Question 1

Which of the following best describes the difference between a true pathogen and an opportunistic pathogen?

Accepted Answer

A true pathogen can cause disease in healthy individuals, whereas an opportunistic pathogen causes disease primarily in hosts with weakened immune systems.

Question 2

A patient develops a fever and cough after being bitten by a mosquito carrying the West Nile virus. In this scenario, what role does the mosquito play?

Accepted Answer

Vector

Question 3

Which of the following best defines a nosocomial infection?

Accepted Answer

An infection acquired in a hospital or healthcare facility

Question 4

Which of the following is the correct order of events in phagocytosis?

Accepted Answer

Chemotaxis → Adherence → Ingestion → Digestion → Elimination

Question 5

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

Accepted Answer

Phagocytic white blood cells

Question 6

A patient is diagnosed with a zoonotic disease. Which of the following best describes this type of disease?

Accepted Answer

A disease that is acquired from animals

Question 7

Which of the following statements about antibodies is correct?

Accepted Answer

Antibodies are composed of two heavy chains and two light chains, forming a Y-shaped structure.

Question 8

Which class of antibody is most abundant in serum and is responsible for long-term immunity?

Accepted Answer

IgG

Question 9

Which of the following best describes the function of the complement system's classical pathway?

Accepted Answer

It is activated by antigen-antibody complexes and leads to the formation of the membrane attack complex (MAC).

Question 10

A laboratory test detects the presence of interferon-gamma ($$\gamma) in a $$patient's blood. Which of the following is a primary function of interferon-gamma?

Accepted Answer

Activating macrophages and enhancing phagocytosis

Question 11

Which of the following white blood cells is classified as a non-phagocyte but plays a crucial role in killing virus-infected and tumor cells?

Accepted Answer

Natural killer (NK) cell

Question 12

During an inflammatory response, which of the following events occurs first?

Accepted Answer

Vasodilation and increased permeability of blood vessels

Question 13

A patient receives an injection of pre-formed antibodies to treat a snake bite. This is an example of:

Accepted Answer

Passive immunotherapy

Question 14

Which of the following best describes the function of Major Histocompatibility Complex (MHC) proteins in adaptive immunity?

Accepted Answer

They present antigen fragments to T cells, initiating an adaptive immune response.

Question 15

Which of the following is a key difference between exogenous and endogenous antigens?

Accepted Answer

Exogenous antigens originate from outside the host cell, while endogenous antigens are generated within the host cell.

Question 16

Which of the following best explains why fever is considered a component of innate immunity?

Accepted Answer

Fever enhances the activity of immune cells and inhibits the growth of some pathogens.

Question 17

A patient is given a vaccine containing inactivated (killed) pathogens. Which type of vaccine is this?

Accepted Answer

Inactivated (killed) vaccine

Question 18

Which of the following best describes the principle behind the ELISA (Enzyme-Linked Immunosorbent Assay) test?

Accepted Answer

It detects the presence of antigens or antibodies using enzyme-linked reactions that produce a color change.

Question 19

Which of the following cytokines is primarily responsible for promoting inflammation and recruiting immune cells to the site of infection?

Accepted Answer

Interleukin-1 (IL-1)

Question 20

A laboratory technician is testing for the presence of antibodies in a patient's serum using immunodiffusion. Which of the following best describes the result if the patient's serum contains the specific antibody?

Accepted Answer

A visible precipitin line forms where the antibody and antigen meet.

Microbiology Immunology & Host Defense Study Guide

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