Question 1

Which of the following statements best differentiates viruses from bacteria?

Accepted Answer

Viruses are obligate intracellular parasites that lack ribosomes and an ATP-generating mechanism.

Question 2

A scientist is studying a newly discovered infectious agent. It is acellular, contains only RNA, and lacks a plasma membrane. Which of the following best describes this agent?

Accepted Answer

A virus

Question 3

Which of the following is a unique feature of the extracellular state of a virus?

Accepted Answer

It contains a protein coat called a capsid surrounding the nucleic acid.

Question 4

A virus with a single, circular, double-stranded DNA genome and a polyhedral capsid would be classified based on which primary characteristic?

Accepted Answer

The type and structure of its nucleic acid

Question 5

Which of the following best explains why viruses are not considered alive by some scientists?

Accepted Answer

They lack metabolic pathways and cannot respond to their environment.

Question 6

A researcher observes clear zones on a bacterial lawn after adding a viral sample. What is the most likely explanation for these clear zones?

Accepted Answer

They are plaques formed by lysis of bacteria due to viral infection.

Question 7

Which of the following is a correct sequence of events in the lytic cycle of a T-even bacteriophage?

Accepted Answer

Attachment → Penetration → Biosynthesis → Maturation → Release

Question 8

During the lysogenic cycle of bacteriophage lambda (λ), what is the term for the phage DNA that is integrated into the host cell's chromosome?

Accepted Answer

Prophage

Question 9

Which of the following best describes the process of specialized transduction?

Accepted Answer

Transfer of specific bacterial genes by a lysogenic phage

Question 10

A patient is diagnosed with cervical cancer caused by a virus. Which of the following mechanisms most likely contributed to the development of this cancer?

Accepted Answer

The virus integrated its DNA into the host genome, activating oncogenes.

Question 11

Which of the following best explains why continuous cell lines are useful for culturing animal viruses?

Accepted Answer

They can be maintained and divide indefinitely, providing a consistent host for viral replication.

Question 12

Which of the following laboratory techniques would be most appropriate for identifying the presence of influenza virus in a patient sample?

Accepted Answer

Serological tests and PCR

Question 13

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that cause spongiform encephalopathies.

Question 14

A virus with a single-stranded RNA genome that uses reverse transcriptase to produce DNA is most likely a member of which viral family?

Accepted Answer

Retroviridae

Question 15

Which of the following best describes a latent viral infection?

Accepted Answer

The virus remains dormant in the host cell and may reactivate later.

Question 16

Which of the following is a persistent viral infection?

Accepted Answer

HIV/AIDS with continuous decrease in CD4+ T cells

Question 17

Which of the following best explains how prion diseases are transmitted?

Accepted Answer

By ingestion, transplantation, or contact with infected tissues

Question 18

A virus is found to have a helical capsid, an envelope, and spikes. Which of the following best describes its structure?

Accepted Answer

Enveloped helical virus

Question 19

Which of the following is a correct statement about the host range of viruses?

Accepted Answer

Most viruses infect only specific types of cells in one host, determined by attachment sites and cellular factors.

Question 20

Which of the following best explains why standard sterilization procedures may not be effective against prions?

Accepted Answer

Prions are resistant to heat and chemicals that denature proteins.

Viruses and Prions: Structure, Classification, Replication, and Pathogenicity

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