Question 1

Which of the following statements best distinguishes viruses from bacteria?

Accepted Answer

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

Question 2

A scientist is studying a newly discovered infectious agent. It is acellular, contains only RNA, and lacks a protein coat. Based on these characteristics, what is the agent most likely to be?

Accepted Answer

A viroid

Question 3

Which of the following best describes the extracellular state of a virus?

Accepted Answer

It is called a virion and consists of nucleic acid surrounded by a protein capsid, sometimes with an envelope.

Question 4

Which of the following is a correct statement about viral genomes?

Accepted Answer

Viral genomes may be composed of DNA or RNA, which can be single- or double-stranded, linear or circular.

Question 5

A virus is classified as a member of the family Papillomaviridae. What would be the correct genus name for this virus?

Accepted Answer

Papillomavirus

Question 6

Which laboratory method is most commonly used to quantify the number of infectious bacteriophages in a sample?

Accepted Answer

Plaque assay, where each plaque corresponds to a single infectious virus particle

Question 7

Which of the following best explains why continuous cell lines, such as HeLa cells, are useful for culturing animal viruses?

Accepted Answer

They are immortalized cells that can divide indefinitely, providing a consistent environment for viral replication.

Question 8

Which of the following is NOT a step in the lytic cycle of a T-even bacteriophage?

Accepted Answer

Integration of phage DNA into the host genome

Question 9

During the lysogenic cycle of bacteriophage lambda ($$\lambda$$), what is the term for the phage DNA that is integrated into the host chromosome?

Accepted Answer

Prophage

Question 10

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

Accepted Answer

Transfer of specific bacterial genes adjacent to a prophage by a lysogenic phage

Question 11

Which of the following is a key difference between the multiplication of DNA-containing and RNA-containing animal viruses?

Accepted Answer

DNA viruses replicate their genomes in the host cell nucleus, while RNA viruses typically replicate in the cytoplasm.

Question 12

Retroviruses, such as HIV, are unique among viruses because they:

Accepted Answer

Use reverse transcriptase to synthesize DNA from their RNA genome, which then integrates into the host genome.

Question 13

Which of the following is an example of a latent viral infection?

Accepted Answer

Cold sores caused by herpes simplex virus

Question 14

Which of the following statements about prions is TRUE?

Accepted Answer

Prions are infectious proteins that cause spongiform encephalopathies.

Question 15

A patient presents with a rapidly progressive neurodegenerative disease. Brain biopsy reveals large vacuoles and a spongy appearance. Which infectious agent is most likely responsible?

Accepted Answer

A prion

Question 16

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

Accepted Answer

They lack metabolic pathways and cannot generate ATP.

Question 17

Which of the following is a mechanism by which viruses can contribute to the development of cancer?

Accepted Answer

Integration of viral oncogenes into the host genome, leading to uncontrolled cell division

Question 18

Which of the following is a persistent viral infection?

Accepted Answer

HIV/AIDS

Question 19

Which of the following best describes the role of spikes on the surface of some viruses?

Accepted Answer

They are used for attachment to specific host cell receptors.

Question 20

Which of the following laboratory techniques could be used to identify the presence of influenza virus in a patient sample?

Accepted Answer

Serological tests detecting antibodies against influenza

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

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