Question 1

Which of the following best describes the extracellular form of a virus and its primary function?

Accepted Answer

The virion, which exists outside the host and enables transmission between hosts.

Question 2

A virus that contains only nucleic acid and a capsid, but lacks a lipid membrane, is classified as which type?

Accepted Answer

Naked virus

Question 3

Which enzyme is packaged in the virion of retroviruses and is essential for converting viral RNA into DNA?

Accepted Answer

Reverse transcriptase

Question 4

During the lytic cycle of bacteriophage T4, what is the primary mechanism by which the viral genome enters the host cell?

Accepted Answer

Tail fibers bind to LPS receptors, tail sheath contracts, and DNA is injected like a syringe.

Question 5

Which of the following is NOT a typical result of viral infection in a host cell?

Accepted Answer

Binary fission

Question 6

What is the main reason RNA viruses must package their own RNA-dependent RNA polymerase in the virion?

Accepted Answer

Host cells cannot synthesize RNA from RNA templates.

Question 7

Which viral symmetry is characterized by a rod-shaped structure and is exemplified by the Tobacco Mosaic Virus?

Accepted Answer

Helical symmetry

Question 8

A plaque assay is used to determine viral titer. What does each plaque represent?

Accepted Answer

One infectious virus particle

Question 9

Which of the following is a key difference between animal and plant viruses regarding entry into host cells?

Accepted Answer

Animal viruses often enter by membrane fusion or endocytosis, while plant viruses enter through wounds or vectors.

Question 10

Which enzyme is responsible for breaking bacterial cell walls to allow viral genome entry and virion release?

Accepted Answer

Lysozyme

Question 11

What is the burst size in viral replication?

Accepted Answer

The number of virions released from a single infected cell.

Question 12

Which of the following best explains why enveloped viruses are rare in bacteria and plants?

Accepted Answer

Bacteria and plants have cell walls that prevent easy exit by budding.

Question 13

Which viral infection outcome is associated with the transformation of host cells into cancerous cells?

Accepted Answer

Transformation

Question 14

What is the primary function of neuraminidase in influenza virus?

Accepted Answer

Helps release influenza virus from the host cell surface.

Question 15

Which of the following statements about viral genomes is TRUE?

Accepted Answer

Viral genomes can be DNA or RNA, single- or double-stranded, and are much smaller than cellular genomes.

Question 16

Which host defense mechanism specifically targets and degrades foreign DNA, such as viral genomes, in bacteria?

Accepted Answer

Restriction enzymes

Question 17

Which step in the viral replication cycle is characterized by the assembly of new virions inside the host cell?

Accepted Answer

Maturation

Question 18

A virus infects a cell and integrates its genome into the host DNA, remaining silent until triggered by stress. What is this process called?

Accepted Answer

Lysogeny

Question 19

Which of the following features distinguishes viruses from bacteria in terms of growth and reproduction?

Accepted Answer

Viruses exhibit a one-step growth curve and reproduce only in a host, while bacteria grow exponentially and reproduce independently.

Question 20

Which of the following is a real-world example of a virus with complex symmetry?

Accepted Answer

Bacteriophage T4

Viruses: Structure, Replication, and Diversity

Study Guide - Practice Questions