Question 1

Which of the following best describes the difference between signs and symptoms of a disease?

Accepted Answer

Signs are objective measurements, such as temperature or blood pressure, while symptoms are subjective experiences reported by the patient, such as pain or nausea.

Question 2

A patient develops a yeast infection while taking antibiotics for a bacterial infection. This is an example of which type of infection?

Accepted Answer

Secondary infection

Question 3

Which of the following is NOT a step in Koch's original postulates for determining the etiology of a disease?

Accepted Answer

The suspected pathogen must be found in healthy individuals.

Question 4

Which of the following best explains why Molecular Koch's Postulates are necessary in some cases?

Accepted Answer

Some pathogens cannot be cultured, or only certain strains with specific genes cause disease.

Question 5

A patient is infected with a virus that remains dormant in their body for years before causing symptoms again. This is an example of which type of disease?

Accepted Answer

Latent disease

Question 6

Which of the following is a property of an opportunistic infection?

Accepted Answer

It is caused by a microbe that is normally harmless but can infect immunocompromised individuals.

Question 7

Which of the following is a mechanism by which bacteria evade the host immune system?

Accepted Answer

Producing capsules to prevent phagocytosis

Question 8

A Gram-negative bacterium releases a toxin that is part of its outer membrane and can cause septic shock. What is this toxin called?

Accepted Answer

Endotoxin (lipopolysaccharide, LPS)

Question 9

Which of the following best describes the function of an AB toxin?

Accepted Answer

The B subunit binds to the host cell, and the A subunit enters the cell to alter its function.

Question 10

A patient presents with diarrhea after ingesting contaminated water. Laboratory analysis reveals the presence of a toxin that specifically targets the intestines. What type of toxin is most likely responsible?

Accepted Answer

Enterotoxin

Question 11

Which of the following is an example of antigenic variation as an immune evasion strategy?

Accepted Answer

A pathogen changes its surface proteins to avoid recognition by antibodies.

Question 12

Which of the following best describes a subclinical infection?

Accepted Answer

An infection with no noticeable symptoms in the host.

Question 13

A researcher is studying a new bacterial strain suspected of causing disease. The strain cannot be cultured in the lab. Which method should the researcher use to establish causation?

Accepted Answer

Molecular Koch's Postulates using PCR to detect specific genes

Question 14

Which of the following is a correct sequence of steps in the establishment of infection by a pathogen?

Accepted Answer

Adherence, colonization/invasion, reproduction, damage to host

Question 15

A patient with HIV develops pneumonia caused by Pneumocystis jirovecii, a fungus that rarely infects healthy individuals. This is an example of:

Accepted Answer

Opportunistic infection

Question 16

Which of the following best describes the role of superantigen toxins?

Accepted Answer

They activate T cells without the need for antigen specificity, causing an inappropriate immune response.

Question 17

Which of the following is a plausible reason why a pathogen might mimic host antigens?

Accepted Answer

To avoid detection by the host's immune system by appearing as 'self'

Question 18

A patient is infected with a virus that blocks interferon gene transcription. What is the likely benefit to the virus?

Accepted Answer

It prevents the host from sending antiviral signals, allowing the virus to replicate undetected.

Question 19

Which of the following best defines virulence?

Accepted Answer

The degree of pathogenicity or how severe the disease caused by a pathogen is.

Question 20

A bacterial pathogen produces an enzyme that destroys host cell junctions, allowing it to penetrate between cells. Which type of virulence factor is this?

Accepted Answer

Exoenzyme

Pathogenesis and Mechanisms of Infectious Disease

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