$$\text{C3b} + \text{Pathogen} \rightarrow \text{Opsonized Pathogen}$$

$$\text{C5b} + \text{C6} + \text{C7} + \text{C8} + \text{C9} \rightarrow \text{MAC}$$

Question 1

Which of the following best describes the function of keratin in the skin as a physical barrier in innate immunity?

Accepted Answer

Keratin is a protein that forms a tough, protective layer, preventing pathogen entry.

Question 2

A patient with a deficiency in neutrophils would most likely have difficulty with which aspect of the immune response?

Accepted Answer

Performing phagocytosis to destroy bacteria and dead cells.

Question 3

Which of the following is a chemical barrier that specifically targets Gram-positive bacteria?

Accepted Answer

Lysozyme in perspiration, tears, saliva, and urine

Question 4

Which process is illustrated by the formation of a phagosome and its subsequent fusion with a lysosome?

Accepted Answer

Phagocytosis

Question 5

Streptococcus pneumoniae evades phagocytosis primarily by which mechanism?

Accepted Answer

Forming a capsule that inhibits adherence

Question 6

Which of the following is NOT a function of the complement system?

Accepted Answer

Direct production of antibodies

Question 7

A microbe that prevents phagosome/lysosome fusion is most likely to survive inside which cell type?

Accepted Answer

Macrophage

Question 8

Which pathway of complement activation is triggered by antibodies bound to a pathogen?

Accepted Answer

Classical pathway

Question 9

Which of the following equations best represents the process of opsonization in complement activation?

Accepted Answer

$$	ext{C3b} + 	ext{Pathogen} ightarrow 	ext{Opsonized Pathogen}$$

Question 10

Which acute-phase protein is primarily responsible for increasing blood vessel permeability during inflammation?

Accepted Answer

Kinins

Question 11

A patient infected with Listeria monocytogenes is at risk because this bacterium can:

Accepted Answer

Escape from the phagosome by lysing the phagocyte's membrane

Question 12

Which of the following best describes the role of IFN-α and IFN-β in viral infections?

Accepted Answer

They stimulate nearby cells to produce antiviral proteins that block viral replication.

Question 13

Which leukocyte is most likely to be elevated in a patient with a parasitic worm infection?

Accepted Answer

Eosinophil

Question 14

Which of the following is a correct sequence for the steps of phagocytosis as shown in the diagram?

Accepted Answer

Chemotaxis → Adherence → Ingestion → Digestion → Discharge

Question 15

Which of the following equations best represents the formation of the membrane attack complex (MAC) in complement activation?

Accepted Answer

$$	ext{C5b} + 	ext{C6} + 	ext{C7} + 	ext{C8} + 	ext{C9} ightarrow 	ext{MAC}$$

Question 16

Which of the following is a plausible outcome if a pathogen enzymatically digests C5a?

Accepted Answer

Reduced chemotaxis of phagocytes to the infection site

Question 17

Which of the following best explains why the alternative pathway of complement activation provides immediate defense?

Accepted Answer

It is directly activated by pathogen surfaces without the need for antibodies.

Question 18

Which of the following equations best represents the process of fever induction by cytokines?

Accepted Answer

$$	ext{Cytokines} ightarrow 	ext{Brain} ightarrow 	ext{Increased Body Temperature}$$

Question 19

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

Accepted Answer

Capturing foreign invaders and presenting them to other immune cells

Innate Immunity: Mechanisms and Cellular Components

Study Guide - Practice Questions