Exam 1

Question 1

Which of the following pairs is mismatched?

a. phagocytosis: uptake and killing of microbes
b. secondary immune response: immunology memory
c. hematopoiesis: bone marrow
d. lymphocyte recirculation: continuous transport between blood and lymph
e. innate immunity: highly specialized defenses

Answer 1

e. innate immunity: highly specialized defenses

Question 2

Which of the following statement is false?

a. Hematopoietic stem cells are self-renewing
b. The hematopoietic stem cell gives rise to white blood cells but a different stem cell is the progenitor of red blood cells
c. During human development, hematopoiesis takes place at different anatomical locations
d. Platelets participate in clotting reactions to prevent blood loss.
e. Megakaryocytes do not circulate and reside only in the bone marrow

Answer 2

b. The hematopoietic stem cell gives rise to white blood cells but a different stem cell is the progenitor of red blood cells

Question 3

Secondary lymphoid organs are able to trap antigen, generally from nearby tissues or vascular spaces and are sites where mature lymphocytes can interact effectively with antigen. The secondary lymphoid organs include:

a. thymus and bone marrow
b. lymph nodes, spleen, and mucosal-associated lymphoid tissues (MALT), and bone marrow
c. lymph nodes, spleen, and thymus
d. liver, lungs, and heart
e. lymphnodes, spleen, and mucosal-associated lymphoid tissues (MALT)

Answer 3

e. lymph nodes, spleen, and mucosal-associated lymphoid tissues (MALT)

Question 4

Which of the following describes the flow of lymph through a lymph node draining an infected tissue?

a. artery -> lymph node-> efferent lymphatic vessel
b. efferent lymphatic vessel -> lymph node -> afferent lymphatic vessel
c. venule -> lymph node -> efferent lymphatic vessel
d. afferent lymphatic vessel -> lymph node -> efferent lymphatic vessel
e. afferent lymphatic vessel -> lymph node -> artery

Answer 4

d. afferent lymphatic vessel -> lymph node -> efferent lymphatic vessel

Question 5

Identify the incorrect statement regarding hematopoiesis.

a. Hematopoiesis is a continuous process that occurs throughout one’s lifetime.
b. The location for hematopoiesis differs with age
c. self renewal is necessary to replenish the supply of hematopoietic stem cells
d. Most hematopoiesis occurs in the bone marrow after birth
e. leukocytes, but not erythrocytes, must go through hematopoiesis in order to develop

Answer 5

e. leukocytes, but not erythrocytes, must go through hematopoiesis in order to develop

Question 6

All of the following statements are characteristic of secondary immune responses except _____.

a. secondary immune responses are orders of magnitude greater than primary immune responses
b. secondary immune responses are restricted to adaptive immune responses
c. memory cells are activated rapidly during secondary immune responses
d. secondary immune responses are activated when primary immune responses fail to completely eradicate an infection
e. during a secondary immune response to a booster vaccine, it is possible to experience a primary immune response to an unrelated vaccine component encountered for the first time

Answer 6

d. secondary immune responses are activated when primary immune responses fail to completely eradicate an infection

Question 7

Which statement below is FALSE regarding vaccines and vaccination?

a. in 1796, Edward Jenner, a British doctor, showed how inoculation with non-attenuated smallpox virus offered protection against subsequent smallpox virus challenge
b. Edward Jenner inoculated cowpox virus to induce protection against subsequent smallpox virus challenge. He called his procedure “vaccination”, after vaccinia, the name given to the mild disease produced by cowpox, and he is generally credited with its invention
c. Active immunization: stimulation with a specific antigen to induce an immune response
d. passive immunization: the conferral of specific immune reactivity on previously non immune individuals by administration of sensitized lymphoid cells or serum from immune individuals
e. the smallpox vaccine does not contain the smallpox virus and it cannot cause smallpox

Answer 7

a. in 1796, Edward Jenner, a British doctor, showed how inoculation with non attenuated smallpox virus offered protection against subsequent smallpox virus challenge

Question 8

As to human stem cells, which statement below is FALSE?

a. stem cells are undifferentiated or unspecialized cells that can differentiate into different cell types.
b. embryonic stem cells are unipotent, that is, they can only generate the same cell type as themselves. In contrast, adult (somatic) stem cells are pluripotent and can give rise to most but not all of the cell types.
c. adult (or somatic) stem cells are undifferentiated cells found among differentiated cells in a tissue or organ, and can renew themselves and become the specific cells of the tissues they reside
d. all stem cells, regardless of their source, have three general properties: 1) they are capable of dividing and renewing themselves for long periods; 2) they are unspecialized; and 3) they can give rise to specialized cell types.
e. The 2012 Noble Prize in physiology and medicine was awarded to John Gurdon and Shinya Yamanaka, for the discovery that mature adult cells could be reprogrammed to become immature stem cells. Surprisingly, yamanaka showed that by introducing only four genes into mature cells they would become pluripotent stem cells, i.e., immature cells that are able to develop into all types of cells in the body

Answer 8

b. embryonic stem cells are unipotent, that is, they can only generate the same cell type as themselves. In contrast, adult (somatic) stem cells are pluripotent and can give rise to most but not all of the cell types.

Question 9

Which statement below is FALSE regarding commensals?

a. In mammals, the gut microbiota has coevolved to provide essential functions for host physiological processes, such as the acquisition of nutrients, the development and maturation of the immune system and enhancement of the intestinal barrier
b. the microbial communities that colonize living organisms are collectively referred to as the ‘microbiota’. more than 500 microbial commensal species live in the healthy adult human gut and contribute about two pounds to the body’s weight. There are 10 times more bacterial cells in a human body than human cells
c. commensals are well adapted to the ecological conditions of their host and constitute a complex ecosystem in which host-microbe, environment-microbe and microbe-microbe interactions dictate the composition and dynamics of the community
d. in contrast to the dominant role of the gut microbiota, which can control the development of the immune system and set systemic thresholds for immune activation, the microbiota at sites other than the gut has a more local and discrete influence on processes such as tissue homeostasis, immune responses and tissue repair
e. to facilitate homeostasis, the immune system ensures that the diverse microbial (commensal) load is not tolerated and a strong immune response is constantly mounted against commensals

Answer 9

e. to facilitate homeostasis, the immune system ensures that the diverse microbial (commensal) load is not tolerated and a strong immune response is constantly mounted against commensals

Question 10

Which statement below is TRUE regarding vaccines?

a. it has been scientifically proven that vaccines cause autism
b. there are few vaccines available and they do not protect the majority of people against infection.
c. vaccines have saved millions of people throughout the years; however, they have has also killed thousands of people due to the severe side effects they may cause.
d. vaccines have saved many millions of people worldwide since they have been introduced as regular public health policy in most countries
e. in the US alone, vaccines have caused more deaths than tobacco, alcohol, and non steroidal anti inflammatory drugs combined.

Answer 10

d. vaccines have saved many millions of people worldwide since they have been introduced as regular public health policy in most countries

Question 11

Which of complement pathway(s) becomes activated soonest after an initial infection?

a. the classical pathway
b. the lectin pathway
c. the alternative pathway
d. both classical and alternative pathways
e. both classical and lectin pathways

Answer 11

c. the alternative pathway

Question 12

(T or F) The enzyme responsible for cleaving C3 into C3a and C3b is called C3 convertase, and it differs in composition depending on the particular complement pathway. The classical and lectin pathways use the classical C3 convertase (C4b2a), wheras the alternative pathway uses the alternative convertase (C3bBb).

Answer 12

True

Question 13

(T or F) C2 is the most abundant complement component in the plasma and circulates as a zymogen, an inactive enzyme. When cleaved into C2a and C2b, three different effector mechanisms are armed: (1) C2b binds to and tags pathogens for destruction by phagocytes through binding to a C2b receptor, CR1; (2) C2b contributes to a multicomponent enzyme, C5 convertase, that catalyzes the assembly of the terminal complement components and the formation of the membrane-attack complex; and (3) C2a is an inflammatory mediator that serves as a chemoattractant and recruits inflammatory cells to the infection site.

Answer 13

False

Question 14

Regarding the three pathways of complement: (1) The classical pathway is activated in two ways, either by the presence of antibody bound to the surface of the microorganism (for example IgM bound to lipopolysaccharide of Gram-negative bacteria) or by the presence of C-reactive protein bound to a bacterium. (2) The lectin pathway requires the presence of mannose-binding lectin, an acute-phase protein made by the liver in response to interleukin-6 (IL-6) (secreted by activated macrophages) and which accumulates in plasma during infection. (3) The alternative pathway requires an activating surface of a pathogen, which stabilizes complement components.

Answer 14

True

Question 15

During the formation of the membrane-attack complex, it is important to expose the hydrophobic sites of C7 and C8, because these sites enable anchoring of these two complement components into the membrane of the pathogen. Once anchored in the membrane, the hydrophobic site of C8 facilitates C9 polymerization, which completes the formation of the membrane-attack complex.

Answer 15

True

Question 16

Which of the following does not describe the actions of the coagulation system?

a. wound healing
b. blood clot formation
c. decrease in blood loss and fluid into interstitial spaces in tissues
d. release of inflammatory mediators by platelets
e. enhancement of dissemination of microbes into lymphatics and bloodstream

Answer 16

e. enhancement of dissemination of microbes into lymphatics and bloodstream

Question 17

(T or F) Anaphylatoxins C3a and C5a contribute physiologically to inflammation during complement activation. G-protein-coupled receptors for the anaphylatoxins C3a and C5a are found on phagocytes, mast cells, and the endothelial cells of blood vessel walls. Anaphylatoxin bound to mast cells causes them to degranulate, releasing inflammatory mediators such as histamine and leading to increased vascular permeability. Through their action on endothelial cells, anaphylatoxins exert vasoactive effects on blood vessels, contributing to increased vascular permeability and increased blood flow, which facilitate the extravasation of plasma proteins, such as complement proteins and antibodies, and the recruitment of cells to infected tissues through increased adherence and chemotaxis. Phagocytic activity is enhanced by anaphylatoxins, which bring about increased levels of CR1 and CR3 and microbicidal activity. All these activities enhance inflammation.

Answer 17

True

Question 18

Damage to tissues triggers a cascade of plasma proteins involving bradykinin and is known as _______.

a. the kinin system
b. the alternative pathway of complement
c. the acute phase response
d. the coagulation system
e. receptor mediated endocytosis

Answer 18

a. the kinin system

Question 19

Lectins recognize microbial ____.

a. carbohydrates
b. phosphate containing lipoteichoic acids
c. nucleic acids
d. flagellin
e. peptides

Answer 19

a. carbohydrates

Question 20

All of the following cytokines induce fever except ______.

a. IL-6
b. IL-1
c. IL-12
d. TNF-alpha
e. none of the above

Answer 20

c. IL-12

Question 21

The pH of the phagosome increases following phagocytosis because _____.

a. hydrogen ions are eliminated by the activity of NADPH oxidase and superoxide dismutase
b. the microbe delivers a significant number of hydroxyl ions in its cytosol that are released upon membrane disruption
c. azurophilic granules deliver alkaline substances
d. catalase consumes hydrogen ions once activated

Answer 21

a. hydrogen ions are eliminated by the activity of NADPH oxidase and superoxide dismutase

Question 22

In common with toll-like receptors, NOD-like receptors also contain ____ that is/are used for pathogen-recognition of microbial ligands.

a. caspase-recruitment domains (CARD)
b. leucine-rich repeat regions (LRRs)
c. Toll interleukin 1 receptor (TIR) domain
d. C-type lectin domain (CTLD)
e. variable extracellular domain

Answer 22

b. leucine-rich repeat regions (LRRs)

Question 23

Toll-like receptors differ from scavenger receptors in that they _____.

a. bind to common repetitive arrays on microbial surfaces
b. mediate signal transduction pathways. causing cytokine production
c. stimulate a pathway that causes enzymatic degradation of the microbe to which they bind
d. are soluble receptors that bind to microbes in extracellular spaces
e. they are soluble receptors found in the nucleus of the cell

Answer 23

b. mediate signal transduction pathways, causing cytokine production

Question 24

All of the following are correct in reference to type 1 interferons except _______.

a. Type 1 interferons inhibit the replication of viruses promoting NK-cell proliferation and differentiation into cytotoxic cells
b. the receptor for type 1 interferons is abundant in the cytosol
c. in the presence of type 1 interferons, virus-infected cells undergo cell-surface changes that render them more susceptible to attack by NK cells
d. Type 1 interferons function in autocrine and paracrine fashions
e. not only can most cells synthesize type 1 interferons, but they can also respond them

Answer 24

b. the receptor for type 1 interferons is abundant in the cytosol

Question 25

Which of the following does not describe a safety mechanism to ensure that only infected cells are attacked by NK cells?

a. the default state is one of active inhibition, which must be overcome by activating signals before killing occurs.
b. no single receptor-ligand interaction induces cytotoxicity, but instead many combinations of receptor-ligand interactions influence the decision to kill or not to kill a target cell
c. all of the above describe a safety mechanism to ensure that only infected cells are attacked by NK cells
d. intimate contact with target cells is required
e. activating receptors are induced only after encountering an infected cell.

Answer 25

b. no single receptor-ligand interaction induces cytotoxicity, but instead many combinations of receptor-ligand interactions influence the decision to kill or not to kill a target cell

Question 26

(T or F) The first domain of the TLR is an intracellular domain, also known as the pathogen-recognition domain, which contains a hydrophobic, leucine-rich repeat region (LRR) forming a horseshoe-shaped structure that binds specifically to arrays on microbial surfaces. The second domain of the TLR is the extracellular signaling domain, also known as the Toll interleukin receptor (TIR) domain, which facilitates the transmission of information to the exterior of the cell.

Answer 26

False

Question 27

Which of the following properties is common to macrophages and neutrophils in an uninfected individual?

a. life-span
b. anatomical location
c. ability to phagocytose
d. morphology
e. formation of pus

Answer 27

c. ability to phagocytose

Question 28

(T or F) During inflammation, host tissue may be damaged owing to the release of toxic oxygen derivatives produced by activated macrophages and neutrophils. Toxic oxygen species including superoxide, hydrogen peroxide, singlet oxygen, hydroxyl radical, hypohalite, and nitric oxide are produced during the respiratory burst in macrophages and neutrophils. Simultaneous extraphagosomal production of enzymes that neutralize these compounds occurs. Specifically, superoxide dismutase metabolizes superoxide to hydrogen peroxide, which is further metabolized by catalase to innocuous water and molecular oxygen.

Answer 28

True

Question 29

The name given to a fully activated and differentiated B cell that secretes antibody is ______.

a. secretory cell
b. plasma cell
c. T cell
d. antigen-presenting cell
e. hematopoietic cell

Answer 29

b. plasma cell

Question 30

the immunoglobulin heavy-chain gene consists of ____ segments, whereas the immunoglobulin light-chain gene consists of ______ segments.

a. κ;λ
b. VDJ;VJ
c. VJ; VDJ
d. P;N
e. RAG-1; RAG-2

Answer 30

b. VDJ; VJ

Question 31

Which of the following corresponds to the antigen-binding site of immunoglobulins?

a. VH:CH
b. VH:CL
c. VL:CL
d. CH:CL
e. VH:VL

Answer 31

e. VH:VL

Question 32

Another term commonly used to describe hypervariable loops is ______.

a. signal joint
b. multivalency
c. complementary-determining regions (CDR)
d. framework regions
e. hinge region

Answer 32

c. complementarity-determining regions (CDR)

Question 33

With the exception of B cells, all other cells of the body have the immunoglobulin genes in the _______.

a. monoclonal form
b. recombined configuration
c. chimeric form
d. expressed configuration
e. germline configuration

Answer 33

e. germline configuration

Question 34

Which of the following enzymes facilitates the process of affinity maturation?

a. DNA ligase
b. V(D)J recombinase
c. terminal deoxynucleotidyl transferase
d. activation-induced cytidine deaminase (AID)
e. exonuclease

Answer 34

d. activation-induced cytidine deaminase (AID)

Question 35

The process of gene rearrangement in immunoglobulin and T-cell receptor genes is called _____.

a. somatic hypermutation
b. isotype switching
c. apoptosis
d. somatic recombination
e. clonal selection

Answer 35

d. somatic recombination

Question 36

A circulating B cell that has never before encountered antigen expresses ____ on the cell surface.

a. IgM
b. IgD
c. IgM and IgG
d. IgM and IgD
e. IgG

Answer 36

d. IgM and IgD

Question 37

Which of the following does not describe B-cell receptors?

a. B-cell receptors are membrane-bound and secreted
b. B-cell receptors lack specificity and can bind to a number of different antigens
c. B-cell receptors consist of a variable region and a constant region
d. B-cell receptors possess specificity and can therefore bind only to unique epitopes
e. B-cell receptors undergo affinity maturation as a consequence of somatic hypermutation

Answer 37

b. B-cell receptors lack specificity and can bind to a number of different antigens

Question 38

The highest degree of diversity resulting from somatic recombination is concentrated _______ of the VH and VL domains, whereas the point mutations caused by somatic hypermutation are found _____.

a. in CDR3; throughout the V region
b. in CDR3; in CDR1 and CDR2 of VH and VL domains
c. in CDR1 and CDR2; in CDR3
d. in CDR1 and CDR2; throughout the V region
e. in all three CDRs; in C regions

Answer 38

a. in CDR3; throughout the V region

Question 39

Which of the following statements about the production and use of monoclonal antibodies is incorrect?

a. humanized monoclonal antibodies reduce complications associated with using mouse monoclonal antibodies
b. A monoclonal antibody has specificity for only one epitope of an antigen
c. B cells are fused with a tumor cell called a myeloma, to immortalize the resulting hybridoma
d. monoclonal antibodies made in mice have limited therapeutic potential
e. production of monoclonal antibodies requires a purified form of antigen

Answer 39

e. production of monoclonal antibodies requires a purified form of antigen

Question 40

The process of _______ results in change in the constant region of the heavy-chain of antibodies, causing a change in the effector function and transport properties of antibodies.

a. complement fixation
b. neutralization
c. somatic hypermutation
d. isotype switching
e. somatic recombination

Answer 40

d. isotype switching