$$\text{Microbial Growth} = \frac{\text{Available Nutrients}}{\text{Competition from Microbiota}}$$

Question 1

Which of the following best describes the role of lysozyme in the innate immune system?

Accepted Answer

Lysozyme destroys the cell wall of bacteria, particularly by breaking down peptidoglycan.

Question 2

A patient with a skin injury is at increased risk for infection. Which property of the skin is most compromised in this scenario?

Accepted Answer

The tightly packed layers of the epidermis that act as a physical barrier.

Question 3

Which of the following is NOT a function of the normal microbiota in innate immunity?

Accepted Answer

Directly attacking and killing pathogenic microbes.

Question 4

Which secretion in the digestive system is responsible for sequestering iron, making it unavailable for microbial use?

Accepted Answer

Gastroferritin

Question 5

Why are antimicrobial peptides considered a crucial part of the first line of defense?

Accepted Answer

They act against a variety of microbes and are present in skin, mucous membranes, and neutrophils.

Question 6

Which of the following best explains why the skin is inhospitable to most microbes?

Accepted Answer

Salt, defensins, enzymes, and a low pH make the skin inhospitable for most microbes.

Question 7

Which of the following is a unique feature of mucous membranes compared to skin?

Accepted Answer

Presence of cilia in certain locations, such as the trachea and uterine tubes.

Question 8

A patient with dry skin is more susceptible to microbial invasion. Which chemical defense is most likely reduced in this patient?

Accepted Answer

Sebum

Question 9

Which of the following equations best represents the relationship between microbial antagonism and nutrient availability?

Accepted Answer

$$	ext{Microbial Growth} = \frac{	ext{Available Nutrients}}{	ext{Competition from Microbiota}}$$

Question 10

Which of the following is a primary function of the lacrimal apparatus in innate immunity?

Accepted Answer

Producing tears that contain lysozyme to destroy bacteria.

Question 11

Which process in the digestive system is most directly responsible for eliminating potential pathogens?

Accepted Answer

Peristalsis

Question 12

Which of the following is NOT a characteristic of the epithelium in mucous membranes?

Accepted Answer

Cells are dead in the outer layers.

Question 13

Which secretion in the urinary system contributes to innate immunity by inhibiting microorganisms?

Accepted Answer

Urine

Question 14

A patient with iron-deficiency anemia is found to have increased susceptibility to infections. Which innate immune mechanism is most likely affected?

Accepted Answer

Secretion of iron-binding proteins in reproductive and digestive systems.

Question 15

Which of the following best describes the function of dendritic cells in the epidermis?

Accepted Answer

They phagocytize pathogens and present antigens to the adaptive immune system.

Question 16

Which equation best represents the effect of skin pH on bacterial growth?

Accepted Answer

$$	ext{Bacterial Growth} \propto \frac{1}{	ext{Skin pH}}$$

Question 17

Which of the following is a second-line defense in innate immunity?

Accepted Answer

Phagocytosis by leukocytes

Question 18

Which of the following is a real-world example of microbial antagonism?

Accepted Answer

Normal gut microbiota outcompete Clostridium difficile for nutrients, preventing infection.

Question 19

Which of the following is a function of blood flow in innate immunity?

Accepted Answer

Removes microorganisms from wounds.

Question 20

Which of the following is a multi-step process involving both physical and chemical defenses in the respiratory tract?

Accepted Answer

Ciliated columnar cells move mucus containing trapped pathogens toward the pharynx, where it is swallowed and exposed to stomach acid.

Innate Immunity: The First Line of Defense

Study Guide - Practice Questions