Question 1

Which of the following best explains why RNA viruses tend to evolve more rapidly than DNA viruses?

Accepted Answer

RNA viruses have higher mutation rates due to the lack of proofreading activity in their polymerases.

Question 2

Which of the following is NOT one of the four main criteria used to classify viruses?

Accepted Answer

Ability to cause cancer

Question 3

A patient is diagnosed with cervical cancer linked to a viral infection. Which virus is most likely responsible, and what makes it oncogenic?

Accepted Answer

Human papillomavirus (HPV); it integrates into host DNA and disrupts cell cycle regulation.

Question 4

Which step is unique to retroviruses during their replication in animal cells?

Accepted Answer

Synthesis of DNA from an RNA template using reverse transcriptase: $$RNA \rightarrow DNA$$

Question 5

Which laboratory method is most commonly used to culture and study animal viruses?

Accepted Answer

Inoculation of viruses into living cell cultures (e.g., HeLa cells)

Question 6

Which of the following best describes antigenic drift in influenza viruses?

Accepted Answer

Gradual accumulation of point mutations in viral genes encoding surface proteins

Question 7

A bacteriophage infects a bacterium and integrates its genome into the host chromosome, remaining dormant. What is this process called?

Accepted Answer

Lysogenic replication

Question 8

Why is phage conversion medically significant?

Accepted Answer

It can result in bacteria acquiring new virulence factors, such as toxin genes.

Question 9

Which of the following antiviral drugs targets the viral enzyme neuraminidase, and what is its primary use?

Accepted Answer

Oseltamivir (Tamiflu); used to treat influenza infections

Question 10

Which of the following statements about prions is TRUE?

Accepted Answer

Prions are infectious proteins that cause neurodegenerative diseases such as Creutzfeldt-Jakob disease.

Question 11

A hospital outbreak of influenza is traced to a new viral strain resulting from the reassortment of gene segments between human and avian influenza viruses. What is this process called, and why is it significant?

Accepted Answer

Antigenic shift; it can lead to pandemics due to the emergence of novel viruses.

Question 12

Which of the following is a generalized step in animal virus replication that directly follows viral attachment?

Accepted Answer

Penetration of the host cell membrane

Question 13

Which of the following viruses is classified as oncogenic and is associated with liver cancer?

Accepted Answer

Hepatitis B virus (HBV)

Question 14

Which of the following best describes the lytic cycle of a bacteriophage?

Accepted Answer

The phage replicates and lyses the host cell, releasing new phage particles.

Question 15

Which of the following is a method by which prion diseases can be transmitted?

Accepted Answer

Consumption of contaminated neural tissue

Question 16

Which antiviral drug is a nucleoside analog that inhibits reverse transcriptase, and what is its main clinical use?

Accepted Answer

Zidovudine (AZT); used in the treatment of HIV infection

Question 17

Which of the following best explains why viruses are not considered living organisms?

Accepted Answer

They lack cellular structure and cannot carry out metabolism independently.

Question 18

A laboratory is attempting to isolate a new virus. Which of the following would be the most effective initial step?

Accepted Answer

Inoculating susceptible cell cultures and observing for cytopathic effects

Question 19

Which of the following is a correct sequence of events in the replication of an enveloped animal virus?

Accepted Answer

Attachment $$\rightarrow$$ Penetration $$\rightarrow$$ Uncoating $$\rightarrow$$ Synthesis $$\rightarrow$$ Assembly $$\rightarrow$$ Release

Question 20

Which of the following best describes the role of reverse transcriptase in viral replication?

Accepted Answer

It synthesizes complementary DNA from an RNA template: $$RNA \rightarrow DNA$$

Microbiology Study Guide – Module 4: Viruses and Prions

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