Question 1

Which of the following best describes a virion?

Accepted Answer

A complete, infectious virus particle composed of nucleic acid and a protein coat, and sometimes an envelope.

Question 2

Which structure is found in all viruses, regardless of whether they are enveloped or naked?

Accepted Answer

Capsid

Question 3

A scientist is studying a virus that enters animal cells by fusing its envelope with the host cell membrane. Which process is being described?

Accepted Answer

Membrane fusion

Question 4

Which of the following statements about the genetic material of viruses is correct?

Accepted Answer

Viral genomes may consist of either DNA or RNA, but never both in the same virion.

Question 5

Which of the following best explains why most viruses infect only specific species and cell types?

Accepted Answer

Viral surface proteins (spikes) must specifically bind to complementary receptors on the host cell surface.

Question 6

A researcher is working with a positive-sense single-stranded RNA virus. Which of the following best describes the replication process of this virus?

Accepted Answer

The viral RNA can serve directly as mRNA for protein synthesis.

Question 7

Which of the following is a key difference between the replication of retroviruses and double-stranded DNA viruses?

Accepted Answer

Retroviruses use reverse transcriptase to synthesize DNA from their RNA genome.

Question 8

Which of the following best defines an obligate intracellular parasite?

Accepted Answer

An organism or agent that can only reproduce inside a living host cell.

Question 9

Why are continuous cell cultures preferred over diploid cell cultures for growing viruses in the laboratory?

Accepted Answer

Continuous cell cultures can be maintained and subcultured indefinitely, providing a consistent supply of host cells.

Question 10

A patient develops a persistent infection with a virus that remains dormant in host cells and can reactivate later. What is the term for this type of virus?

Accepted Answer

Latent virus

Question 11

Which of the following is a mechanism by which animal viruses are released from host cells?

Accepted Answer

Budding, which allows enveloped viruses to acquire their envelope from the host cell membrane.

Question 12

Which of the following best describes a prion?

Accepted Answer

An infectious protein that lacks nucleic acids and causes spongiform encephalopathies.

Question 13

A virus is found to cause neoplasia in infected tissue. What does this mean?

Accepted Answer

The virus induces uncontrolled cell growth, potentially leading to cancer.

Question 14

Which scientist is credited with the discovery of viruses as filterable agents?

Accepted Answer

Dmitri Ivanowsky

Question 15

A viroid differs from a typical virus in that it:

Accepted Answer

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

Question 16

Which of the following best explains why prion diseases are difficult to treat?

Accepted Answer

Prions lack nucleic acids, so treatments targeting DNA or RNA are ineffective.

Question 17

A virus with a helical capsid shape is observed under the electron microscope. Which of the following best describes its structure?

Accepted Answer

The capsid proteins are arranged in a spiral around the nucleic acid, forming a rod-like structure.

Question 18

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

Accepted Answer

They mediate attachment to specific host cell receptors.

Question 19

A laboratory is attempting to cultivate a newly discovered virus. Which of the following is a major difference between cultivating viruses and bacteria?

Accepted Answer

Viruses require living host cells for replication, while bacteria can be grown on nutrient media.

Question 20

A patient is diagnosed with a spongiform encephalopathy. Which of the following is the most likely cause?

Accepted Answer

Infection by a prion, which is a misfolded protein.

Characterizing and Classifying Viruses, Viroids, and Prions – Study Guide

Guida di studio - Domande di pratica

Study guide - Flashcard