AI prac quizz

Question 1

Which of the following is NOT a characteristic of adaptive immunity?
A) Specificity
B) Memory
C) Immediate response
D) Diversity

Answer 1

C

Question 2

Adaptive immunity develops:
A) Immediately upon pathogen entry
B) After exposure to an antigen
C) Without exposure to antigens
D) Through genetic inheritance

Answer 2

B

Question 3

What is the main function of memory cells?
A) Produce enzymes
B) Provide nonspecific immunity
C) Respond rapidly to re-exposure
D) Eliminate self-antigens

Answer 3

C

Question 4

What distinguishes adaptive immunity from innate immunity?
A) Use of physical barriers
B) Inflammatory response
C) Antigen specificity
D) Use of phagocytes

Answer 4

C

Question 5

Which is an example of passive immunity?
A) Flu vaccine
B) Recovery from measles
C) Receiving maternal antibodies via breastmilk
D) B cell activation

Answer 5

C

Question 6

The third line of defense is also known as:
A) Innate immunity
B) Inflammatory response
C) Adaptive immunity
D) Complement activation

Answer 6

C

Question 7

Which type of adaptive immunity involves antibodies?
A) Cell-mediated
B) Passive
C) Humoral
D) Innate

Answer 7

C

Question 8

Which type of immunity would fight cancerous cells directly?
A) Humoral
B) Innate
C) Passive
D) Cell-mediated

Answer 8

D

Question 9

Active immunity always leads to:
A) Autoimmunity
B) Antibody transfer
C) Immunological memory
D) Temporary protection

Answer 9

C

Question 10

Diversity in adaptive immunity comes from:
A) Antibody class switching
B) Constant region variation
C) Receptor gene rearrangement
D) Phagocytosis

Answer 10

C

Question 11

What cell type produces antibodies?
A) Helper T cells
B) Plasma cells
C) Memory T cells
D) Macrophages

Answer 11

B

Question 12

The main role of antibodies is to:
A) Activate neutrophils
B) Phagocytose pathogens
C) Recognize and neutralize antigens
D) Suppress inflammation

Answer 12

C

Question 13

The first antibody class to appear in an infection is:
A) IgG
B) IgE
C) IgM
D) IgA

Answer 13

C

Question 14

Which antibody is most abundant in serum?
A) IgD
B) IgA
C) IgM
D) IgG

Answer 14

D

Question 15

What is another name for antibodies?
A) Cytokines
B) γ-globulins
C) Leukocytes
D) MHC proteins

Answer 15

B

Question 16

Antibody molecules are composed of:
A) 1 heavy and 1 light chain
B) 2 light chains and 1 heavy chain
C) 2 heavy and 2 light chains
D) 4 light chains

Answer 16

C

Question 17

The antigen-binding part of an antibody is found in the:
A) Constant region
B) Disulfide bridge
C) Variable region
D) Fc region

Answer 17

C

Question 18

IgE is primarily involved in:
A) Bacterial infections
B) Allergic responses
C) Mucosal immunity
D) Long-term memory

Answer 18

B

Question 19

Which immunoglobulin protects mucosal surfaces?
A) IgM
B) IgG
C) IgA
D) IgD

Answer 19

C

Question 20

Which function is NOT performed by antibodies?
A) Opsonization
B) Neutralization
C) Complement activation
D) Direct cell lysis

Answer 20

D

Question 21

Which cell presents antigens using MHC class I?
A) CD4 T cell
B) B cell
C) Dendritic cell
D) Macrophage

Answer 21

C

Question 22

MHC class I molecules activate which T cell type?
A) CD4+ helper T cells
B) CD8+ cytotoxic T cells
C) Regulatory T cells
D) Plasma cells

Answer 22

B

Question 23

Cytotoxic T cells destroy infected cells via:
A) Opsonization
B) Complement activation
C) Apoptosis
D) Phagocytosis

Answer 23

C

Question 24

Helper T cells are identified by:
A) CD4 markers
B) Antibodies
C) MHC II receptors
D) CD8 markers

Answer 24

A

Question 25

The main function of helper T cells is to: A) Kill infected cells directly B) Suppress immune responses C) Activate B cells and other immune cells D) Produce antibodies

Answer 25

C

Question 26

Regulatory T cells: A) Promote memory formation B) Moderate the immune response C) Secrete antibodies D) Kill foreign cells

Answer 26

B

Question 27

Which T cell subset forms after antigen activation and aids in future responses? A) Plasma cells B) Memory T cells C) Naive T cells D) NK cells

Answer 27

B

Question 28

CD8+ T cells become: A) Plasma cells B) Cytotoxic T cells C) Helper T cells D) Dendritic cells

Answer 28

B

Question 29

Activation of a CD4+ T cell requires antigen presentation via: A) MHC I B) Immunoglobulin C) TCRs D) MHC II

Answer 29

D

Question 30

Which of the following is an antigen-presenting cell (APC)? A) Neutrophil B) Mast cell C) Dendritic cell D) Eosinophil

Answer 30

C

Question 31

A vaccine typically generates which type of immunity? A) Passive B) Active C) Innate D) Autoimmune

Answer 31

B

Question 32

What triggers differentiation of B cells into plasma cells? A) Antigen presentation by MHC I B) Cytokines from CD4+ T cells C) Maturation in the thymus D) NK cell activation

Answer 32

B

Question 33

Which cells produce cytokines to recruit and activate immune cells? A) Memory B cells B) CD8+ T cells C) Helper T cells D) Neutrophils

Answer 33

C

Question 34

What is the role of opsonization? A) Inhibit virus replication B) Increase antibody production C) Tag pathogens for phagocytosis D) Neutralize toxins

Answer 34

C

Question 35

Where does T cell maturation occur? A) Spleen B) Bone marrow C) Thymus D) Lymph nodes

Answer 35

C

Question 36

Which immunoglobulin plays a major role in allergic reactions? A) IgG B) IgA C) IgM D) IgE

Answer 36

D

Question 37

The secondary immune response is: A) Slower than the primary B) Weaker than the primary C) Enhanced by memory cells D) Absent in active immunity

Answer 37

C

Question 38

CD8+ cells are best known for: A) Antibody secretion B) Killing infected host cells C) Activating B cells D) Regulating inflammation

Answer 38

B

Question 39

MHC molecules are essential for: A) Antibody secretion B) Cytokine production C) Antigen presentation D) Plasma cell formation

Answer 39

C

Question 40

Which immunoglobulin acts primarily as a B cell receptor? A) IgA B) IgD C) IgE D) IgG

Answer 40

B

Question 41

Explain how the adaptive immune system distinguishes between self and non-self antigens. Why is this ability crucial?

Answer 41

T and B lymphocytes undergo selection processes during development to ensure they recognize foreign (non-self) antigens but are tolerant to self-antigens. In the thymus, T cells that strongly react to self-antigens are eliminated through negative selection. This discrimination is essential to prevent autoimmunity, where the immune system attacks the body’s own tissues.

Question 42

Compare and contrast the roles of CD4+ and CD8+ T cells in the adaptive immune response. Include their modes of activation and primary functions.

Answer 42

CD4+ T cells (Helper T cells) are activated by antigen presented on MHC class II molecules and help activate B cells, cytotoxic T cells, and macrophages by secreting cytokines. CD8+ T cells (Cytotoxic T cells) are activated by antigen presented on MHC class I and directly kill infected or abnormal cells through induction of apoptosis. Both form memory cells after activation for long-term immunity.

Question 43

Describe the process of B cell activation and differentiation, including the role of helper T cells in this mechanism.

Answer 43

B cells recognize a specific antigen using their surface-bound immunoglobulin (Ig). For full activation (especially with protein antigens), they present the antigen via MHC II to a CD4+ helper T cell, which then provides co-stimulatory signals and cytokines. Activated B cells differentiate into plasma cells (which secrete antibodies) and memory B cells for future responses.

Question 44

What are the structural components of an antibody molecule, and how does its structure relate to its function?

Answer 44

Antibodies have a Y-shaped structure with 2 heavy chains and 2 light chains, linked by disulfide bridges. Each chain has a variable region (binds specific antigens) and a constant region (determines antibody class and function). This structure allows antibodies to specifically recognize antigens and recruit immune mechanisms such as complement activation or opsonization

Question 45

Outline the differences between primary and secondary humoral immune responses. What immunological mechanisms account for these differences?

Answer 45

Primary response is slower and weaker, occurring on first exposure to an antigen, involving naïve B cells. Secondary response is faster and stronger due to the presence of memory B cells, which rapidly differentiate into plasma cells upon re-exposure. It also produces more IgG antibodies compared to the IgM-dominant primary response.

Question 46

Discuss the role of antigen-presenting cells (APCs) in initiating T cell-mediated immunity. Include the significance of MHC class I and II molecules.

Answer 46

APCs (e.g., dendritic cells) capture and process antigens, then present them on MHC molecules. MHC class II presents to CD4+ T cells (helper T cells), triggering cytokine production and immune coordination. MHC class I presents to CD8+ T cells (cytotoxic T cells), leading to the killing of infected cells. This presentation is necessary for T cell activation.

Question 47

What is the functional significance of each major class of immunoglobulin (IgM, IgG, IgA, IgE, IgD)? Provide one example of when each might be important.

Answer 47

IgM: First produced during infection; activates complement. Example: Initial response to bacterial infection. IgG: Most abundant; long-term immunity. Example: Post-vaccination immunity. IgA: Found in mucosal secretions. Example: Breastmilk or protection at mucosal surfaces. IgE: Involved in allergies and parasites. Example: Allergic rhinitis or helminth infection. IgD: Acts as a receptor on naïve B cells. Example: Early B cell development.

Question 48

Describe the pathway of T cell maturation from origin to effector function, including key tissues and differentiation signals involved

Answer 48

T cells originate in the red bone marrow and migrate to the thymus for maturation. There, they develop T cell receptors (TCRs) and are tested for self-tolerance (positive and negative selection). Depending on the signals received, they differentiate into CD4+ or CD8+ cells. Once activated by APCs in lymphoid tissues, they become effector T cells (e.g., helper or cytotoxic) or memory T cells.

Question 49

Explain how cytotoxic T lymphocytes (CD8+ T cells) eliminate infected or abnormal cells. Include the steps involved in target recognition and killing.

Answer 49

CD8+ T cells recognize antigens presented on MHC class I of infected or abnormal cells. Upon binding, they release perforin (forms pores) and granzymes (enter cells to trigger apoptosis). This leads to programmed cell death, eliminating the pathogen-infected or cancerous cells.

Question 50

Passive and active immunity are both important in disease prevention. Compare their sources, duration, and clinical uses.

Answer 50

Passive immunity: Antibodies are transferred (e.g., maternal IgA via breastmilk or antiserum). It is immediate but short-lived. Used in post-exposure treatments (e.g., rabies or tetanus). Active immunity: Developed via infection or vaccination. It is slower to develop but long-lasting due to memory cell formation. Used in preventative immunization.

Question 51

Compare and contrast MHC class I and MHC class II molecules in terms of their expression, function, and role in the activation of different T cell subsets

Answer 51

MHC class I (MHC I) molecules are expressed on all nucleated cells in the body. Their primary function is to present endogenous (intracellular) antigens, such as viral or tumor-derived peptides, to CD8+ cytotoxic T cells. This interaction triggers the destruction of infected or abnormal cells by inducing apoptosis. MHC class II (MHC II) molecules are expressed only on professional antigen-presenting cells (APCs), such as dendritic cells, macrophages, and B cells. MHC II presents exogenous (extracellular) antigens to CD4+ helper T cells, which then coordinate immune responses by activating B cells, cytotoxic T cells, and macrophages via cytokine secretion. While both MHC I and II are crucial for T cell activation, MHC I is associated with cell-mediated cytotoxicity, and MHC II is associated with immune regulation and coordination through helper T cells

Question 52

What is required for T cells to recognize antigens? A) Free-floating antigens B) Antigen-antibody complexes C) Antigen presentation by MHC D) B cell activation

Answer 52

C

Question 53

Antigen-presenting cells (APCs) include all EXCEPT: A) Dendritic cells B) Macrophages C) B cells D) Erythrocytes

Answer 53

D

Question 54

The primary function of antigen presentation is to: A) Destroy antigens B) Generate antibodies C) Stimulate the adaptive immune response D) Activate neutrophils

Answer 54

C

Question 55

Which cell is primarily activated by antigen presentation on MHC II? A) CD8+ T cell B) Natural killer cell C) CD4+ T cell D) B cell

Answer 55

C

Question 56

B cells differ from T cells because: A) They produce cytokines B) They don't recognize antigens C) They recognize free antigens D) They mature in the thymus

Answer 56

C

Question 57

Which type of antigen is typically presented via MHC Class I? A) Bacterial toxins B) Viral proteins C) Parasite-derived antigens D) Exogenous antigens

Answer 57

B

Question 58

MHC is located on which chromosome in humans? A) 3 B) 6 C) 14 D) 21

Answer 58

B

Question 59

In humans, MHC molecules are also referred to as: A) MLC B) HLA C) DLA D) CMA

Answer 59

B

Question 60

The antigen-binding groove of MHC I is formed between: A) α1 and β1 B) α2 and β2 C) α1 and α2 D) β1 and β2

Answer 60

C

Question 61

Which cells express MHC Class I? A) Only APCs B) Only immune cells C) All nucleated cells D) Red blood cells only

Answer 61

C

Question 62

MHC Class II molecules are composed of: A) One α and one β2-microglobulin B) One α chain C) Two chains (α and β) D) A β and γ chain

Answer 62

C

Question 63

MHC Class I is recognized by: A) CD4+ T cells B) CD8+ T cells C) B cells D) NK cells

Answer 63

B

Question 64

MHC Class II presents antigens to: A) Cytotoxic T cells B) Helper T cells C) Dendritic cells D) Plasma cells

Answer 64

B

Question 65

The peptide-binding groove of MHC Class II is between: A) α1 and β1 B) α2 and β2 C) β1 and β2 D) α1 and α2

Answer 65

A

Question 66

The invariant chain in MHC Class II: A) Binds CD8+ cells B) Prevents peptide binding in the ER C) Activates cytokine secretion D) Forms the antigen groove

Answer 66

B

Question 67

What transports peptides into the ER during MHC I presentation? A) CLIP B) TAP C) HLA-DM D) Lysosomes

Answer 67

B

Question 68

HLA-DM is involved in: A) Stabilizing MHC I B) Transporting peptides to the ER C) Replacing CLIP in MHC II D) Recognizing antigens

Answer 68

C

Question 69

CLIP is derived from which molecule? A) MHC II B) TAP C) Invariant chain D) CD4

Answer 69

C

Question 70

Which process occurs in the proteasome during MHC I processing? A) Peptide fusion B) Antibody production C) Protein degradation D) CLIP replacement

Answer 70

C

Question 71

Where are peptides loaded onto MHC Class II molecules? A) Endoplasmic reticulum B) Golgi apparatus C) Lysosome/endosome D) Plasma membrane

Answer 71

C

Question 72

Which immune component is first to act against viral infection? A) Cytotoxic T cells B) B cells C) Natural killer cells D) IgG antibodies

Answer 72

C

Question 73

Which interferons are primarily antiviral in the innate response? A) IFN-γ and IL-6 B) IFN-α and IFN-β C) IL-1 and TNF D) IFN-γ and TGF-β

Answer 73

B

Question 74

IgA prevents viral: A) DNA replication B) Entry into mucosal cells C) Protein synthesis D) Antigen presentation

Answer 74

B

Question 75

IgM prevents viral infection by: A) Promoting apoptosis B) Activating NK cells C) Agglutinating viral particles D) Binding Fc receptors

Answer 75

C

Question 76

IgG functions include all EXCEPT: A) Enhancing phagocytosis B) Triggering antibody production C) Activating complement D) Neutralizing pathogens

Answer 76

B

Question 77

The most effective response to intracellular viruses involves: A) CD4+ T cells B) Plasma cells C) CD8+ T cells D) B cell memory

Answer 77

C

Question 78

Fungi are primarily cleared by: A) Antibodies B) Eosinophils C) Phagocytosis D) Toxins

Answer 78

C

Question 79

Which complement pathway is especially active against fungi? A) Classical B) Lectin C) Alternate D) Lytic

Answer 79

B

Question 80

Early bacterial infections are often cleared by: A) Cytokines alone B) Phagocytic cells C) CD8+ T cells D) IFN-γ

Answer 80

B

Question 81

Strongly pathogenic bacteria induce: A) Suppression of immunity B) Innate only C) Adaptive immune response D) Fungal-like response

Answer 81

C

Question 82

Which immune components neutralize bacterial toxins? A) NK cells B) T cells C) Antibodies D) Complement proteins

Answer 82

C

Question 83

In malaria, sporozoites first invade: A) Red blood cells B) Liver cells C) Lymph nodes D) Bone marro

Answer 83

B

Question 84

Merozoites primarily infect: A) Liver B) Brain C) Red blood cells D) Endothelium

Answer 84

C

Question 85

Antibodies prevent malaria by: A) Killing mosquitoes B) Inhibiting sporozoite invasion C) Activating CD8+ cells D) Releasing histamine

Answer 85

B

Question 86

CD8+ T cells help control malaria by: A) Enhancing NK cell function B) Inhibiting B cell maturation C) Killing infected hepatocytes D) Activating eosinophil

Answer 86

C

Question 87

A deficiency in TAP would impair: A) MHC II loading B) CLIP replacement C) MHC I antigen presentation D) CD4+ T cell signaling

Answer 87

C

Question 88

Which would most likely fail to respond to exogenous bacterial antigens? A) CD4+ T cells B) MHC II-deficient cells C) APCs D) B cells

Answer 88

B

Question 89

Which step is shared between MHC I and II pathways? A) Peptide loading in ER B) Use of proteasome C) Transport to cell surface D) Invariant chain use

Answer 89

C

Question 90

What would happen if CLIP was not removed from MHC II? A) Overactivation of CD8+ T cells B) Inhibition of CD4+ T cell activation C) Increased phagocytosis D) Excessive complement activation

Answer 90

B

Question 91

Which immune cell bridges innate and adaptive immunity via antigen presentation? A) Neutrophil B) NK cell C) Dendritic cell D) Plasma cell

Answer 91

C

Question 92

Explain the role of the Major Histocompatibility Complex (MHC) in antigen presentation and its significance in adaptive immunity. Answer:

Answer 92

MHC molecules present antigenic peptides on the surface of cells to T lymphocytes. This is crucial because T cells can only recognize antigens when presented in the context of self-MHC molecules. MHC presentation ensures that the immune response is specific to foreign antigens and allows for the activation of CD4+ or CD8+ T cells, triggering adaptive immunity.

Question 93

Compare and contrast MHC Class I and MHC Class II molecules in terms of their structure, expression patterns, and the types of antigens they present.

Answer 93

MHC Class I: Found on all nucleated cells; presents endogenous antigens (e.g., viral proteins); composed of one α chain and β2-microglobulin; interacts with CD8+ cytotoxic T cells. MHC Class II: Expressed only on professional antigen-presenting cells (APCs); presents exogenous antigens (e.g., bacterial peptides); made of two chains (α and β); interacts with CD4+ helper T cells.

Question 94

Describe the steps involved in the MHC Class I antigen presentation pathway.

Answer 94

Intracellular proteins (e.g., viral) are degraded by the proteasome. Resulting peptides are transported into the endoplasmic reticulum (ER) by the TAP transporter. Peptides are loaded onto MHC I molecules in the ER. The peptide–MHC I complex is transported to the cell surface for recognition by CD8+ T cells.

Question 95

Outline the MHC Class II antigen presentation pathway, highlighting the role of the invariant chain and HLA-DM.

Answer 95

Exogenous antigens are endocytosed and degraded in endosomes. MHC II is synthesized in the ER and associates with the invariant chain (Ii) to prevent premature peptide loading. In endosomes, the invariant chain is degraded, leaving CLIP in the groove. HLA-DM facilitates removal of CLIP and replaces it with an antigenic peptide. The MHC II–peptide complex is transported to the surface for recognition by CD4+ T cells.

Question 96

Why do T cells require antigens to be presented via MHC molecules, whereas B cells can recognize free antigens? What advantage does this provide in immune coordination?

Answer 96

cell receptors (TCRs) can only recognize peptide antigens bound to MHC molecules. In contrast, B cell receptors (BCRs) recognize free, intact antigens. MHC-restricted presentation ensures that T cell activation is tightly regulated, occurs only in response to processed, relevant antigens, and prevents unintended responses to harmless substances, improving immune specificity and control.

Question 97

Describe the differences in immune response to bacterial vs. viral infections, emphasizing the role of antigen presentation and resulting immune effector functions.

Answer 97

Bacterial antigens (exogenous) are presented by MHC II to CD4+ helper T cells, which activate B cells to produce antibodies, leading to neutralization and opsonization. Viral antigens (endogenous) are presented by MHC I to CD8+ cytotoxic T cells, which kill infected cells. Viral infections also trigger interferon production and NK cell activation for early defense

Question 98

What is the function of TAP in antigen processing, and what would be the consequence of a defect in the TAP transporter?

Answer 98

TAP (Transporter Associated with Antigen Processing) moves peptides from the cytosol into the ER where they can bind to MHC I molecules. A TAP defect would prevent peptide loading onto MHC I, leading to impaired activation of CD8+ T cells and a weakened cytotoxic immune response to viruses and intracellular pathogens.

Question 99

Explain how the immune system responds to malaria infection, and specify the immune cells and mechanisms involved in targeting both sporozoite and merozoite stages.

Answer 99

Sporozoites infect liver cells: blocked by antibodies, and controlled by CD8+ T cells and IFN-γ, which limit parasite development. Merozoites infect red blood cells: targeted by antibodies, which block invasion and promote clearance. NK cells also help kill parasitized cells. These combined humoral and cellular responses reduce parasite replication and spread.

Question 100

Discuss the role of interferons and Natural Killer (NK) cells in the early immune response to viral infection.

Answer 100

Type I interferons (IFN-α, IFN-β) are produced early during viral infection and induce an antiviral state in neighboring cells by inhibiting viral replication. They also enhance the cytotoxic activity of NK cells, which can recognize and kill virally infected cells that lack MHC I expression, helping control infection before the adaptive immune system is activated.

Question 101

How do antigen-presenting cells (APCs) contribute to bridging the innate and adaptive immune systems? Give examples of professional APCs and their functions.

Answer 101

APCs such as dendritic cells, macrophages, and B cells take up antigens, process them, and present peptide fragments on MHC molecules to naïve T cells, initiating adaptive immunity. They also secrete cytokines that guide T cell differentiation and activation. Dendritic cells are especially efficient at activating naïve T cells, making them crucial for linking innate recognition with adaptive response.

Question 102

Which of the following is a primary lymphoid organ? A. Spleen B. Bone marrow C. Lymph node D. MALT

Answer 102

B

Question 103

T-cell maturation occurs in the: A. Spleen B. Bone marrow C. Thymus D. Lymph node

Answer 103

C

Question 104

Which of the following is not a cellular component of the immune system? A. Macrophage B. Neutrophil C. Platelet D. NK cell

Answer 104

C

Question 105

The spleen is responsible for: A. Producing antibodies B. Filtering lymph C. Filtering blood D. Maturation of B cells

Answer 105

C

Question 106

Which of the following is a molecular component of the immune system? A. NK cell B. Bone marrow C. Cytokine D. Dendritic cell

Answer 106

C

Question 107

What type of immunity is present from birth and does not improve over time? A. Adaptive immunity B. Acquired immunity C. Passive immunity D. Innate immunity

Answer 107

D

Question 108

The first line of immune defense includes: A. NK cells B. Surface barriers C. Complement system D. Fever

Answer 108

B

Question 109

The mucosa-associated lymphoid tissue (MALT) is primarily found in the: A. Thymus B. Spleen C. Small intestine D. Liver

Answer 109

C

Question 110

Which white blood cells are involved in innate immunity? A. B cells B. Plasma cells C. T-helper cells D. Neutrophils

Answer 110

D

Question 111

Which is the major function of chemokines? A. Inducing fever B. Causing lysis C. Attracting immune cells D. Producing antibodies

Answer 111

C

Question 112

Which of the following is a phagocyte that circulates in the blood? A. Dendritic cell B. Macrophage C. Monocyte D. Kupffer cell

Answer 112

C

Question 113

Kupffer cells are fixed phagocytes found in the: A. Lung B. Spleen C. Liver D. Skin

Answer 113

C

Question 114

Which of the following is not a function of phagocytes? A. Cytokine secretion B. Phagocytosis C. Antibody production D. Chemotaxis

Answer 114

C

Question 115

Which of the following initiates immune surveillance by recognizing abnormal cells? A. T helper cells B. Basophils C. NK cells D. Dendritic cells

Answer 115

C

Question 116

Natural Killer (NK) cells are best described as: A. Antibody-producing B cells B. Small agranular leukocytes C. Large granular lymphocytes D. Helper T cells

Answer 116

C

Question 117

Dendritic cells function mainly to: A. Release histamine B. Produce antibodies C. Present antigens to T cells D. Lyse infected cells

Answer 117

C

Question 118

Which cytokines guide immune cells to sites of infection? A. Interferons B. Antibodies C. Chemokines D. Antigens

Answer 118

C

Question 119

Which immune cell is not phagocytic? A. Neutrophil B. Macrophage C. B cell D. Dendritic cell

Answer 119

B

Question 120

Which of the following phagocytes can also present antigens? A. Neutrophils B. Dendritic cells C. NK cells D. Mast cells

Answer 120

B

Question 121

Phagocytosis is primarily a mechanism of: A. Adaptive immunity B. Humoral immunity C. Innate immunity D. Passive immunity

Answer 121

C

Question 122

Acute inflammation involves recruitment of which immune cells? A. B cells B. T cells C. Neutrophils D. Basophils

Answer 122

C

Question 123

The complement system includes how many proteins? A. 10 B. 20 C. 30 D. 40

Answer 123

C

Question 124

The complement system is primarily activated by: A. Pyrogens B. Pathogen surfaces C. NK cells D. B-cell receptors

Answer 124

B

Question 125

Which of the following is not a function of the complement system? A. Cell lysis B. Antibody production C. Opsonization D. Inflammation

Answer 125

B

Question 126

The membrane attack complex (MAC) results in: A. Fever B. Cell lysis C. Cytokine release D. B-cell activation

Answer 126

B

Question 127

The classical complement pathway is initiated by: A. NK cells B. Bacterial cell walls C. Antigen-antibody complexes D. Pyrogens

Answer 127

C

Question 128

Which immunoglobulins can activate the classical pathway? A. IgA, IgE B. IgM, IgG C. IgD, IgA D. IgE, IgG4

Answer 128

B

Question 129

Alternative pathway is activated by: A. Immune complexes B. Antibodies C. Host membranes D. Foreign cell surfaces

Answer 129

D

Question 130

Which pathway involves mannose-binding lectin (MBL)? A. Classical B. Alternative C. Lectin D. Adaptive

Answer 130

C

Question 131

Sialic acid on mammalian cell membranes helps: A. Activate complement B. Inhibit C3b binding C. Increase inflammation D. Produce pyrogens

Answer 131

B

Question 132

Fever is initiated by the release of: A. Histamines B. Pyrogens C. Interferons D. MAC

Answer 132

B

Question 133

Pyrogens act on the: A. Liver B. Spleen C. Hypothalamus D. Bone marrow

Answer 133

C

Question 134

What is the normal body temperature threshold exceeded during a fever? A. 35°C B. 36°C C. 37°C D. 38.5°C

Answer 134

C

Question 135

Interferons function to: A. Kill bacteria B. Enhance NK cell activity C. Produce antibodies D. Lower fever

Answer 135

B

Question 136

Antimicrobial proteins enhance innate defense by: A. Stimulating B cells B. Attacking pathogens directly C. Decreasing inflammation D. Neutralizing antibodies

Answer 136

B

Question 137

Which of the following is not an antimicrobial protein? A. Complement B. Interferon C. Pyrogen D. Defensin

Answer 137

C

Question 138

Complement proteins are part of: A. Adaptive immunity B. Acquired immunity C. Innate immunity D. Passive immunity

Answer 138

C

Question 139

Which of the following can trigger interferon release? A. Viruses B. Fungi C. Parasites D. Allergens

Answer 139

A

Question 140

The role of interferons is mostly directed against: A. Bacteria B. Viruses C. Parasites D. Toxins

Answer 140

B

Question 141

Antimicrobial proteins do not function by: A. Enhancing phagocytosis B. Killing pathogens C. Neutralizing toxins D. Producing antibodies

Answer 141

D

Question 142

What are the primary lymphoid organs and their functions?

Answer 142

The bone marrow (site of hematopoiesis and B-cell maturation) and thymus (site of T-cell maturation).

Question 143

Name two types of phagocytes and describe their role.

Answer 143

Neutrophils and macrophages. They ingest and eliminate pathogens and debris through phagocytosis and release cytokines to recruit other immune cells.

Question 144

What is the function of NK (Natural Killer) cells in innate immunity?

Answer 144

NK cells identify and destroy abnormal or infected cells, providing immune surveillance without the need for antigen presentation.

Question 145

What triggers a fever and how is it beneficial?

Answer 145

Pyrogens released by leukocytes act on the hypothalamus to raise body temperature, which helps inhibit pathogen growth and enhances immune activity.

Question 146

What are the three pathways of complement activation?

Answer 146

Classical pathway (triggered by antigen-antibody complexes), alternative pathway (triggered by foreign cell surfaces), and lectin pathway (triggered by mannose-binding lectin binding to pathogens).

Question 147

Define opsonization and its importance.

Answer 147

Opsonization is the coating of pathogens with complement proteins or antibodies to enhance their recognition and ingestion by phagocytes.