Question 1

Which of the following best describes the function of neutrophils in innate immunity?

Accepted Answer

Phagocytize bacteria and fungi, acting as 'first responders' during infection

Question 2

A patient presents with a low white blood cell count. Which of the following is LEAST likely to be the cause?

Accepted Answer

Mild bacterial infection

Question 3

Which physical barrier is most effective at preventing microbial penetration in healthy individuals?

Accepted Answer

Epidermis with keratin

Question 4

The ciliary escalator is a defense mechanism found in which part of the body, and what is its primary function?

Accepted Answer

Respiratory tract; transports trapped microbes away from the lungs

Question 5

Which chemical factor is responsible for lowering the pH of the skin and inhibiting microbial growth?

Accepted Answer

Sebum

Question 6

Normal microbiota protect the host by all of the following mechanisms EXCEPT:

Accepted Answer

Directly producing antibodies against pathogens

Question 7

Which of the following is a correct sequence for the mechanism of phagocytosis?

Accepted Answer

Chemotaxis → Adherence → Ingestion → Digestion → Elimination (exocytosis)

Question 8

During inflammation, which vasoactive mediator is released by mast cells and basophils to increase vascular permeability?

Accepted Answer

Histamine

Question 9

Which process describes the movement of phagocytes from the bloodstream into tissues at the site of inflammation?

Accepted Answer

Diapedesis

Question 10

A patient with a deficiency in complement proteins is most likely to experience:

Accepted Answer

Susceptibility to bacterial infections

Question 11

Which pathway of complement activation is triggered by antibodies binding to antigens?

Accepted Answer

Classical pathway

Question 12

What is the primary outcome of the membrane attack complex (MAC) formed during complement activation?

Accepted Answer

Cytolysis

Question 13

Which interferon is produced by viral-infected host cells and induces nearby cells to produce antiviral proteins?

Accepted Answer

IFN-\alpha and IFN-\beta

Question 14

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

Accepted Answer

Compete with host iron-binding proteins to acquire iron for bacterial growth

Question 15

Which antimicrobial peptide is produced by neutrophils and macrophages and acts by forming pores in microbial membranes?

Accepted Answer

Defensins

Question 16

A patient with sickle cell trait is less susceptible to malaria caused by Plasmodium falciparum. This is an example of:

Accepted Answer

Genetic resistance

Question 17

Which of the following equations correctly represents the conversion of C3 in the classical pathway of complement activation?

Accepted Answer

$$C3 \rightarrow C3a + C3b$$

Question 18

During acute inflammation, which sequence of events occurs first?

Accepted Answer

Vasodilation and increased vascular permeability

Question 19

Which cell type is most active in the early stages of a bacterial infection and can leave the blood to enter infected tissue?

Accepted Answer

Neutrophil

Question 20

Which of the following is NOT a function of acute-phase proteins released during inflammation?

Accepted Answer

Directly destroying pathogens by phagocytosis

Innate Immunity: Nonspecific Defenses of the Host

Study Guide - Practice Questions