,BIOD 171 Module 6 Exam | Essential Microbiology
| Portage Learning | Q & A | 2026 Edition
1. Which of the following best defines a virus?
A) A cellular organism that reproduces by binary fission
B) An obligate intracellular parasite composed of genetic material and a capsid
C) A type of bacterium that lacks a cell wall
D) A eukaryotic microorganism that contains a nucleus
Correct Answer: An obligate intracellular parasite composed of genetic material and a capsid
Rationale: A virus is an obligate intracellular parasite, meaning it cannot replicate outside a host cell. It is
composed of genetic material (DNA or RNA) surrounded by a protective protein coat called a capsid.
2. What are the two basic components of a virus?
A) A cell wall and a plasma membrane
B) A nucleus and cytoplasm
C) Genomic material and a capsid
D) A capsid and an envelope
Correct Answer: Genomic material and a capsid
Rationale: The two fundamental components of a virus are its genomic material, which can be either
DNA or RNA, and a capsid, a membrane-like protective structure that encases the genetic material.
3. What is a viral capsid?
A) The lipid bilayer surrounding the viral genome
B) A membrane-like protective structure that contains the genetic material
C) The genetic material of the virus
,D) An enzyme that helps the virus replicate
Correct Answer: A membrane-like protective structure that contains the genetic material
Rationale: The capsid is a protein shell that surrounds and protects the viral genome. It is similar in
function to the nucleus of a eukaryotic cell, but it is not a true membrane-bound organelle.
4. The envelope of some viruses surrounds which structure?
A) The genomic material
B) The capsid
C) The host cell receptor
D) The tail fibers
Correct Answer: The capsid
Rationale: In enveloped viruses, the viral envelope is a lipid membrane that surrounds the capsid. This
envelope is acquired from the host cell membrane during viral budding.
5. True or False: Because a virus's genome is contained within an enclosed space, viruses are classified as
eukaryotic.
A) True
B) False, viruses are classified as prokaryotic
C) False, viruses are neither eukaryotic nor prokaryotic
D) True, but only for DNA viruses
Correct Answer: False, viruses are neither eukaryotic nor prokaryotic
Rationale: Viruses are not classified as eukaryotic or prokaryotic because they are not considered living
organisms. They lack cellular structure and cannot replicate independently.
, 6. Which of the following is a characteristic of a viral envelope?
A) It is present in all viruses
B) It is acquired from the host cell membrane
C) It is composed of peptidoglycan
D) It surrounds the genomic material directly
Correct Answer: It is acquired from the host cell membrane
Rationale: The viral envelope is a lipid bilayer derived from the host cell membrane, often containing
viral glycoproteins. It is not present in all viruses and typically surrounds the capsid, not the genetic
material directly.
7. A student is studying a virus that infects a plant cell. Would they expect to see a viral envelope?
A) Yes, because all viruses are enveloped
B) No, because most plant viruses are non-enveloped
C) Yes, because plant cells have membranes that can be used
D) No, because plant viruses are too small to have an envelope
Correct Answer: No, because most plant viruses are non-enveloped
Rationale: The overwhelming majority of viruses that infect plants or bacteria are non-enveloped.
Enveloped viruses are more common among animal viruses.
8. Rank the following viruses from largest to smallest: Orthomyxovirus, Poliovirus, Variolavirus.
A) Poliovirus > Orthomyxovirus > Variolavirus
B) Orthomyxovirus > Poliovirus > Variolavirus
C) Variolavirus > Orthomyxovirus > Poliovirus
D) Variolavirus > Poliovirus > Orthomyxovirus
Correct Answer: Variolavirus > Orthomyxovirus > Poliovirus
| Portage Learning | Q & A | 2026 Edition
1. Which of the following best defines a virus?
A) A cellular organism that reproduces by binary fission
B) An obligate intracellular parasite composed of genetic material and a capsid
C) A type of bacterium that lacks a cell wall
D) A eukaryotic microorganism that contains a nucleus
Correct Answer: An obligate intracellular parasite composed of genetic material and a capsid
Rationale: A virus is an obligate intracellular parasite, meaning it cannot replicate outside a host cell. It is
composed of genetic material (DNA or RNA) surrounded by a protective protein coat called a capsid.
2. What are the two basic components of a virus?
A) A cell wall and a plasma membrane
B) A nucleus and cytoplasm
C) Genomic material and a capsid
D) A capsid and an envelope
Correct Answer: Genomic material and a capsid
Rationale: The two fundamental components of a virus are its genomic material, which can be either
DNA or RNA, and a capsid, a membrane-like protective structure that encases the genetic material.
3. What is a viral capsid?
A) The lipid bilayer surrounding the viral genome
B) A membrane-like protective structure that contains the genetic material
C) The genetic material of the virus
,D) An enzyme that helps the virus replicate
Correct Answer: A membrane-like protective structure that contains the genetic material
Rationale: The capsid is a protein shell that surrounds and protects the viral genome. It is similar in
function to the nucleus of a eukaryotic cell, but it is not a true membrane-bound organelle.
4. The envelope of some viruses surrounds which structure?
A) The genomic material
B) The capsid
C) The host cell receptor
D) The tail fibers
Correct Answer: The capsid
Rationale: In enveloped viruses, the viral envelope is a lipid membrane that surrounds the capsid. This
envelope is acquired from the host cell membrane during viral budding.
5. True or False: Because a virus's genome is contained within an enclosed space, viruses are classified as
eukaryotic.
A) True
B) False, viruses are classified as prokaryotic
C) False, viruses are neither eukaryotic nor prokaryotic
D) True, but only for DNA viruses
Correct Answer: False, viruses are neither eukaryotic nor prokaryotic
Rationale: Viruses are not classified as eukaryotic or prokaryotic because they are not considered living
organisms. They lack cellular structure and cannot replicate independently.
, 6. Which of the following is a characteristic of a viral envelope?
A) It is present in all viruses
B) It is acquired from the host cell membrane
C) It is composed of peptidoglycan
D) It surrounds the genomic material directly
Correct Answer: It is acquired from the host cell membrane
Rationale: The viral envelope is a lipid bilayer derived from the host cell membrane, often containing
viral glycoproteins. It is not present in all viruses and typically surrounds the capsid, not the genetic
material directly.
7. A student is studying a virus that infects a plant cell. Would they expect to see a viral envelope?
A) Yes, because all viruses are enveloped
B) No, because most plant viruses are non-enveloped
C) Yes, because plant cells have membranes that can be used
D) No, because plant viruses are too small to have an envelope
Correct Answer: No, because most plant viruses are non-enveloped
Rationale: The overwhelming majority of viruses that infect plants or bacteria are non-enveloped.
Enveloped viruses are more common among animal viruses.
8. Rank the following viruses from largest to smallest: Orthomyxovirus, Poliovirus, Variolavirus.
A) Poliovirus > Orthomyxovirus > Variolavirus
B) Orthomyxovirus > Poliovirus > Variolavirus
C) Variolavirus > Orthomyxovirus > Poliovirus
D) Variolavirus > Poliovirus > Orthomyxovirus
Correct Answer: Variolavirus > Orthomyxovirus > Poliovirus
