Question 1

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

Accepted Answer

They require host cell machinery to replicate their nucleic acids and synthesize proteins.

Question 2

A virus with a helical capsid and an envelope is most likely to enter an animal cell by which mechanism?

Accepted Answer

Fusion with the host cell membrane

Question 3

Which of the following statements about viral genomes is correct?

Accepted Answer

Viral genomes can be either single-stranded or double-stranded, and either DNA or RNA.

Question 4

During the lysogenic cycle of a bacteriophage, what is the fate of the viral DNA?

Accepted Answer

It is integrated into the host genome and replicated along with host DNA.

Question 5

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

Accepted Answer

The host cell may acquire new properties, such as toxin production.

Question 6

A retrovirus differs from other RNA viruses because it:

Accepted Answer

Synthesizes DNA from its RNA genome using reverse transcriptase.

Question 7

Which of the following best explains why antiviral drugs are often less effective than antibiotics?

Accepted Answer

Viruses use host cell machinery for replication, making it difficult to target the virus without harming the host cell.

Question 8

Which of the following is NOT a characteristic of viroids?

Accepted Answer

They infect animal cells and cause neurological diseases.

Question 9

A patient is diagnosed with a persistent viral infection. Which of the following best describes this condition?

Accepted Answer

The virus causes disease symptoms that develop gradually over a long period and are often fatal.

Question 10

Which of the following laboratory methods is used to quantify the number of infectious bacteriophage particles in a sample?

Accepted Answer

Counting plaque-forming units (PFU) on a bacterial lawn

Question 11

Which of the following best describes the role of protooncogenes in cancer development related to viral infection?

Accepted Answer

Viruses can activate protooncogenes or insert oncogenes, leading to uncontrolled cell division.

Question 12

Which of the following is a unique property of prions compared to viruses?

Accepted Answer

Prions are infectious proteins that lack nucleic acids.

Question 13

A virus is isolated that contains a single-stranded, negative-sense RNA genome. What must occur before viral proteins can be synthesized?

Accepted Answer

A complementary positive-sense RNA must be synthesized by viral RNA-dependent RNA polymerase.

Question 14

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

Accepted Answer

They cannot carry out metabolism or reproduce independently outside a host cell.

Question 15

Which of the following is a correct sequence of events in the lytic replication cycle of a bacteriophage?

Accepted Answer

Attachment → Entry → Synthesis → Assembly → Release

Question 16

A scientist is studying a virus that acquires its envelope from the host cell. Which of the following best describes how this envelope is formed?

Accepted Answer

The envelope is derived from the host cell membrane during viral budding.

Question 17

Which of the following is a plausible reason why a plant virus cannot infect animal cells?

Accepted Answer

Animal cells do not have the specific receptors required for plant virus attachment.

Question 18

Which of the following best describes specialized transduction?

Accepted Answer

Transfer of specific bacterial genes adjacent to the prophage during lysogenic induction

Question 19

Which of the following is a key difference between latent and persistent viral infections?

Accepted Answer

Latent infections involve periods of dormancy without symptoms, while persistent infections involve continuous viral production.

Question 20

Which of the following methods is commonly used to culture animal viruses in the laboratory?

Accepted Answer

Inoculating embryonated eggs

Characterizing and Classifying Viruses, Viroids, and Prions

Study Guide - Practice Questions