Question 1

Which of the following best describes the main difference between the first and second lines of defense in innate immunity?

Accepted Answer

The first line of defense consists of physical and chemical barriers, while the second line involves cellular and chemical responses to pathogens that breach these barriers.

Question 2

A patient with a genetic defect that prevents the formation of the membrane attack complex (MAC) would have the most difficulty with which aspect of innate immunity?

Accepted Answer

Lysis of pathogens via the complement system

Question 3

Which of the following is NOT a component of the first line of defense?

Accepted Answer

Phagocytosis

Question 4

Which cell type is primarily responsible for attacking parasitic helminths through extracellular killing?

Accepted Answer

Eosinophils

Question 5

A viral infection triggers the production of interferons. Which class of interferons is most likely to be present early in the infection?

Accepted Answer

Alpha and beta interferons

Question 6

Which of the following best explains why fever can be beneficial during an infection?

Accepted Answer

Fever enhances the effects of interferons and may inhibit the growth of some microorganisms.

Question 7

Which of the following statements about Toll-like receptors (TLRs) is correct?

Accepted Answer

TLRs are integral proteins of the cytoplasmic membrane of phagocytic cells that recognize PAMPs and trigger apoptosis of pathogens.

Question 8

A patient with a burn injury loses a large portion of their skin. Which aspect of their innate immunity is most compromised?

Accepted Answer

First line of defense, specifically the physical barrier provided by the skin

Question 9

Which of the following is a chemotactic factor that attracts phagocytes to the site of infection during inflammation?

Accepted Answer

Fibrin

Question 10

Which process is described by the following steps: recognition of a pathogen, engulfment, formation of a phagosome, fusion with a lysosome, and digestion of the pathogen?

Accepted Answer

Phagocytosis

Question 11

Which of the following best describes the role of the complement protein C3b in the immune response?

Accepted Answer

Promotes opsonization, enhancing phagocytosis of pathogens

Question 12

Which of the following is a correct sequence of events during acute inflammation after a cut becomes infected?

Accepted Answer

Release of inflammatory chemicals, vasodilation, increased permeability, migration of phagocytes, tissue repair

Question 13

Which of the following is NOT a function of the complement system?

Accepted Answer

Stimulating antibody production

Question 14

A patient is infected with an RNA virus. Which innate immune response is most likely to be activated to inhibit the spread of this virus?

Accepted Answer

Production of alpha and beta interferons

Question 15

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

Accepted Answer

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

Question 16

Which of the following is a correct statement about NOD proteins?

Accepted Answer

They are proteins in the cytosol of phagocytic cells that recognize PAMPs and trigger apoptosis of pathogens.

Question 17

Which of the following is a benefit of fever during infection?

Accepted Answer

It enhances the performance of phagocytes.

Question 18

A patient with a deficiency in neutrophils would be most susceptible to which of the following?

Accepted Answer

Reduced ability to phagocytose and kill bacteria

Question 19

Which of the following chemical mediators is responsible for both vasodilation and chemotactic effects during inflammation?

Accepted Answer

Complement fragment C5a

Question 20

Which of the following best describes the role of natural killer (NK) cells in innate immunity?

Accepted Answer

They secrete toxins onto the surface of virally infected cells and tumors, leading to cell death.

Innate Immunity: The First and Second Lines of Defense

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