Question 1

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

Accepted Answer

Innate immunity responds rapidly and is fixed, while adaptive immunity responds slowly and improves during response.

Question 2

Which structure is NOT considered part of the body's first line of defense against pathogens?

Accepted Answer

Complement proteins

Question 3

How does lysozyme, found in sweat and tears, contribute to innate immunity?

Accepted Answer

It destroys the cell wall of Gram-positive bacteria.

Question 4

A patient presents with elevated eosinophil counts. Which infection is most likely?

Accepted Answer

Parasitic helminth infection

Question 5

Which of the following is a function of sebum secreted by sebaceous glands?

Accepted Answer

Lowers skin pH to inhibit bacterial growth

Question 6

Which process involves the migration of phagocytes through blood vessel walls to reach sites of infection?

Accepted Answer

Diapedesis

Question 7

Which complement pathway is activated directly by microbial surface components?

Accepted Answer

Alternate pathway

Question 8

What is the role of C3b in the complement cascade?

Accepted Answer

Acts as an opsonin to enhance phagocytosis

Question 9

Which of the following is a classic sign of acute inflammation?

Accepted Answer

Loss of joint function

Question 10

A patient develops a fever after a bacterial infection. Which molecule is most directly responsible for signaling the hypothalamus to increase body temperature?

Accepted Answer

Interleukin-1

Question 11

Which of the following best explains why normal microbiota are important in innate immunity?

Accepted Answer

They compete with pathogens for nutrients and space, making it difficult for pathogens to establish.

Question 12

Which cell type is most involved in the adaptive immune response?

Accepted Answer

Lymphocytes

Question 13

Which of the following is a direct effect of the membrane attack complex (MAC) formed by complement proteins?

Accepted Answer

Formation of holes in the cytoplasmic membrane of pathogens

Question 14

Which of the following is a chemical defense found in all body secretions and acts by inducing holes in bacterial membranes?

Accepted Answer

Antimicrobial peptides

Question 15

Which of the following events is mediated by prostaglandins and leukotrienes during inflammation?

Accepted Answer

Dilation and increased permeability of blood vessels

Question 16

Which of the following is a function of Toll-like receptors (TLRs) on phagocytic cells?

Accepted Answer

Bind to pathogen-associated molecular patterns (PAMPs) and initiate defensive responses

Question 17

Which of the following is NOT a direct result of complement activation?

Accepted Answer

Increased antibody production

Question 18

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

Accepted Answer

Fever results from pyrogens triggering the hypothalamus, which increases the body's core temperature to inhibit pathogen growth.

Question 19

Which of the following is a plausible consequence if the skin's pH is increased to neutral (pH 7)?

Accepted Answer

Increased susceptibility to bacterial colonization

Question 20

Which equation best represents the activation of complement via the classical pathway?

Accepted Answer

$$C1 + Antibody \rightarrow C4b2a (C3 $$convertase)

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

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