Question 1

Which of the following best describes the main function of the immune system?

Accepted Answer

To provide resistance to disease by identifying and eliminating pathogens.

Question 2

Which of the following is NOT a component of the first line of defense in the innate immune system?

Accepted Answer

Phagocytes

Question 3

A patient has a genetic defect that prevents the production of lysozyme in their saliva. Which of the following would most likely result from this defect?

Accepted Answer

Increased susceptibility to bacterial infections in the mouth

Question 4

Which of the following best explains the role of opsonization in phagocytosis?

Accepted Answer

Opsonins coat pathogens, making them easier for phagocytes to recognize and engulf.

Question 5

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

Accepted Answer

Adherence → Engulfment → Phagosome formation → Phagolysosome formation → Digestion → Exocytosis

Question 6

Natural killer (NK) cells differ from phagocytes in that NK cells:

Accepted Answer

Induce apoptosis in target cells without engulfing them.

Question 7

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

Accepted Answer

Fever

Question 8

During the inflammatory response, which chemical is primarily responsible for vasodilation and increased vascular permeability?

Accepted Answer

Histamine

Question 9

A patient with a severe bacterial infection is found to have a deficiency in complement proteins. Which of the following would most likely be impaired?

Accepted Answer

Cell lysis of bacteria via the membrane attack complex (MAC)

Question 10

Which of the following best describes the benefit of moderate fever during infection?

Accepted Answer

It causes the liver and spleen to sequester iron and zinc, limiting bacterial growth.

Question 11

Which of the following is a function of interferons in the innate immune response?

Accepted Answer

They stimulate neighboring cells to produce antiviral proteins.

Question 12

A cut on the skin allows bacteria to enter the tissue. Which line of defense is activated first?

Accepted Answer

First line of defense: surface barriers (skin and mucous membranes)

Question 13

Which of the following best explains why swelling (edema) occurs during inflammation?

Accepted Answer

Increased capillary permeability allows fluid to leak into tissues.

Question 14

Which of the following is the correct order of phagocyte mobilization during inflammation?

Accepted Answer

Leukocytosis → Margination → Diapedesis → Chemotaxis

Question 15

A patient is unable to produce defensins. Which of the following would most likely be affected?

Accepted Answer

Inhibition of microbial growth on skin and mucous membranes

Question 16

Which of the following is a real-world example of the benefit of the acid mantle in the immune system?

Accepted Answer

The low pH of the skin inhibits the growth of many bacteria, reducing the risk of infection after minor cuts.

Question 17

Which of the following best describes the role of cilia in the upper respiratory tract?

Accepted Answer

They sweep dust- and bacteria-laden mucus toward the mouth for removal.

Question 18

A patient with a genetic disorder cannot produce pyrogens. Which of the following would most likely be impaired?

Accepted Answer

Ability to develop a fever in response to infection

Question 19

Which of the following is a benefit of edema during the inflammatory response?

Accepted Answer

It delivers clotting proteins and antibodies to the injured area.

Question 20

Which of the following best explains why some bacteria are resistant to phagocytosis?

Accepted Answer

They have external capsules that hide their surface carbohydrates, preventing recognition by phagocytes.

Innate Defenses of the Immune System: First and Second Lines

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