Question 1

Which of the following best explains why the terms 'alive' or 'dead' are not appropriate for describing viruses?

Accepted Answer

Viruses can only reproduce inside living cells and lack independent metabolism, so they do not meet the criteria for life.

Question 2

Which suffix is used to denote viral families?

Accepted Answer

-viridae

Question 3

A virus that infects only respiratory epithelial cells but not liver cells demonstrates which concept?

Accepted Answer

Tropism

Question 4

Which of the following structures is found in all viruses?

Accepted Answer

Capsid

Question 5

What is the function of reverse transcriptase in certain viruses?

Accepted Answer

It synthesizes DNA from an RNA template.

Question 6

Which of the following best describes a virion?

Accepted Answer

A fully formed, infectious viral particle outside a host cell.

Question 7

Which of the following is a key difference between enveloped and naked viruses?

Accepted Answer

Enveloped viruses have a lipid membrane derived from the host cell, while naked viruses lack this membrane.

Question 8

Which of the following best describes the process by which an enveloped animal virus enters a host cell?

Accepted Answer

Fusion of the viral envelope with the host cell membrane or endocytosis followed by uncoating.

Question 9

During the synthesis stage of the animal virus life cycle, where does replication of viral DNA typically occur?

Accepted Answer

In the host cell nucleus.

Question 10

Which of the following is NOT a possible type of genetic material found in a virion?

Accepted Answer

Double-stranded DNA and single-stranded RNA can both be found, but not both at the same time in a single virion.

Question 11

A bacteriophage attaches to a bacterial cell and injects its DNA, which then integrates into the host genome and remains dormant. What is this state called?

Accepted Answer

Prophage

Question 12

Which of the following best describes lysogenic conversion?

Accepted Answer

A change in the phenotype of a bacterium due to the presence of a prophage.

Question 13

Which of the following is a method bacteria use to defend against bacteriophage infection?

Accepted Answer

Restriction endonucleases that degrade foreign DNA.

Question 14

Which of the following is a correct sequence of the five-step life cycle of animal viruses?

Accepted Answer

Adsorption, penetration, uncoating, synthesis, assembly, release

Question 15

A patient is diagnosed with Creutzfeldt-Jakob disease. What type of infectious agent is responsible for this disease?

Accepted Answer

Prion

Question 16

Which of the following best describes a vaccine?

Accepted Answer

A preparation of antigens that stimulates an immune response to confer protection against a specific disease.

Question 17

Which of the following is a function of viral envelope proteins (spikes)?

Accepted Answer

They mediate attachment to specific host cell receptors, determining host and tissue specificity.

Question 18

Which of the following best describes the structure of a bacteriophage?

Accepted Answer

A head containing nucleic acid, a tail sheath, and tail fibers for attachment.

Question 19

Which of the following is a real-world application of viruses in biotechnology?

Accepted Answer

Using modified viruses as vectors in gene therapy to deliver therapeutic genes.

Question 20

A scientist is studying a virus with an icosahedral capsid, single-stranded RNA genome, and no envelope. Which of the following best describes this virus?

Accepted Answer

A naked virus with icosahedral symmetry and an ssRNA genome.

Chapter 5: Viruses – Structure, Classification, and Life Cycles

Guida di studio - Domande di pratica

Study guide - Flashcard