Question 1

Which of the following best describes the mechanism by which prions cause disease?

Accepted Answer

They are misfolded proteins that induce abnormal folding of normal proteins, leading to spongy tissue in the brain.

Question 2

A patient presents with a slow, progressive infection that remains detectable for years. Which type of persistent viral infection does this scenario best illustrate?

Accepted Answer

Chronic infection

Question 3

Which of the following is a correct example of a vector in disease transmission?

Accepted Answer

A mosquito transmitting malaria

Question 4

Which of the following best explains why prions are unique among pathogens?

Accepted Answer

They lack nucleic acids entirely.

Question 5

A hospital is investigating an outbreak of Clostridioides difficile (C. diff) infection. Which of the following most likely contributed to this outbreak?

Accepted Answer

Antibiotic disruption of normal microbiota

Question 6

Which of the following is a key difference between endotoxins and exotoxins?

Accepted Answer

Endotoxins are lipopolysaccharides released from Gram-negative bacteria, while exotoxins are proteins secreted by both Gram-positive and Gram-negative bacteria.

Question 7

A patient is diagnosed with hepatitis B, a virus known to cause cancer in some cases. Which mechanism best explains its oncogenic potential?

Accepted Answer

Integration of viral genome into host DNA, leading to chronic inflammation

Question 8

Which of the following best describes the 'tropism' of a pathogen?

Accepted Answer

The specific tissue or cell type a pathogen infects

Question 9

During which stage of infection is a patient most likely to be asymptomatic but still infectious?

Accepted Answer

Incubation period

Question 10

Which of the following is the correct order of the five steps to infection?

Accepted Answer

Entry → Adhesion → Invasion/Nutrient acquisition → Immune evasion → Transmission

Question 11

A new strain of influenza emerges with a novel hemagglutinin gene. Which process is responsible for this change?

Accepted Answer

Antigenic shift

Question 12

Which of the following best describes the function of the basic reproduction number $R_0$ in epidemiology?

Accepted Answer

It represents the average number of secondary infections produced by one infected individual in a susceptible population.

Question 13

A patient is a chronic carrier of Salmonella typhi but shows no symptoms. Which term best describes this state?

Accepted Answer

Carrier state

Question 14

Which of the following is an example of an endogenous source of infection?

Accepted Answer

E. coli from the patient's own gut flora causing a urinary tract infection

Question 15

Which of the following best distinguishes pathogenicity from virulence?

Accepted Answer

Pathogenicity is the ability to cause disease, while virulence is the severity of disease caused.

Question 16

A patient develops sepsis after infection with a Gram-negative bacterium. Which molecule is most likely responsible for triggering septic shock?

Accepted Answer

Lipopolysaccharide (Lipid A)

Question 17

Which of the following is a standard precaution for infection control in healthcare settings?

Accepted Answer

Wearing gloves when handling blood

Question 18

Which of the following best explains why biofilms contribute to chronic infections?

Accepted Answer

Biofilms protect bacteria from antibiotics and immune responses.

Question 19

A patient is infected with a pathogen that only infects humans. Which term best describes this phenomenon?

Accepted Answer

Host range

Question 20

Which of the following is an example of a healthcare-associated infection (HAI)?

Accepted Answer

A patient develops a urinary tract infection after catheterization in the hospital.

Viruses, Prions, and Host–Microbe Interactions: Key Concepts and High-Yield Themes

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