Innate Immunity: A Comprehensive Guide for Medical Students

Question 1

Which of the following is NOT a mechanism of innate immunity?

Accepted Answer

Antibody production

Answer

Physical barriers

Answer

Phagocytosis

Question 2

Which of the following is NOT a physical barrier that contributes to innate immunity?

Accepted Answer

Neutrophils

Answer

Skin

Answer

Mucous membranes

Answer

Gastric acid

Question 3

Which chemical mediator triggers the inflammatory response?

Accepted Answer

Histamine

Answer

Interferon

Answer

Complement

Answer

C-reactive protein

Question 4

Which process involves engulfment and destruction of pathogens?

Accepted Answer

Phagocytosis

Answer

Opsonization

Answer

Complement activation

Answer

Antibody-mediated cytotoxicity

Question 5

Which is a non-specific mechanism of innate immunity?

Accepted Answer

Recognition of pathogen-associated molecular patterns (PAMPs)

Answer

Production of antibodies

Answer

Generation of cytotoxic T cells

Answer

Memory formation

Question 6

Which complement protein forms a membrane attack complex?

Accepted Answer

C5b-C9

Answer

C3a

Answer

C4

Answer

C6

Question 7

Which cell releases histamine in allergic reactions?

Accepted Answer

Basophil

Answer

Eosinophil

Answer

Neutrophil

Answer

Macrophage

Question 8

Which immune response releases antimicrobial peptides?

Accepted Answer

Defensin response

Answer

Interferon response

Answer

Complement response

Answer

Natural killer cell response

Question 9

Which of the following is a component of adaptive immunity?

Accepted Answer

Antibodies

Answer

Physical barriers

Answer

Chemical mediators

Answer

Phagocytes

Question 10

Which of the following is NOT a component of the innate immune response?

Accepted Answer

Antibodies

Answer

Physical barriers

Answer

Chemical mediators

Answer

Cellular components

Question 11

The process by which pathogens are engulfed and destroyed by phagocytes is known as:

Accepted Answer

Phagocytosis

Answer

Chemotaxis

Answer

Opsonization

Answer

Cytotoxicity

Question 12

The process of attracting phagocytes to the site of infection is called:

Accepted Answer

Chemotaxis

Answer

Recruitment

Answer

Inflammation

Answer

Phagocytosis

Question 13

The release of histamine and leukotrienes from mast cells is a characteristic feature of:

Accepted Answer

Type I hypersensitivity reaction

Answer

Type II hypersensitivity reaction

Answer

Type III hypersensitivity reaction

Answer

Type IV hypersensitivity reaction

Question 14

Explain the coordinated interplay between cytokines and chemokines in innate immune responses, providing specific examples of their roles in inflammation and recruitment of immune cells.

Accepted Answer

Cytokines trigger chemokine production, which subsequently directs immune cell recruitment to the site of infection or injury.

Answer

Cytokines independently promote inflammation, while chemokines recruit immune cells, operating in isolation.

Answer

Chemokines activate cytokine production, leading to the release of antimicrobial peptides.

Answer

Cytokines and chemokines have no direct interaction in innate immune responses.

Question 15

Which of the following is NOT a mechanism of innate immunity?

Accepted Answer

Adaptive immune response

Answer

Physical barriers

Answer

Chemical mediators

Answer

Cellular components

Question 16

Which of the following is NOT a cell type involved in innate immunity?

Accepted Answer

Antibodies

Answer

Macrophages

Answer

Natural killer cells

Answer

Neutrophils

Question 17

Which chemical mediator is responsible for vasodilation and increased vascular permeability during inflammation?

Accepted Answer

Histamine

Answer

Interferon

Answer

Complement

Answer

Cytokines

Question 18

What is the process by which phagocytic cells engulf and destroy microorganisms?

Accepted Answer

Phagocytosis

Answer

Opsonization

Answer

Cytokine release

Answer

Chemotaxis

Question 19

Which of the following is a characteristic of natural killer (NK) cells?

Accepted Answer

Ability to kill virus-infected cells

Answer

Expression of MHC class II molecules

Answer

Requirement for antigen presentation

Answer

Production of antibodies

Question 20

What is the primary function of dendritic cells in innate immunity?

Accepted Answer

Antigen presentation and linking innate and adaptive immunity

Answer

Complement activation

Answer

Phagocytosis

Answer

Cytokine secretion

Question 21

Which of the following is NOT a physical barrier of innate immunity?

Accepted Answer

Lysozyme

Answer

Skin

Answer

Mucous membranes

Answer

Epithelial cells

Question 22

Which of the following is NOT a type of physical barrier in innate immunity?

Accepted Answer

Antibodies

Answer

Mucus membranes

Answer

Tight junctions

Answer

Intact skin

Question 23

Which chemical mediator, released by activated macrophages, promotes vasodilation and increased vascular permeability, causing redness and swelling?

Accepted Answer

Histamine

Answer

Defensins

Answer

Cytokines

Answer

Interferon

Question 24

Which of the following cells is NOT involved in phagocytosis?

Accepted Answer

Lymphocytes

Answer

Neutrophils

Answer

Macrophages

Answer

Dendritic cells

Question 25

Which part of the complement cascade directly kills bacteria by forming pores in their membranes?

Accepted Answer

Membrane attack complex

Answer

Classical pathway

Answer

Lectin pathway

Answer

Alternative pathway

Question 26

Which of the following is a characteristic of innate immune responses?

Accepted Answer

Rapid, nonspecific and provides a first line of defense

Answer

Highly adaptive

Answer

Involves memory cells

Answer

Slow and specific

Question 27

Which of the following is NOT a function of natural killer (NK) cells?

Accepted Answer

Antibody production

Answer

Regulating adaptive immune responses

Answer

Releasing cytokines

Answer

Killing virus-infected cells

Question 28

Which cytokine is a major mediator of inflammation and causes the increased temperature, redness, swelling and pain associated with an immune response?

Accepted Answer

Tumor necrosis factor-alpha (TNF-alpha)

Answer

Interleukin-2 (IL-2)

Answer

Interferon-gamma (IFN-gamma)

Answer

Transforming growth factor-beta (TGF-beta)

Question 29

Which of the following is a key difference between innate and adaptive immunity?

Accepted Answer

Innate immunity lacks memory and is not tailored to specific pathogens, while adaptive immunity develops a targeted response to specific pathogens

Answer

Innate immunity is less effective against pathogens

Answer

Innate immunity is more specific

Answer

Innate immunity is only present in vertebrates

Question 30

Which of the following Toll-like receptors (TLRs) specifically recognizes bacterial lipopolysaccharide (LPS), a major component of Gram-negative bacterial cell walls?

Accepted Answer

TLR4

Answer

TLR2

Answer

TLR3

Answer

TLR5

Question 31

Which of the following is a primary mechanism of action of interferons?

Accepted Answer

Inhibiting viral replication by blocking mRNA translation

Answer

Activating the complement system through the classical pathway

Answer

Killing infected cells through perforin release

Answer

Promoting inflammation by releasing cytokines

Question 32

What is a defining feature of innate immunity?

Accepted Answer

Variety of recognition mechanisms

Answer

Specificity for particular pathogens

Answer

Ability to create long-term memory

Answer

Necessity for prior exposure to a pathogen

Question 33

Which of the following is NOT a physical barrier in the innate immune system?

Accepted Answer

Neutrophils

Answer

Skin

Answer

Mucous membranes

Answer

Epithelial cells

Question 34

Which of the following is NOT considered a physical barrier of innate immunity?

Accepted Answer

Fever

Answer

Intact skin acting as a mechanical barrier

Answer

Stomach acid with its low pH

Answer

Mucus produced by epithelial cells

Question 35

Which chemical mediator is primarily responsible for promoting vasodilation and increased vascular permeability during inflammation?

Accepted Answer

Histamine

Answer

Cytokine interleukin-6 (IL-6)

Answer

Interferon-gamma (IFN-γ)

Answer

Complement protein C3a

Question 36

What type of phagocytic cell is specialized in recognizing and engulfing foreign particles, such as bacteria and debris?

Accepted Answer

Macrophage

Answer

Neutrophil, primarily involved in acute inflammation

Answer

Basophil, involved in allergic reactions

Answer

Lymphocyte, part of the adaptive immune system

Question 37

Which pattern recognition receptor (PRR) is primarily responsible for recognizing bacterial lipopolysaccharide (LPS), a component of the outer membrane of Gram-negative bacteria?

Accepted Answer

Toll-like receptor 4 (TLR4)

Answer

C-type lectin receptor, recognizing carbohydrates on pathogens

Answer

NOD-like receptor, involved in intracellular pathogen detection

Answer

RIG-I-like receptor, recognizing viral RNA

Question 38

What is the primary function of the complement system in innate immunity?

Accepted Answer

Opsonization of pathogens and cell lysis through the formation of membrane attack complexes (MACs)

Answer

Antibody production, a function of adaptive immunity

Answer

Antigen presentation, primarily performed by antigen-presenting cells (APCs)

Answer

Inflammation, mainly mediated by the release of cytokines and chemokines

Question 39

Which type of innate immune response is characterized by the systemic release of pyrogenic cytokines, leading to an increase in body temperature, also known as fever?

Accepted Answer

Systemic inflammatory response syndrome (SIRS)

Answer

Delayed-type hypersensitivity, a cell-mediated immune response involving T cells

Answer

Anaphylaxis, a severe systemic allergic reaction mediated by IgE antibodies

Answer

Arthus reaction, a localized inflammatory reaction caused by antibody-antigen complexes

Question 40

What is the primary mechanism by which natural killer (NK) cells kill target cells, such as virus-infected cells or tumor cells?

Accepted Answer

Exocytosis of cytotoxic granules containing perforin and granzymes

Answer

Antibody-dependent cell-mediated cytotoxicity (ADCC), a mechanism mediated by antibodies and Fc receptors

Answer

Complement-mediated lysis, a mechanism involving the formation of membrane attack complexes (MACs)

Answer

Fas-mediated apoptosis, a mechanism triggered by the binding of Fas ligand to Fas receptors

Question 41

Excessive inflammation can lead to which of the following?

Accepted Answer

Tissue damage

Answer

Immune tolerance

Answer

Enhanced phagocytosis

Answer

Increased immune response

Question 42

Which of the following is NOT a physical barrier of innate immunity?

Accepted Answer

IgA

Answer

Mucous membranes

Answer

Gastric acid

Answer

Skin

Question 43

Which chemical mediator is primarily responsible for increased vascular permeability and vasodilation?

Accepted Answer

Histamine

Answer

Complement

Answer

Interferon

Answer

C-reactive protein

Question 44

What is the primary mechanism by which neutrophils eliminate ingested microorganisms?

Accepted Answer

Phagocytosis and production of reactive oxygen species

Answer

Antibody-mediated cytotoxicity

Answer

Complement-mediated lysis

Question 45

Which cell type plays a crucial role in the complement system?

Accepted Answer

Mast cell

Answer

T cell

Answer

Erythrocyte

Answer

B cell

Question 46

What is the primary function of natural killer (NK) cells?

Accepted Answer

Killing of virus-infected and tumor cells

Answer

Activation of the complement system

Answer

Phagocytosis of bacteria

Answer

Production of antibodies

Question 47

Which of the following cytokines is a key mediator of inflammation?

Accepted Answer

Tumor necrosis factor (TNF)

Answer

Interferon gamma (IFN-gamma)

Answer

Interleukin-10 (IL-10)

Answer

Transforming growth factor-beta (TGF-beta)

Question 48

What is the primary function of Toll-like receptors (TLRs)?

Accepted Answer

Recognition of pathogen-associated molecular patterns (PAMPs)

Answer

Binding to antibodies

Answer

Activation of the complement system

Question 49

What is a primary physiological effect of fever in innate immunity?

Accepted Answer

Inhibition of bacterial and viral replication

Answer

Activation of the complement system

Answer

Production of cytokines

Answer

Recruitment of phagocytic cells

Question 50

Which of the following is NOT a component of the innate immune system?

Accepted Answer

Antibodies

Answer

Skin

Answer

Complement system

Answer

Macrophages

Question 51

Which of the following is a defining characteristic of inflammation?

Accepted Answer

Increased vascular permeability

Answer

Reduced leukocyte migration

Answer

Decreased blood flow

Question 52

Toll-like receptors (TLRs) play a crucial role in innate immunity by:

Accepted Answer

Recognizing pathogen-associated molecular patterns (PAMPs)

Answer

Producing antibodies

Answer

Directly killing infected cells

Question 53

What is a key function of the skin in the innate immune system?

Accepted Answer

Physical barrier to pathogens

Answer

Activation of cytotoxic T cells

Answer

Secretion of cytokines

Answer

Production of antibodies

Question 54

A patient with a deficiency in interferon-alpha production would be most susceptible to which type of infection?

Accepted Answer

Viral infections

Answer

Bacterial infections

Answer

Parasitic infections

Answer

Fungal infections

Question 55

Natural killer (NK) cells contribute to innate immunity by:

Accepted Answer

Killing infected cells and tumor cells

Answer

Engulfing and destroying bacteria

Answer

Activating complement

Answer

Producing antibodies

Question 56

The release of which of the following is most likely responsible for a patient's fever?

Accepted Answer

Pyrogens

Answer

Histamine

Answer

Antibodies

Answer

Complement