Question 1

Which of the following best describes the main difference between innate (nonspecific) and acquired (specific) immunity?

Accepted Answer

Innate immunity provides immediate, general defense mechanisms, while acquired immunity targets specific pathogens and improves with repeated exposure.

Question 2

Which of the following is NOT a function of the skin as a first line of defense against pathogens?

Accepted Answer

Production of antibodies to neutralize viruses

Question 3

A patient presents with a parasitic worm infection. Which white blood cell type is most likely to be elevated in their blood count?

Accepted Answer

Eosinophils

Question 4

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

Accepted Answer

Fever enhances the effects of interferons and inhibits the growth of some microbes by limiting iron availability.

Question 5

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

Accepted Answer

Chemotaxis → Binding → Ingestion → Lysozyme Fusion → Killing and Destruction → Waste Elimination

Question 6

Which of the following antimicrobial mechanisms is most directly associated with the formation of hypochlorite (ClO–) during the oxidative burst in phagocytes?

Accepted Answer

Myeloperoxidase

Question 7

A mutation in the gene encoding TLR4 would most likely impair the immune system’s ability to recognize which microbial component?

Accepted Answer

Lipid A in LPS (outer membrane of Gram-negative bacteria)

Question 8

Which of the following is NOT a classic sign of acute inflammation?

Accepted Answer

Cyanosis (bluish discoloration)

Question 9

Which of the following best describes the role of the complement system in innate immunity?

Accepted Answer

It triggers a cascade reaction resulting in inflammation, attraction of phagocytes, and formation of the membrane attack complex.

Question 10

Which of the following best explains why the microbiome is considered part of the first line of defense?

Accepted Answer

It competes with pathogens for nutrients and attachment sites, and can produce antimicrobial compounds.

Question 11

Which of the following is a function of natural killer (NK) cells in the second line of defense?

Accepted Answer

Secreting toxins onto the surface of virally infected cells and tumors

Question 12

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

Accepted Answer

It digests bacterial cell walls by hydrolyzing the bonds in peptidoglycan.

Question 13

A patient with a genetic deficiency in neutrophil extracellular trap (NET) formation would be most susceptible to which of the following?

Accepted Answer

Reduced ability to trap and kill extracellular bacteria

Question 14

Which of the following is a correct statement about the difference between plasma and serum?

Accepted Answer

Plasma contains clotting factors, while serum does not.

Question 15

Which of the following best explains why iron-binding compounds in plasma are important for innate immunity?

Accepted Answer

They limit the availability of iron, which is essential for microbial metabolism.

Question 16

Which of the following is a key difference between neutrophils and eosinophils?

Accepted Answer

Neutrophils are primarily involved in phagocytosis and killing of bacteria, while eosinophils are specialized for attacking large eukaryotic pathogens such as helminths.

Question 17

Which of the following best describes the process of diapedesis during inflammation?

Accepted Answer

The movement of phagocytes out of the bloodstream by squeezing between endothelial cells of blood vessels

Question 18

Which of the following is a direct effect of bradykinins, prostaglandins, leukotrienes, and histamine during inflammation?

Accepted Answer

Increased vasodilation and permeability of blood vessels

Question 19

Which of the following is a function of interferon alpha (IFN-α) and beta (IFN-β) in the innate immune response?

Accepted Answer

They stimulate phagocytosis and inhibit the spread of viral infections.

Innate Immunity: The Body’s First and Second Lines of Defense

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