Weekly Year 2: Cellular Immunology Exam - May 15, 2026 (Sect

Question 1

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

Accepted Answer

Fluorescence microscopy — Fluorescence microscopy utilizes UV light to excite fluorophores in a specimen, causing them to emit light at longer wavelengths for visualization.

Question 2

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

ELISA (Enzyme-Linked Immunosorbent Assay) — ELISA is a common and cost-effective method for initial screening of antibodies against specific antigens, such as those of HIV, due to its sensitivity and ability to process large numbers of samples.

Question 3

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 fluorophore that absorbs light in the blue-violet region of the spectrum and emits green fluorescence.

Question 4

Which of the following diagnostic tests utilizes the enzyme horseradish peroxidase (HRP)?

Accepted Answer

ELISA — ELISA often employs HRP as an enzyme conjugate. When a substrate is added, HRP catalyzes a reaction that produces a detectable signal, typically a color change.

Question 5

Which of the following methods 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) is a technique that uses antibodies to detect specific antigens within cells or tissue samples. It is also used to identify auto-antibodies that target cellular or tissue components.

Question 6

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

Accepted Answer

Western blot — A Western blot involves separating proteins by SDS-PAGE, transferring them to a membrane, and then probing with specific antibodies to detect particular proteins.

Question 7

Each polypeptide chain (heavy and light) on an immunoglobulin has a variable (V) and constant (C) region. Which part is primarily responsible for antigen binding?

Accepted Answer

Variable regions of both heavy and light chains — The variable regions of both the heavy and light chains form the antigen-binding site (Fab region) of the antibody molecule, determining its specificity for a particular antigen.

Question 8

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

Accepted Answer

D gene segment; variable — In the development of B cells, D gene segments typically rearrange first, followed by V and J segments. This process generates the variable region of the antibody, which is crucial for antigen binding. The question is slightly misleading as the entire variable region, not just a part of it, is generated via somatic recombination. However, the D segment rearrangement is an early and critical step.

Question 9

The two types of light chains found in immunoglobulins are:

Accepted Answer

Kappa and Lambda — Immunoglobulins can have either kappa (κ) or lambda (λ) light chains. A single antibody molecule will always have the same type of light chain.

Question 10

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

Accepted Answer

Somatic hypermutation occurs primarily in the constant regions of immunoglobulin genes. — Somatic hypermutation primarily targets the variable regions of immunoglobulin genes, introducing point mutations that can increase antibody affinity for the antigen. It does not predominantly affect the constant regions.

Question 11

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. 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. This co-expression is achieved through alternative splicing of a single primary RNA transcript, not class switching. Both IgM and IgD on a single B cell recognize the same antigen.

Question 12

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

Accepted Answer

Membrane-bound IgM mRNA — Alternative splicing and polyadenylation of the primary transcript determine whether the resulting immunoglobulin is membrane-bound or secreted, and which isotype is produced. In the context of IgM/IgD co-expression, using the first polyadenylation site typically leads to membrane-bound IgM.

Question 13

In liver cells, bilirubin is mainly conjugated with:

Accepted Answer

Glucuronic acid — In the liver, bilirubin is conjugated primarily with glucuronic acid by the enzyme UDP-glucuronosyltransferase to form bilirubin diglucuronide, which is more water-soluble and excretable.

Question 14

Which of the following pathways are important in RBC energy metabolism?

Accepted Answer

Glycolysis and Pentose Phosphate Pathway — Red blood cells (RBCs) rely almost exclusively on anaerobic glycolysis for ATP production. The Pentose Phosphate Pathway is also crucial in RBCs to produce NADPH, which is essential for reducing oxidative stress.

Question 15

An abnormal increase in red blood cell count is characterized by:

Accepted Answer

Polycythemia — Polycythemia is a condition characterized by an abnormally high concentration of red blood cells (erythrocytosis) in the blood.

Question 16

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

Accepted Answer

Glucose — The brain relies almost exclusively on glucose for energy, especially during fed states. While it can utilize ketone bodies during prolonged fasting or starvation, glucose is its primary and preferred fuel.

Question 17

Which of these statements is TRUE?

Accepted Answer

Rh immune globulin (RhoGAM) increases the risk of hemolytic disease of the newborn. — Hemolytic disease of the newborn (HDN) is caused by maternal antibodies that cross the placenta and attack the fetus's red blood cells. This commonly occurs when there is an Rh incompatibility (mother Rh-negative, fetus Rh-positive) or ABO incompatibility.

Question 18

One of the following statements is TRUE regarding hemolytic disease of the newborn:

Accepted Answer

It is caused by maternal antibodies against fetal red blood cell antigens. — Hemolytic disease of the newborn is a consequence of maternal antibodies destroying fetal red blood cells, leading to anemia and other complications.

Question 19

Hematocrit is a measure of:

Accepted Answer

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

Question 20

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 rapidly regenerate ATP from ADP during the initial moments of intense muscle activity, providing energy for instant contraction.

Question 21

The Rapapport-Luebering cycle is mainly located in:

Accepted Answer

Erythrocytes (Red blood cells) — The Rapapport-Luebering cycle, which produces 2,3-bisphosphoglycerate (2,3-BPG), is a shunt in glycolysis that occurs exclusively in erythrocytes. 2,3-BPG is crucial for regulating hemoglobin's oxygen affinity.

Question 22

The major site of erythrocyte production in humans is the:

Accepted Answer

Bone marrow — Erythropoiesis, the production of red blood cells, primarily occurs in the red bone marrow in adults.

Question 23

The most rapid method to resynthesize ATP during exercise is through:

Accepted Answer

Creatine phosphate system — The creatine phosphate system provides the most immediate and rapid way to regenerate ATP, crucial for short bursts of intense activity like the start of exercise.

Question 24

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

Accepted Answer

Both are under voluntary control. — Skeletal muscles are under voluntary control, whereas cardiac muscle is involuntary.

Question 25

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

Accepted Answer

The site of infection/inflammation — Following skin breach, phagocytic cells like neutrophils and macrophages are recruited from the bloodstream to the site of infection or inflammation to engulf and destroy invading pathogens.

Question 26

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

Accepted Answer

Interferons — Interferons are signaling proteins produced by infected cells that interfere with viral replication and alert neighboring cells. They are a key component of the early innate immune response to viral infections.

Question 27

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

Accepted Answer

Cytokines — Cytokines are soluble signaling molecules that are produced by cells of both innate and adaptive immunity. They play a crucial role in orchestrating the immune response and bridging the innate and adaptive arms of the immune system.

Question 28

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

Accepted Answer

Pattern Recognition Receptor (PRR) — Pattern Recognition Receptors (PRRs) recognize conserved molecular patterns on microbes (PAMPs) rather than specific macromolecular epitopes. Antibodies, TCRs, and BCRs are designed to recognize specific epitopes on antigens.

Question 29

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

Accepted Answer

Histocompatibility Complex (MHC) — The Major Histocompatibility Complex (MHC) is a crucial gene region in vertebrates that plays a central role in adaptive immunity by presenting antigens to T cells.

Question 30

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 to undergo maturation and selection.

Question 31

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)?

Accepted Answer

CD8 — CD8 is a co-receptor typically found on cytotoxic T lymphocytes (CTLs). It binds to MHC class I molecules on antigen-presenting cells, stabilizing the interaction with the TCR and playing a role in T cell activation.

Question 32

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

Accepted Answer

Plasma cells — Plasma cells are terminally differentiated B cells that are specialized for the production and secretion of large quantities of antibodies. Their development and function are often regulated by CD4+ T helper cells.

Question 33

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 surface glycoprotein that serves as a co-receptor for the T cell receptor (TCR) on helper T cells, regulatory T cells, and also on cells of the innate immune system such as monocytes, macrophages, and dendritic cells.

Question 34

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

Accepted Answer

Dendritic cells — Dendritic cells are considered the most potent antigen-presenting cells (APCs) in the immune system. They are crucial for initiating adaptive immune responses by efficiently capturing, processing, and presenting antigens to naive T cells.

Question 35

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

B cell — B cells use their B cell receptor (BCR), which is a membrane-bound immunoglobulin, to bind specific antigens. This binding triggers internalization, processing, and presentation of peptide fragments on MHC class II molecules to T helper cells.

Question 36

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

Accepted Answer

Macrophage — Macrophages are professional phagocytes and are particularly efficient at engulfing, degrading, and presenting particulate antigens (like bacteria and cellular debris) to T cells, especially during inflammatory responses.

Weekly Year 2: Cellular Immunology Exam - May 15, 2026 (Sect

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