Question 1

Which of the following best describes the nature of viruses?

Accepted Answer

Viruses are best described as active or inactive, rather than alive or dead.

Question 2

Which property distinguishes viruses from cellular life forms?

Accepted Answer

Viruses are obligate intracellular parasites and lack machinery for protein synthesis.

Question 3

A virus with a helical capsid structure is most likely to have which of the following features?

Accepted Answer

Rod-shaped capsomeres forming a continuous helix around the nucleic acid.

Question 4

Which of the following is NOT a standard criterion used in virus classification systems?

Accepted Answer

Disease caused

Question 5

What is the main difference between the replication of DNA viruses and RNA viruses in animal cells?

Accepted Answer

DNA viruses replicate in the nucleus, while RNA viruses replicate in the cytoplasm.

Question 6

Which step in the animal virus multiplication cycle involves the release of the viral genome into the host cell cytoplasm?

Accepted Answer

Uncoating

Question 7

A persistent viral infection in a human cell is characterized by:

Accepted Answer

The host cell harbors the virus and is not immediately lysed.

Question 8

Which phenomenon explains how a bacterium acquires the ability to produce a toxin due to viral infection?

Accepted Answer

Lysogenic conversion

Question 9

Which of the following is a correct statement about prions?

Accepted Answer

Prions are composed of protein.

Question 10

A scientist is attempting to culture influenza virus for vaccine production. Which method is traditionally used?

Accepted Answer

Cultivation in bird embryos.

Question 11

Which of the following best explains why antiviral drugs are more difficult to design than antibacterial drugs?

Accepted Answer

Viruses use host cell machinery for replication, making it hard to target them without harming host cells.

Question 12

Which viral enzyme is responsible for synthesizing DNA from an RNA template?

Accepted Answer

Reverse transcriptase

Question 13

A virus with a (+) sense single-stranded RNA genome can:

Accepted Answer

Be immediately translated into proteins by host ribosomes.

Question 14

Which of the following is a cytopathic effect (CPE) caused by viral infection in animal cells?

Accepted Answer

Fusion of multiple host cells into a single large cell with multiple nuclei (syncytium).

Question 15

Which of the following statements about viral genomes is correct?

Accepted Answer

Viruses may have double-stranded DNA, single-stranded DNA, single-stranded RNA, or double-stranded RNA.

Question 16

Which of the following is true regarding the release of enveloped animal viruses from host cells?

Accepted Answer

They are released by budding or exocytosis, often without destroying the host cell.

Question 17

Which of the following is a real-world example of lysogenic conversion?

Accepted Answer

Corynebacterium diphtheriae produces diphtheria toxin due to a prophage gene.

Question 18

Which of the following is a correct statement about viroids?

Accepted Answer

Viroids are composed only of naked strands of RNA and lack a capsid.

Question 19

A scientist observes clear, well-defined patches in a cell sheet after viral infection. What are these called?

Accepted Answer

Plaques

Viruses and Prions: Structure, Classification, and Impact on Human Health

Study Guide - Practice Questions