Question 1

Which of the following best describes the main difference between the first and second lines of host defense?

Accepted Answer

The first line of defense consists of physical and chemical barriers, while the second line involves internalized protective cells and fluids such as phagocytes and inflammation.

Question 2

Which of the following is NOT a function of the lymphatic system?

Accepted Answer

Transporting oxygen to tissues

Question 3

A patient with a severe burn is at increased risk for infection primarily because:

Accepted Answer

The first line of defense (physical barrier) is lost, allowing easier microbial entry

Question 4

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

Accepted Answer

$$6 \rightarrow 4 \rightarrow 1 \rightarrow 3 \rightarrow 7 \rightarrow 2 \rightarrow 5$$

Question 5

Which of the following is a chemical barrier involved in the first line of defense?

Accepted Answer

Hydrochloric acid in the stomach

Question 6

Which of the following statements about the complement system is TRUE?

Accepted Answer

It consists of a cascade of over 30 proteins that can be activated by antibodies or directly by pathogens, leading to cell lysis.

Question 7

Which of the following cells is considered a histiocyte?

Accepted Answer

A macrophage that has taken up permanent residence in the liver (Kupffer cell)

Question 8

Which of the following is a pro-inflammatory cytokine?

Accepted Answer

Interleukin-1 (IL-1)

Question 9

A child who has had their spleen removed is at higher risk for infection because:

Accepted Answer

The spleen filters pathogens from the blood and its absence severely compromises immune function in children

Question 10

Which of the following best describes the role of pattern recognition receptors (PRRs) in innate immunity?

Accepted Answer

They are found on phagocytes and recognize pathogen-associated molecular patterns (PAMPs) common to many microbes.

Question 11

Which of the following is NOT typically found in lymphatic fluid?

Accepted Answer

Red blood cells

Question 12

Which of the following is a function of interferon?

Accepted Answer

Inducing the production of proteins that inhibit viral replication in host cells

Question 13

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

Accepted Answer

Sloughing of skin

Question 14

Which of the following best explains why normal microbiota are considered part of the first line of defense?

Accepted Answer

They compete with pathogens for nutrients and alter local pH, making it less favorable for pathogen growth.

Question 15

Which of the following is a correct statement about the movement of lymph in the body?

Accepted Answer

Lymph moves only through the contraction of skeletal muscles.

Question 16

Which of the following is a key function of inflammation?

Accepted Answer

To mobilize and attract immune components to the site of injury

Question 17

Which of the following is a characteristic sign of inflammation?

Accepted Answer

Rubor (redness)

Question 18

Which of the following best describes the classical pathway of complement activation?

Accepted Answer

It is initiated by antibodies bound to microbes, leading to a cascade of protein activation.

Question 19

Which of the following is a benefit of fever during infection?

Accepted Answer

It inhibits multiplication of temperature-sensitive microorganisms.

Question 20

Which of the following is a correct statement about antimicrobial peptides?

Accepted Answer

They are short proteins that can insert into bacterial membranes and cause cell lysis.

Chapter 12: Host Defenses – Overview and Innate Defenses (Microbiology Fundamentals)

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