Title: The Immune System
Course: Question Banks

Q: Pathogens are killed or inactivated on the skin by ________.
- desiccation and immune cells (Incorrect. The immune cells do not play a role until the pathogen has passed through the skin barrier.)
- immune cells and acidity (Incorrect. The immune cells do not play a role until the pathogen has passed through the skin barrier.)
- desiccation and acidity (Correct.)
A: desiccation and acidity

Q: What is a defense against pathogens in the stomach?
- cilia (Incorrect. These are found in respiratory passages such as the nasal cavity.)
- hormones (Incorrect. Hormones are chemical messengers of the endocrine system.)
- low pH (Correct.)
A: low pH

Q: What acts as continuous, impassible barrier to potentially infectious pathogens?
- immune cells (Incorrect. Although they function as a barrier, they are not a continuous barrier.)
- Cell membrane (Incorrect. The cell membrane is not necessarily impassable to pathogens.)
- skin (Correct.)
A: skin

Q: When a pathogen enters the body, cells in the blood and lymph detect ________ on the pathogen’s surface.
- toll-like receptors (TLRs) (Incorrect. Toll-like receptors (TLRs) are a type of PRR that recognizes molecules that are shared by pathogens but distinguishable from host molecules.)
- pattern recognition receptors (PRRs) (Incorrect. PRRs are molecules on macrophages and dendritic cells which are in contact with the external environment.)
- specific pathogen-associated molecular patterns (PAMPs) (Correct.)
A: specific pathogen-associated molecular patterns (PAMPs)

Q: What ancient component of the immune system is found in vertebrates and invertebrates?
- specific pathogen-associated molecular patterns (PAMPs) (Incorrect.)
- hormone receptors (Incorrect. These are not components of the immune system.)
- toll-like receptors (TLRs) (Correct.)
A: toll-like receptors (TLRs)

Q: What is a macrophage?
- a type of lymphocyte that matures in the thymus (Incorrect. This is a T cell.)
- a leukocyte that produces inflammatory molecules, such as histamine, in response to large pathogens (Incorrect. This is a mast cell.)
- a large phagocytic cell that engulfs foreign particles and pathogens (Correct.)
A: a large phagocytic cell that engulfs foreign particles and pathogens

Q: What is the function of natural killer cells?
- They produce inflammatory molecules, such as histamine, in response to large pathogens. (Incorrect. This is the function of mast cells.)
- They present antigens on their surface, thereby triggering adaptive immunity. (Incorrect. This is the function of dendritic cells.)
- They kill cells infected with viruses or tumor cells. (Correct.)
A: They kill cells infected with viruses or tumor cells.

Q: NK cells identify intracellular infections, especially from viruses, by the altered expression of ________ on the surface of infected cells.
- major histocompatibility class (MHC) II molecules (Incorrect. MHC II molecules are found mainly on cells containing antigens (“non-self proteins”) and on lymphocytes. MHC II molecules interact with helper T-cells to trigger the appropriate immune response, which may include the inflammatory response.)
- toll-like receptors (TLRs) (Incorrect. Toll-like receptors (TLRs) are a type of PRR that recognizes molecules that are shared by pathogens but distinguishable from host molecules)
- major histocompatibility class (MHC) I molecules (Correct.)
A: major histocompatibility class (MHC) I molecules

Q: Perforin is secreted from granules in the cytoplasm of ________ when an infected or tumor cell is detected.
- mast cells (Incorrect. Mast cells release histamines and heparin.)
- dendritic cells (Incorrect. Dendritic cells present antigens on their surface, thereby triggering adaptive immunity.)
- natural killer cells (Correct.)
A: natural killer cells

Q: What cells produce complement proteins continuously?
- mast cells (Incorrect. Mast cells produce inflammatory molecules, such as histamine, in response to large pathogens.)
- neutrophils (Incorrect. Neutrophils are first responders at the site of infection and release toxins that kill or inhibit bacteria.)
- cells of the liver and macrophages (Correct.)
A: cells of the liver and macrophages

Q: What is the function of attack complexes formed by certain complement proteins?
- to present antigens on their surface, thereby triggering adaptive immunity. (Incorrect. This is the function of dendritic cells.)
- to identify the altered expression of major histocompatibility class (MHC) I molecules on the surface of infected cells (Incorrect. This is the function of NK cells.)
- to destroy pathogens by causing their contents to leak (Correct.)
A: to destroy pathogens by causing their contents to leak

Q: What is the immune process where particles such as bacteria are targeted for destruction by phagocytes?
- osmosis (Incorrect. Osmosis is the spontaneous net movement of solvent molecules through a semi-permeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides)
- apoptosis (Incorrect. Apoptosis is a process of programmed cell death.)
- opsonization (Correct.)
A: opsonization

Q: What are B lymphocytes?
- immune cells that process antigen material (Incorrect. This are dendritic cells.)
- a large phagocytic cell that engulfs foreign particles and pathogens (Incorrect. This is a macrophage.)
- a type of white blood cell that gives rise to antibodies (Correct.)
A: a type of white blood cell that gives rise to antibodies

Q: What is an antigen?
- a chemical messenger that regulates cell differentiation, proliferation and gene expression to affect immune cells (Incorrect. This is a cytokine.)
- a destructive protein that creates a pore in a target cell (Incorrect. This is a perforin.)
- a foreign or “non-self” macromolecule that reacts with cells of the immune system (Correct.)
A: a foreign or “non-self” macromolecule that reacts with cells of the immune system

Q: After phagocytosis by antigen presenting cells, the phagocytic vesicle fuses with ________.
- a pattern recognition receptor (PRRs) (Incorrect. PRRs are molecules on macrophages and dendritic cells which are in contact with the external environment.)
- the nucleus (Incorrect. The phagocytic vesicles fuse with intracellular lysosomes.)
- an intracellular lysosome (Correct.)
A: an intracellular lysosome

Q: What is important about CD4 and CD8 molecules?
- They recognize molecules that are shared by pathogens but distinguishable from host molecules. (Incorrect. These are PAMPs pattern-associated molecular patterns.)
- Stimulate histamine release. (Incorrect.)
- They regulate how a T cell will interact with and respond to an APC. (Correct.)
A: They regulate how a T cell will interact with and respond to an APC.

Q: An important attribute of T cells is ________.
- their ability to release histamine (Incorrect. This is a function of Mast cells.)
- their ability to mature in macrophages (Incorrect. This is a function of monocytes.)
- their ability to recognize antigens (Correct.)
A: their ability to recognize antigens

Q: The T_H1-mediated response involves ________and is associated with inflammation.
- Plasma cells (Incorrect. A plasma cell is an immune cell that secretes antibodies)
- Epithelium (Incorrect. This cell type is not associated with the T_H1-mediated response.)
- Macrophages (Correct.)
A: Macrophages

Q: Naïve B cells differentiate into antibody-secreting plasma cells when stimulated by ________.
- the T_H1 pathway (Incorrect. This pathway does not stimulate B cells to differentiate into antibody-secreting cells.)
- the complement pathway (Incorrect. This pathway promotes inflammation, and attacks the pathogen's plasma membrane.)
- the T_H2 pathway (Correct.)
A: the T_H2 pathway

Q: What part of the B cell receptor is involved in antigen binding?
- constant region (Incorrect. This part embeds into the plasma membrane and is involved in signal transduction.)
- disulphide linkage (Incorrect. The B cell receptor has two heavy chains and two light chains connected by disulfide linkages.)
- variable region (Correct.)
A: variable region

Q: In what fundamental way do T and B cells differ?
- B cells bind antigens that have been digested and embedded in MHC molecules by APCs. (Incorrect. This is the case with T cells.)
- Binding of BCRs with antigens activates cells to release perforin and granzyme, degradative enzymes that will induce apoptosis of the infected cell. (Incorrect. This is the case of cytotoxic T cells.)
- B cells function as APCs that bind intact antigens that have not been processed. (Correct.)
A: B cells function as APCs that bind intact antigens that have not been processed.

Q: What does Mucosa-associated lymphoid tissue (MALT) do?
- It releases perforin and granzyme, degradative enzymes that will induce apoptosis of the infected cell. (Incorrect. This is what cytotoxic T cells do.)
- It works in the immune system to protect the body from invasion in the gut. (Incorrect. This is gut-associated lymphoid tissue (GALT).)
- It functions as the immune barrier and response in areas of the body with direct contact to the external environment. (Correct.)
A: It functions as the immune barrier and response in areas of the body with direct contact to the external environment.

Q: What is immune tolerance?
- the creation of immunological memory after an initial response to a specific pathogen (Incorrect. This is acquired immunity.)
- the activation of antigen-specific cytotoxic T cells that are able to induce apoptosis in body cells displaying epitopes of foreign antigen on their surface (Incorrect. This is T cell mediated immunity.)
- an acquired ability to prevent an unnecessary or harmful immune response to a detected foreign substance known not to cause disease (Correct.)
A: an acquired ability to prevent an unnecessary or harmful immune response to a detected foreign substance known not to cause disease

Q: What are regulatory T (T_reg) cells?
- Specialized lymphocytes that releases perforin and granzyme, degradative enzymes that will induce apoptosis of an infected cell. (Incorrect. This is a cytotoxic T cell)
- A large phagocytic cell that engulfs foreign particles and pathogens (Incorrect. This is a macrophage.)
- Specialized lymphocytes that suppress local inflammation and inhibit the secretion of stimulatory immune factors. (Correct.)
A: Specialized lymphocytes that suppress local inflammation and inhibit the secretion of stimulatory immune factors.

Q: What happens when the host is re-exposed to the same pathogen type?
- Memory cells will not respond to antigens and do not contribute to host defenses. (Incorrect. Memory cells will differentiate.)
- Circulating memory cells will undergo apoptosis. (Incorrect. They only undergo apoptosis when the infection is cleared or subsides.)
- Circulating memory cells will immediately differentiate into plasma cells and CTLs. (Correct.)
A: Circulating memory cells will immediately differentiate into plasma cells and CTLs.

Q: What is a memory cell?
- a specialized lymphocyte that suppress local inflammation and inhibit the secretion of stimulatory immune factors (Incorrect. This is a regulatory T (T_reg) cells)
- a large phagocytic cell that engulfs foreign particles and pathogens (Incorrect. This is a cytotoxic T cell.)
- an antigen-specific B or T cell that does not differentiate into effector cells during the primary immune response (Correct.)
A: an antigen-specific B or T cell that does not differentiate into effector cells during the primary immune response

Q: Once an infection is cleared and pathogenic stimuli subside, effector cells ________.
- continue to produce antibodies (Incorrect. They undergo apoptosis.)
- continue to circulate for the lifespan of the person (Incorrect. They undergo apoptosis.)
- undergo apoptosis (Correct.)
A: undergo apoptosis

Q: What is lymph?
- body fluid that delivers nutrients and oxygen to the cells and transports metabolic waste products away from those same cells (Incorrect. This is blood.)
- dark green to yellowish brown fluid, produced by the liver, that aids the digestion of lipids in the small intestine (Incorrect. This is bile.)
- watery fluid that bathes tissues and organs with protective white blood cells (Correct.)
A: watery fluid that bathes tissues and organs with protective white blood cells

Q: What cells are found in the spleen?
- Macrophages, B and T cells, and neutrophils (Incorrect. The spleen does not contain neutrophils.)
- B and T cells, macrophages and mast cells (Incorrect. The spleen does not contain mast cells.)
- B and T cells, macrophages, dendritic cells, and NK cells (Correct.)
A: B and T cells, macrophages, dendritic cells, and NK cells

Q: What two types of tissue does the spleen contain?
- white matter and grey matter (Incorrect. These make up the central nervous system (CNS).)
- white pulp and grey pulp (Incorrect. Its red pulp and white pulp.)
- red pulp and white pulp (Correct.)
A: red pulp and white pulp

Q: An antibody molecule is comprised of ________ polypeptides
- two (Incorrect. An antibody molecule is comprised of four polypeptides: two identical heavy chains which are flanked by two identical light chains.)
- eight (Incorrect. An antibody molecule is comprised of four polypeptides: two identical heavy chains which are flanked by two identical light chains.)
- four (Correct.)
A: four

Q: The antibody base is composed of ________ domains.
- bariable (Incorrect. The areas where the antigen is recognized on the antibody are variable domains and the antibody base is composed of constant domains.)
- disulfide bridge (Incorrect. The areas where the antigen is recognized on the antibody are variable domains and the antibody base is composed of constant domains.)
- constant (Correct.)
A: constant

Q: As a germ-line B cell matures, ________ randomly excises V and J segments from the light chain gene.
- DNA polymerase (Incorrect. This enzyme is involved in DNA replication.)
- DNA ligase (Incorrect. This enzyme is involved in DNA replication.)
- DNA recombinase (Correct.)
A: DNA recombinase

Q: Antibodies can be divided into ________ classes.
- seven (Incorrect.)
- six (Incorrect.)
- five (Correct.)
A: five

Q: What antibody class is responsible for allergic reactions?
- IgM (Incorrect. May be attached to the surface of a B cell or secreted into the blood. Responsible for early stages of immunity)
- IgG (Incorrect. Secreted by plasma cells in the blood. Able to cross the placenta into the fetus.)
- IgE (Correct.)
A: IgE

Q: Which two antibodies are synthesized by the mucosal immune system?
- IgA and IgE (Incorrect.)
- IgM and IgE (Incorrect.)
- IgA and IgM (Correct.)
A: IgA and IgM

Q: Which of the following accurately describes passive immunity?
- Immunity can be obtained from the development of antibodies in response to exposure to an antigen. (Incorrect. This is acquired immunity.)
- Nonspecific defense mechanisms come into play immediately or within hours of an antigen's appearance in the body. (Incorrect. This is innate immunity.)
- Antibodies can be transferred from one individual to another to temporarily protect against infectious disease. (Correct.)
A: Antibodies can be transferred from one individual to another to temporarily protect against infectious disease.

Q: How do antibodies inhibit infection by pathogens?
- They induce apoptosis in the pathogen. (Incorrect. Antibodies are not capable of this.)
- They destroy the pathogen directly. (Incorrect. Antibodies are not capable of this.)
- They mark pathogens for destruction by phagocytic cells. (Correct.)
A: They mark pathogens for destruction by phagocytic cells.

Q: What is cross reactivity?
- binding by antibody classes that are secreted as joined, multivalent structures. (Incorrect. This is avidity.)
- the strength of a single antibody-antigen interaction. (Incorrect. This is affinity.)
- when an antibody binds not to the antigen that elicited its synthesis and secretion, but to a different antigen. (Correct.)
A: when an antibody binds not to the antigen that elicited its synthesis and secretion, but to a different antigen.

Q: What is Immunodeficiency?
- an immune reaction in which an antibody-mediated immune response occurs within minutes of exposure to a harmless antigen (Incorrect. This is an allergy)
- a system of immune responses of an organism against its own healthy cells and tissues. (Incorrect. This is autoimmunity.)
- the failure, insufficiency, or delay in the response of the immune system (Correct.)
A: the failure, insufficiency, or delay in the response of the immune system

Q: What is an example of a genetic disorder results in an immunodeficiency?
- systemic lupus erythematosus (Incorrect. This is an autoimmune disease.)
- Graves’ disease (Incorrect. This is an autoimmune disease.)
- bare lymphocyte syndrome (Correct.)
A: bare lymphocyte syndrome

Q: What is the maladaptive immune response toward harmless foreign substances or self-antigens that occur after tissue sensitization?
- immunodeficiency (Incorrect. Immunodeficiency is a failure, insufficiency, or delay in the response of the immune system.)
- autoimmune disease (Incorrect.)
- hypersensitivity (Correct.)
A: hypersensitivity

Q: Most types of autoimmunity involve the ________.
- innate immune response (Incorrect. It is the humoral response: antibody mediated responses.)
- complement cascade (Incorrect. It is the humoral response: antibody mediated responses.)
- humoral immune response (Correct.)
A: humoral immune response