Question 1

Which of the following best describes the role of lysozyme in the body's first line of defense?

Accepted Answer

Lysozyme is an enzyme that breaks down peptidoglycan in bacterial cell walls, leading to cell lysis.

Question 2

A patient presents with an abnormally high number of eosinophils in their blood. Which of the following is the most likely explanation for this finding?

Accepted Answer

The patient is suffering from a helminth (parasitic worm) infection.

Question 3

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

Accepted Answer

The complement system can be activated by three pathways: classical, alternative, and lectin.

Question 4

A scientist is studying the process by which phagocytes are attracted to the site of infection. Which of the following best explains this process?

Accepted Answer

Phagocytes are attracted by chemotactic factors such as chemokines released at the site of infection.

Question 5

Which of the following best describes the process of opsonization?

Accepted Answer

Opsonization is the process by which pathogens are coated with proteins to enhance their recognition and ingestion by phagocytes.

Question 6

A patient with a genetic defect in Toll-like receptors (TLRs) would most likely have difficulty with which aspect of innate immunity?

Accepted Answer

Recognizing pathogen-associated molecular patterns (PAMPs) and initiating appropriate immune responses.

Question 7

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

Accepted Answer

Chemotaxis → Adhesion → Ingestion → Phagosome formation → Phagolysosome formation → Killing of pathogen

Question 8

Which of the following best explains why the low pH of the stomach is an effective defense against many pathogens?

Accepted Answer

The acidic environment denatures microbial proteins and inactivates many pathogens.

Question 9

A laboratory test shows a patient has a high number of neutrophils and a low number of lymphocytes. Which of the following is the most likely explanation?

Accepted Answer

The patient is experiencing an acute bacterial infection.

Question 10

Which of the following is a function of natural killer (NK) cells in the second line of defense?

Accepted Answer

NK cells attack and destroy virus-infected and cancerous cells nonphagocytically.

Question 11

Which of the following best describes the difference between plasma and serum?

Accepted Answer

Serum is plasma without clotting factors.

Question 12

A patient is given a probiotic supplement. What is the intended effect of this treatment?

Accepted Answer

To introduce beneficial microbes that compete with potential pathogens and improve health.

Question 13

Which of the following is a correct statement about the role of dendritic cells in the immune system?

Accepted Answer

Dendritic cells are phagocytic cells in the epidermis that devour pathogens as part of the first line of defense.

Question 14

Which of the following best explains the function of antimicrobial peptides (defensins)?

Accepted Answer

Defensins are small peptides that disrupt microbial membranes, acting against a broad range of pathogens.

Question 15

Which of the following best describes the process of margination during inflammation?

Accepted Answer

Leukocytes stick to the walls of blood vessels near the site of infection before exiting into the tissue.

Question 16

Which of the following is a correct statement about the activation of antiviral proteins (AVPs) by interferons?

Accepted Answer

Alpha and beta interferons trigger the production of AVPs in neighboring cells to inhibit viral replication.

Question 17

A patient develops a fever after a bacterial infection. Which of the following best explains the physiological mechanism behind this response?

Accepted Answer

Pyrogens released by bacteria and phagocytes cause the hypothalamus to reset the body's temperature to a higher level.

Question 18

Which of the following best describes the function of membrane attack complexes (MACs) formed by the complement system?

Accepted Answer

MACs create multiple holes in the membranes of pathogens, leading to cell lysis.

Question 19

Which of the following is a distinguishing feature of chronic inflammation compared to acute inflammation?

Accepted Answer

Chronic inflammation develops slowly and can cause tissue damage leading to disease.

Question 20

A patient has a genetic deficiency in NOD proteins. Which of the following immune responses would most likely be impaired?

Accepted Answer

Recognition of intracellular pathogen-associated molecular patterns (PAMPs) and initiation of innate immune responses.

Innate Immunity: The Body's First and Second Lines of Defense

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