Question 1

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

Accepted Answer

Innate immunity is present from birth and responds rapidly without specificity, while adaptive immunity is slower, specific, and has memory.

Question 2

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

Accepted Answer

Antibodies

Question 3

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

Accepted Answer

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

Question 4

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

Accepted Answer

It is composed of tightly packed dead epithelial cells containing keratin, which is periodically shed.

Question 5

Which of the following is a function of bacteriocins produced by normal microbiota?

Accepted Answer

They help good bacteria colonize, kill closely related pathogenic species, and signal immune cells to activate immune responses.

Question 6

A patient is exposed to a bacterial toxin that is resistant to lysozyme. Which first line defense is most likely to still be effective?

Accepted Answer

Skin shedding

Question 7

Which leukocyte is the most abundant in the blood and is usually the first to arrive at the site of infection?

Accepted Answer

Neutrophil

Question 8

Which of the following best describes the role of natural killer (NK) cells in innate immunity?

Accepted Answer

They recognize and lyse infected or damaged cells using perforin.

Question 9

Which of the following chemical barriers is correctly matched with its antimicrobial mechanism?

Accepted Answer

Lysozyme: breaks down bacterial cell walls

Question 10

A patient with a deficiency in defensins would most likely experience which of the following?

Accepted Answer

Increased susceptibility to bacterial infections due to impaired membrane damage

Question 11

Which of the following is a correct sequence of events in the innate immune response to a skin wound contaminated with bacteria?

Accepted Answer

Physical barrier breach → Recognition of PAMPs by PRRs → Cytokine release → Recruitment of neutrophils

Question 12

Which of the following best describes the function of dendritic cells in the immune system?

Accepted Answer

They phagocytose pathogens and present antigens to adaptive immune cells.

Question 13

Which of the following is an example of a damage-associated molecular pattern (DAMP) that could trigger an innate immune response?

Accepted Answer

Extracellular ATP released from damaged host cells

Question 14

Which of the following best explains why the microbiome is considered a first line defense?

Accepted Answer

It competes with pathogens for nutrients and space, and produces bacteriocins that inhibit pathogen growth.

Question 15

Which of the following is a function of basophils in the immune response?

Accepted Answer

Release of histamine and facilitation of inflammatory responses

Question 16

A patient with a severe burn loses a large area of skin. Which aspect of their immune defense is most compromised?

Accepted Answer

First line defense: physical barrier

Question 17

Which of the following best describes the role of chemokines in the immune response?

Accepted Answer

They guide the migration of immune cells to sites of infection or injury.

Question 18

Which of the following is a correct statement about mast cells?

Accepted Answer

They are found in connective tissue and release histamine, proteases, and cytokines.

Question 19

Which of the following best explains why gastric secretions are effective as a chemical barrier?

Accepted Answer

They are acidic and contain proteolytic enzymes that denature microbial proteins.

Innate and Adaptive Immunity: Host Defenses in Microbiology

Study Guide - Practice Questions