Question 1

Which of the following statements best distinguishes a virus from a viroid?

Accepted Answer

A virus is an acellular infectious agent with a protein capsid, while a viroid is a naked, circular RNA molecule lacking a capsid.

Question 2

A patient is diagnosed with a viral infection. The virus is found to have a single-stranded RNA genome that can be directly translated by host ribosomes. Which type of viral genome does this virus possess?

Accepted Answer

$$+ssRNA$$

Question 3

Which of the following best explains why enveloped viruses are generally more sensitive to alcohol-based disinfectants than naked viruses?

Accepted Answer

Alcohol disrupts the phospholipid bilayer of the viral envelope, compromising the virus's ability to infect host cells.

Question 4

A bacteriophage infects a bacterial cell and integrates its DNA into the host genome, remaining dormant until the host is exposed to UV light, which triggers the production of new phages. This process is best described as:

Accepted Answer

The lysogenic cycle with induction

Question 5

Which of the following is a function of viral glycoprotein spikes?

Accepted Answer

They allow the virus to attach to specific host cell receptors, determining host specificity.

Question 6

A patient develops a yeast infection after taking broad-spectrum antibiotics for several weeks. Which of the following best explains this phenomenon?

Accepted Answer

The antibiotics eliminated normal bacterial microbiota, allowing opportunistic fungi to overgrow.

Question 7

Which of the following is NOT a typical function of a viral capsid?

Accepted Answer

Carrying out viral genome replication

Question 8

A patient is infected with a virus that remains dormant in nerve cells for years before reactivating and causing symptoms. This type of infection is best described as:

Accepted Answer

Latent infection

Question 9

Which of the following best describes the difference between incidence and prevalence in epidemiology?

Accepted Answer

Incidence measures new cases over a period of time, while prevalence measures all existing cases at a given time.

Question 10

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

Accepted Answer

A fly carrying Salmonella on its legs from feces to food without the pathogen developing inside the fly

Question 11

A hospital patient develops pneumonia after being intubated for surgery. The infection is traced to bacteria present on the ventilator equipment. This infection is best classified as:

Accepted Answer

An exogenous healthcare-associated infection

Question 12

Which of the following is a limitation of Koch's postulates?

Accepted Answer

Some pathogens cannot be grown in pure culture outside the host.

Question 13

Which of the following best describes the role of antiphagocytic factors in microbial virulence?

Accepted Answer

They help pathogens evade destruction by immune cells such as phagocytes.

Question 14

A disease that is constantly present at a relatively stable level within a specific geographic region is best described as:

Accepted Answer

Endemic

Question 15

Which of the following is an example of amensalism?

Accepted Answer

A fungus secreting an antibiotic that kills nearby bacteria, while the fungus is unaffected

Question 16

A patient presents with fever, rash, and vomiting. Which of the following best describes these findings?

Accepted Answer

Signs

Question 17

Which of the following is a characteristic of prions that makes them difficult to destroy using standard sterilization methods?

Accepted Answer

They lack nucleic acids and consist only of misfolded proteins, making them resistant to heat and chemicals.

Question 18

Which of the following best describes the difference between pathogenicity and virulence?

Accepted Answer

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

Question 19

A person is exposed to a pathogen on their skin, but the organism does not multiply or cause any symptoms. This situation is best described as:

Accepted Answer

Contamination

Question 20

Which of the following is a real-world example of a zoonosis?

Accepted Answer

A person contracts rabies after being bitten by a dog.

Viruses, Viroids, Prions, and Principles of Infectious Disease & Epidemiology

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