exam 3

Question 1

Biochemical tests include all of the following except_________.
A) presence of catalase
B) presence of oxidase
C) colony morphology
D) sugar fermentation
E) gas production

Answer 1

Colony morphology

Question 2

Which sample does not require sterile needle aspiration?
A. Feces
B. CSF (cerebrospinalfluid)
C. Blood

Answer 2

Feces

Question 3

What type of test will detect minute amount of soluble antigens?
A. Precipitation
B. Agglutination
C. Specificity
D. sensitivity

Answer 3

Precipitation

Question 4

Which of the following is not one of the main categories for identifying microbes?
A) Radiologic
B) Phenotypic
C) Genotypic
D) Immunologic

Answer 4

Radiologic

Question 5

Which medium contains three sugar sources and allows to differentiate between Salmonella, Shigella, Ecoli and Pseudomonas?
A) Triple sugar Iron Agar
B) EMB
C) McConkey
D) MTM

Answer 5

Triple sugar iron agar

Question 6

What is the purpose of selective media?
a) To inhibit the growth of specific organisms
b) To differentiate between bacteria based on growth and appearance
c) To enhance the growth of fastidious organisms
d) To identify antibiotic resistance

Answer 6

To inhibit the growth of specific organisms

Question 7

What diagnostic technique is mismatched?
A) EIA(enzymelinkedimmunoassay)-detectingantibodies(orantigen)usingenzymatic
reaction as a reporter
B) IF(Immunofluorescence)-detectingantibodies(orantibodies)usingfluorescentdyeas
a reporter
C) PCR (polymerase chain reaction - Detecting specific pathogen DNA using nucleic acid
probes
D) Microscopy - observation of stained cells or colonies on the plate

Answer 7

PCR (polymerase chain reaction - Detecting specific pathogen DNA using nucleic acid
probes

Question 8

Phenotypic methods of identifying microorganisms in a patient sample are characterized as those that_________.
A) directly examine the organism’s appearance or behavior, which includes its metabolic abilities, environmental preferences and drug susceptibilities
B) analyze the genetic makeup of the microorganism, which conclusively diagnoses the infection
C) make use of the patient’s antibodies to precipitate the microorganism out of solution, or agglutinate the antigens in the sample
D) make use of color-changing antibodies directed against the microbe that will become visible to the naked eye when bound

Answer 8

Directly examine the organism’s appearance or behavior, which includes its metabolic abilities, environmental preferences, and drug susceptibilities

Question 9

What is the primary difference between general-purpose media and selective media? a) Selective media are used to differentiate between different bacterial types. b) General-purpose media promote the growth of all microorganisms. c) Selective media inhibit the growth of certain bacteria. d) General-purpose media are only used for fungal cultures.

Answer 9

General-purpose media promote the growth of all microorganisms.

Question 10

Which type of media is most appropriate for culturing Escherichia coli from a urinary tract infection? a) Blood agar b) MacConkey agar c) Triple-sugar iron (TSI) agar d) Thayer-Martin agar

Answer 10

MacConkey agar

Question 11

How does the use of differential media help in the identification of bacteria? a) It provides a nutrient source for all bacteria. b) It allows for the visualization of different metabolic reactions. c) It prevents the growth of harmful bacteria. d) It inhibits the growth of anaerobic bacteria.

Answer 11

It allows for the visualization of different metabolic reactions.

Question 12

What challenge is associated with the isolation of anaerobic pathogens? a) They are difficult to culture in the presence of oxygen. b) They grow rapidly on selective media. c) They do not survive well in the human body. d) They are resistant to most antibiotics.

Answer 12

They are difficult to culture in the presence of oxygen.

Question 13

What is the purpose of a serial dilution tube test in antimicrobial susceptibility testing? a) To determine the smallest amount of agent needed to inhibit microbial growth. b) To distinguish
between aerobic and anaerobic bacteria. c) To differentiate between pathogenic and non-pathogenic bacteria. d) To identify the source of a urinary tract infection.

Answer 13

To determine the smallest amount of agent needed to inhibit microbial growth.

Question 14

Adaptive immunity involves the response of_________.
A) skin barriers
B) B and T lymphocytes
C) lysozyme
D) mucous membranes
E) interferon

Answer 14

B and T lymphocytes

Question 15

What type of cells secretes cytokines and helps to activate other immune cells? A) T cells
B) B cells
C) Dendritic cells D) Mast cells

Answer 15

T cells

Question 16

3. Killed or inactivated vaccines are prepared by_________.
   removal of virulence genes from the microbe
   treatment with formalin, heat, or radiation
   passage of the pathogen through unnatural hosts or tissue culture long-term subculturing of the microbe
   Allofthechoicesarecorrect

Answer 16

Treatment with formalin, heat, or radiation

Question 17

Which of the following contribute to the limitless diversity generated from a relatively fixed number of immunoglobulin genes?
A)Random heavy and light chain reassortment only
B)Hypermutation, random heavy and light chain reassortment, and somatic recombination C)Hypermutation only
D)Somatic recombination only

Answer 17

Hypermutation, random heavy and light chain reassortment, and somatic recombination

Question 18

The selection of T cells in thymus results in formation of
A) T-cells that are able to recognize self but do not bind too hard to it
B) T cells that are able to recognize self and bind hard to it
C) T cells that are unable to recognize self and only bind foreign antibodies
D) T cells that are unable to recognize self and unable to bind foreign antibodies

Answer 18

T-cells that are able to recognize self but do not bind too hard to it

Question 19

What type of immunity is associated with B cells? A. Intracellular immunity
B. Humoral immunity
C. Tolerance immunity
D. Adaptive immunity

Answer 19

Humoral immunity

Question 20

What is the exact purpose of T cell positive selection in the thymus?
A. To eliminate T cells that bind strongly to self-antigens
B. To retain T cells that can recognize MHC and self-peptides, but don’t bind too strongly to them
C. To generate memory T cells
D. To eliminate T cells that can not recognize MHC and self peptides

Answer 20

To retain T cells that can recognize MHC and self-peptides, but don’t bind too strongly to them

Question 21

Which of the following is an intrinsic factor that determines immunogenicity? A. Size and nature of the molecule
B. Route of antigen exposure
C. Antigen dose
D. Presence of antibodies

Answer 21

Size and nature of the molecule

Question 22

What is the role of MHC molecules in antigen recognition by T cells? A. To produce antibodies that bind to antigens
B. To present antigens to T cell receptors
C. To enhance antibody-antigen interaction
D. To eliminate antigens through phagocytosis

Answer 22

To present antigens to T cell receptors

Question 23

What does the process of clonal selection in B cells involve? A. B cells binding to MHC molecules
B. Production of multiple types of antibodies by a single B cell C. Proliferation of antigen-specific B cells after activation
D. Elimination of B cells that bind weakly to antigens

Answer 23

Proliferation of antigen-specific B cells after activation

Question 24

Which of the following is a key characteristic of active immunity?
A) Immunity is conferred immediately
B) No exposure to antigen is required
C) It develops memory cells, leading to long-lasting immunity
D) It involves the transfer of pre-formed antibodies

Answer 24

It develops memory cells, leading to long-lasting immunity

Question 25

Passive immunity differs from active immunity in that:
A) It is achieved through exposure to antigens
B) It involves the activation of the recipient’s immune system
C) It provides rapid immunity without forming immune memory
D) It is maintained through memory cells

Answer 25

It provides rapid immunity without forming immune memory

Question 26

Which of the following is an example of natural passive immunity?
A) Recovery from a disease
B) Receiving a vaccination
C) Transfer of antibodies through breast milk
D) Administration of antiserum

Answer 26

Transfer of antibodies through breast milk

Question 27

Artificial active immunity involves:
A) Injecting pre-formed antibodies into the individual
B) The development of immunity after receiving a vaccination
C) Passing antibodies from mother to fetus via the placenta
D) Transfer of immune cells from a donor

Answer 27

The development of immunity after receiving a vaccination

Question 28

Which of the following is true regarding passive immunity?
A) It requires exposure to an antigen for activation
B) It is maintained through the stimulation of memory cells
C) It decays rapidly and cannot be maintained
D) It develops over weeks and involves a latent period

Answer 28

It decays rapidly and cannot be maintained

Question 29

What examples below are NOT active immunity types?
A) Contractingarhinovirusandgettingsickwiththecommoncold B) GettingvaccinatedagainstCovid19
C) Getting the pre-made antiserum injections for a serious illness D) Getting vaccinated against influenza

Answer 29

Getting serum injection

Question 30

Which of the following terms and definitions is mismatched?
A) Neutralization - Antibodies bind to bacterial toxins or viruses to prevent host cell damage
B) Opsonization - Antibodies coat foreign cells to enhance phagocytosis
C) Fab region - Stem of the antibody that binds phagocyte receptors
D) IgM - Produced during primary immune response

Answer 30

Fab region

Question 31

Compare and contrast IgG and IgM antibodies. Which of the following statements is correct?
A) IgG is a pentamer, while IgM has two antigen-binding sites
B) Both IgG and IgM are produced in the secondary immune response
C) IgG has two antigen-binding sites, while IgM is a pentamer
D) Both IgG and IgM are primarily produced during the primary immune response

Answer 31

IgG has two antigen-binding sites, while IgM is a pentamer

Question 32

Which of the following correctly describes B cell activation and antibody production?
A) B cells recognize free antigens and present them to activated T helper cells
B) Cytokines from T helper cells help B cells differentiate into plasma and memory cells
C) Plasma cells produce antibodies, while memory cells provide long-term protection
D) All of the above

Answer 32

All of the above

Question 33

Which of the following correctly pairs antibody structure with its function?
A) Fab region - Binds to phagocyte receptors to enhance phagocytosis
B) Fc region - Contains the antigen-binding site for neutralization
C) Fab region - Contains the antigen-binding site for specificity
D) Fc region - Neutralizes bacterial toxins and viruses

Answer 33

Fab region - Contains the antigen-binding site for specificity

Question 34

Which of the following steps in antibody-mediated immunity is mismatched?
A) Antigen presentation - B cells present antigens to T helper cells on MHC type II
B) Cytokine release - T helper cells release cytokines to activate B cells
C) Plasma cell production - Short-lived cells that generate memory for long-term protection
D) Neutralization - Antibodies bind to viral proteins to prevent host cell destruction

Answer 34

Plasma cell production - Short-lived cells that generate memory for long-term protection

Question 35

Which of the following statements about the primary and secondary immune responses is incorrect?
A) Primary immune response includes a latent period where no antibodies are detected.
B) IgM is the predominant antibody produced during the primary immune response.
C) Secondary immune responses depend on T helper cells to initiate antibody production. D) IgG is the predominant antibody produced during the secondary immune response.

Answer 35

Secondary immune responses depend on T helper cells to initiate antibody production.

Question 36

What is the most likely reason for the shorter response time during a secondary immune response compared to a primary response?
A) Rapid production of IgM by naïve B cells.
B) The activation of pre-existing memory B cells that quickly produce IgG.
C) Faster activation of T helper cells by antigen-presenting cells.
D) Increased proliferation of plasma cells during the secondary response.

Answer 36

The activation of pre-existing memory B cells that quickly produce IgG.

Question 37

Which of the following correctly pairs the feature with the immune response phase? A) IgM production - Primary immune response.
B) No latent period - Primary immune response.
C) Memory cell formation - Secondary immune response.
D) IgG predominance - Primary immune response.

Answer 37

IgM production - Primary immune response.

Question 38

Which of the following events is shared by both primary and secondary immune responses? A) IgM is the main antibody produced.
B) Memory B cells are activated.
C) Antigen presentation by antigen-presenting cells.
D) No need for T helper cell activation.

Answer 38

Antigen presentation by antigen-presenting cells.

Question 39

Which of the following combinations best summarizes the difference between primary and secondary immune responses?
A) Primary response: short-lived plasma cells, IgM; Secondary response: long-lived memory cells, IgG.
B) Primary response: no antigen presentation, IgG; Secondary response: requires T helper cells, IgM.
C) Primary response: long latency period, IgG; Secondary response: rapid antibody production, IgM.
D) Primary response: memory cells predominate, IgM; Secondary response: T helper cells predominate, IgG.

Answer 39

Primary response: short-lived plasma cells, IgM; Secondary response: long-lived memory cells, IgG.

Question 40

Which of the following statements about complementarity-determining regions (CDRs) is correct?
A) CDRs are identical in all antibodies.
B) CDRs are part of the constant region of antibodies.
C) CDRs are variable regions within the antigen-binding site of antibodies. D) CDRs interact exclusively with the light chain of the antibody.

Answer 40

CDRs are variable regions within the antigen-binding site of antibodies.

Question 41

What is the primary mechanism responsible for generating antibody diversity? A) Allelic exclusion in B cells.
B) Random somatic recombination of immunoglobulin gene segments.
C) Inactivation of meiotic recombination in somatic cells.
D) Binding of multiple epitopes to the same antibody.

Answer 41

Random somatic recombination of immunoglobulin gene segments.

Question 42

Which of the following best describes allelic exclusion in B cells?
A) Each B cell expresses multiple antibody types simultaneously.
B) Each B cell expresses only one heavy and one light chain combination. C) Each B cell excludes CDR regions to produce a functional antibody.
D) B cells combine several antibody types to recognize diverse antigens.

Answer 42

Each B cell expresses only one heavy and one light chain combination.

Question 43

Which of the following features contribute to the diversity of antigen-binding sites in antibodies?
A) Somatic recombination of gene segments only.
B) Hypermutation and random heavy/light chain reassortment only.
C) Random heavy/light chain reassortment, somatic recombination, and hypermutation. D) Random heavy/light chain reassortment and somatic recombination, excluding hypermutation.

Answer 43

Random heavy/light chain reassortment, somatic recombination, and hypermutation.

Question 44

Which of the following combinations is mismatched?
A) Epitope - Recognized by antibodies, typically 8-12 amino acids long.
B) Binding affinity - Strength of binding between an antibody and its epitope.
C) Hypermutation - Occurs at a lower rate in the variable region compared to other genome areas.
D) Active gene - Result of somatic recombination in B cells.

Answer 44

Hypermutation - Occurs at a lower rate in the variable region compared to other genome areas.

Question 45

What determines the specificity of antigen-antibody reactions? A. The size of the antigen
B. The complexity of the immune response
C. Lymphocyte receptors interacting with individual pathogens D. Physical form of the antigen

Answer 45

Lymphocyte receptors interacting with individual pathogens

Question 46

What type of receptors do T lymphocytes (T cells) express? A. Membrane-bound immunoglobulins
B. B cell receptors (BCRs)
C. T cell receptors (TCRs)
D. Antibodies

Answer 46

T cell receptors (TCRs)

Question 47

What type of immunity is associated with B cell receptors (BCRs)? A. Intracellular immunity
B. Humoral immunity
C. Adaptive immunity
D. Cellular immunity

Answer 47

Humoral immunity

Question 48

What happens to the lymphocytes most efficiently reacting with an antigen?
A. They die due to negative selection.
B. They proliferate to form a clone of identical cells.
C. They recognize MHC molecules.
D. They bind to self-antigens strongly.

Answer 48

They proliferate to form a clone of identical cells.

Question 49

Which property of adaptive immunity allows for a stronger and faster response upon subsequent antigen exposure?
A. Immunogenicity
B. Specificity
C. Tolerance D. Memory

Answer 49

Memory

Question 50

What is the difference between a primary and secondary immune response?
A. Primary response involves memory cells, while secondary response does not.
B. Primary response occurs faster than secondary response.
C. Primary response activates lymphocytes, while secondary response is faster and stronger. D. Primary response occurs only in T cells, while secondary response involves B cells.

Answer 50

Primary response activates lymphocytes, while secondary response is faster and stronger.

Question 51

What does vaccination achieve?
A. Activates autoimmunity
B. Induces tolerance to foreign pathogens
C. Confers immunity by exposing the immune system to weakened or killed pathogens D. Enhances the primary immune response

Answer 51

Confers immunity by exposing the immune system to weakened or killed pathogens

Question 52

What is tolerance in the immune system?
A. The ability to attack self-antigens
B. The acquired inability to react to one’s own antigens
C. The capacity to bind to MHC molecules strongly D. The proliferation of B and T cells

Answer 52

The acquired inability to react to one’s own antigens

Question 53

Which type of MHC is found on all nucleated cells? A. MHC Type II
B. MHC Type I
C. MHC Complex III
D. Both MHC Type I and Type II Answer:

Answer 53

MHC Type I

Question 54

What happens if tolerance fails in the immune system? A. Clonal deletion occurs
B. Autoimmunity develops
C. T cells fail to recognize foreign antigens
D. Immunogens fail to induce a response

Answer 54

Autoimmunity develops

Question 55

Where do precursor T cells mature and undergo selection? A. Bone marrow
B. Thymus
C. Spleen
D. Lymph nodes

Answer 55

Thymus

Question 56

What is the purpose of negative selection during T cell development? A. To ensure T cells recognize self-antigens strongly
B. To eliminate T cells that bind too strongly to self-antigens
C. To proliferate T cells that fail to recognize MHC molecules D. To retain all T cells entering the thymus

Answer 56

To eliminate T cells that bind too strongly to self-antigens

Question 57

What determines whether an antigen is an immunogen? A. The antigen’s ability to bind to TCRs
B. The antigen’s intrinsic and extrinsic properties
C. Its ability to evade recognition by lymphocytes
D. Its capacity to generate autoimmunity

Answer 57

The antigen’s intrinsic and extrinsic properties

Question 58

Why are haptens not immunogenic on their own? A. They are too complex.
B. They are small molecules and lack carriers.
C. They do not bind to MHC molecules.
D. They interact only with B cell receptors.

Answer 58

They are small molecules and lack carriers.

Question 59

What is an epitope?
A. A molecule that triggers autoimmunity
B. The entire antigen recognized by antibodies
C. A specific portion of an antigen bound by antibodies or TCRs D. A carrier molecule for haptens

Answer 59

A specific portion of an antigen bound by antibodies or TCRs

Question 60

What is required for antigens to be recognized by T cell receptors (TCRs)? A. Binding to free-floating antigens
B. Association with MHC molecules
C. Presence of haptens
D. Interaction with antibodies

Answer 60

Association with MHC molecules

Question 61

How is active immunity achieved?
A. By injecting pre-formed antibodies
B. By receiving immune cells from a donor
C. By exposure to an antigen through infection or vaccination D. By receiving antibodies through the placenta

Answer 61

By exposure to an antigen through infection or vaccination

Question 62

What is a characteristic of passive immunity? A. It develops memory cells.
B. It provides long-lasting immunity.
C. It does not activate the immune system.
D. It requires exposure to an antigen.

Answer 62

It does not activate the immune system.

Question 63

What is the key difference between active and passive immunity?
A. Active immunity uses pre-formed antibodies, while passive immunity generates a specific immune response.
B. Active immunity involves immune system activation, while passive immunity does not.
C. Passive immunity requires exposure to an antigen, while active immunity does not. D. Passive immunity lasts longer than active immunity.

Answer 63

Active immunity involves immune system activation, while passive immunity does not.

Question 64

Which type of immunity develops memory cells? A. Passive immunity
B. Active immunity
C. Both active and passive immunity
D. Neither active nor passive immunity Answer:

Answer 64

Active immunity

Question 65

Which is an example of natural active immunity? A. Vaccination for rabies
B. Recovering from an infection
C. Passing antibodies through breast milk
D. Receiving an antiserum injection

Answer 65

Recovering from an infection

Question 66

Which scenario represents artificial passive immunity? A. Receiving a vaccination shot
B. Developing antibodies after infection
C. Passing antibodies to a fetus through the placenta
D. Receiving pre-formed antibodies through an antiserum injection

Answer 66

Receiving pre-formed antibodies through an antiserum injection

Question 67

What distinguishes artificial immunity from natural immunity?
A. Artificial immunity is achieved through medical intervention, while natural immunity occurs naturally.
B. Artificial immunity always involves memory cell formation, while natural immunity does not. C. Natural immunity is faster than artificial immunity.
D. Natural immunity is only passive.

Answer 67

Artificial immunity is achieved through medical intervention, while natural immunity occurs naturally.

Question 68

Why does passive immunity decay rapidly?
A. It lacks immune system activation and memory cell formation. B. It requires repeated antigen exposure.
C. It depends on booster immunizations.
D. It relies on antigen-reactive T cells.

Answer 68

It lacks immune system activation and memory cell formation.

Question 69

What is an example of natural passive immunity? A. Breastfeeding
B. Receiving a vaccine
C. Developing antibodies after an infection
D. Receiving a blood transfusion with antibodies

Answer 69

Breastfeeding

Question 70

How quickly does passive immunity confer protection? A. Over weeks with a latent period
B. Immediately upon receiving antibodies
C. Over a few months after infection
D. After repeated exposure to antigens

Answer 70

Immediately upon receiving antibodies

Question 71

How is natural active immunity maintained? A. Through repeated antibody injections
B. Via stimulation of memory cells C. By constant exposure to antigens D. It cannot be maintained

Answer 71

Via stimulation of memory cells

Question 72

What is an example of artificial active immunity? A. Passing antibodies through breast milk
B. Recovering from a disease naturally
C. Receiving a vaccination shot
D. Receiving pre-formed antibodies

Answer 72

Receiving a vaccination shot

Question 73

What occurs during natural passive immunity?
A. The immune system produces antibodies in response to infection.
B. Antibodies are transferred from mother to child through breastfeeding. C. Pre-formed antibodies are injected into the body.
D. The immune system activates memory cells.

Answer 73

Antibodies are transferred from mother to child through breastfeeding

Question 74

What type of immunity is conferred by receiving a rabies antiserum injection? A. Natural active immunity
B. Natural passive immunity
C. Artificial active immunity
D. Artificial passive immunity

Answer 74

Artificial passive immunity

Question 75

What is the main role of an antibody? A. Facilitate antigen internalization
B. Neutralize foreign substances
C. Trigger apoptosis
D. Bind antigens and facilitate their removal

Answer 75

Bind antigens and facilitate their removal

Question 76

How many B cell receptors (BCRs) are found on each B cell? A. About 10,000
B. About 50,000
C. About 100,000
D. About 1,000,000

Answer 76

About 100,000

Question 77

What is the sequence of events in humoral immunity?
A. B cells bind antigens → T cells activate B cells → B cells proliferate and differentiate B. Antibodies are produced → B cells bind antigens → T cells activate B cells
C. Cytokines are released → Memory cells form → B cells bind antigens
D. B cells bind antigens → Memory cells degrade → Antibodies are stored

Answer 77

B cells bind antigens → T cells activate B cells → B cells proliferate and differentiate

Question 78

What function do helper T cells perform during B cell activation? A. Degrade antigens
B. Release cytokines
C. Stimulate B cell proliferation and differentiation
D. Both B and C

Answer 78

Both B and C

Question 79

Which of the following processes are performed by antibodies? A. Neutralization of toxins
B. Opsonization of pathogens
C. Phagocytosis of pathogens
D. Both A and B

Answer 79

Both A and B

Question 80

Which class of antibody is most abundant in the body and produced during secondary immune responses?
A. IgM
B. IgA
C. IgG D. IgE

Answer 80

IgG

Question 81

What is unique about the structure of IgM?
A. It is a dimer with two subunits.
B. It is a pentamer made of five IgG-like subunits. C. It has a single antigen-binding site.
D. It is found only on the surface of B cells.

Answer 81

It is a pentamer made of five IgG-like subunits.

Question 82

Which region of an antibody binds to antigens? A. Fc region
B. Fab region
C. Heavy chain
D. Light chain

Answer 82

Fab region

Question 83

What is the role of the Fc region of an antibody?
A. Binds to antigens
B. Facilitates antigen degradation
C. Binds to receptors on phagocytes to promote opsonization D. Prevents host cell destruction

Answer 83

Binds to receptors on phagocytes to promote opsonization

Question 84

Which of the following are true about IgG?
A. It has two antigen-binding sites.
B. It is the most numerous antibody in serum.
C. It is produced mostly during the secondary immune response. D. All of the above

Answer 84

All of the above

Question 85

What defines the class of an antibody? A. The Fc region
B. The type of light chain
C. The heavy chain
D. The Fab region

Answer 85

The heavy chain

Question 86

During which immune response is IgM produced? A. Secondary immune response
B. Primary immune response
C. Both primary and secondary immune responses D. Neither primary nor secondary immune response

Answer 86

Primary immune response

Question 87

What are the components of an antibody molecule? A. Two heavy chains and one light chain
B. Two heavy chains and two light chains
C. Four heavy chains
D. One heavy chain and two light chains

Answer 87

Two heavy chains and two light chains

Question 88

Which of the following is a function of the Fab region? A. Binding to antigen
B. Binding to Fc receptors on phagocytes
C. Stimulating B cell proliferation
D. Both A and C

Answer 88

Binding to antigen

Question 89

What is the function of antibodies during neutralization?
A. Coating foreign cells to promote phagocytosis
B. Preventing destruction of host cells by binding to toxins or viruses C. Triggering apoptosis of infected cells
D. Binding to the Fc receptors of phagocytes

Answer 89

Preventing destruction of host cells by binding to toxins or viruses

Question 90

What occurs during the latent period of a primary immune response? A. Plasma cells produce IgM antibodies.
B. Memory cells are activated.
C. Antibodies are not detected.
D. IgG antibodies rise in the blood.

Answer 90

Antibodies are not detected.

Question 91

Which antibody is primarily produced during the primary immune response? A. IgA
B. IgG
C. IgE
D. IgM

Answer 91

IgM

Question 92

What type of cells are generated during the primary immune response? A. Short-lived plasma cells
B. Memory T cells
C. Memory B cells
D. All of the above

Answer 92

All of the above

Question 93

What distinguishes the secondary immune response from the primary immune response? A. It produces mostly IgM.
B. It has a latent period.
C. It is faster and produces mostly IgG.
D. It requires T helper cell help for memory cells.

Answer 93

It is faster and produces mostly IgG.

Question 94

What happens to IgG levels in the absence of antigen? A. They remain constant.
B. They continue to rise.
C. They decrease over time.
D. They convert to IgM.

Answer 94

They decrease over time

Question 95

What allows the secondary immune response to be faster? A. Memory cells do not require T helper cell help.
B. Plasma cells are longer-lived.
C. Antigens bind more easily to B cells.
D. IgM antibodies are already present.

Answer 95

Memory cells do not require T helper cell help.

Question 96

Which of the following steps are involved in adaptive immune response? A. Antigen-independent lymphocyte development
B. Antigen presentation to T and B cells
C. Antigen challenge and response by T and B cells
D. All of the above

Answer 96

All of the above

Question 97

What type of immunity do B cells provide during an adaptive immune response? A. T cell-mediated immunity
B. Antibody-mediated immunity
C. Innate immunity
D. Phagocytic immunity

Answer 97

Antibody-mediated immunity

Question 98

During the secondary immune response, what is the primary antibody produced? A. IgA
B. IgG
C. IgE
D. IgM

Answer 98

IgG

Question 99

Which cells respond first to a secondary antigen exposure? A. Naive B cells
B. Plasma cells from the primary response
C. Memory cells
D. Helper T cells

Answer 99

Memory cells

Question 100

Which of the following occurs during antigen challenge? A. Antibodies bind to the antigen.
B. T and B cells are activated.
C. Cytokines are released.
D. All of the above

Answer 100

All of the above

Question 101

What is measured during a primary immune response to monitor antibody levels? A. IgG concentration
B. Antibody titer
C. Antigen concentration
D. Cytokine levels

Answer 101

Antibody titer

Question 102

What is the primary role of memory cells during a secondary immune response? A. Activate T helper cells.
B. Ramp up antibody production quickly.
C. Produce cytokines.
D. Convert IgG to IgM.

Answer 102

Ramp up antibody production quickly.

Question 103

Why are plasma cells in the primary immune response short-lived? A. They are quickly replaced by memory cells.
B. They only produce IgM.
C. They respond only to antigen-specific signals.
D. They function only during the latent period.

Answer 103

They are quickly replaced by memory cells.

Question 104

What type of immune response involves T cell-mediated immunity? A. Innate immunity
B. Adaptive immunity
C. Humoral immunity
D. Passive immunity

Answer 104

Adaptive immunity

Question 105

What is the primary characteristic of variable (V) domains in antibodies? A. They are different in complementarity-determining regions (CDRs).
B. They are identical in all antibodies.
C. They interact with the constant region of the antibody. D. They form the antigen-binding site.

Answer 105

They are different in complementarity-determining regions (CDRs).

Question 106

What is an epitope?
A. The constant region of an antibody.
B. A type of antibody.
C. The part of the antigen recognized by the immune system. D. A receptor on B cells.

Answer 106

The part of the antigen recognized by the immune system.

Question 107

How long is a typical epitope? A. 2–4 amino acids.
B. 8–12 amino acids long.
C. 20–30 amino acids.
D. More than 50 amino acids.

Answer 107

8–12 amino acids long.

Question 108

What determines the strength of an antibody’s binding to its epitope? A. Hypermutation.
B. Binding affinity.
C. Allelic exclusion.
D. Antibody titer.

Answer 108

Binding affinity.

Question 109

What mechanism generates antibody diversity? A. Somatic recombination.
B. Meiotic recombination.
C. Transcription and translation.
D. Hypermutation.

Answer 109

Somatic recombination.

Question 110

What is the “genes in pieces” hypothesis?
A. Genes are inherited intact without changes.
B. Antibody genes are assembled from several gene segments. C. Genes are transcribed as a single unit.
D. Only the light chain contributes to diversity.

Answer 110

Antibody genes are assembled from several gene segments.

Question 111

What is allelic exclusion?
A. Each B cell expresses only one antibody type.
B. Each T cell expresses multiple antibody types.
C. Only heavy chains are excluded during recombination. D. It ensures all antibodies are identical in structure.

Answer 111

Each B cell expresses only one antibody type.

Question 112

How are heavy and light chains combined during antibody generation? A. They are assembled from a single gene segment.
B. They are randomly reassorted.
C. They are formed in response to hypermutation.
D. They do not undergo any recombination.

Answer 112

They are randomly reassorted.

Question 113

What contributes to joint diversity in antibodies? A. Mutations in the constant region.
B. Random recombination of gene segments.
C. Use of pre-made antibodies.
D. Antigen binding to the Fc region.

Answer 113

Random recombination of gene segments.

Question 114

What process introduces small changes in variable regions at a higher rate? A. Transcription errors.
B. Hypermutation.
C. Genetic recombination.
D. Epitope interactions.

Answer 114

Hypermutation.

Question 115

What does the antigen-binding site of an antibody accommodate?
A. Binding of an epitope with both heavy and light chain variable regions. B. Binding of T cells to plasma cells.
C. Recognition of the Fc region of the antibody.
D. Interaction with complement proteins.

Answer 115

Binding of an epitope with both heavy and light chain variable regions.

Question 116

What is somatic recombination?
A. A process where immunoglobulin genes rearrange in lymphocytes. B. A type of meiotic recombination occurring in sexual cells.
C. A mutation in T cell receptors.
D. A type of antigen-binding mechanism.

Answer 116

A process where immunoglobulin genes rearrange in lymphocytes.

Question 117

Why does hypermutation occur in antibody genes? A. To enhance diversity in the variable regions.
B. To increase binding affinity for antigens.
C. To replace heavy chains with light chains.
D. To remove unwanted epitopes.

Answer 117

To enhance diversity in the variable regions.

Question 118

What role do complementarity-determining regions (CDRs) play? A. They form the antigen-binding site of an antibody.
B. They enhance Fc region binding.
C. They ensure allelic exclusion.
D. They bind T cell receptors.

Answer 118

They form the antigen-binding site of an antibody.

Question 119

How does the immune system generate almost limitless antibody diversity? A. Through somatic recombination.
B. By combining heavy and light chains randomly.
C. Through hypermutation.
D. By preventing somatic recombination.

Answer 119

Through somatic recombination, random reassortment, and hypermutation.

Question 120

What are MHC molecules also called in humans? A) Major histocompatibility molecules
B) Human leukocyte antigens
C) Cytotoxic T cell markers
D) B cell receptors

Answer 120

Human leukocyte antigens

Question 121

What type of cells do MHC Class I molecules present antigens to?
A) CD4+ T cells
B) CD8+ T cells
C) B cells
D) Macrophages

Answer 121

CD8+ T cells

Question 122

What types of proteins can antigens processed by APCs originate from? A) Bacterial proteins
B) Viral proteins or cancer proteins
C) Only bacterial proteins
D) None of the above

Answer 122

Viral proteins or cancer proteins

Question 123

What occurs when MHC Class I self-antigens trigger a host vs graft disease? A) The graft is recognized as foreign and attacked by T cytotoxic cells
B) The host cells attack the graft causing tissue rejection
C) The graft’s T cells attack the host body
D) The host immune system becomes tolerant of the graft

Answer 123

The graft is recognized as foreign and attacked by T cytotoxic cells

Question 124

What is the opposite of host vs graft disease? A) Transplant rejection
B) Graft vs host disease
C) Immune tolerance
D) MHC compatibility

Answer 124

Graft vs host disease

Question 125

Where are MHC Class II molecules primarily found?
A) On all nucleated cells
B) On antigen presenting cells, such as macrophages and dendritic cells C) On cytotoxic T cells
D) On red blood cells

Answer 125

On antigen presenting cells, such as macrophages and dendritic cells

Question 126

What is the role of MHC Class II molecules in immune responses? A) To present antigens to CD8+ T cells
B) To present internalized antigens to CD4+ T cells
C) To activate cytotoxic T cells D) To destroy infected cells

Answer 126

To present internalized antigens to CD4+ T cells

Question 127

What does the activation of Helper T cells (CD4+) by MHC Class II molecules result in? A) Activation of cytotoxic T cells
B) Destruction of infected cells
C) Release of cytokines that help other immune cells
D) Suppression of the immune response

Answer 127

Release of cytokines that help other immune cells

Question 128

What does polymorphism in MHC molecules mean?
A) MHC molecules are identical across all individuals
B) There are many different alleles for each of the MHC genes C) There is only one type of MHC allele in a population
D) MHC molecules cannot vary between individuals

Answer 128

There are many different alleles for each of the MHC genes

Question 129

What does polygeny in MHC molecules refer to?
A) Multiple copies of the same MHC gene
B) The presence of many different alleles for each gene
C) Different MHC molecules being expressed by different cells
D) Multiple genes contributing to the MHC molecules expressed in an individual

Answer 129

Multiple genes contributing to the MHC molecules expressed in an individual

Question 130

What is the result of the unique combination of MHC molecules in each person?
A) Each person has identical immune responses
B) The immune system can only recognize a small number of pathogens C) Every person has a unique set of MHC molecules
D) The immune system becomes tolerant of all pathogens

Answer 130

Every person has a unique set of MHC molecules

Question 131

What is the significance of HLA in humans?
A) It is a generic name for MHC molecules
B) It refers to the unique set of MHC molecules in humans C) It is a gene responsible for MHC expression
D) It is a foreign antigen in the body

Answer 131

It refers to the unique set of MHC molecules in humans

Question 132

What is the primary role of T Cell Receptors (TCRs)? A) To bind only to self-MHC molecules
B) To bind both self-MHC and foreign peptides
C) To activate macrophages directly
D) To produce antibodies in response to pathogens

Answer 132

To bind both self-MHC and foreign peptides

Question 133

Which of the following is NOT a mechanism that generates diversity in T Cell Receptors? A) Somatic recombination
B) Random chain reassortment C) Coding for joint diversity
D) Exon shuffling

Answer 133

Exon shuffling

Question 134

How are T Cell Receptors similar to B cell receptors?
A) Both generate diversity through genetic mechanisms
B) Both bind to antigens on the surface of pathogens
C) Both have a constant region encoded by the same gene segments D) Both produce cytokines to fight infection

Answer 134

Both generate diversity through genetic mechanisms

Question 135

What do MHC proteins on a cell’s surface reflect? A) The type of pathogens inside the cell
B) The composition of the proteins inside the cell
C) The cell’s external environment
D) The DNA sequence of the cell

Answer 135

The composition of the proteins inside the cell

Question 136

What type of foreign antigens do T cytotoxic cells recognize? A) Foreign antigens embedded in MHC Class II molecules
B) Foreign antigens embedded in MHC Class I molecules
C) Antigens on the surface of pathogens
D) None of the above

Answer 136

Foreign antigens embedded in MHC Class I molecules

Question 137

Which T cell subset interacts with macrophages and B cells, recognizing foreign antigens bound to MHC Class II molecules?
A) T cytotoxic cells B) T helper 1 cells
C) T helper 2 cells
D) None of the above

Answer 137

T helper 2 cells

Question 138

What is the role of T cytotoxic cells?
A) To activate B cells to produce antibodies
B) To directly kill infected cells displaying foreign antigens on MHC Class I C) To activate macrophages to kill intracellular bacteria
D) To regulate immune responses after infection

Answer 138

To directly kill infected cells displaying foreign antigens on MHC Class I

Question 139

What is the function of perforin in T cytotoxic cells?
A) To stimulate the production of antibodies
B) To create pores in the target cell membrane, leading to cell death C) To neutralize bacterial toxins
D) To activate helper T cells

Answer 139

To create pores in the target cell membrane, leading to cell death

Question 140

Which of the following is a function of the Th1 subset of T helper cells? A) Activates B cells to produce antibodies
B) Activates macrophages to kill intracellular bacteria
C) Regulates the immune response after infection D) None of the above

Answer 140

Activates macrophages to kill intracellular bacteria

Question 141

What is the primary function of Th2 cells?
A) To activate macrophages for innate immunity
B) To help B cells differentiate into plasma cells and produce antibodies C) To directly kill infected cells
D) To secrete cytokines that inhibit immune responses

Answer 141

To help B cells differentiate into plasma cells and produce antibodies

Question 142

What is the role of T regulatory cells in the immune response? A) To promote inflammation
B) To activate cytotoxic T cells
C) To curb the immune response after the pathogen is defeated D) To increase the production of antibodies

Answer 142

To curb the immune response after the pathogen is defeated

Question 143

Which of the following cytokines is secreted by Th1 cells to activate macrophages? A) Gamma interferon
B) Interleukin-10
C) Interleukin-4
D) None of the above

Answer 143

Gamma interferon

Question 144

What is hypersensitivity?
A) An appropriate immune response that causes no harm to the body B) An inappropriate immune response that results in host damage
C) An immune response to only bacterial infections
D) None of the above

Answer 144

An inappropriate immune response that results in host damage

Question 145

Which of the following describes the two major types of hypersensitivity? A) Antibody-mediated and cell-mediated
B) IgE-mediated and IgG-mediated
C) Acute and chronic
D) None of the above

Answer 145

Antibody-mediated and cell-mediated

Question 146

How are hypersensitivity diseases categorized?
A) According to the organ involved and duration of the disease
B) According to antigens and effector mechanisms that produce disease C) Based on the severity of the disease
D) All of the above

Answer 146

All of the above

Question 147

Which of the following is characteristic of Type 1 hypersensitivity? A) Immediate response mediated by IgE and mast cell sensitization B) Takes hours to develop
C) Involves IgG interaction with cell surface antigens
D) None of the above

Answer 147

Immediate response mediated by IgE and mast cell sensitization

Question 148

What is an example of Type 1 hypersensitivity? A) Reaction to penicillin
B) Hay fever and bee venom reaction
C) Systemic lupus erythematosus (SLE)
D) Tuberculin test

Answer 148

Hay fever and bee venom reaction

Question 149

What is the key feature of Type 2 hypersensitivity? A) Immediate reaction mediated by IgE
B) Cytotoxic IgG interaction with cell surface antigens C) Immune complex formation involving IgG
D) All of the above

Answer 149

Immune complex formation involving IgG

Question 150

Which type of hypersensitivity involves the formation of immune complexes? A) Type 1
B) Type 2
C) Type 3
D) None of the above

Answer 150

Type 3

Question 151

What is an example of Type 3 hypersensitivity? A) Hay fever
B) Systemic lupus erythematosus (SLE)
C) Poison ivy
D) Tuberculin test

Answer 151

Systemic lupus erythematosus (SLE)

Question 152

Which type of hypersensitivity is delayed and mediated by Th1 cells and macrophages? A) Type 1
B) Type 2
C) Type 3
D) Type 4

Answer 152

Type 4

Question 153

What is an example of Type 4 hypersensitivity? A) Systemic lupus erythematosus (SLE)
B) Tuberculin test and poison ivy
C) Reaction to penicillin
D) Hay fever

Answer 153

Tuberculin test and poison ivy

Question 154

What occurs during immediate hypersensitivity (Type 1)? A) Release of vasoactive products from IgE-coated mast cells B) Release of cytokines from Th1 cells

C) Formation of immune complexes with IgG D) None of the above

Answer 154

Release of vasoactive products from IgE-coated mast cells

Question 155

What are the major symptoms of Type 1 hypersensitivity? A) Swelling, pain, and constriction of smooth muscles
B) Swelling and blood vessel constriction
C) Difficulty in breathing and inflammation of joints
D) None of the above

Answer 155

Swelling, pain, and constriction of smooth muscles

Question 156

What is the role of epinephrine (EpiPen) in Type 1 hypersensitivity reactions? A) It dilates blood vessels to reduce swelling
B) It constricts blood vessels to prevent bleeding
C) It relaxes smooth muscles of the bronchioles to improve breathing
D) All of the above

Answer 156

It relaxes smooth muscles of the bronchioles to improve breathing

Question 157

What is a characteristic of Delayed-Type Hypersensitivity (DTH)? A) Immediate reaction mediated by IgE antibodies
B) Cell-mediated hypersensitivity causing tissue damage
C) Caused by antigen-antibody complexes in the bloodstream
D) None of the above

Answer 157

Cell-mediated hypersensitivity causing tissue damage

Question 158

Which of the following is a symptom of Delayed-Type Hypersensitivity (DTH)? A) Poison ivy blisters
B) Swelling of the face
C) Severe itching and rash
D) None of the above

Answer 158

Severe itching and rash

Question 159

What type of cells are primarily involved in Delayed-Type Hypersensitivity (DTH)? A) T helper 1 (Th1) cells
B) T cytotoxic (Tc) cells
C) B cells
D) Neutrophils

Answer 159

T helper 1 (Th1) cells

Question 160

Which of the following is a typical antigen involved in Type 4 hypersensitivity?

A) Microbes, self-antigens, and chemicals that bind to skin B) Bee venom and pollen
C) Antigens on the surface of red blood cells
D) Antibodies against soluble antigens

Answer 160

Microbes, self-antigens, and chemicals that bind to skin

Question 161

What is the mechanism behind Type 2 hypersensitivity?
A) IgE antibodies bind to mast cells, causing degranulation
B) Antigen-antibody complexes deposit in tissues, causing inflammation
C) IgG or IgM antibodies bind to cell surface antigens, leading to cell destruction D) None of the above

Answer 161

IgG or IgM antibodies bind to cell surface antigens, leading to cell destruction

Question 162

What is a common example of Type 2 hypersensitivity? A) Penicillin-induced hemolysis
B) Contact dermatitis
C) Systemic lupus erythematosus
D) Tuberculin test

Answer 162

Penicillin-induced hemolysis

Question 163

In Type 3 hypersensitivity, where do the antigen-antibody complexes typically deposit? A) Skin and respiratory tract
B) Kidneys, joints, and blood vessels
C) Heart and lungs
D) Lymph nodes

Answer 163

Kidneys, joints, and blood vessels

Question 164

Which of the following is an example of a Type 3 hypersensitivity reaction? A) Rheumatoid arthritis
B) Poison ivy
C) Bee sting reaction
D) Asthma

Answer 164

Rheumatoid arthritis

Question 165

What occurs during a Type 3 hypersensitivity reaction?
A) Antigen-antibody complexes trigger complement activation and inflammation B) T helper cells activate macrophages to kill infected cells
C) IgE antibodies bind to mast cells, leading to histamine release
D) All of the above

Answer 165

Antigen-antibody complexes trigger complement activation and inflammation

Question 166

What autoimmune condition is commonly associated with Type 3 hypersensitivity? A) Rheumatoid arthritis
B) Systemic lupus erythematosus (SLE)
C) Multiple sclerosis
D) Type 1 diabetes

Answer 166

Systemic lupus erythematosus (SLE)

Question 167

Which of the following best describes Type 2 hypersensitivity?
A) IgE-mediated response leading to immediate degranulation of mast cells
B) Antibodies bind to antigens on cell surfaces, leading to complement activation

C) Immune complexes cause inflammation and tissue damage D) T-cell activation leads to chronic inflammation

Answer 167

Antibodies bind to antigens on cell surfaces, leading to complement activation

Question 168

What is a common cause of tissue damage in Type 3 hypersensitivity? A) Complement activation and deposition of immune complexes in tissues B) T-cell activation of macrophages
C) Activation of mast cells and release of histamine
D) IgE binding to allergens

Answer 168

Complement activation and deposition of immune complexes in tissues

Question 169

What causes autoimmune diseases?
A) T and B cells activated to produce immune reactions against self proteins B) Genetic mutations in immune cells
C) Overproduction of cytokines
D) None of the above

Answer 169

T and B cells activated to produce immune reactions against self proteins

Question 170

Which of the following autoimmune conditions involves antibodies interacting with self antigens?
A) Allergic encephalitis
B) Type 1 diabetes mellitus C) Both A and B
D) None of the above

Answer 170

Both A and B

Question 171

Which organ is primarily affected in Type 1 diabetes mellitus? A) Liver
B) Pancreas
C) Kidneys
D) Heart

Answer 171

Pancreas

Question 172

What is the mechanism behind Type 1 diabetes mellitus? A) Autoantibodies against beta cells of the pancreas
B) Cell-mediated destruction of pancreatic beta cells
C) Both A and B
D) Inflammatory response in the pancreas

Answer 172

Both A and B

Question 173

What is the primary organ affected by rheumatoid arthritis? A) Heart
B) Lungs
C) Cartilage in the major joints
D) Kidneys

Answer 173

Cartilage in the major joints

Question 174

Which type of hypersensitivity is involved in the mechanism of rheumatoid arthritis? A) Type I hypersensitivity
B) Type II hypersensitivity
C) Type III hypersensitivity
D) Type IV hypersensitivity

Answer 174

Type III hypersensitivity

Question 175

In Hashimoto’s disease, what is the mechanism behind thyroid destruction? A) Autoantibodies against thyroid surface antigen
B) T-cell mediated destruction of thyroid cells
C) Autoantibodies against thyroid-stimulating hormone
D) Activation of mast cells in the thyroid

Answer 175

Autoantibodies against thyroid surface antigen

Question 176

Which autoimmune disease is characterized by the formation of autoantibodies against DNA, cardiolipin, and blood clotting proteins?
A) Rheumatoid arthritis
B) Systemic lupus erythematosus C) Type 1 diabetes mellitus
D) Hashimoto’s disease

Answer 176

Systemic lupus erythematosus

Question 177

What is the main mechanism behind systemic lupus erythematosus (SLE)?
A) Autoantibodies against thyroid antigens
B) Formation of immune complexes involving DNA and other proteins C) T-cell mediated destruction of joint cartilage
D) Activation of complement by autoantibodies

Answer 177

Formation of immune complexes involving DNA and other proteins

Question 178

Which of the following is a common feature of autoimmune diseases? A) Activation of immune responses against self proteins
B) Damage to host tissues
C) Both A and B
D) None of the above

Answer 178

Both A and B

Question 179

What is a characteristic of superantigens?
A) They activate a normal number of T cells
B) They activate more T cells than a normal immune response C) They suppress T cell activation
D) They directly kill infected cells

Answer 179

They activate more T cells than a normal immune response

Question 180

Which of the following is a source of superantigens? A) Only bacteria
B) Only viruses
C) Both viruses and bacteria
D) T cells themselves

Answer 180

Both viruses and bacteria

Question 181

What is the consequence of superantigen activation in T cells? A) A localized immune response
B) A systemic inflammatory response
C) Immediate clearance of pathogens
D) Suppression of immune system function

Answer 181

A systemic inflammatory response

Question 182

Immunodeficiency is a broad term referring to: A) An overactive immune response
B) A deficiency in immune system reactions
C) Normal immune system functioning
D) Excessive T cell activation

Answer 182

A deficiency in immune system reactions

Question 183

Which of the following describes individuals with B cell deficiencies? A) Prone to viral infections and cancers
B) Prone to bacterial infections
C) Not susceptible to any infections
D) Prone to fungal infections

Answer 183

Prone to bacterial infections

Question 184

What type of infections are individuals with T cell deficiencies more susceptible to? A) Bacterial infections
B) Fungal infections
C) Viral infections and cancers D) All of the above

Answer 184

Viral infections and cancers

Question 185

Which of the following is a characteristic of Severe Combined Immunodeficiency (SCID)? A) Deficiency of both B and T cells
B) Deficiency of only B cells
C) A deficiency of only T cells
D) Overactive immune response

Answer 185

Deficiency of both B and T cells

Question 186

What is the nickname for Severe Combined Immunodeficiency (SCID) due to its restricted life requirements?
A) “Bubble Boy” syndrome
B) “T Cell Deficiency” syndrome
C) “AIDS” syndrome
D) “Autoimmune Disorder” syndrome

Answer 186

“Bubble Boy” syndrome

Question 187

Which virus causes Acquired Immunodeficiency Syndrome (AIDS)? A) Hepatitis B virus
B) Epstein-Barr virus
C) HIV (Human Immunodeficiency Virus)
D) Human papillomavirus (HPV)

Answer 187

HIV (Human Immunodeficiency Virus)

Question 188

What immune deficiency is seen in AIDS patients? A) Deficiency of CD8+ T cells
B) Deficiency of CD4+ T cells
C) Deficiency of B cells
D) Deficiency of neutrophils

Answer 188

Deficiency of CD4+ T cells

Question 189

Which of the following is a characteristic of vaccines against bacterial diseases like anthrax and tetanus?
A) Live attenuated bacteria
B) Killed bacteria or toxoid
C) Recombinant DNA vaccine D) None of the above

Answer 189

Killed bacteria or toxoid

Question 190

Which type of vaccine is used for the prevention of hepatitis B? A) Recombinant DNA vaccine or inactivated virus
B) Attenuated virus
C) Conjugate vaccine
D) Killed bacteria

Answer 190

Recombinant DNA vaccine or inactivated virus

Question 191

Which vaccine is made from a polysaccharide-toxoid conjugate to enhance T cell response? A) Pneumococcal vaccine
B) Diphtheria vaccine
C) Polio vaccine
D) Yellow fever vaccine

Answer 191

Pneumococcal vaccine

Question 192

Why are live attenuated virus vaccines often more effective than inactivated ones? A) They require fewer booster doses
B) They stimulate both the humoral and cell-mediated immune responses
C) They are easier to produce
D) They are cheaper

Answer 192

They stimulate both the humoral and cell-mediated immune responses

Question 193

What is the primary advantage of synthetic and genetically engineered vaccines? A) They are less expensive to produce
B) They provide stronger immune responses compared to live attenuated vaccines C) They are made from the entire microorganism
D) They use engineered antigenic components to stimulate the immune response

Answer 193

They use engineered antigenic components to stimulate the immune response

Question 194

Which of the following vaccines is made from a genetically engineered DNA plasmid? A) Hepatitis A
B) Pneumococcal vaccine
C) DNA vaccine
D) Smallpox vaccine

Answer 194

DNA vaccine

Question 195

Which of the following is a key feature of conjugate vaccines?
A) They are composed of live bacteria
B) They combine a small antigenic protein with a larger carrier protein
C) They use inactivated virus particles
D) They are primarily used for viral diseases

Answer 195

They combine a small antigenic protein with a larger carrier protein

Question 196

What is the key reason why vaccines against viral diseases, like polio and rabies, are crucial despite the lack of effective antiviral medications?
A) Vaccines provide immunity before infection occurs
B) Viral diseases are more difficult to treat with antibiotics C) Antivirals are effective in all cases
D) Vaccines are cheaper than antiviral medications

Answer 196

Vaccines provide immunity before infection occurs

Question 197

What type of vaccine is used for measles and mumps? A) Inactivated virus
B) Attenuated virus
C) Recombinant DNA vaccine
D) Conjugate vaccine

Answer 197

Attenuated virus

Question 198

What is the role of booster immunizations in vaccination schedules?
A) They help to induce primary immune responses
B) They increase the antibody titer by stimulating a secondary immune response C) They are used to prevent disease in the elderly
D) None of the above

Answer 198

They increase the antibody titer by stimulating a secondary immune response

Question 199

Which of the following best describes the purpose of anticancer vaccines? A) To stimulate the body’s natural immune response to cancer cells
B) To prevent the activation of immune cells in the body
C) To treat viral infections associated with cancer
D) To neutralize tumor-promoting cytokines

Answer 199

To stimulate the body’s natural immune response to cancer cells

Question 200

Prophylactic anticancer vaccines are designed to target which of the following?
A) Tumor cells directly
B) Oncogenic pathogens such as viruses
C) The immune system’s ability to produce antibodies D) Cancer stem cells

Answer 200

Oncogenic pathogens such as viruses

Question 201

Which type of anticancer vaccine is designed to treat existing cancer by stimulating the body’s immune system?
A) Therapeutic vaccines B) Prophylactic vaccines C) Vaccine adjuvants
D) Passive vaccines

Answer 201

Therapeutic vaccines

Question 202

What is the primary goal of checkpoint inhibitors in cancer immunotherapy?
A) To neutralize tumor cells directly
B) To prevent the activation of the immune system
C) To prevent the neutralization of cytotoxic T cells and stimulate their tumor-killing activity D) To inhibit the growth of cancer cells by targeting oncogenes

Answer 202

To prevent the neutralization of cytotoxic T cells and stimulate their tumor-killing activity

Question 203

Which checkpoint inhibitor drug targets the PD-1 receptor on T cells or its ligand PD-L1 on cancer cells?
A) Trastuzumab
B) Pembrolizumab (Keytruda®) C) Ipilimumab (Yervoy®)
D) Rituximab

Answer 203

Pembrolizumab (Keytruda®)

Question 204

What is the primary mechanism of action of Pembrolizumab (Keytruda®)? A) It inhibits the expression of tumor suppressor genes
B) It stimulates the production of antibodies against cancer cells
C) It blocks the PD-1/PD-L1 interaction to restore T cell activity against tumors D) It induces cancer cell apoptosis through immune activation

Answer 204

It blocks the PD-1/PD-L1 interaction to restore T cell activity against tumors

Question 205

In adoptive T cell transfer (ACT) therapy, what is the primary focus? A) Boosting the production of antibodies
B) Harnessing the tumor-targeting abilities of T cells
C) Suppressing the immune response to cancer
D) Enhancing the function of dendritic cells in antigen presentation

Answer 205

Harnessing the tumor-targeting abilities of T cells

Question 206

What are the two main approaches developed for ACT therapy?
A) Tumor-infiltrating lymphocytes (TILs) and monoclonal antibodies
B) Tumor-infiltrating lymphocytes (TILs) and chimeric antigen receptor (CAR) T cells C) Chimeric antigen receptor (CAR) T cells and dendritic cell vaccines
D) T cells and B cells activated by checkpoint inhibitors

Answer 206

Tumor-infiltrating lymphocytes (TILs) and chimeric antigen receptor (CAR) T cells

Question 207

How does the gut microbiome affect the efficacy of cancer immunotherapy? A) It has no effect on immunotherapy outcomes
B) The composition of gut microbes can influence the immune system’s response to treatment C) Only harmful bacteria can improve the efficacy of treatment
D) It directly alters cancer cell metabolism

Answer 207

The composition of gut microbes can influence the immune system’s response to treatment

Question 208

What is the goal of studying the gut microbiome in relation to immunotherapy? A) To identify bacteria that suppress immune function
B) To determine which microbes enhance the effectiveness of immunotherapies C) To formulate antibiotics that neutralize harmful bacteria
D) To develop probiotic treatments that prevent cancer

Answer 208

To determine which microbes enhance the effectiveness of immunotherapies

Question 209

What is the primary feature that makes antibiotics useful for treating infections?
A) They are produced by fungi and bacteria
B) They exhibit selective toxicity, targeting pathogens while leaving host cells unharmed C) They are synthetic compounds
D) They are effective against all microbes, including viruses

Answer 209

They exhibit selective toxicity, targeting pathogens while leaving host cells unharmed

Question 210

Which of the following best describes the classification of antibiotics? A) Antibiotics are classified by their origin (natural or synthetic)
B) Antibiotics are classified by their mechanism of action
C) Antibiotics are classified by their side effects
D) Antibiotics are classified based on the organisms they target

Answer 210

Antibiotics are classified by their mechanism of action

Question 211

What is the key difference between broad-spectrum and narrow-spectrum antibiotics? A) Broad-spectrum antibiotics target only one type of bacteria
B) Narrow-spectrum antibiotics are effective against both gram-positive and gram-negative bacteria
C) Broad-spectrum antibiotics target both gram-positive and gram-negative bacteria, while narrow-spectrum antibiotics are effective against only certain groups of bacteria
D) Narrow-spectrum antibiotics are more toxic to host cells

Answer 211

Broad-spectrum antibiotics target both gram-positive and gram-negative bacteria, while narrow-spectrum antibiotics are effective against only certain groups of bacteria

Question 212

Which of the following antibiotics are primarily used to target bacterial cell wall synthesis? A) β-lactam antibiotics (e.g., penicillin, cephalosporins)
B) Aminoglycosides (e.g., streptomycin)
C) Macrolides (e.g., azithromycin)
D) Tetracyclines (e.g., doxycycline)

Answer 212

β-lactam antibiotics (e.g., penicillin, cephalosporins)

Question 213

Which of the following is NOT a feature of β-lactam antibiotics?
A) They are effective against both gram-positive and gram-negative bacteria B) They contain a β-lactam ring structure
C) They are effective against Archaea and Eukaryotes
D) They are among the most widely used antibiotics globally

Answer 213

They are effective against Archaea and Eukaryotes

Question 214

Which of the following is NOT a target of β-lactam antibiotics? A) Peptidoglycan synthesis
B) Protein synthesis
C) Bacterial cell wall
D) They do not target Eukaryotic cells

Answer 214

Protein synthesis

Question 215

Which type of bacteria are most likely affected by β-lactam antibiotics? A) Gram-positive bacteria only
B) Gram-negative bacteria only
C) Both gram-positive and gram-negative bacteria
D) Archaea

Answer 215

Both gram-positive and gram-negative bacteria

Question 216

Which of the following antibiotics is a macrolide, commonly used in clinical practice? A) Erythromycin
B) Penicillin
C) Cephalosporin D) Streptomycin

Answer 216

Erythromycin

Question 217

What percentage of global antibiotic usage is attributed to agricultural (animal) use? A) 36%
B) 64%
C) 11%
D) 13%

Answer 217

64%

Question 218

Which of the following antibiotics targets protein synthesis by binding to the bacterial ribosome’s 30S or 50S subunits?
A) Tetracycline
B) Rifampin
C) Polymyxins D) Sulfonamides

Answer 218

Tetracycline

Question 219

Why do antibiotics that target protein synthesis typically exhibit selective toxicity? A) Bacterial ribosomes are identical to eukaryotic ribosomes
B) Eukaryotic cells have no ribosomes
C) Bacterial ribosomes differ from eukaryotic ribosomes
D) Eukaryotic cells have more efficient ribosomes than bacteria

Answer 219

Bacterial ribosomes differ from eukaryotic ribosomes

Question 220

What is the mechanism of resistance to tetracycline? A) Mutation in RNA polymerase
B) Efflux pump that removes the antibiotic
C) Mutation in the 30S ribosomal subunit
D) Altered target site for folic acid synthesis

Answer 220

Efflux pump that removes the antibiotic

Question 221

Which antibiotic class is known for blocking the exit tunnel in the bacterial ribosome, preventing peptide chain elongation?
A) Aminoglycosides
B) Macrolides
C) Tetracyclines D) Quinolones

Answer 221

Macrolides

Question 222

Which class of antibiotic inhibits DNA gyrase and is effective against both gram-positive and gram-negative bacteria?
A) Macrolides ( erythromycin)
B) aminoglycoside (Streptomycin)
C) Quinolones (ciprofloxacin, nalidixic acid, chloroquine(as antimalarial agent) D) Polymyxins (Polymyxin B)
E) sulfa drugs or sulfonamide (trimetoprim)

Answer 222

Quinolones

Question 223

How do quinolones, such as nalidixic acid, interfere with bacterial DNA? A) By inhibiting RNA polymerase
B) By inhibiting DNA gyrase, preventing supercoiling
C) By inhibiting ribosome function
D) By preventing protein synthesis

Answer 223

By inhibiting DNA gyrase, preventing supercoiling

Question 224

Which of the following antibiotics interferes with RNA transcription by inhibiting RNA polymerase?
A) Tetracycline
B) Rifampin
C) Penicillin
D) Streptomycin

Answer 224

Rifampin

Question 225

What is the mechanism of resistance to quinolones? A) Mutation in the DNA gyrase gene
B) Efflux pumps in bacterial membranes
C) Modification of ribosomal subunits
D) Production of protective proteins for ribosomes

Answer 225

Mutation in the DNA gyrase gene

Question 226

Which drug class inhibits folic acid synthesis by mimicking a growth factor, preventing bacterial cell division?
A) Sulfonamides
B) Isoniazid
C) Rifampin D) Macrolides

Answer 226

Sulfonamides

Question 227

Which of the following antibiotics inhibits mycolic acid synthesis in Mycobacterium species? A) Rifampin
B) Isoniazid
C) Tetracycline
D) Polymyxin

Answer 227

Isoniazid

Question 228

What is the mechanism of action of platensimycin? A) Inhibition of protein synthesis
B) Inhibition of lipid biosynthesis
C) Inhibition of DNA replication
D) Disruption of bacterial cell membrane

Answer 228

Inhibition of lipid biosynthesis

Question 229

Which antibiotic disrupts bacterial cell membranes and is effective against multi-drug resistant organisms like MRSA?
A) Isoniazid
B) Rifampin
C) Polymyxins D) Platensimycin

Answer 229

Polymyxins

Question 230

What do most antiviral drugs target? A) Viral structures
B) Viral RNA
C) Host structures D) Viral proteins

Answer 230

Host structures

Question 231

Which class of antiviral drugs does AZT (zidovudine) belong to? A) Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
B) Protease inhibitors
C) Nucleoside reverse transcriptase inhibitors (NRTIs)
D) Fusion inhibitors

Answer 231

Nucleoside reverse transcriptase inhibitors (NRTIs)

Question 232

What is the main action of Nucleoside reverse transcriptase inhibitors (NRTIs)? A) Inhibit viral RNA replication
B) Block reverse transcriptase and production of viral DNA
C) Prevent the fusion of the virus with the host cell
D) Inhibit protease enzymes

Answer 232

Block reverse transcriptase and production of viral DNA

Question 233

How do Non-nucleoside reverse transcriptase inhibitors (NNRTIs) work? A) They inhibit viral DNA polymerase
B) They block reverse transcriptase by binding directly to the enzyme
C) They incorporate into viral RNA
D) They prevent viral fusion with the host cell

Answer 233

They block reverse transcriptase by binding directly to the enzyme

Question 234

What is the primary function of fusion inhibitors in antiviral therapy? A) Block reverse transcription
B) Prevent the fusion of the virus with the host cell
C) Inhibit protease activity
D) Block viral DNA replication

Answer 234

Prevent the fusion of the virus with the host cell

Question 235

Why can antiviral drugs lead to toxicity in the host? A) They target only viral structures
B) They interfere with normal host DNA replication
C) They often lead to toxicity in the host
D) They inhibit host protein synthesis

Answer 235

They often lead to toxicity in the host

Question 236

What is the difference between NRTIs and NNRTIs?
A) NRTIs prevent viral RNA synthesis, while NNRTIs block viral DNA production
B) NRTIs block reverse transcriptase by incorporating into DNA, while NNRTIs inhibit reverse transcriptase directly
C) NRTIs prevent fusion, while NNRTIs inhibit viral RNA transcription
D) NRTIs inhibit protease, while NNRTIs block reverse transcriptase

Answer 236

NRTIs block reverse transcriptase by incorporating into DNA, while NNRTIs inhibit reverse transcriptase directly

Question 237

What enzyme do most HIV antiviral drugs target? A) Reverse transcriptase
B) Integrase
C) Protease
D) RNA polymerase

Answer 237

Reverse transcriptase

Question 238

Why are traditional antibacterial agents generally ineffective against fungi? A) Fungi lack a cell wall
B) Fungi are eukaryotic cells
C) Fungi do not have ribosomes
D) Fungi do not have a plasma membrane

Answer 238

Fungi are eukaryotic cells

Question 239

What unique structure in fungal cells makes them a good target for antifungal drugs? A) Mitochondria
B) Chitin cell wall and ergosterol in the membrane
C) DNA in the nucleus
D) Ribosomal RNA

Answer 239

Chitin cell wall and ergosterol in the membrane

Question 240

Which component of the fungal cell membrane is targeted by ergosterol inhibitors? A) Phospholipids
B) Chitin
C) Ergosterol
D) Protein receptors

Answer 240

Ergosterol

Question 241

Which class of antifungal drugs targets ergosterol in the fungal membrane? A) Azoles and Polyenes
B) Echinocandins
C) Allylamines
D) Griseofulvin

Answer 241

Azoles and Polyenes

Question 242

What is the target of cell wall inhibitors in antifungal therapy? A) 1,3 β-D glucan synthase
B) DNA polymerase
C) Chitin synthase
D) Ergosterol

Answer 242

1,3 β-D glucan synthase

Question 243

Which antifungal drug class is used to treat Candida infections by inhibiting cell wall synthesis?
A) Echinocandins
B) Azoles
C) Polyenes D) Allylamines

Answer 243

Echinocandins

Question 244

What process is disrupted by antifungal drugs that target microtubules? A) Protein synthesis
B) Mitosis
C) DNA replication
D) Membrane fluidity

Answer 244

Mitosis

Question 245

8. Which of the following is a common mechanism of antifungal resistance? A) Overproduction of ergosterol
   B) Increased chitin synthesis
   C) Inhibition of ribosomal activity
   D) Enhanced DNA repair mechanisms

Answer 245

Overproduction of ergosterol

Question 246

Which antifungal drug is used to target fungal mitosis by disrupting microtubule aggregation? A) Griseofulvin
B) Caspofungin
C) Fluconazole
D) Amphotericin B

Answer 246

Griseofulvin

Question 247

Which of the following drugs is specifically used to treat fungal infections through its action on DNA synthesis?
A) Griseofulvin
B) Flucytosine
C) Itraconazole D) Ketoconazole

Answer 247

Flucytosine

Question 248

Which of the following drugs is primarily used to combat malaria? A) Albendazole
B) Ivermectin
C) Chloroquine
D) Flucytosine

Answer 248

Chloroquine

Question 249

How does albendazole work to combat parasitic worms?
A) Inhibits cell wall synthesis
B) Binds to the beta-tubulin protein, causing immobilization and death C) Disrupts DNA replication
D) Inhibits protein synthesis

Answer 249

Binds to the beta-tubulin protein, causing immobilization and death

Question 250

What is the primary mechanism of action of ivermectin?
A) Inhibits the synthesis of folic acid
B) Inhibits mitosis in parasitic cells
C) Modulates glutamate-gated chloride channels leading to cell hyperpolarization D) Binds to ergosterol in the fungal membrane

Answer 250

Modulates glutamate-gated chloride channels leading to cell hyperpolarization

Question 251

Which of the following animals is ivermectin most commonly used for in anti-worming treatments?
A) Horses and cats
B) Humans
C) Dogs and birds D) Cattle and pigs

Answer 251

Horses and cats

Question 252

Which drug targets beta-tubulin in parasitic worms, immobilizing them and causing death? A) Chloroquine
B) Ivermectin
C) Albendazole
D) Griseofulvin

Answer 252

Albendazole

Question 253

Penicillin is _____ by nature A) B-lactam
B) Quinolone C) Sulfa drug D) Tetracycline

Answer 253

B-lactam

Question 254

Some antibiotics interfere with bacterial DNA synthesis by interacting with A) Ribosome
B) RNApolymerase C) DNA gyrase
D) None of the above

Answer 254

DNA gyrase

Question 255

What is the mechanism of action of tetracycline?
A. Bindsto30Sribosomalsubunitandinterruptsproteinsynthesis
B. BindstoDNAgyraseandinterfereswithDNAsynthesis
C. BindstotheenzymethatsynthesizesB12
D. Bindstothepenicillinbindingproteinandinterfereswithcellwallsynthesis

Answer 255

Binds to 30S ribosomal subunit and interrupts protein synthesis

Question 256

Substances that are naturally produced by certain microorganisms that can inhibit or destroy other microorganisms are called_________.
A) antibiotics
B) narrow-spectrum drugs
C) semisynthetic drugs
D) synthetic drugs
E) broad-spectrum drugs

Answer 256

Antibiotics

Question 257

Which of the following would be useful for treating fungal infections like Candida? A. Tetracycline
B. Penicillin
C. Azole
D. AZT

Answer 257

Azole

Question 258

What antibiotics and its chemical nature are mismatched?
A. Macrolide - Streptomycin
B. B-lactam- penicillin, amoxicillin
C. Quinolone - nalidixic acid, chloroquine
D. Sulfonamide (or sulfa-drug) - sulfamethoxazole, trimetoprim

Answer 258

Macrolide - Streptomycin

Question 259

WHich of the following would be useful for treating HIV patients?
A. AZT and NRTI
B. Tetracycline
C. Azoles

Answer 259

AZT and NRTI

Question 260

What is the primary focus of clinical microbiology?
a) Developing vaccines
b) Diagnosing infectious diseases and advising on treatment c) Studying genetic disorders
d) Monitoring environmental microbes

Answer 260

Diagnosing infectious diseases and advising on treatment

Question 261

How are clinical laboratories classified in terms of safety? a) Based on the type of equipment used
b) According to their biosafety levels (BSL-1 to BSL-4)
c) Based on the size of the laboratory
d) By the number of personnel employed

Answer 261

According to their biosafety levels (BSL-1 to BSL-4)

Question 262

What is the safest biosafety level in a clinical laboratory? a) BSL-1
b) BSL-2
c) BSL-3
d) BSL-4

Answer 262

BSL-1

Question 263

What percentage of healthcare-associated infections (HAI) are attributed to surgical site infections?
a) 10%
b) 22%
c) 30% d) 50%

Answer 263

22%

Question 264

Which of the following is a key measure to control healthcare-associated infections? a) Minimizing patient interaction
b) Applying basic aseptic techniques
c) Using only antibiotics for treatment
d) Increasing the number of hospital personnel

Answer 264

Applying basic aseptic techniques

Question 265

What makes healthcare-associated infections challenging to treat? a) They spread too quickly
b) They are often resistant to antibiotics
c) They occur only in isolated cases
d) They are caused by rare pathogens

Answer 265

They are often resistant to antibiotics

Question 266

What is the second most common type of healthcare-associated infection after surgical site infections?
a) Gastrointestinal infections
b) Respiratory infections
c) Urinary infections
d) Bloodstream infections

Answer 266

Respiratory infections

Question 267

Where do healthcare-associated infections originate from? a) Only from patients
b) Only from hospital personnel
c) From patients or hospital personnel
d) From environmental sources only

Answer 267

From patients or hospital personnel

Question 268

What is the first step in diagnosing an infectious disease in the laboratory? a) Culturing the pathogen in a pure medium
b) Identifying pathogen genes using molecular assays
c) Collecting samples such as blood, urine, or tissue
d) Applying antibiotics to the sample

Answer 268

Collecting samples such as blood, urine, or tissue

Question 269

Which assay is used to detect antibodies against a suspected pathogen? a) Antigen assays
b) Immunological assays
c) Molecular assays
d) Growth-dependent microbiology

Answer 269

Immunological assays

Question 270

What type of media is used to enrich the growth of fastidious organisms like Neisseria gonorrhoeae?
a) General-purpose media
b) Selective media
c) Enriched selective media d) Differential media

Answer 270

Enriched selective media

Question 271

What is the purpose of antibiotics in Modified Thayer-Martin (MTM) agar? a) To enhance the growth of all bacteria
b) To inhibit the growth of non-target organisms
c) To differentiate bacterial colonies
d) To support anaerobic bacteria

Answer 271

To inhibit the growth of non-target organisms

Question 272

What does sensitivity in a diagnostic test indicate? a) Ability to identify the correct pathogen
b) Minimizing false positives
c) Minimum amount of pathogen needed for detection d) Growth of colonies on differential media

Answer 272

Minimum amount of pathogen needed for detection

Question 273

How can Neisseria gonorrhoeae be identified microscopically? a) By observing growth on blood agar
b) Through colony morphology on EMB agar
c) Using a selective medium like MTM agar
d) By direct microscopic examination of tissue samples

Answer 273

By direct microscopic examination of tissue samples

Question 274

What distinguishes differential media from other types of media? a) Inhibits certain bacteria while allowing others to grow
b) Enriches growth for fastidious bacteria
c) Identifies organisms based on growth appearance
d) Contains general nutrients for a variety of microbes

Answer 274

Identifies organisms based on growth appearance

Question 275

What is an example of a bacterium that exhibits a greenish sheen on EMB agar?

a) Pseudomonas aeruginosa b) Escherichia coli
c) Neisseria gonorrhoeae
d) Staphylococcus aureus

Answer 275

E. coli

Question 276

Why is EMB agar considered both selective and differential?
a) It inhibits Gram-positive bacteria and differentiates between gram negative lactose fermenters b) It contains antibiotics for selective growth
c) It enhances the growth of all organisms
d) It supports anaerobic growth while differentiating bacteria

Answer 276

It inhibits Gram-positive bacteria and differentiates between gram negative lactose fermenters

Question 277

What does specificity in a diagnostic test measure? a) The pathogen’s growth speed
b) Ability to minimize false positives
c) The minimum pathogen quantity needed for detection d) The effectiveness of enriched media

Answer 277

Ability to minimize false positives

Question 278

What is bacteremia?
a) The presence of a large number of bacteria in the blood
b) The presence of small numbers of bacteria in the blood
c) An infection limited to cerebrospinal fluid
d) A severe bacterial infection causing systemic inflammation

Answer 278

The presence of small numbers of bacteria in the blood

Question 279

How is septicemia defined?
a) The presence of bacteria in the blood without symptoms
b) A blood infection characterized by bacterial colonization and high bacterial numbers c) A fungal infection of the bloodstream
d) The absence of bacteria in the blood

Answer 279

A blood infection characterized by bacterial colonization and high bacterial numbers

Question 280

What is the standard volume of blood drawn for blood cultures? a) 5 to 10 milliliters
b) 10 to 20 milliliters
c) 15 to 30 milliliters
d) 20 to 40 milliliters

Answer 280

10 to 20 milliliters

Question 281

Why are two bottles used in blood cultures? a) To separate blood components
b) To culture aerobic and anaerobic bacteria c) To test for bacterial and viral pathogens
d) To reduce contamination risks

Answer 281

To culture aerobic and anaerobic bacteria

Question 282

What method is used to monitor bacterial growth in an automated blood culture system? a) Microscopic examination
b) Measuring turbidity, CO2 production, or fluorescence
c) Staining techniques
d) DNA sequencing

Answer 282

Measuring turbidity, CO2 production, or fluorescence

Question 283

What makes urinary tract infections (UTIs) common in women? a) Frequent exposure to antibiotics
b) Proximity of the urethra to other anatomical structures
c) Inability to produce acid in the urinary tract d) Absence of normal flora in the urinary tract

Answer 283

Proximity of the urethra to other anatomical structures

Question 284

Which type of medium is used to identify E. coli in urinary cultures? a) General-purpose media
b) Selective media like MacConkey agar
c) Differential media for sugar fermentation
d) Blood agar

Answer 284

Selective media like MacConkey agar

Question 285

What is the purpose of differential media?
a) To inhibit the growth of specific organisms
b) To differentiate between bacteria based on growth and appearance c) To enhance the growth of fastidious organisms
d) To identify antibiotic resistance

Answer 285

To differentiate between bacteria based on growth and appearance

Question 286

How is acid production in sugar fermentation tests indicated? a) Formation of gas bubbles
b) Change in media color to yellow
c) Blackening of the agar
d) Turbidity increase in the medium

Answer 286

Change in media color to yellow

Question 287

What does the blackening of the agar in a triple-sugar iron (TSI) test indicate? a) Gas production due to fermentation
b) Hydrogen sulfide formation
c) Acid production from glucose fermentation
d) Inhibition of bacterial growth

Answer 287

Hydrogen sulfide formation

Question 288

What does the breaking up of the agar in a TSI test indicate? a) Fermentation of lactose or sucrose
b) Hydrogen sulfide production
c) Gas production during sugar fermentation
d) Growth without fermentation

Answer 288

Gas production during sugar fermentation

Question 289

What is the primary advantage of miniaturized media kits in clinical microbiology? a) They allow faster culturing of bacteria
b) They facilitate simultaneous testing of many biochemical reactions
c) They eliminate the need for manual analysis
d) They improve the growth of anaerobic organisms

Answer 289

They facilitate simultaneous testing of many biochemical reactions

Question 290

What kind of test can differentiate enteric bacteria based on sugar fermentation patterns? a) MacConkey agar test
b) Triple-sugar iron (TSI) test
c) Blood culture analysis
d) Fluorescence-based automated systems

Answer 290

Triple-sugar iron (TSI) test

Question 291

Which bacterium typically ferments only glucose in a TSI test? a) Escherichia coli
b) Salmonella
c) Pseudomonas
d) Shigella

Answer 291

Shigella

Question 292

What is indicated by gas bubbles in a sugar fermentation test? a) No fermentation
b) Acid production
c) Gas production from sugar fermentation
d) Hydrogen sulfide formation

Answer 292

Gas production from sugar fermentation

Question 293

Why are urinary tract infections (UTIs) more common in women? a) Women have a stronger immune response
b) Proximity of the urethra to the anus
c) Higher resistance of bacteria in women
d) Increased hydration levels in women

Answer 293

Proximity of the urethra to the anus

Question 294

Which medium is specifically selective for culturing E. coli in urinary tract infections? a) Blood agar
b) MacConkey agar
c) Chocolate agar
d) Thayer–Martin agar

Answer 294

MacConkey agar

Question 295

What indicates acid production in a sugar fermentation test? a) Formation of gas bubbles
b) Media color changing to red

c) Media color changing to yellow d) Blackening of the agar

Answer 295

Media color changing to yellow

Question 296

What is the purpose of miniaturized media kits in microbiological testing? a) To isolate anaerobic bacteria
b) To simultaneously run multiple biochemical tests
c) To eliminate contamination during testing
d) To test antibiotic resistance

Answer 296

To simultaneously run multiple biochemical tests

Question 297

What characteristic result does Salmonella produce in a triple-sugar iron (TSI) agar test? a) Growth without fermentation
b) Hydrogen sulfide formation causing blackening
c) Fermentation of glucose only
d) Acid formation throughout the slant

Answer 297

acid formation throughout the slant

Question 298

Which bacterium typically ferments all three sugars in the TSI test with gas production? a) Pseudomonas
b) Shigella
c) Salmonella
d) Escherichia coli

Answer 298

e coli

Question 299

What medium is commonly used to identify MRSA in wound cultures? a) Blood agar
b) Chromogenic agar
c) Selective agar for anaerobes
d) Thayer–Martin agar

Answer 299

Chromogenic agar

Question 300

Which medium is selective for Neisseria gonorrhoeae in genital cultures? a) Blood agar
b) Chocolate agar
c) Thayer–Martin agar
d) MacConkey agar

Answer 300

Thayer–Martin agar

Question 301

What is the purpose of the Minimum Inhibitory Concentration (MIC) test?
a) To assess bacterial growth rates
b) To determine the smallest antibiotic concentration to inhibit bacterial growth c) To evaluate aerobic bacterial metabolism
d) To measure acid production in sugar fermentation

Answer 301

To determine the smallest antibiotic concentration to inhibit bacterial growth

Question 302

What is the principle behind the Kirby-Bauer test? a) Detecting sugar fermentation
b) Measuring gas production
c) Assessing inhibition zones formed by antibiotics
d) Identifying obligate anaerobes

Answer 302

Assessing inhibition zones formed by antibiotics

Question 303

Immunoassays are used for:
a) Identifying pathogens using in vitro tests

b) Measuring cell size
c) Observing bacterial motility
d) Determining pH levels in blood

Answer 303

Identifying pathogens using in vitro tests

Question 304

What does an elevated antibody titer indicate? a) Recovery from an infection
b) An ongoing infection or exposure to a pathogen c) Complete elimination of the pathogen
d) Autoimmune diseases

Answer 304

An ongoing infection or exposure to a pathogen

Question 305

Monoclonal antibodies (mAbs) are produced by: a) Isolating single clones of T cells
b) Fusing B cells with cancer cells
c) Amplifying DNA using PCR
d) Purifying blood plasma proteins

Answer 305

Fusing B cells with cancer cells

Question 306

Which of the following is NOT an application of monoclonal antibodies? a) Immunological typing of bacterial pathogens
b) Blood and tissue typing
c) DNA sequencing
d) Cancer detection and treatment

Answer 306

DNA sequencing

Question 307

Precipitation occurs when:
a) Antigen and antibody are at equivalent concentrations
b) Antibody binds to soluble antigen forming a visible clump c) Antigen and antibody react under UV light
d) Antigen breaks down into smaller molecules

Answer 307

Antigen and antibody are at equivalent concentrations

Question 308

What is a key feature of agglutination tests?
a) They require advanced laboratory equipment
b) They are rapid, sensitive, and inexpensive
c) They cannot be used for blood group identification d) They do not use antibodies

Answer 308

They are rapid, sensitive, and inexpensive

Question 309

Passive agglutination is:
a) The agglutination of soluble antibodies on red blood cells
b) Clumping of soluble antigens or antibodies adsorbed onto particles c) Less sensitive than direct agglutination

d) The reaction of fluorescent antigens

Answer 309

Clumping of soluble antigens or antibodies adsorbed onto particles

Question 310

In direct immunofluorescence, the antibody is: a) Nonfluorescent
b) Covalently linked to a fluorescent dye
c) Attached to an enzyme
d) Coupled to latex beads

Answer 310

Covalently linked to a fluorescent dye

Question 311

Fluorescent antibody assays are useful for diagnosing: a) Infectious diseases only
b) Noninfectious diseases like cancer
c) Both infectious and noninfectious diseases
d) Only bacterial infections

Answer 311

Both infectious and noninfectious diseases

Question 312

What is a primary difference between rapid tests and ELISA?
a) Rapid tests use fluorescent labels, while ELISA does not
b) Rapid tests provide results within minutes, while ELISA takes hours c) Rapid tests require a laboratory setting, while ELISA is point-of-care d) ELISA is less sensitive than rapid tests

Answer 312

Rapid tests provide results within minutes, while ELISA takes hours

Question 313

Rapid diagnostic tests detect antigens by: a) Measuring nucleic acid sequences
b) Observing visible clumping reactions
c) Using a colored molecule bound to a matrix d) Calculating antibody titers

Answer 313

Using a colored molecule bound to a matrix

Question 314

Nucleic acid hybridization involves:
a) Amplifying DNA using PCR
b) Detecting specific pathogen DNA using nucleic acid probes c) Counting microbes in a sample
d) Using antibodies for fluorescent labeling

Answer 314

Detecting specific pathogen DNA using nucleic acid probes

Question 315

What is the main function of RT-PCR?
a) Amplifying pathogen DNA
b) Detecting RNA viruses by converting RNA into cDNA c) Performing rapid antigen-antibody reactions
d) Measuring fluorescence in immunoassays

Answer 315

Detecting RNA viruses by converting RNA into cDNA

Question 316

Quantitative PCR (qPCR) is used to:
a) Detect insoluble complexes of antibodies and antigens b) Obtain a count of microbes in a sample
c) Identify blood group antigens
d) Measure antibody titers in serum

Answer 316

Obtain a count of microbes in a sample

Question 317

Which of the following assays can estimate the number of mRNA molecules in a sample? a) Passive agglutination
b) ELISA
c) Reverse transcription PCR (RT-PCR)
d) Precipitation tests

Answer 317

Reverse transcription PCR (RT-PCR)

Question 318

What stage of acute infection occurs when symptoms are at their peak? A) Incubation period
B) Acute period
C) Decline period
D) Convalescent period

Answer 318

Acute period

Question 319

What is a zoonosis?
A) A disease that only affects humans
B) A disease that primarily infects animals but can occasionally be transmitted to humans C) A disease that spreads through human-to-human transmission only
D) A disease caused by a microorganism that lives in the human gut

Answer 319

A disease that primarily infects animals but can occasionally be transmitted to humans

Question 320

Which of the following best distinguishes a mechanical vector from a biological vector?
A) A mechanical vector transmits the pathogen by carrying it on its body, while a biological vector involves pathogen replication inside the vector
B) A mechanical vector carries the pathogen inside its body, while a biological vector transmits it only on its surface
C) A biological vector only transmits bacteria, while a mechanical vector transmits viruses D) Both vectors involve pathogen replication inside the human host

Answer 320

A mechanical vector transmits the pathogen by carrying it on its body, while a biological vector involves pathogen replication inside the vector

Question 321

What is a common vehicle in disease transmission?
A) A living organism that carries the pathogen from one host to another B) A mode of transmission that involves direct contact between hosts C) A nonliving agent, such as water or food, that transmits pathogens D) A vector that transmits diseases only through the air

Answer 321

A nonliving agent, such as water or food, that transmits pathogens

Question 322

Which of the following is the most accurate description of the number of dead individuals in a population due to a specific disease?
A) Morbidity
B) Mortality rate
C) Prevalence rate
D) Incidence rate

Answer 322

Mortality rate

Question 323

What stage of acute infection occurs when symptoms are at their peak?
A) Incubation period
B) Acute period
C) Decline period
D) Convalescent period

Answer 323

Acute period

Question 324

What is a zoonosis?
A) A disease that only affects humans
B) A disease that primarily infects animals but can occasionally be transmitted to humans C) A disease that spreads through human-to-human transmission only
D) A disease caused by a microorganism that lives in the human gut

Answer 324

A disease that primarily infects animals but can occasionally be transmitted to humans

Question 325

Which of the following best distinguishes a mechanical vector from a biological vector?
A) A mechanical vector transmits the pathogen by carrying it on its body, while a biological vector involves pathogen replication inside the vector
B) A mechanical vector carries the pathogen inside its body, while a biological vector transmits it only on its surface
C) A biological vector only transmits bacteria, while a mechanical vector transmits viruses D) Both vectors involve pathogen replication inside the human host

Answer 325

A mechanical vector transmits the pathogen by carrying it on its body, while a biological vector involves pathogen replication inside the vector

Question 326

What is a common vehicle in disease transmission?
A) A living organism that carries the pathogen from one host to another B) A mode of transmission that involves direct contact between hosts C) A nonliving agent, such as water or food, that transmits pathogens D) A vector that transmits diseases only through the air

Answer 326

A nonliving agent, such as water or food, that transmits pathogens

Question 327

Which of the following is the most accurate description of the number of dead individuals in a population due to a specific disease?
A) Morbidity
B) Mortality rate C) Prevalence rate D) Incidence rate

Answer 327

Mortality rate

Question 328

Which of the following is an example of an emergent disease that has recently become prevalent in the United States?
A) Tuberculosis
B) Lyme disease
C) Smallpox
D) Cholera

Answer 328

Lyme disease

Question 329

Which factor is primarily responsible for the emergence of influenza pandemics, occurring every 10 to 40 years?
A) Increased vaccination rates
B) Antigenic shift in the influenza genome
C) Genetic mutation of bacteria
D) Water contamination

Answer 329

Antigenic shift in the influenza genome

Question 330

What is a key characteristic that distinguishes reemerging diseases from emergent diseases?
A) Reemerging diseases are always viral infections
B) Reemerging diseases were previously under control but have regained prevalence
C) Reemerging diseases always occur in new geographic areas
D) Reemerging diseases are always caused by bacterial pathogens

Answer 330

Reemerging diseases were previously under control but have regained prevalence

Question 331

What is the primary mode of transmission for cholera?
A) Vector-borne through mosquito bites
B) Airborne through respiratory droplets
C) Direct contact with infected bodily fluids
D) Ingestion of contaminated water or food

Answer 331

Ingestion of contaminated water or food

Question 332

What is the most likely explanation for the occurrence of reemerging diseases such as tuberculosis?
A) Decreased vaccination coverage
B) Increased antibiotic resistance
C) Improved sanitation and water purification
D) Genetic modification of pathogens for better survival

Answer 332

Increased antibiotic resistance

Question 333

Which of the following is a key characteristic of biological weapons used in warfare?
A) They are difficult to produce and deliver
B) They do not affect civilians
C) They are capable of incapacitating or killing individuals in a consistent manner
D) They can only be used for medical purposes

Answer 333

They are capable of incapacitating or killing individuals in a consistent manner

Question 334

Which of the following best explains the emergence of the 2009 H1N1 influenza pandemic (swine flu)?
A) A single mutation in a bird flu virus
B) Gene reassortment involving swine, bird, and human influenza viruses
C) The eradication of seasonal influenza vaccines
D) A new bacterial strain spreading rapidly in Europe

Answer 334

Gene reassortment involving swine, bird, and human influenza viruses

Question 335

What is a primary factor limiting the long-distance transmission of many respiratory pathogens?
a) High humidity levels
b) Poor survival in air
c) Low temperatures
d) Rapid immune response

Answer 335

Poor survival in air

Question 336

Which characteristic differentiates the upper and lower respiratory tracts? a) Air flow
b) Temperature
c) pH levels
d) All of the above

Answer 336

All of the above

Question 337

Which pathogen is commonly found in low numbers in the upper respiratory tract of healthy individuals?
a) Mycobacterium tuberculosis
b) Streptococcus pyogenes
c) Bordetella pertussis
d) Chlamydophila pneumoniae

Answer 337

Streptococcus pyogenes

Question 338

What is the primary diagnostic method for identifying Streptococcus pyogenes infections? a) Fluorescent antibody staining
b) Culture and beta-hemolysis observation
c) DNA sequencing
d) Immunohistochemistry

Answer 338

Culture and beta-hemolysis observation

Question 339

Streptococcus pyogenes is the causative agent of which disease? a) Pertussis
b) Tuberculosis
c) Strep throat

d) Leprosy

Answer 339

Strep throat

Question 340

What toxin contributes to the virulence of beta-hemolytic Streptococcus strains?
a) Endotoxin
b) Hemolysin
c) Neurotoxin
d) Lipopolysaccharide

Answer 340

Hemolysin

Question 341

Which pathogen causes pertussis (whooping cough)? a) Streptococcus pneumoniae
b) Bordetella pertussis
c) Mycobacterium tuberculosis
d) Mycobacterium leprae

Answer 341

Bordetella pertussis

Question 342

What symptom characterizes pertussis? a) Persistent fever
b) Recurrent, violent cough
c) Chest pain
d) Difficulty swallowing

Answer 342

Recurrent, violent cough

Question 343

What is the primary method of pertussis prevention? a) Isolation
b) Antibiotics
c) Vaccination
d) Air filtration

Answer 343

Vaccination

Question 344

Which pathogen is transmitted via airborne droplets and can cause tuberculosis? a) Mycobacterium tuberculosis
b) Mycobacterium leprae
c) Haemophilus influenzae
d) Streptococcus pneumoniae

Answer 344

Mycobacterium tuberculosis

Question 345

What immune mechanism plays a key role in preventing active tuberculosis? a) Antibody-mediated immunity
b) Cell-mediated immunity
c) Complement activation
d) Humoral immunity

Answer 345

Cell-mediated immunity

Question 346

Which organism causes leprosy? a) Mycobacterium tuberculosis
b) Mycobacterium leprae
c) Bordetella pertussis
d) Chlamydophila pneumoniae

Answer 346

Mycobacterium leprae

Question 347

What is a hallmark of lepromatous leprosy? a) Pulmonary lesions
b) Folded, bulb-like lesions on the body
c) Recurrent high fevers
d) Chronic cough

Answer 347

Folded, bulb-like lesions on the body

Question 348

Where are leprosy lesions most likely to form? a) Warmer parts of the body
b) Cooler parts of the body
c) Internal organs
d) The gastrointestinal tract

Answer 348

Cooler parts of the body

Question 349

What cells do M. leprae grow in to cause nerve-related symptoms? a) Schwann cells
b) Red blood cells
c) White blood cells
d) Epithelial cells

Answer 349

Schwann cells

Question 350

Why are viral infections among the most prevalent in humans? a) Viruses replicate faster than bacteria
b) Viruses can remain infectious in dried mucus for long periods c) Vaccines for viral infections are ineffective
d) Viral infections are always chronic

Answer 350

Viruses can remain infectious in dried mucus for long periods

Question 351

What is a common characteristic of most viral diseases? a) Chronic and progressive
b) Acute and self-limiting
c) Always requiring hospitalization
d) Caused by multiple pathogens

Answer 351

acute and self-limiting

Question 352

Which of the following has been effectively controlled by vaccination? a) Measles and mumps
b) Smallpox and rabies
c) Chicken pox and rubella

d) Influenza and HIV

Answer 352

Measles and mumps

Question 353

What caused the decline in measles cases after the mid-1960s?
a) Better sanitation
b) Antibiotic treatments
c) Widespread immunization programs
d) Natural immunity

Answer 353

Widespread immunization programs

Question 354

What is “immune amnesia” caused by the measles virus?
a) Loss of long-term immunity due to age
b) Destruction of memory B cells by the virus
c) Immune system’s inability to recognize viruses
d) Mutation of memory T cells

Answer 354

Destruction of memory B cells by the virus

Question 355

Which serious complications can result from measles infections?
a) Meningitis and hepatitis
b) Encephalitis and pneumonia
c) Kidney failure and anemia
d) Chronic fatigue and arthritis

Answer 355

Encephalitis and pneumonia

Question 356

What has caused recent increases in measles outbreaks?
a) Antiviral drug resistance
b) Genetic mutations in the virus
c) Populations not immunized or inadequately immunized
d) Increased global travel

Answer 356

Populations not immunized or inadequately immunized

Question 357

What type of virus causes rubella?

a) DNA virus from the paramyxovirus family
b) Positive-strand RNA virus of the togavirus group c) Retrovirus from the lentivirus group
d) Negative-strand RNA virus of the filovirus family

Answer 357

Positive-strand RNA virus of the togavirus group

Question 358

What is a significant risk of rubella if contracted during the first three months of pregnancy? a) Permanent immune suppression
b) Severe congenital defects in the infant
c) Increased risk of maternal death
d) Chronic respiratory infections in the infant

Answer 358

Severe congenital defects in the infant

Question 359

Which symptom is associated with congenital rubella syndrome?
a) High fever
b) Cataracts in the eyes
c) Painful skin rash
d) Enlarged spleen

Answer 359

Cataracts in the eyes

Question 360

What is a defining feature of mumps infection? a) Chronic cough
b) Inflammation of the salivary glands
c) Persistent fever
d) Skin lesions

Answer 360

Inflammation of the salivary glands

Question 361

Which group was most affected by mumps outbreaks in the United States in 2006, 2016, and 2017?
a) Infants
b) Elderly
c) Young adults (18–34 years old) d) Healthcare workers

Answer 361

Young adults (18–34 years old)

Question 362

What was a key recommendation to reduce mumps cases in the United States? a) Mass distribution of antiviral drugs
b) Immunization targeting school-age children and healthcare workers

c) Regular testing for mumps antibodies d) Quarantine of infected individuals

Answer 362

Immunization targeting school-age children and healthcare workers

Question 363

What virus causes chicken pox and shingles? a) Varicella-zoster virus (VZV)
b) Paramyxovirus
c) Togavirus
d) Epstein-Barr virus

Answer 363

Varicella-zoster virus (VZV)

Question 364

What happens during a shingles outbreak?
a) Chronic coughing develops
b) Nerve cells migrate to skin tissue
c) The virus reactivates and causes painful skin eruptions d) The immune system fails to fight new infections

Answer 364

The virus reactivates and causes painful skin eruptions

Question 365

Where does the varicella-zoster virus remain latent? a) Bone marrow
b) Salivary glands
c) Nerve cells
d) Lymph nodes

Answer 365

Nerve cells

Question 366

Which virus is the most common cause of the common cold?
a) Coronavirus
b) Rhinovirus
c) Adenovirus
d) Influenza virus

Answer 366

Rhinovirus

Question 367

Why is complete protective immunity against the common cold challenging to achieve?
a) Cold viruses do not induce specific immunity
b) The large number of cold pathogens prevents complete protection
c) Antiviral drugs eliminate protective immunity
d) The cold virus mutates annually

Answer 367

The large number of cold pathogens prevents complete protection

Question 368

What distinguishes Influenza A viruses from other types of influenza viruses?
a) They contain a positive-sense, single-stranded RNA genome
b) They are segmented DNA viruses
c) They have unique surface glycoproteins, HA and NA
d) They lack a lipid bilayer in their envelope

Answer 368

They have unique surface glycoproteins, HA and NA

Question 369

What is the difference between antigenic drift and antigenic shift in influenza viruses?
a) Antigenic drift involves gene mutation; antigenic shift involves gene reassortment
b) Antigenic drift occurs in coronaviruses; antigenic shift occurs in adenoviruses
c) Antigenic drift causes pandemics; antigenic shift causes minor outbreaks
d) Antigenic drift and shift are both caused by environmental factors

Answer 369

Antigenic drift involves gene mutation; antigenic shift involves gene reassortment

Question 370

Which influenza strain caused a pandemic in 2009 and is also known as “swine flu”?
a) H5N1
b) H3N2
c) H1N1
d) H7N9

Answer 370

H1N1

Question 371

Why should aspirin be avoided in treating influenza, particularly in children?
a) It may lead to antigenic shift
b) It can exacerbate antigenic drift
c) It is ineffective against influenza A
d) It may cause Reye’s Syndrome

Answer 371

It may cause Reye’s Syndrome

Question 372

What characteristic distinguishes Staphylococcus species from other bacteria? a) They form spherical spores.
b) They form irregular clumps resembling grape clusters.
c) They are gram-negative, spiral-shaped bacteria.
d) They are strictly anaerobic.

Answer 372

They form irregular clumps resembling grape clusters.

Question 373

Which metabolic property allows Staphylococcus species to grow on mannitol salt agar (MSA)?
a) Ability to ferment maltose only
b) Tolerance to salt and ability to ferment mannitol
c) Strict aerobic respiration
d) Fermentation of sucrose exclusively

Answer 373

Tolerance to salt and ability to ferment mannitol

Question 374

What is a major virulence factor that protects Staphylococcus aureus from phagocytosis? a) Hemolysin toxin
b) Protein A and coagulase
c) Urease enzyme
d) CagA protein

Answer 374

Protein A and coagulase

Question 375

Which Staphylococcus exotoxin is associated with food poisoning? a) TSST-1 (toxic shock syndrome toxin)
b) Hemolysin
c) Enterotoxin

d) Exfoliatin

Answer 375

Enterotoxin

Question 376

What type of disease is caused by Staphylococcus aureus producing exfoliatin toxin? a) Toxic shock syndrome
b) Food poisoning
c) Scalded skin syndrome
d) Osteomyelitis

Answer 376

Scalded skin syndrome

Question 377

Which enzyme produced by Staphylococcus aureus contributes to tissue invasion? a) Urease
b) Hyaluronidase
c) Catalase
d) CagA

Answer 377

Hyaluronidase

Question 378

What type of bacterium is Helicobacter pylori? a) Gram-positive, facultative aerobe
b) Gram-negative, highly motile, spiral-shaped c) Gram-positive, spore-forming, rod-shaped
d) Gram-negative, spherical

Answer 378

Gram-negative, highly motile, spiral-shaped

Question 379

Where does Helicobacter pylori typically colonize in the human body? a) Acid-secreting mucosa of the stomach
b) Non-acid-secreting mucosa of the stomach and upper intestine
c) Lymphatic tissue in the intestines
d) Respiratory tract epithelium

Answer 379

Non-acid-secreting mucosa of the stomach and upper intestine

Question 380

Which Helicobacter pylori virulence factor promotes duodenal ulcers? a) Catalase
b) DupA
c) Exotoxin A
d) Hemolysin

Answer 380

DupA

Question 381

What diagnostic test can confirm the presence of Helicobacter pylori? a) Blood culture
b) Urease breath test for ammonia
c) Gram staining of gastric tissue
d) Catalase activity assay

Answer 381

Urease breath test for ammonia

Question 382

Which disease is most strongly linked to Helicobacter pylori colonization? a) Scalded skin syndrome
b) Gastric adenocarcinoma
c) Impetigo
d) Pneumonia

Answer 382

Gastric adenocarcinoma

Question 383

How is Helicobacter pylori primarily transmitted?
a) Airborne droplets
b) Person-to-person contact or ingestion of contaminated food or water c) Direct blood exposure
d) Contact with animal reservoirs

Answer 383

Person-to-person contact or ingestion of contaminated food or water

Question 384

What is a key characteristic of sexually transmitted infections (STIs)?
a) They are always caused by bacteria
b) They are found only in the gastrointestinal tract
c) Pathogens are generally found in body fluids exchanged during sexual activity
d) They cannot be transmitted through direct contact

Answer 384

Pathogens are generally found in body fluids exchanged during sexual activity

Question 385

What distinguishes gonorrhea from syphilis in terms of prevalence and symptoms?
a) Gonorrhea is rare and always symptomatic, while syphilis is common and asymptomatic
b) Gonorrhea is prevalent and often asymptomatic, especially in women, while syphilis has low
prevalence and exhibits obvious symptoms
c) Both are highly prevalent and have similar symptoms d) Syphilis is more common and rarely shows symptoms

Answer 385

Gonorrhea is prevalent and often asymptomatic, especially in women, while syphilis has low
prevalence and exhibits obvious symptoms

Question 386

Which bacterium causes gonorrhea? a) Treponema pallidum
b) Chlamydia trachomatis
c) Neisseria gonorrhoeae
d) Herpes simplex virus

Answer 386

Neisseria gonorrhoeae

Question 387

What is a common complication of untreated gonorrhea in women? a) Cervical cancer
b) Pelvic inflammatory disease
c) Genital warts
d) Lymphogranuloma venereum

Answer 387

Pelvic inflammatory disease

Question 388

What are the stages of syphilis progression? a) Acute, chronic, and latent
b) Primary, secondary, and tertiary
c) Initial, recurring, and chronic
d) Localized, systemic, and congenital

Answer 388

Primary, secondary, and tertiary

Question 389

Which STI is the most prevalent bacterial infection worldwide? a) Gonorrhea
b) Syphilis
c) Chlamydia
d) Genital herpes

Answer 389

the clap

Question 390

What causes cold sores and fever blisters around the mouth? a) Human papillomavirus (HPV)
b) Herpes simplex virus 1 (HSV-1)
c) Herpes simplex virus 2 (HSV-2)
d) Treponema pallidum

Answer 390

Herpes simplex virus 1 (HSV-1)

Question 391

Which STI is primarily associated with the anogenital region? a) Herpes simplex virus 1 (HSV-1)
b) Herpes simplex virus 2 (HSV-2)
c) Chlamydia trachomatis
d) Human papillomavirus (HPV)

Answer 391

Herpes simplex virus 2 (HSV-2)

Question 392

What is the relationship between human papillomavirus (HPV) and cervical cancer? a) All HPV infections cause cervical cancer
b) HPV infections may progress to cervical neoplasia, and some lead to cervical cancers c) HPV only causes genital warts, not cancer
d) Cervical cancer is unrelated to HPV infections

Answer 392

HPV infections may progress to cervical neoplasia, and some lead to cervical cancers

Question 393

10. What is the main cause of acquired immunodeficiency syndrome (AIDS)? a) Treponema pallidum
    b) Neisseria gonorrhoeae
    c) Human papillomavirus (HPV)
    d) Human immunodeficiency virus (HIV)

Answer 393

HIV

Question 394

Which cell type is progressively depleted in HIV infections? a) CD8+ cytotoxic T cells

b) CD4+ helper T cells
c) B cells
d) Natural killer (NK) cells

Answer 394

CD4+ helper T cells

Question 395

Which diagnostic test is used for early detection of HIV infection? a) HIV-EIA antibody test
b) RT-PCR to detect HIV RNA
c) Culture of infected cells
d) Rapid blood glucose test

Answer 395

RT-PCR to detect HIV RNA

Question 396

What is a common limitation of antibody-based tests for HIV diagnosis? a) They cannot detect antibodies to HIV
b) They fail to detect infection in individuals who recently acquired HIV
c) They are not specific to HIV
d) They cannot be performed on blood samples

Answer 396

They fail to detect infection in individuals who recently acquired HIV

Question 397

Which therapy is used to delay the symptoms of AIDS and prolong life? a) Antibiotics
b) Highly active antiretroviral therapy (HAART)
c) Chemotherapy
d) Vaccination

Answer 397

Highly active antiretroviral therapy (HAART)

Question 398

Why is HAART often inaccessible in developing countries? a) It is ineffective against HIV strains in those regions
b) It requires specialized medical equipment
c) It is prohibitively expensive
d) It lacks approval for use in low-income areas

Answer 398

It is prohibitively expensive

Question 399

What is the primary focus of epidemiology?
A) Treating diseases in individual patients
B) The occurrence and distribution of health and disease
C) Creating vaccines for all infectious diseases D) None of the above

Answer 399

The occurrence and distribution of health and disease

Question 400

What is the goal of identifying the nature of a disease and its transmission? A) To improve hospital infrastructure
B) To develop public health policies
C) To trace and control the spread of diseases
D) Both A and B

Answer 400

To trace and control the spread of diseases

Question 401

In developed countries, which of the following is true regarding infectious diseases? A) They cause more deaths than noninfectious diseases
B) They are less of a threat than in developing countries
C) They account for nearly half of all deaths
D) All of the above

Answer 401

They are less of a threat than in developing countries

Question 402

What is the term for the total number of new and existing cases of a disease in a population over time?
A) Incidence B) Prevalence C) Mortality D) Morbidity

Answer 402

Prevalence

Question 403

What is an epidemic?
A) A disease constantly present at low levels in a population
B) A large number of cases of a disease occurring simultaneously in a population C) A short-term localized disease outbreak
D) A worldwide disease spread

Answer 403

A large number of cases of a disease occurring simultaneously in a population

Question 404

What term refers to individuals who are infected but show no or mild symptoms? A) Reservoirs
B) Carriers
C) Hosts
D) None of the above

Answer 404

Carriers

Question 405

Which of the following describes a chronic infection?
A) The pathogen quickly overcomes the host, causing death B) The pathogen and host exist in a balanced relationship C) The disease lasts only a few days
D) All of the above

Answer 405

The pathogen and host exist in a balanced relationship

Question 406

Which of the following is not part of the stages of disease progression? A) Incubation period
B) Decline period
C) Herd immunity period
D) Convalescent period

Answer 406

Herd immunity period

Question 407

What is the meaning of morbidity in epidemiology? A) Incidence of death in a population
B) Incidence of disease, both fatal and nonfatal
C) The number of new disease cases over time
D) The number of immune individuals in a population

Answer 407

Incidence of disease, both fatal and nonfatal

Question 408

Disability-Adjusted Life Year (DALY) measures disease burden in terms of: A) Years lost due to disease
B) Disability caused by disease
C) Premature death
D) All of the above

Answer 408

All of the above

Question 409

What happens to the virulence of a pathogen during host-to-host transmission over time? A) It increases significantly
B) It diminishes as the host develops resistance
C) It remains unchanged
D) None of the above

Answer 409

It diminishes as the host develops resistance

Question 410

Which condition could lead to a pathogen remaining highly virulent? A) Effective herd immunity
B) Host-to-host transmission
C) Non-reliance on host-to-host transmission D) Both A and B

Answer 410

Non-reliance on host-to-host transmission

Question 411

Herd immunity protects a population by:
A) Preventing the pathogen from being passed on B) Ensuring all individuals are vaccinated
C) Eliminating the pathogen entirely
D) Reducing the prevalence of all diseases

Answer 411

Preventing the pathogen from being passed on

Question 412

What is a characteristic of diseases like influenza?
A) They occur in cycles
B) They rarely spread person-to-person C) They are always endemic
D) They are unaffected by herd immunity

Answer 412

They occur in cycles

Question 413

Which of the following is true regarding the coevolution of a host and its pathogen? A) A highly virulent pathogen will always spread rapidly
B) Pathogens killing hosts too quickly may become extinct
C) Virulence always increases over time
D) None of the above

Answer 413

Pathogens killing hosts too quickly may become extinct

Question 414

What is the leading cause of death among infectious diseases? A) Tuberculosis
B) Diarrheal diseases
C) Lower respiratory tract infections
D) Malaria

Answer 414

Tuberculosis

Question 415

2. Which of the following diseases is categorized as a lower respiratory tract infection? A) COVID-19
   B) Cholera
   C) Tuberculosis
   D) All of the above

Answer 415

COVID

Question 416

What is the second leading cause of death among infectious diseases? A) Diarrheal diseases
B) Malaria
C) AIDS
D) Tuberculosis

Answer 416

Diarrheal diseases

Question 417

Which pathogens are significant contributors to diarrheal diseases? A) Cholera and Rotavirus
B) Shigella and certain E. coli strains
C) Cryptosporidium
D) All of the above

Answer 417

) All of the above

Question 418

Which of the following is a protozoan associated with diarrheal diseases? A) Cholera
B) Cryptosporidium
C) Rotavirus
D) Shigella

Answer 418

Cryptosporidium

Question 419

What is the third leading infectious disease killer globally? A) Malaria
B) AIDS
C) Tuberculosis
D) Diarrheal diseases

Answer 419

Tuberculosis

Question 420

Among infectious diseases, what comes after Tuberculosis in terms of global mortality? A) Lower respiratory tract infections
B) AIDS
C) Diarrheal diseases
D) Malaria

Answer 420

AIDS

Question 421

Which of the following statements about malaria is true? A) Its global mortality rate is 10%
B) 90% of deaths occur in children under 5 years old C) It is caused by a bacterium
D) None of the above

Answer 421

90% of deaths

Question 422

What percentage of malaria-related deaths occur in children under the age of five? A) 50%
B) 70% C) 90% D) 100%

Answer 422

90%

Question 423

Which of the following diseases has the lowest mortality rate globally but still significantly impacts children?
A) Malaria
B) Tuberculosis C) Cholera
D) AIDS

Answer 423

Malaria

Question 424

Which of these diseases includes significant contributions from bacterial pathogens? A) Malaria and AIDS
B) Tuberculosis and Shigella
C) COVID-19 and Rotavirus
D) All of the above

Answer 424

aTuberculosis and Shigella

Question 425

Which of the following lists ranks infectious diseases in order of their mortality rates, starting with the highest?
A) Tuberculosis > Malaria > Diarrheal diseases
B) Lower respiratory tract infections > Diarrheal diseases > Tuberculosis C) AIDS > Tuberculosis > Diarrheal diseases
D) None of the above

Answer 425

Lower respiratory tract infections > Diarrheal diseases > Tuberculosis

Question 426

Which of the following is not a diarrheal disease? A) Cholera
B) Rotavirus
C) Malaria
D) Shigella

Answer 426

malaria

Question 427

Which of these infectious diseases is caused by a virus? A) Cryptosporidium
B) Rotavirus
C) Cholera
D) Shigella

Answer 427

rotavirus

Question 428

Which of the following diseases has protozoan origins? A) Tuberculosis
B) Malaria and Cryptosporidium
C) AIDS
D) Cholera

Answer 428

malaria and Cryptosporidium

Question 429

What is a typical outcome of host-to-host coevolution?
A) The parasite becomes more virulent
B) The parasite becomes extinct
C) The host becomes more resistant, and the parasite’s virulence diminishes D) The parasite relies more on non-host reservoirs

Answer 429

The host becomes more resistant, and the parasite’s virulence diminishes

Question 430

The host becomes more resistant, and the parasite’s virulence diminishes

Answer 430

It kills its host before transmission

Question 431

What type of pathogen transmission involves living or nonliving intermediaries? A) Direct transmission
B) Indirect transmission
C) Zoonotic transmission
D) Airborne transmission

Answer 431

indirect transmission

Question 432

Which of the following is a living agent of indirect transmission? A) Soil
B) Vector
C) Fomite
D) Air

Answer 432

vector

Question 433

What is an example of a zoonotic disease? A) Influenza
B) Cholera
C) Rabies
D) None of the above

Answer 433

rabies

Question 434

Typhoid Mary is an example of: A) A vector
B) A common-source epidemic C) A carrier
D) A zoonotic reservoir

Answer 434

carrier

Question 435

hich of the following has the highest basic reproduction number? A) Influenza
B) Measles
C) Rubella
D) Polio

Answer 435

measles

Question 436

Which disease control strategy involves restricting the movement of infected individuals? A) Surveillance
B) Immunization
C) Quarantine

D) Eradication

Answer 436

quarantine

Question 437

How are airborne pathogens typically controlled? A) Quarantine of infected individuals
B) Water purification systems
C) They are difficult to control effectively
D) Immunization of the host

Answer 437

They are difficult to control effectively

Question 438

What is the goal of pathogen eradication? A) Eliminate a pathogen from living hosts only B) Remove all pathogens from reservoirs
C) Reduce the pathogen’s virulence
D) Control the host population

Answer 438

Remove all pathogens from reservoirs

Question 439

Which of these diseases has been eradicated through immunization? A) Polio
B) Smallpox
C) Rabies
D) Measles

Answer 439

smallpox

Question 440

What is a significant difference between infectious disease patterns in Africa and the Americas?

A) Noninfectious diseases dominate mortality in Africa
B) Infectious disease death rates are higher in the Americas C) Infectious diseases cause most deaths in Africa
D) Travelers to Africa are not at risk for infection

Answer 440

Infectious diseases cause most deaths in Africa

Question 441

Which of the following diseases is considered one of the least transmissible? A) Influenza
B) Measles
C) Pertussis
D) Polio

Answer 441

influenza

Question 442

What are diseases that suddenly become prevalent called? A) Epidemic diseases
B) Endemic diseases
C) Emergent diseases
D) Reemerging diseases

Answer 442

Emergent diseases

Question 443

Reemerging diseases are defined as:
A) Diseases that have become prevalent after being under control B) Diseases that were eradicated but have reappeared globally

C) Newly discovered diseases with high mortality rates D) Diseases restricted to developing countries

Answer 443

Diseases that have become prevalent after being under control

Question 444

Which of the following is an emergent disease in the United States? A) Polio
B) Lyme disease
C) Malaria
D) Tuberculosis

Answer 444

Lyme

Question 445

What is the vector for Lyme disease? A) Mosquitoes
B) Ticks
C) Fleas
D) Rodents

Answer 445

Ticks

Question 446

Which disease is caused by Vibrio cholerae? A) AIDS
B) Cholera
C) Influenza
D) Hemorrhagic fever

Answer 446

cholera

Question 447

How is cholera primarily transmitted?

A) Aerosol spray
B) Direct host-to-host contact
C) Ingestion of contaminated water D) Vector-borne transmission

Answer 447

Ingestion of contaminated water

Question 448

What characteristic differentiates antigenic shift from antigenic drift in influenza viruses? A) Antigenic shift involves gene reassortment, while antigenic drift involves gene mutation B) Antigenic drift causes pandemics, while antigenic shift causes localized outbreaks
C) Antigenic shift is a minor change, while antigenic drift is a major change
D) Antigenic drift occurs every 10 years, while antigenic shift is constant

Answer 448

Antigenic shift involves gene reassortment, while antigenic drift involves gene mutation

Question 449

8. What type of influenza was responsible for the 2009 pandemic? A) Avian influenza
   B) Swine influenza (H1N1)
   C) Human influenza (H3N2)
   D) Reassorted bird-human influenza

Answer 449

swine

Question 450

Which of the following is a characteristic of an effective biological weapon? A) Complex to produce and deliver
B) Debilitates but does not kill
C) Safe for offensive personnel to use
D) Difficult to spread consistently

Answer 450

C) Safe for offensive personnel to use

Question 451

Which bacterial toxin is considered a potential biological weapon? A) Cholera toxin
B) Botulinum toxin
C) Tetanus toxin
D) Diphtheria toxin

Answer 451

botulinum

Question 452

Why is the smallpox virus considered a potential biological weapon? A) It has a low mortality rate but is hard to control
B) It can be spread by aerosol and contact, causing a high mortality rate C) Vaccines are widely available and used by the general population
D) It is challenging to deliver consistently

Answer 452

It can be spread by aerosol and contact, causing a high mortality rate

Question 453

How was the 2009 H1N1 swine flu pandemic an example of reassortment?
A) It was caused by gene mutation in a single influenza strain
B) It resulted from simultaneous infections with swine, bird, and human influenza strains C) It emerged from a shift in human behavior and agricultural practices
D) It was a result of antigenic drift over several decades

Answer 453

It resulted from simultaneous infections with swine, bird, and human influenza strains

Question 454

Which disease is transmitted via a small water crustacean as part of its cycle? A) Cholera
B) Influenza

C) Tuberculosis D) Zika virus

Answer 454

Zika virus

Question 455

What is the estimated mortality rate of smallpox in unvaccinated populations? A) 10%
B) 20%
C) 30% or more
D) 50%

Answer 455

30%

Question 456

Why is the potential deployment of smallpox as a biological weapon considered low? A) It is no longer infectious in nature
B) Military personnel are routinely vaccinated against smallpox
C) The vaccine has not been developed for civilian use
D) Smallpox virus cannot be easily spread

Answer 456

Military personnel are routinely vaccinated against smallpox