Question 1

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

Accepted Answer

They require living host cells to multiply because they lack the necessary metabolic machinery.

Question 2

A scientist is studying a virus with a genome composed of single-stranded RNA. Which of the following statements about this virus is correct?

Accepted Answer

Its nucleic acid can be either linear or segmented.

Question 3

Which component of a virus is primarily responsible for determining its host range?

Accepted Answer

The specific attachment sites on the virus and host cell receptors

Question 4

A bacteriophage forms clearings called plaques on a bacterial lawn. What does each plaque represent?

Accepted Answer

A single virus particle that has infected and lysed bacterial cells

Question 5

Which of the following best describes the structure and function of viral spikes?

Accepted Answer

They are projections from the viral envelope that aid in attachment to host cells.

Question 6

Which laboratory method is most appropriate for identifying a virus based on its reaction with specific antibodies?

Accepted Answer

ELISA (Enzyme-Linked Immunosorbent Assay)

Question 7

A researcher is using HeLa cells to grow a virus in the laboratory. What type of cell line is HeLa, and why is it useful?

Accepted Answer

Continuous cell line; it can be maintained indefinitely for virus cultivation

Question 8

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

Accepted Answer

The lytic cycle results in the destruction of the host cell, while the lysogenic cycle allows the phage DNA to persist in the host genome without killing the cell.

Question 9

A virus is described as having an icosahedral capsid. Which of the following best describes its morphology?

Accepted Answer

It is many-sided, typically with 20 triangular facets and 12 corners.

Question 10

Which of the following statements about viral genomes is correct?

Accepted Answer

Viral genomes may be single-stranded or double-stranded, and can be linear, circular, or segmented.

Question 11

Why are continuous cell lines, such as HeLa cells, preferred for long-term cultivation of animal viruses?

Accepted Answer

They are derived from transformed (cancerous) cells and can be maintained indefinitely.

Question 12

A virologist observes cytopathic effects in a monolayer of animal cells after viral infection. What does this indicate?

Accepted Answer

The virus has caused visible changes or deterioration in the host cells.

Question 13

Which of the following best explains why viruses do not generate ATP?

Accepted Answer

They lack ribosomes and metabolic enzymes necessary for ATP production.

Question 14

A new virus is discovered with a lipid, protein, and carbohydrate covering external to its capsid. What is this structure called?

Accepted Answer

Envelope

Question 15

Which of the following is a correct statement about the Baltimore classification system for viruses?

Accepted Answer

It groups viruses according to their nucleic acid type and how mRNA is produced.

Question 16

A scientist is using PCR to identify a virus in a patient sample. What is PCR detecting in this context?

Accepted Answer

Viral nucleic acids

Question 17

Which of the following best describes a viral species?

Accepted Answer

A group of viruses sharing the same genetic information and ecological niche (host)

Question 18

A virus is found to have a helical capsid. Which disease might this virus cause?

Accepted Answer

Rabies

Question 19

Which of the following is a key reason why some animal viruses are grown in embryonated eggs?

Accepted Answer

It provides a suitable environment for viral replication and is used for vaccine production.

Question 20

A virologist is studying a polyhedral virus. Which of the following statements about its structure is correct?

Accepted Answer

It is many-sided, often with 20 triangular facets and 12 corners.

Viruses: Structure, Taxonomy, Cultivation, and Multiplication

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