Question 1

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

Accepted Answer

Innate immunity is present at birth and provides immediate, nonspecific defense, while adaptive immunity develops over time and provides specific, tailored responses.

Question 2

Which of the following is NOT a function of normal microbiota in shaping immune responses?

Accepted Answer

Directly causing autoimmunity by attacking self-tissues.

Question 3

According to the hygiene hypothesis, what is the proposed effect of decreased diversity in normal microbiota?

Accepted Answer

It may negatively affect immune responses, increasing the risk of allergies and autoimmunity.

Question 4

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

Accepted Answer

Mucociliary escalator in the respiratory tract

Question 5

Which of the following statements about antimicrobial peptides (AMPs) is TRUE?

Accepted Answer

AMPs can disrupt plasma membranes, target intracellular components, and stimulate leukocytes.

Question 6

Which of the following best describes the role of the lymphatic system in immunity?

Accepted Answer

It collects, circulates, and filters interstitial fluid, screening it for pathogens before returning it to the bloodstream.

Question 7

Which of the following leukocytes is most abundant in circulation and is the first to respond to tissue injury?

Accepted Answer

Neutrophils

Question 8

A patient presents with an elevated eosinophil count. Which of the following is the most likely cause?

Accepted Answer

Parasitic infection or allergic reaction

Question 9

Which of the following is a function of dendritic cells in innate immunity?

Accepted Answer

Phagocytizing antigens and modulating immune responses

Question 10

Which of the following cytokines is primarily responsible for signaling the presence of viral infections and activating antiviral defenses?

Accepted Answer

Interferons

Question 11

A bacterial pathogen produces siderophores. What is the primary function of these molecules?

Accepted Answer

To steal iron from host iron-binding proteins

Question 12

Which complement pathway is initiated when antibodies bind to a pathogen?

Accepted Answer

Classical pathway

Question 13

What is the main outcome of complement protein C3b binding to a pathogen?

Accepted Answer

Opsonization, enhancing phagocytosis by immune cells

Question 14

Which of the following is NOT a cardinal sign of inflammation?

Accepted Answer

Fever

Question 15

During the vascular changes phase of inflammation, which of the following occurs?

Accepted Answer

Blood vessels dilate and become more permeable, allowing exudate to accumulate in tissues

Question 16

Which molecule is a key early mediator released by mast cells during inflammation?

Accepted Answer

Histamine

Question 17

Which process describes leukocytes slowing down and adhering to the vessel wall during inflammation?

Accepted Answer

Margination

Question 18

A patient with a fever is given ibuprofen. What is the mechanism by which this drug reduces fever?

Accepted Answer

It limits the production of prostaglandins in the hypothalamus.

Question 19

Which of the following is a potential consequence of chronic inflammation?

Accepted Answer

Exacerbation of tissue injury and promotion of diseases such as atherosclerosis and certain cancers

Question 20

Which of the following best explains why a fever above $$43^{\circ}$$\mathrm{C}$$ is considered fatal?

Accepted Answer

Essential cellular enzymes and proteins begin to denature and stop functioning.

Innate Immunity: Principles and Mechanisms

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