Question 1

Which of the following best describes the difference between innate and adaptive immunity?

Accepted Answer

Innate immunity provides immediate, nonspecific defense against pathogens, while adaptive immunity develops more slowly and targets specific pathogens.

Question 2

Which physical barrier is most responsible for preventing the entry of pathogens into the human body?

Accepted Answer

Intact skin with keratinized cells

Question 3

A patient with a genetic defect in the production of lysozyme would be most susceptible to infections in which body fluids?

Accepted Answer

Perspiration, tears, saliva, and urine

Question 4

Which of the following is a chemical factor that inhibits microbial growth on the skin?

Accepted Answer

Fungistatic fatty acid in sebum

Question 5

Which process describes the movement of phagocytes from blood vessels to infected tissues during inflammation?

Accepted Answer

Diapedesis

Question 6

A bacterial pathogen that produces a capsule is most likely to evade which aspect of the innate immune response?

Accepted Answer

Phagocytosis by neutrophils and macrophages

Question 7

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

Accepted Answer

Chemotaxis → Adherence → Ingestion → Formation of phagosome → Fusion with lysosome → Digestion → Discharge

Question 8

Which of the following white blood cells is primarily responsible for the production of toxic proteins against certain parasites and some phagocytosis?

Accepted Answer

Eosinophils

Question 9

Which of the following best explains the role of Toll-like receptors (TLRs) in innate immunity?

Accepted Answer

TLRs attach to pathogen-associated molecular patterns (PAMPs) and induce cytokine production.

Question 10

A patient develops a fever after a Gram-negative bacterial infection. Which of the following best describes the physiological mechanism leading to fever?

Accepted Answer

Endotoxins cause phagocytes to release interleukin-1 (IL-1), which leads to prostaglandin release and resetting of the hypothalamic set point.

Question 11

Which of the following complement proteins is directly responsible for opsonization?

Accepted Answer

C3b

Question 12

A mutation that prevents the formation of the membrane attack complex (MAC) would most directly impair which function of the complement system?

Accepted Answer

Cytolysis

Question 13

Which pathway of complement activation is initiated by the binding of antibodies to antigens?

Accepted Answer

Classical pathway

Question 14

Which of the following is a function of interferon-γ (IFN-γ)?

Accepted Answer

Causes neutrophils and macrophages to phagocytize bacteria

Question 15

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

Accepted Answer

Bacterial infections due to increased availability of iron

Question 16

Which of the following best describes microbial antagonism?

Accepted Answer

Normal microbiota compete with pathogens for nutrients and space, inhibiting pathogen colonization.

Question 17

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

Accepted Answer

Pallor (paleness)

Question 18

A patient infected with Mycobacterium tuberculosis is able to survive inside macrophages. Which microbial evasion strategy is most likely responsible?

Accepted Answer

Prevention of phagosome–lysosome fusion

Question 19

Which of the following best explains why the low pH of gastric juice is an effective innate defense?

Accepted Answer

It denatures microbial proteins and inactivates most ingested pathogens.

Question 20

Which of the following is a multi-step process that involves both the innate and adaptive immune systems and results in the lysis of a pathogen?

Accepted Answer

Complement activation via the classical pathway

Innate Immunity: Nonspecific Defenses of the Host

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