,BIOD 171 Module 6 | Practice Q&A | 2026/2027 | Microbiology |
Portage Learning
1. True or False: Viruses can be classified as either prokaryotic or eukaryotic.
A) True
B) False
C) Only if they contain DNA
D) Only if they contain RNA
Correct Answer: False
Rationale: Viruses are acellular and are not classified as either eukaryotic or
prokaryotic despite having their genome in an enclosed structure. Viruses
lack cellular machinery and are considered obligate intracellular parasites.
2. What are the two basic components of a virus?
A) Nucleus and cytoplasm
B) Cell wall and plasma membrane
C) Genomic material and a capsid
D) Ribosomes and mitochondria
Correct Answer: Genomic material and a capsid
Rationale: A virus has (1) genomic material comprised of either DNA or RNA
and (2) a capsid, a membrane-like protective structure that contains the
genetic material.
3. A virus is defined as an:
A) Eukaryotic organism
,B) Prokaryotic organism
C) Obligate intracellular parasite
D) Free-living organism
Correct Answer: Obligate intracellular parasite
Rationale: Viruses cannot replicate unless inside a living host cell. As a
parasite, a virus depends on its living host to provide the framework
(proteins, etc.) to replicate—to make additional copies of itself.
4. What is a viral capsid?
A) The genetic material of the virus
B) A membrane-like protective structure that contains the genetic material
C) The lipid bilayer surrounding the virus
D) The enzymes used for viral replication
Correct Answer: A membrane-like protective structure that contains the
genetic material
Rationale: The capsid is a membrane-like protective structure that contains
the genetic material, similar to the nucleus of a eukaryotic cell. It protects
the viral genome from degradation.
5. The ________ surrounds the capsid of some viruses.
A) Envelope
B) Nucleus
C) Cell wall
D) Ribosome
, Correct Answer: Envelope
Rationale: The envelope surrounds the capsid in some viruses, primarily
animal viruses. Plant and bacterial viruses are typically non-enveloped.
6. True or False: You would expect to see a viral envelope on a virus infecting
a bacterial cell.
A) True
B) False
Correct Answer: False
Rationale: The overwhelming majority of animal viruses are enveloped
whereas the majority of plant or bacteria-infecting viruses are not.
Bacteriophages typically lack an envelope.
7. Describe the appearance of a bacterial culture infected with virus at the
time of infection versus later once viral replication is occurring at a high rate.
A) Remains turbid throughout
B) Turns from turbid to clear
C) Turns from clear to turbid
D) Remains clear throughout
Correct Answer: Turns from turbid to clear
Rationale: At the time of infection, the culture is turbid with bacteria. Once
viral replication occurs at a high rate, the culture turns from turbid to clear,
Portage Learning
1. True or False: Viruses can be classified as either prokaryotic or eukaryotic.
A) True
B) False
C) Only if they contain DNA
D) Only if they contain RNA
Correct Answer: False
Rationale: Viruses are acellular and are not classified as either eukaryotic or
prokaryotic despite having their genome in an enclosed structure. Viruses
lack cellular machinery and are considered obligate intracellular parasites.
2. What are the two basic components of a virus?
A) Nucleus and cytoplasm
B) Cell wall and plasma membrane
C) Genomic material and a capsid
D) Ribosomes and mitochondria
Correct Answer: Genomic material and a capsid
Rationale: A virus has (1) genomic material comprised of either DNA or RNA
and (2) a capsid, a membrane-like protective structure that contains the
genetic material.
3. A virus is defined as an:
A) Eukaryotic organism
,B) Prokaryotic organism
C) Obligate intracellular parasite
D) Free-living organism
Correct Answer: Obligate intracellular parasite
Rationale: Viruses cannot replicate unless inside a living host cell. As a
parasite, a virus depends on its living host to provide the framework
(proteins, etc.) to replicate—to make additional copies of itself.
4. What is a viral capsid?
A) The genetic material of the virus
B) A membrane-like protective structure that contains the genetic material
C) The lipid bilayer surrounding the virus
D) The enzymes used for viral replication
Correct Answer: A membrane-like protective structure that contains the
genetic material
Rationale: The capsid is a membrane-like protective structure that contains
the genetic material, similar to the nucleus of a eukaryotic cell. It protects
the viral genome from degradation.
5. The ________ surrounds the capsid of some viruses.
A) Envelope
B) Nucleus
C) Cell wall
D) Ribosome
, Correct Answer: Envelope
Rationale: The envelope surrounds the capsid in some viruses, primarily
animal viruses. Plant and bacterial viruses are typically non-enveloped.
6. True or False: You would expect to see a viral envelope on a virus infecting
a bacterial cell.
A) True
B) False
Correct Answer: False
Rationale: The overwhelming majority of animal viruses are enveloped
whereas the majority of plant or bacteria-infecting viruses are not.
Bacteriophages typically lack an envelope.
7. Describe the appearance of a bacterial culture infected with virus at the
time of infection versus later once viral replication is occurring at a high rate.
A) Remains turbid throughout
B) Turns from turbid to clear
C) Turns from clear to turbid
D) Remains clear throughout
Correct Answer: Turns from turbid to clear
Rationale: At the time of infection, the culture is turbid with bacteria. Once
viral replication occurs at a high rate, the culture turns from turbid to clear,
