BIOL 271 Microbiology w/ Lab Module 6 Exam Review:
Comprehensive Virology, Viral Pathogenesis,
Bacteriophage Biology, and Infectious Disease Transmission
for Portage Learning LockDown Browser Assessment
SECTION 1: VIRUS STRUCTURE AND COMPOSITION (Questions
1-25)
🟢 1. Which of the following statements correctly describes the fundamental composition of all
viruses?
<span style="color:red;border:1px solid red;padding:2px 6px;">A. Genomic
material (DNA or RNA) and a capsid</span>
B. Genomic material (DNA and RNA) and an envelope
C. Capsid and envelope only
D. Genomic material (DNA or RNA) and ribosomes
Rationale: All viruses contain genomic material comprised of either DNA or RNA (never both)
and a capsid, a protein shell that protects the genetic material. Envelopes are present only in
some viruses, and viruses lack ribosomes.
🟢 2. A virologist isolates a novel virus and observes that it possesses an outer lipid bilayer
surrounding its capsid. This structure is correctly termed the:
A. Nucleocapsid
<span style="color:red;border:1px solid red;padding:2px 6px;">B.
Envelope</span>
C. Tegument
D. Matrix protein
Rationale: The envelope is a membrane derived from the host cell that surrounds the capsid of
some viruses. The nucleocapsid refers to the capsid together with the nucleic acid, while
tegument and matrix proteins are found in certain complex viruses.
🟢 3. True or False: Because the viral genome is contained within an enclosed space (much like
the nucleus of a eukaryotic cell), viruses are classified as eukaryotic organisms.
A. True
<span style="color:red;border:1px solid red;padding:2px 6px;">B. False</span>
Rationale: Viruses are neither eukaryotic nor prokaryotic. They are acellular, non-living
infectious agents that lack cellular structures and organelles.
🟢 4. Which of the following viral genomes would you expect to find in a virus that infects
bacteria?
,A. Double-stranded RNA only
B. Single-stranded DNA only
C. Double-stranded DNA only
<span style="color:red;border:1px solid red;padding:2px 6px;">D. The viral
genome can be DNA or RNA, double or single-stranded</span>
Rationale: Viral genomes exhibit remarkable diversity. They can be double or single-stranded,
DNA or RNA, and found in circular or linear arrangements, regardless of the host type.
🟢 5. A student is examining electron micrographs of three different viruses. Virus A measures
approximately 200 nm, Virus B measures 100-150 nm, and Virus C measures approximately 30
nm. Based on size alone, which virus is most likely the poliovirus?
A. Virus A
B. Virus B
<span style="color:red;border:1px solid red;padding:2px 6px;">C. Virus
C</span>
D. Cannot be determined from size alone
Rationale: Poliovirus is a small, non-enveloped virus approximately 30 nm in diameter.
Smallpox virus is about 200 nm, and paramyxoviruses/orthomyxoviruses are 100-150 nm.
🟢 6. Rank the following viruses from largest to smallest: Paramyxovirus, Poliovirus, Smallpox
virus.
A. Poliovirus → Paramyxovirus → Smallpox virus
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Smallpox virus
→ Paramyxovirus → Poliovirus</span>
C. Paramyxovirus → Smallpox virus → Poliovirus
D. Smallpox virus → Poliovirus → Paramyxovirus
Rationale: Smallpox virus (variola virus) is the largest at approximately 200 nm,
paramyxoviruses range from 100-150 nm, and poliovirus is the smallest at approximately 30
nm.
🟢 7. Which of the following statements about viral envelopes is CORRECT?
A. All viruses possess an envelope
B. The envelope is composed entirely of viral-encoded proteins
<span style="color:red;border:1px solid red;padding:2px 6px;">C. The envelope
surrounds the capsid of some viruses and is derived from host cell membranes</span>
D. Enveloped viruses are always more pathogenic than non-enveloped viruses
Rationale: The envelope is an additional membrane that surrounds the capsid and is derived
from the host cell membrane. Not all viruses are enveloped; this structure is acquired from the
host during viral budding.
🟢 8. A researcher discovers a virus that infects a plant species. Based on general virology
principles, this virus is MOST likely to be:
,A. Enveloped
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Non-
enveloped (naked)</span>
C. Possessing a complex capsid with tail fibers
D. Containing both DNA and RNA
Rationale: The overwhelming majority of plant-infecting viruses are non-enveloped (naked),
whereas most animal viruses are enveloped. Bacteriophages are also generally non-enveloped.
🟢 9. What is the smallest biological unit of life, and how do viruses compare?
A. The virus; viruses are the smallest biological units of life
B. The atom; viruses are composed of atoms like all matter
<span style="color:red;border:1px solid red;padding:2px 6px;">C. The cell;
viruses are not cells and are not considered living organisms</span>
D. The protein; viruses are composed primarily of proteins
Rationale: The cell is the smallest biological unit of life. Viruses are non-cellular, non-living
infectious agents that cannot replicate independently and are therefore not considered living
organisms.
🟢 10. Which of the following correctly describes the nucleocapsid of a virus?
A. The lipid bilayer surrounding the viral particle
<span style="color:red;border:1px solid red;padding:2px 6px;">B. The capsid
together with the enclosed nucleic acid genome</span>
C. The protein shell that surrounds the envelope
D. The complex of viral enzymes and host proteins
Rationale: The nucleocapsid refers to the capsid protein shell together with the viral nucleic
acid genome it contains. This term is used when the capsid and genome are considered as a
single structural unit.
🟢 11. A virus is described as having an icosahedral capsid. This means the capsid:
A. Is helical in shape
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Has a spherical
symmetry with 20 triangular faces</span>
C. Is complex with tail fibers and a base plate
D. Has no defined symmetry
Rationale: An icosahedral capsid exhibits spherical symmetry and is composed of 20 equilateral
triangular faces. This is one of the primary capsid morphologies, along with helical and
complex structures.
🟢 12. The pandoravirus possesses one of the largest known viral genomes at approximately
2.5 million nucleotides. Compared to the human genome (approximately 3 billion nucleotides),
the viral genome is:
, A. Larger than the human genome
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Significantly
smaller than the human genome</span>
C. Approximately the same size
D. Twice the size of the human genome
Rationale: While the pandoravirus genome is exceptionally large for a virus at about 2.5 million
nucleotides, it is still much smaller than the human genome (about 3 billion nucleotides).
🟢 13. Which of the following statements about viral genomes is FALSE?
A. Viral genomes can be composed of either DNA or RNA
B. Viral genomes can be single-stranded or double-stranded
C. Viral genomes can be linear or circular
<span style="color:red;border:1px solid red;padding:2px 6px;">D. All viral
genomes contain at least 100,000 base pairs</span>
Rationale: Viral genomes vary greatly in size. Poliovirus, for example, has a genome of only
about 7,700 nucleotide base pairs. Not all viral genomes contain 100,000 base pairs.
🟢 14. A virologist observes a virus under an electron microscope and notes that it appears
spherical, measures approximately 100-150 nm in diameter, and possesses an envelope. Which
of the following viruses could this be?
A. Poliovirus
<span style="color:red;border:1px solid red;padding:2px 6px;">B.
Paramyxovirus</span>
C. Bacteriophage T4
D. Smallpox virus
Rationale: Paramyxoviruses are enveloped, spherical viruses approximately 100-150 nm in
diameter. Poliovirus is only ~30 nm, bacteriophages have complex structures, and smallpox
virus has a distinct dumbbell-shaped capsid.
🟢 15. The capsid of a virus functions primarily to:
A. Provide energy for viral replication
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Protect the
viral genome and facilitate attachment to host cells</span>
C. Synthesize viral proteins
D. Replicate the viral genome
Rationale: The capsid is a protective structure that contains the genetic material and also
contains proteins that facilitate attachment to host cells. It does not provide energy, synthesize
proteins, or replicate the genome.
🟢 16. Which of the following viruses is correctly matched with its genome type?
A. Influenza virus — double-stranded DNA
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Measles virus
Comprehensive Virology, Viral Pathogenesis,
Bacteriophage Biology, and Infectious Disease Transmission
for Portage Learning LockDown Browser Assessment
SECTION 1: VIRUS STRUCTURE AND COMPOSITION (Questions
1-25)
🟢 1. Which of the following statements correctly describes the fundamental composition of all
viruses?
<span style="color:red;border:1px solid red;padding:2px 6px;">A. Genomic
material (DNA or RNA) and a capsid</span>
B. Genomic material (DNA and RNA) and an envelope
C. Capsid and envelope only
D. Genomic material (DNA or RNA) and ribosomes
Rationale: All viruses contain genomic material comprised of either DNA or RNA (never both)
and a capsid, a protein shell that protects the genetic material. Envelopes are present only in
some viruses, and viruses lack ribosomes.
🟢 2. A virologist isolates a novel virus and observes that it possesses an outer lipid bilayer
surrounding its capsid. This structure is correctly termed the:
A. Nucleocapsid
<span style="color:red;border:1px solid red;padding:2px 6px;">B.
Envelope</span>
C. Tegument
D. Matrix protein
Rationale: The envelope is a membrane derived from the host cell that surrounds the capsid of
some viruses. The nucleocapsid refers to the capsid together with the nucleic acid, while
tegument and matrix proteins are found in certain complex viruses.
🟢 3. True or False: Because the viral genome is contained within an enclosed space (much like
the nucleus of a eukaryotic cell), viruses are classified as eukaryotic organisms.
A. True
<span style="color:red;border:1px solid red;padding:2px 6px;">B. False</span>
Rationale: Viruses are neither eukaryotic nor prokaryotic. They are acellular, non-living
infectious agents that lack cellular structures and organelles.
🟢 4. Which of the following viral genomes would you expect to find in a virus that infects
bacteria?
,A. Double-stranded RNA only
B. Single-stranded DNA only
C. Double-stranded DNA only
<span style="color:red;border:1px solid red;padding:2px 6px;">D. The viral
genome can be DNA or RNA, double or single-stranded</span>
Rationale: Viral genomes exhibit remarkable diversity. They can be double or single-stranded,
DNA or RNA, and found in circular or linear arrangements, regardless of the host type.
🟢 5. A student is examining electron micrographs of three different viruses. Virus A measures
approximately 200 nm, Virus B measures 100-150 nm, and Virus C measures approximately 30
nm. Based on size alone, which virus is most likely the poliovirus?
A. Virus A
B. Virus B
<span style="color:red;border:1px solid red;padding:2px 6px;">C. Virus
C</span>
D. Cannot be determined from size alone
Rationale: Poliovirus is a small, non-enveloped virus approximately 30 nm in diameter.
Smallpox virus is about 200 nm, and paramyxoviruses/orthomyxoviruses are 100-150 nm.
🟢 6. Rank the following viruses from largest to smallest: Paramyxovirus, Poliovirus, Smallpox
virus.
A. Poliovirus → Paramyxovirus → Smallpox virus
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Smallpox virus
→ Paramyxovirus → Poliovirus</span>
C. Paramyxovirus → Smallpox virus → Poliovirus
D. Smallpox virus → Poliovirus → Paramyxovirus
Rationale: Smallpox virus (variola virus) is the largest at approximately 200 nm,
paramyxoviruses range from 100-150 nm, and poliovirus is the smallest at approximately 30
nm.
🟢 7. Which of the following statements about viral envelopes is CORRECT?
A. All viruses possess an envelope
B. The envelope is composed entirely of viral-encoded proteins
<span style="color:red;border:1px solid red;padding:2px 6px;">C. The envelope
surrounds the capsid of some viruses and is derived from host cell membranes</span>
D. Enveloped viruses are always more pathogenic than non-enveloped viruses
Rationale: The envelope is an additional membrane that surrounds the capsid and is derived
from the host cell membrane. Not all viruses are enveloped; this structure is acquired from the
host during viral budding.
🟢 8. A researcher discovers a virus that infects a plant species. Based on general virology
principles, this virus is MOST likely to be:
,A. Enveloped
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Non-
enveloped (naked)</span>
C. Possessing a complex capsid with tail fibers
D. Containing both DNA and RNA
Rationale: The overwhelming majority of plant-infecting viruses are non-enveloped (naked),
whereas most animal viruses are enveloped. Bacteriophages are also generally non-enveloped.
🟢 9. What is the smallest biological unit of life, and how do viruses compare?
A. The virus; viruses are the smallest biological units of life
B. The atom; viruses are composed of atoms like all matter
<span style="color:red;border:1px solid red;padding:2px 6px;">C. The cell;
viruses are not cells and are not considered living organisms</span>
D. The protein; viruses are composed primarily of proteins
Rationale: The cell is the smallest biological unit of life. Viruses are non-cellular, non-living
infectious agents that cannot replicate independently and are therefore not considered living
organisms.
🟢 10. Which of the following correctly describes the nucleocapsid of a virus?
A. The lipid bilayer surrounding the viral particle
<span style="color:red;border:1px solid red;padding:2px 6px;">B. The capsid
together with the enclosed nucleic acid genome</span>
C. The protein shell that surrounds the envelope
D. The complex of viral enzymes and host proteins
Rationale: The nucleocapsid refers to the capsid protein shell together with the viral nucleic
acid genome it contains. This term is used when the capsid and genome are considered as a
single structural unit.
🟢 11. A virus is described as having an icosahedral capsid. This means the capsid:
A. Is helical in shape
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Has a spherical
symmetry with 20 triangular faces</span>
C. Is complex with tail fibers and a base plate
D. Has no defined symmetry
Rationale: An icosahedral capsid exhibits spherical symmetry and is composed of 20 equilateral
triangular faces. This is one of the primary capsid morphologies, along with helical and
complex structures.
🟢 12. The pandoravirus possesses one of the largest known viral genomes at approximately
2.5 million nucleotides. Compared to the human genome (approximately 3 billion nucleotides),
the viral genome is:
, A. Larger than the human genome
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Significantly
smaller than the human genome</span>
C. Approximately the same size
D. Twice the size of the human genome
Rationale: While the pandoravirus genome is exceptionally large for a virus at about 2.5 million
nucleotides, it is still much smaller than the human genome (about 3 billion nucleotides).
🟢 13. Which of the following statements about viral genomes is FALSE?
A. Viral genomes can be composed of either DNA or RNA
B. Viral genomes can be single-stranded or double-stranded
C. Viral genomes can be linear or circular
<span style="color:red;border:1px solid red;padding:2px 6px;">D. All viral
genomes contain at least 100,000 base pairs</span>
Rationale: Viral genomes vary greatly in size. Poliovirus, for example, has a genome of only
about 7,700 nucleotide base pairs. Not all viral genomes contain 100,000 base pairs.
🟢 14. A virologist observes a virus under an electron microscope and notes that it appears
spherical, measures approximately 100-150 nm in diameter, and possesses an envelope. Which
of the following viruses could this be?
A. Poliovirus
<span style="color:red;border:1px solid red;padding:2px 6px;">B.
Paramyxovirus</span>
C. Bacteriophage T4
D. Smallpox virus
Rationale: Paramyxoviruses are enveloped, spherical viruses approximately 100-150 nm in
diameter. Poliovirus is only ~30 nm, bacteriophages have complex structures, and smallpox
virus has a distinct dumbbell-shaped capsid.
🟢 15. The capsid of a virus functions primarily to:
A. Provide energy for viral replication
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Protect the
viral genome and facilitate attachment to host cells</span>
C. Synthesize viral proteins
D. Replicate the viral genome
Rationale: The capsid is a protective structure that contains the genetic material and also
contains proteins that facilitate attachment to host cells. It does not provide energy, synthesize
proteins, or replicate the genome.
🟢 16. Which of the following viruses is correctly matched with its genome type?
A. Influenza virus — double-stranded DNA
<span style="color:red;border:1px solid red;padding:2px 6px;">B. Measles virus
