Question 1

Which of the following best describes the role of skin and mucous membranes in immunity?

Accepted Answer

They act as physical barriers in innate immunity, preventing entry of microbes.

Question 2

A patient consumes food contaminated with pathogenic bacteria but does not become ill due to the acidity of the stomach. What type of immunity is this an example of?

Accepted Answer

Innate immunity, which provides nonspecific immunity.

Question 3

Which of the following is NOT considered a first-line defense of the innate immune system?

Accepted Answer

Phagocytosis by immune cells

Question 4

Keratin is important in the skin’s defense against infection because:

Accepted Answer

Keratin is hydrophobic, keeping the skin dry and decreasing microbial growth.

Question 5

Which layer of the skin sheds dead cells along with attached microbes as a defense mechanism?

Accepted Answer

Epidermis

Question 6

Which of the following is a chemical defense of the first-line innate immune system?

Accepted Answer

Stomach acid

Question 7

Antibodies are part of which type of immunity and why?

Accepted Answer

Adaptive immunity; antibodies recognize specific antigens/pathogens.

Question 8

Which of the following is a primary physical barrier of the first-line defense in innate immunity?

Accepted Answer

Epidermis

Question 9

A patient with a burn injury is at increased risk of infection primarily because:

Accepted Answer

The burn destroys the skin barrier, allowing microbes to enter.

Question 10

Which of the following is NOT a function of mucous membranes in immunity?

Accepted Answer

Producing antibodies against all pathogens

Question 11

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

Accepted Answer

Innate immunity provides immediate, nonspecific protection; adaptive immunity develops over time and is specific.

Question 12

Which of the following is an example of a physical barrier in the first-line defense?

Accepted Answer

Epidermis

Question 13

The shedding of the outer layer of skin cells helps prevent infection by:

Accepted Answer

Removing attached microbes from the skin surface.

Question 14

Which of the following is NOT a component of the first-line defense in innate immunity?

Accepted Answer

Phagocytic cells in the blood

Question 15

Which of the following statements about the epidermis is correct?

Accepted Answer

It contains keratin, which repels water and helps prevent microbial growth.

Question 16

Which of the following is a chemical defense found in saliva that helps protect against infection?

Accepted Answer

Lysozyme

Question 17

Which of the following is a function of the human microbiome in the first-line defense?

Accepted Answer

Competing with pathogens for space and nutrients.

Question 18

Which of the following is a correct description of the dermis?

Accepted Answer

It is composed of connective tissue and is thicker than the epidermis.

Question 19

Which equation best represents the relationship between the effectiveness of a physical barrier ($$E$$), the area covered ($$A$$), and the integrity of the barrier ($$I$$)?

Accepted Answer

$$E = A 	imes I$$

Question 20

If the probability of a microbe bypassing the skin barrier is $$P_{skin}$$ and the probability of bypassing the mucous membrane is $$P_{mucous}$$, what is the combined probability ($$P_{total}) $$that a microbe bypasses both barriers?

Accepted Answer

$$P_{total} = P_{skin} 	imes P_{mucous}$$

Innate Immunity: First-Line Defenses and Physical Barriers

Study Guide - Practice Questions

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