Question 1

Which of the following best distinguishes innate immunity from adaptive immunity?

Accepted Answer

Innate immunity is present from birth and responds the same way to all exposures, while adaptive immunity is acquired and responds more strongly to subsequent exposures.

Question 2

A patient is exposed to a pathogen for the first time. Which immune response will act first, and what is a key characteristic of this response?

Accepted Answer

Innate immunity; it responds immediately and does not produce memory.

Question 3

Which cell type is directly responsible for killing virus-infected cells as part of the innate immune response?

Accepted Answer

Natural killer (NK) cells

Question 4

Cytokines are chemical messengers in the immune system. Which of the following is a correct match between a cytokine and its primary action?

Accepted Answer

Colony-stimulating factor: Stimulation of hematopoietic progenitor cell proliferation and differentiation

Question 5

Which of the following is an example of a physical barrier in innate immunity?

Accepted Answer

Skin epithelium

Question 6

A patient with a genetic defect in Toll-like receptor 4 (TLR4) would have difficulty recognizing which microbial component?

Accepted Answer

Lipopolysaccharide (LPS) from Gram-negative bacteria

Question 7

Which of the following best describes the process of opsonization?

Accepted Answer

Coating of pathogens with molecules that enhance phagocytosis

Question 8

A microorganism that blocks the fusion of the phagosome with the lysosome is most likely to survive inside which immune cell?

Accepted Answer

Macrophage

Question 9

Which complement activation pathway is triggered by antibodies bound to antigens?

Accepted Answer

Classical pathway

Question 10

During the acute inflammatory response, which of the following is NOT a classic sign?

Accepted Answer

Bradycardia

Question 11

A patient develops a high fever in response to infection. Which process is responsible for raising the body temperature set point?

Accepted Answer

Release of prostaglandins in the hypothalamus

Question 12

Which of the following best explains why adaptive immunity is faster and stronger upon second exposure to the same pathogen?

Accepted Answer

It has memory cells that recognize the pathogen and mount a rapid response.

Question 13

Which of the following is a correct sequence of events in phagocytosis?

Accepted Answer

Recognition, ingestion, fusion with lysosome, digestion

Question 14

A patient with a deficiency in complement proteins would most likely have increased susceptibility to which of the following?

Accepted Answer

Bacterial infections due to impaired opsonization and cytolysis

Question 15

Which of the following is a function of interferons in the innate immune response?

Accepted Answer

Activation of antiviral properties in neighboring cells

Question 16

A cytokine storm is best described as:

Accepted Answer

A maladaptive, excessive release of cytokines that can cause tissue damage

Question 17

Which of the following best describes the role of chemokines?

Accepted Answer

They control chemotaxis and leukocyte recruitment.

Question 18

A patient is infected with Mycobacterium tuberculosis, which is known to block phagosome-lysosome fusion. What is the likely consequence for the pathogen?

Accepted Answer

It will survive and replicate within the macrophage.

Question 19

Which of the following is a direct result of the membrane attack complex (MAC) formed during complement activation?

Accepted Answer

Lysis of the target cell by creating pores in its membrane

Question 20

Which of the following equations best represents the relationship between the rate of phagocytosis ($$R$$), the number of opsonized pathogens ($$N$$), and a constant of phagocytic efficiency ($$k$$)?

Accepted Answer

$$R = kN$$

Host Defenses: Innate and Adaptive Immunity

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