Weekly Year 2: Cellular Immunology Exam - June 5, 2026 (S...

Question 1

In liver cells, bilirubin is mainly conjugated with which molecule to increase its water solubility for excretion?

Accepted Answer

Glucuronic acid — Hepatocytes conjugate bilirubin primarily with glucuronic acid to form bilirubin diglucuronide, making it water-soluble and excretable in bile.

Question 2

Which of the following pathways are crucial for red blood cell (RBC) energy metabolism, given their lack of mitochondria?

Accepted Answer

Glycolysis and Pentose Phosphate Pathway — RBCs rely exclusively on glycolysis for ATP production and the Pentose Phosphate Pathway to generate NADPH, which is essential for reducing oxidative stress.

Question 3

An abnormal increase in the red blood cell count is characterized by which of the following terms?

Accepted Answer

Polycythemia — Polycythemia refers to an abnormally high red blood cell count, often leading to increased blood viscosity.

Question 4

Which of the following is the brain’s preferred and primary source of energy?

Accepted Answer

Glucose — The brain primarily utilizes glucose for energy due to its high energy demand and limited capacity to store glycogen.

Question 5

Which of the following statements about antibody structure is TRUE?

Accepted Answer

Each antibody molecule consists of two identical heavy chains and two identical light chains. — A typical antibody (immunoglobulin) Y-shaped structure is composed of two identical heavy polypeptide chains and two identical light polypeptide chains, linked by disulfide bonds.

Question 6

One of the following statements is TRUE regarding hemolytic disease of the newborn (HDN).

Accepted Answer

It is caused by maternal antibodies attacking fetal red blood cells. — HDN occurs when maternal antibodies cross the placenta and bind to and destroy fetal red blood cells, typically due to Rh or ABO incompatibility.

Question 7

Hematocrit is a measure of:

Accepted Answer

The percentage of blood volume occupied by red blood cells — Hematocrit (Hct) is defined as the volume percentage of red blood cells in blood, expressed as a fraction or percentage.

Question 8

High-energy phosphate bonds for instant human muscle contraction are readily provided by:

Accepted Answer

Creatine phosphate — Creatine phosphate serves as a readily available phosphate donor to quickly regenerate ATP from ADP during the initial phase of intense muscle activity.

Question 9

The Rapapport-Luebering cycle, which allows for ATP production in the absence of oxygen, is mainly located in which cell type?

Accepted Answer

Erythrocytes (Red Blood Cells) — The Rapapport-Luebering shunt is a pathway within erythrocytes that produces 2,3-bisphosphoglycerate (2,3-BPG), facilitating ATP production during anaerobic conditions.

Question 10

The major site of erythrocyte production (erythropoiesis) in humans after birth is the:

Accepted Answer

Bone marrow — In adults, the bone marrow, particularly the red marrow of flat bones and the epiphyses of long bones, is the primary site of red blood cell production.

Question 11

The most rapid method to resynthesize ATP during short bursts of intense exercise is through which energy system?

Accepted Answer

The phosphagen system (creatine phosphate) — The phosphagen system, utilizing creatine phosphate, is the fastest way to regenerate ATP for immediate, high-intensity muscle work.

Question 12

Which of the following statements is FALSE regarding cardiac and skeletal muscles?

Accepted Answer

Both cardiac and skeletal muscles are under voluntary control. — Skeletal muscles are under voluntary control, while cardiac muscle is involuntary.

Question 13

Which of the following laboratory techniques utilizes ultraviolet (UV) light for examining specimens, often for fluorescence microscopy?

Accepted Answer

Immunofluorescence microscopy — Immunofluorescence microscopy uses fluorochromes that absorb UV or visible light and emit light at a longer wavelength, visualized under a UV or appropriate filter set.

Question 14

Which of the following would be used as preliminary screening for the presence of antibodies to HIV proteins in a patient's blood sample?

Accepted Answer

Enzyme-linked immunosorbent assay (ELISA) — ELISA is a common and cost-effective initial screening test for antibodies against various pathogens, including HIV, due to its sensitivity.

Question 15

What color light is emitted when antigens are exposed to UV light after being treated with fluorescein isothiocyanate (FITC)?

Accepted Answer

Green — FITC is a fluorescent dye that absorbs UV or blue light and emits light in the green spectrum, commonly used in immunofluorescence.

Question 16

Which of the following immunological detection methods uses the enzyme horseradish peroxidase (HRP) conjugated to an antibody or antigen?

Accepted Answer

Enzyme-linked immunosorbent assay (ELISA) — ELISA assays frequently use HRP as an enzyme label. When a substrate is added, HRP catalyzes a reaction that produces a detectable color change.

Question 17

Which of the following techniques is used extensively to detect antigens in cells or tissue sections, as well as to screen for auto-antibodies to cell or tissue antigens?

Accepted Answer

Immunohistochemistry (IHC) — Immunohistochemistry (IHC) uses antibodies to detect specific antigens in tissue samples, allowing for their localization and quantification, and is also used in auto-antibody detection.

Question 18

Which of the following techniques uses protein antigens separated by molecular weight using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE)?

Accepted Answer

Western blotting — Western blotting is used to detect specific proteins in a sample. Proteins are first separated by SDS-PAGE based on size, then transferred to a membrane and detected with specific antibodies.

Question 19

Each polypeptide chain (heavy and light) on an immunoglobulin molecule has a variable (V) region and a constant (C) region. Which part of the antibody determines its effector function?

Accepted Answer

The variable region of the heavy chain — The constant region of the heavy chain (Fc region) of an antibody interacts with other immune system components (e.g., complement, Fc receptors on cells) to mediate effector functions.

Question 20

In somatic recombination, the D segment rearranges first. The variable region of the antibody molecule is generated via somatic recombination and contains both a constant region and a variable region.

Accepted Answer

V, D, J segments; variable — Somatic recombination involves the joining of V, D, and J gene segments to form the variable region of immunoglobulin heavy chains. The variable region is responsible for antigen binding.

Question 21

The two types of light chains found in immunoglobulins are:

Accepted Answer

Kappa (κ) and Lambda (λ) — Immunoglobulins have either kappa (κ) or lambda (λ) light chains, but not both in the same antibody molecule.

Question 22

Which of the following is NOT true regarding the mechanisms of generating antibody diversity?

Accepted Answer

Junctional diversity, including V(D)J recombination, is the primary mechanism for generating variability in the light chains. — V(D)J recombination is crucial for both heavy and light chain variable region diversity. Junctional diversity also contributes significantly to light chain variability, not just the heavy chains.

Question 23

IgM is frequently found on the surface of B cells co-expressed with IgD . These two classes are co-expressed not by class switching but by alternative processing of a primary RNA transcript. Both molecules expressed on the single mature B cell have the same binding specificity for antigen.

Accepted Answer

IgM, IgD — Mature naive B cells express both IgM and IgD on their surface, which are produced from the same precursor mRNA through alternative polyadenylation and splicing.

Question 24

If alternative processing uses the first polyadenylation site during B cell development (for membrane-bound antibody production), then what type of heavy chain mRNA is derived?

Accepted Answer

Membrane-bound IgM heavy chain mRNA — The first polyadenylation site encountered in the primary transcript is typically associated with the production of membrane-bound immunoglobulins, starting with IgM and IgD.

Question 25

Which of the following diseases directly affects the function of neutrophils, impairing their ability to kill ingested bacteria?

Accepted Answer

DiGeorge's syndrome — Chronic granulomatous disease (CGD) is a genetic disorder where neutrophils cannot produce reactive oxygen species, which are essential for killing certain pathogens.

Question 26

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

Accepted Answer

Inflammatory exudate — During inflammation, phagocytic cells migrate from the bloodstream into the injured tissue, forming an inflammatory exudate to clear debris and pathogens.

Question 27

Which of the following mediators is crucial for an early response to viral infections by the innate immune system?

Accepted Answer

Interferons (IFNs) — Interferons, particularly Type I IFNs (IFN-α and IFN-β), are a hallmark of the innate immune response to viral infections, inducing an antiviral state in neighboring cells.

Question 28

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

Accepted Answer

Cytokines (e.g., interleukins, TNF-α) — Cytokines produced by innate immune cells (like macrophages and dendritic cells) are crucial for signaling to and activating adaptive immune cells (T and B cells), bridging the two systems.

Question 29

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

Accepted Answer

T cytotoxic cell receptor (TCR) in conjunction with MHC class I — TCRs on cytotoxic T cells recognize peptide fragments (epitopes) presented by MHC class I molecules, not intact macromolecule epitopes directly.

Question 30

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

Accepted Answer

Major Histocompatibility Complex (MHC) — The Major Histocompatibility Complex (MHC) is a cluster of genes essential for adaptive immunity, encoding cell surface proteins that present antigens to T cells.

Question 31

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

Accepted Answer

Bone marrow; Thymus — T cell precursors originate in the bone marrow and migrate to the thymus for maturation and selection.

Question 32

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) marker?

Accepted Answer

CD8 — CD8 is a co-receptor found on cytotoxic T lymphocytes (CTLs) that binds to MHC class I molecules, enhancing T cell activation and signaling.

Question 33

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

Accepted Answer

Plasma cells — Plasma cells are terminally differentiated B cells that are specialized for the secretion of large quantities of antibodies. Their differentiation is often T cell-dependent.

Question 34

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

Accepted Answer

CD4 — CD4 is a co-receptor that binds to MHC class II molecules and is expressed on T helper cells, regulatory T cells, and also found on monocytes, macrophages, and dendritic cells.

Question 35

Which of the following types of antigen presenting cells (APCs) is critical in uptake and presentation of antigen to T cells, particularly for initiating primary adaptive immune responses?

Accepted Answer

Dendritic cells — Dendritic cells are considered the most potent APCs and are crucial for initiating adaptive immune responses by presenting antigens to naive T cells in lymphoid organs.

Question 36

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?

Accepted Answer

Macrophages — Follicular dendritic cells (FDCs) in lymphoid follicles capture antigens via surface complement receptors and Fc receptors, displaying them to B cells, though they are not primary antigen presenters to T cells.

Question 37

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

Accepted Answer

Macrophages — Macrophages are professional phagocytes that efficiently engulf and degrade particulate antigens, and then present peptide fragments via MHC class II molecules to T helper cells.

Weekly Year 2: Cellular Immunology Exam - June 5, 2026 (S...

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