Question 1

Which of the following best describes the primary function of the first line of host defense?

Accepted Answer

To block invasion at the portal of entry and limit access to internal tissues

Question 2

Markers (antigens) on cell surfaces are crucial for immune function because they:

Accepted Answer

Allow immune cells to distinguish self from nonself and initiate destruction of foreign entities

Question 3

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

Accepted Answer

Filtering worn-out red blood cells from the blood

Question 4

Which blood cell type is primarily responsible for early response to bacterial infection and is a major component of pus?

Accepted Answer

Neutrophils

Question 5

Which of the following is a pro-inflammatory cytokine?

Accepted Answer

Interleukin-1 (IL-1)

Question 6

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

Accepted Answer

Chemotaxis, adhesion, engulfment, phagosome formation, phagolysosome formation, killing, excretion

Question 7

Which of the following is a characteristic of the classical complement pathway?

Accepted Answer

It is initiated by the binding of complement proteins to antibodies already bound to microbes.

Question 8

Which of the following is NOT transported by lymphatic fluid?

Accepted Answer

Red blood cells

Question 9

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

Accepted Answer

Hydrochloric acid in the stomach

Question 10

Which of the following statements about fever is TRUE?

Accepted Answer

Fever inhibits multiplication of temperature-sensitive microorganisms and increases immune reactions.

Question 11

Which of the following is a function of antimicrobial peptides?

Accepted Answer

They insert into bacterial membranes and create pores, leading to cell lysis.

Question 12

Which of the following is a benefit of edema and leaky vessels during inflammation?

Accepted Answer

Dilution of toxic substances and trapping of microbes by fibrin clots

Question 13

Which of the following is a correct statement about interferons?

Accepted Answer

Interferons induce the production of proteins that inhibit viral multiplication in nearby cells.

Question 14

Which of the following is a major function of the mononuclear phagocyte system (MPS)?

Accepted Answer

To provide a network of phagocytic cells for surveillance and destruction of foreign intruders

Question 15

Which of the following is a correct description of diapedesis?

Accepted Answer

The migration of white blood cells out of blood vessels into tissues

Question 16

Which of the following is a characteristic of the third line of defense?

Accepted Answer

It provides long-term immunity through the action of specialized lymphocytes.

Question 17

Which of the following is a correct statement about pattern recognition receptors (PRRs)?

Accepted Answer

PRRs recognize and bind pathogen-associated molecular patterns (PAMPs) on microbes.

Question 18

Which of the following is a correct statement about the complement cascade?

Accepted Answer

The membrane attack complex (MAC) forms pores in the offending cell’s membrane, leading to cell lysis.

Question 19

Which of the following is a correct statement about the role of normal microbiota in the first line of defense?

Accepted Answer

Normal microbiota compete for nutrients and alter local pH, creating an unfavorable environment for pathogens.

Question 20

Which of the following is a correct statement about the structure and function of lymph nodes?

Accepted Answer

Lymph nodes are small, encapsulated organs that filter lymph and are sites of immune cell activation.

Chapter 12: Host Defenses I – Overview and Innate Defenses

Study Guide - Practice Questions