Question 1

Which of the following best describes the role of Toll-like receptors (TLRs) in the innate immune response?

Accepted Answer

TLRs recognize specific patterns associated with microbial invaders and initiate signaling pathways that alter gene expression.

Question 2

Which of the following antimicrobial substances is responsible for sequestering iron, thereby inhibiting microbial growth?

Accepted Answer

Lactoferrin

Question 3

A patient with a genetic defect that prevents the formation of the membrane attack complex (MAC) would be most susceptible to infections by which type of bacteria?

Accepted Answer

Gram-negative bacteria

Question 4

Which of the following is NOT a cardinal sign of inflammation?

Accepted Answer

Fever

Question 5

Which pathway of complement activation is initiated by the binding of mannan-binding lectins to microbial surfaces?

Accepted Answer

Lectin pathway

Question 6

What is the primary function of neutrophils in the innate immune response?

Accepted Answer

Engulfment and digestion of microbes and cellular debris

Question 7

Which of the following best explains why normal flora are considered part of the first line of defense?

Accepted Answer

They compete with pathogens for binding sites and nutrients, limiting pathogen colonization.

Question 8

Which cytokine class is primarily responsible for directing the migration of immune cells to sites of infection?

Accepted Answer

Chemokines

Question 9

A researcher observes that a certain immune cell can engulf pathogens, present antigens, and activate T cells. Which cell type is most likely being observed?

Accepted Answer

Dendritic cell

Question 10

Which of the following events occurs during the process of phagocytosis after the phagocyte engulfs the microbe?

Accepted Answer

The phagosome fuses with a lysosome to form a phagolysosome.

Question 11

Which of the following best describes the role of C3b in the complement system?

Accepted Answer

Functions as an opsonin, enhancing phagocytosis of microbes

Question 12

A patient presents with recurrent bacterial infections but normal viral immunity. Which innate immune defect is most likely?

Accepted Answer

Deficiency in lysozyme activity

Question 13

Which of the following is a correct sequence of events during the inflammatory response?

Accepted Answer

Vasodilation, increased vascular permeability, diapedesis of phagocytes

Question 14

Which of the following statements about apoptosis is TRUE?

Accepted Answer

It is a form of programmed cell death that does not elicit an inflammatory response.

Question 15

Which of the following best explains why fever is considered a beneficial host defense mechanism?

Accepted Answer

Fever elevates body temperature above the maximum growth temperature of many pathogens and accelerates immune responses.

Question 16

Which of the following is a function of adhesion molecules during the immune response?

Accepted Answer

They allow immune cells to adhere to each other and facilitate the recruitment of phagocytes to sites of injury.

Question 17

Which of the following best describes the difference between the classical and alternative pathways of complement activation?

Accepted Answer

The classical pathway is initiated by antigen-antibody complexes, while the alternative pathway is initiated by C3b binding to microbial surfaces.

Question 18

Which of the following is a direct outcome of complement activation?

Accepted Answer

Opsonization, inflammation, and lysis of foreign cells

Question 19

A patient is found to have a deficiency in colony-stimulating factors. Which of the following processes would be most directly affected?

Accepted Answer

Multiplication and differentiation of leukocytes from stem cells

Question 20

Which of the following best describes the role of defensins in innate immunity?

Accepted Answer

They are antimicrobial peptides that insert into microbial membranes, causing disruption.

Innate Immunity: Nonspecific Defenses of the Host

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