Question 1

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

Accepted Answer

They require living host cells to multiply because they lack ribosomes and ATP-generating mechanisms.

Question 2

A researcher is attempting to grow a newly discovered animal virus in the laboratory. Which method would be most appropriate for initial cultivation and why?

Accepted Answer

Growing the virus in a continuous cell line to observe cytopathic effects.

Question 3

Which of the following best describes the difference between the lytic and lysogenic cycles of bacteriophages?

Accepted Answer

The lytic cycle involves the destruction of the host cell, whereas the lysogenic cycle allows the phage DNA to remain latent as a prophage.

Question 4

A patient is diagnosed with a persistent viral infection. Which of the following best characterizes this type of infection?

Accepted Answer

The virus is continuously released over a long period, often leading to fatal outcomes.

Question 5

Which of the following viruses is correctly matched with its genome type and associated disease?

Accepted Answer

Herpesviridae – double-stranded DNA – chickenpox

Question 6

Which step in the multiplication of animal viruses is unique compared to bacteriophage replication?

Accepted Answer

Uncoating of the viral capsid by host or viral enzymes

Question 7

A laboratory technician observes clear zones on a bacterial lawn after bacteriophage infection. What do these zones represent and how are they quantified?

Accepted Answer

They are plaques, each corresponding to a single virus, quantified as plaque-forming units (PFU).

Question 8

Which of the following best explains why antibiotics are ineffective against viruses?

Accepted Answer

Viruses lack cell walls and metabolic pathways targeted by antibiotics.

Question 9

A virus is classified as a member of the family 'Herpesviridae.' According to viral taxonomy, what is the correct ending for the genus and order names of this virus?

Accepted Answer

Genus: -virus; Order: -ales

Question 10

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

Accepted Answer

Specific bacterial genes adjacent to the prophage are transferred to another bacterium via a phage.

Question 11

Which of the following is a unique feature of retroviruses such as HIV?

Accepted Answer

They use reverse transcriptase to produce DNA from their RNA genome, which integrates into the host chromosome as a provirus.

Question 12

A patient presents with cold sores that recur during periods of stress. Which type of viral infection does this scenario illustrate?

Accepted Answer

Latent viral infection

Question 13

Which of the following best describes the structure of a typical virion?

Accepted Answer

A nucleic acid core (DNA or RNA), a protein capsid, and sometimes an envelope with spikes

Question 14

Which of the following is a correct statement about prions?

Accepted Answer

They are infectious proteins that can be inherited or transmitted by ingestion, causing spongiform encephalopathies.

Question 15

Which of the following best explains why plant viruses often require wounds or insect vectors to infect plant cells?

Accepted Answer

Plant cells are protected by an impermeable cell wall that viruses cannot penetrate without assistance.

Question 16

A virus with a single-stranded RNA genome that serves directly as mRNA for protein synthesis belongs to which group?

Accepted Answer

ssRNA; + (sense) strand viruses

Question 17

Which of the following is a real-world example of a DNA oncogenic virus and the cancer it can cause?

Accepted Answer

Papovaviridae (human papillomavirus) – cervical cancer

Question 18

Which of the following laboratory techniques is most appropriate for identifying a virus based on its reaction with specific antibodies?

Accepted Answer

Western blotting

Question 19

Which of the following best describes the eclipse period in a one-step viral growth curve?

Accepted Answer

The period after viral entry but before mature virions are detectable.

Question 20

Which of the following is a plausible multi-step scenario involving viral replication and host cell transformation?

Accepted Answer

A DNA virus infects a host cell, integrates its genome as a provirus, and induces oncogene expression, leading to uncontrolled cell division and tumor formation.

Study Guide: Viruses, Viroids, and Prions (Microbiology - Chapter 13)

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