Question 1

Which of the following statements best distinguishes viruses from living cells?

Accepted Answer

Viruses lack a cell membrane and do not divide by binary fission or mitosis.

Question 2

A scientist is studying a virus with a single-stranded negative-sense RNA genome. Which enzyme must this virus bring into the host cell to initiate replication?

Accepted Answer

RNA-dependent RNA polymerase

Question 3

During the viral life cycle, which step is unique to enveloped animal viruses compared to non-enveloped viruses?

Accepted Answer

Fusion of the viral envelope with the host cell membrane during penetration

Question 4

A retrovirus infects a human cell. Which sequence of events correctly describes the synthesis of new viral genomes?

Accepted Answer

The viral +RNA is used as a template by reverse transcriptase to synthesize complementary DNA, which integrates into the host genome.

Question 5

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

Accepted Answer

They require host cell machinery for energy production, protein synthesis, and nucleic acid replication.

Question 6

A plant biotechnologist introduces a viral coat protein gene into a grapevine. What is the most likely outcome regarding viral infection?

Accepted Answer

The plant is protected because high levels of coat protein prevent viral uncoating and replication.

Question 7

Which of the following viruses is most directly associated with the development of cervical cancer?

Accepted Answer

Human Papilloma Virus (HPV)

Question 8

A patient is diagnosed with a neurodegenerative disease after consuming beef from cattle affected by Bovine Spongiform Encephalopathy (BSE). Which infectious agent is most likely responsible?

Accepted Answer

Prion

Question 9

Which of the following best describes the function of reverse transcriptase in retroviruses?

Accepted Answer

It synthesizes complementary DNA from an RNA template.

Question 10

A viroid infects a plant and causes disease. Which characteristic distinguishes viroids from viruses?

Accepted Answer

Viroids consist solely of a short, circular RNA molecule without a protein coat.

Question 11

Which of the following best explains why protease inhibitors are effective in HIV therapy?

Accepted Answer

They block the cleavage of the HIV polyprotein, preventing the formation of functional viral proteins.

Question 12

A virus with a double-stranded DNA genome infects a cell. Which enzyme is primarily responsible for transcribing viral genes?

Accepted Answer

Host RNA polymerase

Question 13

Which of the following is a correct sequence of events for a +RNA virus (not a retrovirus) after entry into a host cell?

Accepted Answer

Translation of +RNA, synthesis of RNA-dependent RNA polymerase, production of -RNA template, synthesis of new +RNA genomes

Question 14

Which of the following best describes the role of viral oncogenes (vONC) in cancer development?

Accepted Answer

vONC genes are analogs of cellular oncogenes and can disrupt normal cell cycle regulation when introduced by viruses.

Question 15

Which of the following best explains why viruses cannot be classified as living organisms?

Accepted Answer

They do not possess both DNA and RNA simultaneously and lack cellular structures.

Question 16

A researcher is studying a new plant disease caused by an infectious agent that is a short RNA molecule, 350 nucleotides long, with no protein coat. What is the most likely identity of this agent?

Accepted Answer

Viroid

Question 17

Which of the following best describes the process of viral assembly (maturation) in the host cell?

Accepted Answer

Viral components are synthesized and then spontaneously assemble into mature virions when sufficient concentrations are reached.

Question 18

Which of the following is a plausible reason why the use of animal offal in livestock feed was banned in relation to prion diseases?

Accepted Answer

Feeding offal can transmit misfolded prion proteins between species, increasing the risk of diseases like BSE.

Question 19

Which of the following best explains why host ribosomes are essential for viral replication?

Accepted Answer

Viruses lack the machinery to synthesize their own proteins and must use host ribosomes for translation.

Question 20

A patient is infected with a -RNA virus. Which of the following steps must occur before viral proteins can be synthesized?

Accepted Answer

The -RNA must be converted to +RNA by a viral RNA-dependent RNA polymerase.

Study Notes: Viruses, Viroids, and Prions (Chapter 13)

Study Guide - Practice Questions

Study Guide - Flashcards