Question 17

Each antibody molecule contains heavy chains and light chains. Options

Accepted Answer

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. ---

Question 18

Which of the following binds to an Fc receptor on mast cells and basophils? Options

Accepted Answer

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. ---

Question 19

Which of the following is NOT involved in the antigen-antibody interaction? Options

Accepted Answer

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. ---

Question 20

This can complicate the treatment of bacterial infections in these patients because they are unable to take the antibiotics necessary to combat the infection. Options

Accepted Answer

IgE — IgE-mediated allergic reactions to antibiotics (like penicillin) can prevent patients from taking necessary antimicrobial treatments, complicating the management of bacterial infections. ---

Question 21

Which of the following is used to enumerate and/or separate live cells that express an antigen, sorted by applying an electric charge to the stained cells? Options

Accepted Answer

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. ---

Question 22

Which of the following is a very sensitive and simple test for antigens, which uses a covalent complex of enzyme linked to antibody, to detect antigen directly or to bind antibody-antigen complex? Options

Accepted Answer

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. ---

Question 23

Which of the following is used to characterize antigens in complex mixtures biochemically? Options

Accepted Answer

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. ---

Question 24

Which of the following uses ultraviolet (UV) light for examining specimens? Options

Accepted Answer

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. ---

Question 25

is frequently found on the surface of B cells co-expressed with . These two classes are co-expressed not by class switching but by alternative processing of a primary RNA transcript. Options

Accepted Answer

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. ---

Question 26

If alternative processing uses the first polyadenylation site, then what type of heavy chain mRNA is derived? Options

Accepted Answer

μ (mu) — When the first polyadenylation site is used in alternative RNA processing, the μ (mu) heavy chain mRNA is produced, resulting in IgM antibody production. ---

Question 27

Production of secreted antibodies (pAs site) involves a chain of amino acids with a stretch of charged (versus non-charged) amino acids at the terminus, in comparison to membrane bound antibody production (pAm site). Options

Accepted Answer

Shorter; COOH — Secreted antibodies have shorter heavy chains at the COOH terminus with charged amino acids, lacking the transmembrane and cytoplasmic domains present in membrane-bound antibodies. ---

Question 28

In heterozygous individuals who have inherited two alternative forms of the constant region gene for IgG1, which of the following is true regarding the Ig expression by a particular B cell, according to allelic exclusion? Options

Accepted Answer

It will contain only one of the types — Allelic exclusion ensures that each B cell expresses only one allelic form of immunoglobulin, either IgG1m(1) or IgG1m(2), but not both simultaneously. ---

Question 29

Protein and nucleic acid sequence data suggest the existence of how many hypervariable (hv) regions within the variable region of TCRs? Options

Question 30

The biochemical structure of the T-cell receptor (TCR) of the αβ type (95% of human TCRs) is comparable to a immunoglobulin fragment, having very short cytoplasmic tails. Options

Accepted Answer

Membrane-bound; Fab — TCRs are membrane-bound receptors structurally similar to the Fab portion of antibodies, containing variable regions for antigen binding but with very short cytoplasmic tails. ---

Question 31

Where are T cells generally found in the body (location of TCR rearrangement)? Options

Accepted Answer

Thymus — T cell receptor gene rearrangement and T cell maturation occur in the thymus, where T cells undergo positive and negative selection processes. ---

Question 32

Which of the following are located in chromosome 7 within human T-cell receptors? Options

Accepted Answer

Alpha (α)-locus — The α-chain locus (which contains the δ-chain genes) is located on chromosome 7. The β-chain is on chromosome 7, and γ-chain is on chromosome 7. ---

Question 33

Comparing the arrangement of TCR genes and BCR genes, the chain is analogous to the heavy (H) chain and the chain is analogous to the light (L) chain. Options

Accepted Answer

Beta; Alpha — In TCR gene organization, the β-chain is analogous to the immunoglobulin heavy chain (has V, D, and J segments), while the α-chain is analogous to the light chain (has V and J segments only). ---

Question 34

Which of the following TCR genetic chains contain D-segments, similar to immunoglobulin heavy chains? Options

Accepted Answer

Beta (β); Delta (δ) — Both β and δ chains of TCRs contain D (diversity) segments in their gene structure, similar to immunoglobulin heavy chains, which contribute to receptor diversity. ---

Question 35

The process used to increase antigen binding affinity is called somatic and occurs in cells but not cells. Options

Accepted Answer

Hypermutation; B; T — Somatic hypermutation occurs in activated B cells in germinal centers to improve antibody affinity for antigens. T cells do not undergo this process. ---

Question 36

Which of the following is NOT true of T-cell receptors, when compared to immunoglobulin? Options

Accepted Answer

After exposure to antigen, there is somatic hypermutation and class switching — TCRs do NOT undergo somatic hypermutation or class switching after antigen exposure, unlike immunoglobulins. TCRs maintain their original structure and specificity. ---

Question 37

The T cell-APC interaction is MHC -restricted, and the T cell-target cell interaction is MHC -restricted. Options

Accepted Answer

CD4+; Class II; CD8+; Class I — CD4+ T cells interact with APCs via MHC class II molecules, while CD8+ T cells interact with target cells via MHC class I molecules. This reflects their different functional roles. ---

Question 38

Which of the following describes where class I MHC is found and not where class II MHC is found? Options

Accepted Answer

All nucleated cells — MHC class I molecules are found on all nucleated cells, while MHC class II molecules are restricted to antigen-presenting cells (APCs) like B cells, dendritic cells, and macrophages. ---

Question 39

Peptides antigens generated in the cytosolic compartment bind to MHC molecules for presentation to T cells. Peptide antigens generated in vesicles bind to MHC molecules for presentation to T cells. Options

Accepted Answer

Class I; CD8+; Class II; CD4+ — Cytosolic antigens (intracellular pathogens like viruses) are presented on MHC class I to CD8+ T cells. Vesicular antigens (extracellular pathogens) are presented on MHC class II to CD4+ T cells. ---

Question 40

In the processing pathway for extracellular antigens, synthesis of MHC class II and invariant chain (Ii) occurs in the . Options

Accepted Answer

Endoplasmic reticulum — MHC class II molecules and the invariant chain are synthesized in the endoplasmic reticulum, where they assemble before being transported to endosomal compartments. ---

Question 41

In the processing pathway for intracellular antigens, the proteasome will viral protein molecules until peptides of residues are formed. Options

Accepted Answer

Break down; 8-11 — The proteasome degrades intracellular proteins into short peptides of 8-11 amino acid residues, which are the optimal size for binding to MHC class I molecules. ---

Question 42

The transporter associated with antigen presentation (TAP) the peptides to traverse the membrane bilayer of the endoplasmic reticulum and bind in the empty peptide-binding groove of nascent MHC molecules. Options

Accepted Answer

Permits; Class I — TAP transporters allow peptides generated by the proteasome to enter the ER lumen where they can bind to newly synthesized MHC class I molecules. ---

Question 43

What is the major site for hematopoiesis, where all blood cells are formed? Options

Accepted Answer

Bone marrow — The bone marrow is the primary site of hematopoiesis in adults, where all blood cell lineages including immune cells originate from hematopoietic stem cells. ---

Question 44

Patients with MHC class II (or class I) antigen deficiency would exhibit which of the following? Options

Accepted Answer

Persistent bacterial and viral infections — MHC deficiency severely impairs T cell function and antigen presentation, leading to persistent infections with bacteria and viruses due to inadequate adaptive immune responses. ---

Immunology Quiz | MCQ Quiz | OmpathStudy Kenya

Questions, Answers & Explanations