$$-ssRNA \rightarrow +ssRNA \rightarrow \text{protein}$$

Question 1

Which of the following best describes why viruses are considered obligate intracellular parasites?

Accepted Answer

They must invade and infect a host cell in order to reproduce.

Question 2

A scientist observes a virus with an outer envelope and a nucleocapsid. Which of the following statements is TRUE regarding this virus?

Accepted Answer

Its envelope proteins allow it to attach to and infect host cells.

Question 3

Which step in the life cycle of a virulent bacteriophage is responsible for injecting the phage genome into the host cell?

Accepted Answer

Penetration

Question 4

A lysogenic bacteriophage can cause a change in the phenotype of its host bacterium. What is this process called?

Accepted Answer

Lysogenic conversion

Question 5

Which of the following viruses would require host cell DNA polymerase for genome replication?

Accepted Answer

Double-stranded DNA virus

Question 6

A positive-sense single-stranded RNA virus ($$+ssRNA) $$infects a cell. What is the first step in its biosynthesis after entry?

Accepted Answer

Immediate translation of its genome into viral proteins

Question 7

Which of the following is a key difference between naked and enveloped viruses in their release from host cells?

Accepted Answer

Enveloped viruses are released by budding, while naked viruses are released by cell lysis.

Question 8

A virus infects a host cell and integrates its genome into the host DNA, remaining dormant for several generations. What is this phase called?

Accepted Answer

Lysogenic cycle

Question 9

Which of the following best explains why animal viruses can cause latent infections?

Accepted Answer

They can persist in host tissues and reactivate periodically.

Question 10

A retrovirus contains an RNA genome. Which enzyme does it use to synthesize DNA from its RNA template?

Accepted Answer

Reverse transcriptase

Question 11

Which of the following is TRUE regarding the host range of a virus?

Accepted Answer

It is determined by the virus's ability to attach to specific host cell receptors.

Question 12

Which of the following best describes the function of viral capsid proteins?

Accepted Answer

They protect the viral genome and aid in host cell attachment.

Question 13

A virus is described as having a helical capsid and lacking an envelope. Which of the following is most likely TRUE?

Accepted Answer

It is released from the host cell by lysis.

Question 14

Which of the following equations correctly represents the process by which a negative-sense RNA virus ($$-ssRNA) $$produces mRNA for translation?

Accepted Answer

$$-ssRNA ightarrow +ssRNA ightarrow 	ext{protein}$$

Question 15

Which of the following is a plausible consequence of lysogenic conversion in bacteria?

Accepted Answer

The bacterium acquires new pathogenic traits due to phage-encoded toxins.

Question 16

A scientist is cultivating viruses in the laboratory. Which of the following methods would be most appropriate for growing animal viruses?

Accepted Answer

Using live animals or embryonated eggs

Question 17

Which of the following statements about viral replication is CORRECT?

Accepted Answer

All viruses use host cell ribosomes for protein synthesis.

Question 18

A patient is diagnosed with a persistent viral infection that periodically reactivates, causing cold sores. Which virus is most likely responsible?

Accepted Answer

Herpes simplex virus (HSV)

Question 19

Which of the following best explains why enveloped viruses are generally more sensitive to detergents and desiccation than naked viruses?

Accepted Answer

Their lipid envelope is disrupted, preventing attachment to host cells.

Question 20

Which of the following is a major reason why chronic diseases of unknown cause may eventually be connected to viral agents?

Accepted Answer

Viruses are ubiquitous and can persist in host tissues for long periods.

Study Guide: Viruses – Structure, Replication, and Impact (Microbiology Ch. 5)

Study Guide - Practice Questions