Question 1

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

Accepted Answer

They require host cellular machinery to replicate and cannot reproduce on their own.

Question 2

What is the primary function of the capsid in a virus?

Accepted Answer

To protect the viral genetic material and aid in host cell attachment.

Question 3

Which of the following structures is unique to bacteriophages and not found in animal viruses?

Accepted Answer

Tail fibers

Question 4

A virus with an envelope derives it from which source?

Accepted Answer

The host cell membrane during viral exit.

Question 5

Which step in the viral replicative cycle involves the synthesis of viral proteins using host ribosomes?

Accepted Answer

Translation

Question 6

During the lytic cycle of a bacteriophage, what is the fate of the host cell?

Accepted Answer

It is lysed, releasing new viral particles.

Question 7

Which enzyme is crucial for retroviruses to convert their RNA genome into DNA?

Accepted Answer

Reverse transcriptase

Question 8

The CRISPR-Cas9 system in bacteria provides defense against viruses by:

Accepted Answer

Cutting viral DNA at specific sequences using Cas9 enzyme.

Question 9

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

Accepted Answer

The lytic cycle results in immediate destruction of the host cell, while the lysogenic cycle allows viral DNA to persist in the host genome.

Question 10

Which of the following is a sub-viral pathogen that infects plants and consists only of a short strand of circular RNA?

Accepted Answer

Viroid

Question 11

A prion causes disease by:

Accepted Answer

Inducing misfolding of normal proteins in the host.

Question 12

Which of the following viruses is most likely to cause a pandemic due to its ability to rapidly mutate and infect humans?

Accepted Answer

Influenza virus

Question 13

Which of the following best describes the role of reverse transcriptase in the HIV life cycle?

Accepted Answer

It converts viral RNA into DNA for integration into the host genome.

Question 14

Which equation represents the central dogma of molecular biology, and how do retroviruses challenge it?

Accepted Answer

$$DNA \rightarrow RNA \rightarrow Protein$$

Question 15

Which of the following is NOT a key step in the general viral infection cycle?

Accepted Answer

Photosynthesis

Question 16

Which of the following best describes the CRISPR-Cas9 mechanism?

Accepted Answer

It is a bacterial immune system that uses RNA guides to target and cut viral DNA.

Question 17

Which of the following is a plausible consequence of a mutation in the viral capsid protein?

Accepted Answer

The virus may lose its ability to attach to host cells.

Question 18

Which of the following is a correct description of a bacteriophage?

Accepted Answer

A virus that infects bacteria.

Question 19

Which of the following treatments is most effective against viral infections?

Accepted Answer

Antiviral drugs

Question 20

Which of the following is a real-world example of an emerging virus that has caused a recent epidemic?

Accepted Answer

Ebola virus

Chapter 19: Viruses – Structure, Replication, Evolution, and Human Health

Study Guide - Practice Questions