$RNA \xrightarrow{\text{reverse transcriptase}} DNA$

Question 1

Which of the following best describes the genetic material found in viruses?

Accepted Answer

Viruses contain either DNA or RNA as their genetic material, but never both.

Question 2

A virus is considered an obligate intracellular parasite because:

Accepted Answer

It requires host cell machinery to replicate and cannot reproduce independently.

Question 3

Which of the following is TRUE regarding the lytic cycle of bacteriophages?

Accepted Answer

The host cell is lysed, releasing new phage particles.

Question 4

Which structural component of a virus is responsible for host specificity?

Accepted Answer

The spike proteins on the viral envelope or capsid

Question 5

HIV is unable to infect certain individuals because they lack which of the following on their cell membranes?

Accepted Answer

CCR5 co-receptor

Question 6

Which equation best represents the process by which retroviruses like HIV convert their RNA genome into DNA?

Accepted Answer

$RNA \xrightarrow{	ext{reverse transcriptase}} DNA$

Question 7

Which of the following is a major reason why it is difficult to develop drugs that target viruses without harming host cells?

Accepted Answer

Viruses use the host cell's machinery for replication.

Question 8

Which of the following statements about prions is correct?

Accepted Answer

Prions are misfolded proteins that cause degenerative diseases of the nervous system.

Question 9

A plant is infected by an agent that consists only of a short strand of RNA and lacks a protein coat. What is this agent most likely to be?

Accepted Answer

A viroid

Question 10

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

Accepted Answer

Antibiotics target bacterial cell walls and metabolic pathways, which viruses lack.

Question 11

A new viral disease emerges and is found to infect mosquitoes, birds, horses, and humans. This virus is best described as having:

Accepted Answer

A broad host range

Question 12

Which of the following is a correct sequence of events in the replication of a typical animal virus?

Accepted Answer

Attachment → Entry → Replication of viral genome → Transcription → Translation → Self-assembly → Release

Question 13

Which of the following is a real-world consequence of plant viral diseases?

Accepted Answer

Annual crop losses exceeding $30 billion worldwide

Question 14

Which of the following is NOT a typical feature of a virus?

Accepted Answer

Ability to self-replicate outside a host cell

Question 15

Which of the following best describes the lysogenic cycle of bacteriophages?

Accepted Answer

The phage genome integrates into the host genome and is replicated along with it without killing the host.

Question 16

Which of the following is a correct statement about the envelope of some animal viruses?

Accepted Answer

It is derived from the host cell membrane and may contain viral spike proteins.

Question 17

Which of the following is a plausible reason why influenza viruses are difficult to control?

Accepted Answer

They frequently change their surface proteins, evading immune detection.

Question 18

Which of the following is a correct application of the concept of host specificity in viruses?

Accepted Answer

Measles virus infects only humans due to specific receptor interactions.

Question 19

Which of the following is a correct statement about viroids?

Accepted Answer

Viroids are infectious agents composed only of a short strand of RNA and infect plants.

Question 20

Which of the following is a correct example of a prion disease?

Accepted Answer

Mad cow disease (Bovine spongiform encephalopathy)

Viruses, Prions, and Viroids: Structure, Replication, and Impact

Study Guide - Practice Questions