Titer = $$\frac{1}{\text{highest dilution showing a positive reaction}}$$

Question 1

Which of the following best describes the difference between nonspecific (innate) and specific (adaptive) immunity?

Accepted Answer

Nonspecific immunity responds to all pathogens in the same way, while specific immunity targets particular pathogens with tailored responses.

Question 2

Which of the following is a mechanical factor involved in the first line of nonspecific defense?

Accepted Answer

Skin acting as a physical barrier

Question 3

During phagocytosis, which step involves the fusion of a phagosome with a lysosome to form a phagolysosome?

Accepted Answer

Digestion

Question 4

Which chemical signal is primarily responsible for increasing vascular permeability during inflammation?

Accepted Answer

Histamine

Question 5

Which antimicrobial protein is directly involved in forming a membrane attack complex (MAC) that lyses pathogens?

Accepted Answer

Complement

Question 6

Fever is beneficial in fighting infections because:

Accepted Answer

It increases the rate of phagocytosis and inhibits the growth of some pathogens.

Question 7

Which of the following best defines a hapten?

Accepted Answer

A small molecule that is not immunogenic by itself but can become immunogenic when attached to a larger carrier.

Question 8

Which antibody class is most effective at neutralizing toxins and viruses in the bloodstream?

Accepted Answer

IgG

Question 9

Cell-mediated immunity primarily involves which type of cell?

Accepted Answer

Cytotoxic T cells (CD8+)

Question 10

Which of the following is an example of a hypersensitivity reaction?

Accepted Answer

An allergic reaction to pollen

Question 11

Which term describes the ability of the immune system to recognize and not attack the body's own cells?

Accepted Answer

Self tolerance

Question 12

Which of the following best describes the relationship in mutualism?

Accepted Answer

Both organisms benefit from the relationship.

Question 13

A microbe with an ID50 of $$10^3 is$$:

Accepted Answer

More virulent than a microbe with an ID50 of $$10^6$$

Question 14

Which mechanism allows microbes to evade destruction by the immune system?

Accepted Answer

Production of capsules to inhibit phagocytosis

Question 15

Which of the following best describes the difference between exotoxins and endotoxins?

Accepted Answer

Exotoxins are proteins actively secreted by bacteria, while endotoxins are lipopolysaccharides found in the outer membrane of Gram-negative bacteria.

Question 16

Which stage of disease is characterized by the appearance of specific signs and symptoms?

Accepted Answer

Period of illness

Question 17

Which portal of entry is most commonly used by respiratory pathogens?

Accepted Answer

Respiratory tract

Question 18

Which of the following is a real-world example of an ELISA test application?

Accepted Answer

Diagnosing HIV infection

Question 19

Which equation best represents the calculation of antibody titer in a serial dilution?

Accepted Answer

Titer = $$\frac{1}{	ext{highest dilution showing a positive reaction}}$$

Question 20

Which of the following is an example of artificially acquired passive immunity?

Accepted Answer

Receiving antiserum after exposure to rabies

Microbiology Exam Study Guide: Immunity, Host-Microbe Interactions, and Diagnostic Methods

Study Guide - Practice Questions