Question 1

Which of the following best explains why the skin is considered an effective physical barrier against microbial invasion?

Accepted Answer

The skin is dry, nutrient-depleted, tightly packed, and has a high osmotic pressure, making it inhospitable to most pathogens.

Question 2

A patient with a genetic disorder that prevents the production of lysozyme would be most susceptible to infections by which type of microorganism?

Accepted Answer

Gram-positive bacteria, because lysozyme digests their thick peptidoglycan cell walls.

Question 3

Which of the following best describes the role of transferrin in nonspecific host defense?

Accepted Answer

Transferrin binds free iron in the blood, limiting microbial access to this essential nutrient.

Question 4

A child with a persistent high fever (above 104°F) is brought to the hospital. Which of the following statements about fever is most accurate based on the study materials?

Accepted Answer

Moderate fever can stimulate immune cell differentiation and growth, but very high fever can be dangerous.

Question 5

Which of the following is NOT a function of complement proteins activated via the classical pathway?

Accepted Answer

Direct neutralization of viral genomes.

Question 6

A patient is diagnosed with a deficiency in natural killer (NK) cells. Which of the following would most likely be impaired in this patient?

Accepted Answer

Destruction of infected host cells and cancer cells by recognizing abnormal membrane proteins.

Question 7

Which of the following best explains why the low pH of the stomach is considered a chemical barrier to infection?

Accepted Answer

Low pH denatures microbial proteins, inhibiting their growth.

Question 8

A laboratory experiment shows that bacteria are unable to colonize the skin of a subject with abnormally low salt concentration in their sweat. Which mechanism of nonspecific defense is most likely compromised?

Accepted Answer

Increased osmotic pressure due to salt accumulation discourages microbial growth.

Question 9

Which of the following scenarios best illustrates the action of opsonins in the immune response?

Accepted Answer

A complement protein binds to a pathogen, making it easier for a phagocyte to attach and ingest it.

Question 10

During an inflammatory response, which of the following events occurs first?

Accepted Answer

Vasodilation to increase blood flow to the injured area.

Question 11

A patient with a disrupted normal flora in the intestinal tract is more susceptible to infection because:

Accepted Answer

Normal flora prevent colonization by pathogens by competing for nutrients and space.

Question 12

Which of the following best describes the ciliary escalator mechanism?

Accepted Answer

Cilia in the respiratory tract move mucus and trapped pathogens upward toward the throat for removal.

Question 13

A patient is unable to produce sebum. Which of the following consequences is most likely?

Accepted Answer

Increased skin pH, making it more hospitable to pathogens.

Question 14

Which of the following is a direct effect of histamine release during inflammation?

Accepted Answer

Vasodilation, leading to increased blood flow to the affected area.

Question 15

A patient with a genetic defect in complement protein C3 would likely experience which of the following?

Accepted Answer

Reduced ability to lyse pathogens and decreased opsonization.

Question 16

Which of the following best explains why vomiting and diarrhea are considered nonspecific defenses?

Accepted Answer

They physically expel pathogens from the gastrointestinal tract before they can colonize.

Question 17

A patient with a severe burn covering a large area of skin is at increased risk of infection primarily because:

Accepted Answer

The loss of the skin barrier removes a critical physical defense against pathogens.

Question 18

Which of the following best describes the process of phagocytosis?

Accepted Answer

White blood cells bind to, ingest, and destroy foreign bodies.

Question 19

Which of the following is a multi-step process involving both physical and chemical factors in nonspecific host defense?

Accepted Answer

Tears wash away pathogens (physical) and contain lysozyme (chemical) that digests bacterial cell walls.

Question 20

A patient is exposed to a pathogen that is resistant to low pH but is unable to bind iron in the presence of transferrin. Which host defense is most likely to prevent infection?

Accepted Answer

Transferrin binding free iron, limiting microbial growth.

Innate Immunity: Nonspecific Defenses of the Host (Chapter 16 Study Guide)

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