,BIOL271/BIOL 271 Module 6 Exam | Microbiology
w/ Lab | Portage Learning | Q & A | 2026/2027
Edition (PDF)
**1. Which of the following statements is true regarding viruses?**
A) They are living, eukaryotic organisms
B) They contain both DNA and RNA
C) They are acellular and cannot reproduce independently
D) They are classified as prokaryotes
Correct Answer: They are acellular and cannot reproduce independently
Rationale: Viruses are not living organisms; they lack cellular structure and cannot reproduce
independently. They require a host cell's machinery to replicate. Viruses contain either DNA or RNA,
never both, and are neither prokaryotic nor eukaryotic.
**2. The two essential components of every virus are:**
A) A cell wall and a nucleus
B) Genomic material and a capsid
C) A capsid and an envelope
D) DNA and RNA
Correct Answer: Genomic material and a capsid
Rationale: All viruses possess nucleic acid (either DNA or RNA) as their genomic material and a protein
capsid that surrounds and protects the genome. Not all viruses have an envelope; some are considered
"naked" viruses and lack this outer lipid layer.
**3. The protein coat that surrounds the viral genome is called the:**
A) Envelope
,B) Nucleocapsid
C) Capsid
D) Matrix protein
Correct Answer: Capsid
Rationale: The capsid is the protein coat that surrounds and protects the viral genome. The capsid is
composed of protein subunits called capsomeres. The nucleocapsid refers to the capsid together with
the enclosed nucleic acid. The envelope is an outer lipid layer found in some viruses.
**4. A virus that infects bacteria is called a:**
A) Viroid
B) Prion
C) Bacteriophage
D) Retrovirus
Correct Answer: Bacteriophage
Rationale: A bacteriophage (or phage) is a virus that specifically infects and replicates within bacteria.
Bacteriophages are important tools in molecular biology and have been studied extensively for their lytic
and lysogenic life cycles. Viroids and prions are subviral agents, and retroviruses are a type of RNA virus.
**5. A bacteriophage contains a ______-sided polygon capsid.**
A) 12
B) 20
C) 24
D) 30
Correct Answer: 20
, Rationale: Bacteriophages typically have an icosahedral capsid, which is a 20-sided polygon structure.
The icosahedral shape is one of the most common capsid geometries found in viruses, providing a stable
structure that maximizes internal volume while minimizing the amount of protein needed.
**6. True or False: Highly infectious viruses undergo genome replication prior to viral attachment and
entry.**
A) True
B) False
Correct Answer: False
Rationale: Viral replication cannot occur before attachment and entry because the virus must first attach
to a host cell and deliver its genome into the cell. The correct sequence is: attachment, entry, uncoating,
replication, assembly, and release. Replication occurs after the virus has entered the host cell.
**7. Which of the following is a step in the viral life cycle that occurs immediately after entry?**
A) Attachment
B) Replication
C) Uncoating
D) Assembly
Correct Answer: Uncoating
Rationale: After entry into the host cell, the viral capsid is removed during uncoating, releasing the viral
genome. Replication occurs after uncoating, followed by assembly and release. Attachment is the first
step before entry.
**8. The correct order of the viral life cycle is:**
A) Entry → Attachment → Uncoating → Replication → Assembly → Release
B) Attachment → Entry → Uncoating → Replication → Assembly → Release
C) Attachment → Uncoating → Entry → Replication → Assembly → Release
w/ Lab | Portage Learning | Q & A | 2026/2027
Edition (PDF)
**1. Which of the following statements is true regarding viruses?**
A) They are living, eukaryotic organisms
B) They contain both DNA and RNA
C) They are acellular and cannot reproduce independently
D) They are classified as prokaryotes
Correct Answer: They are acellular and cannot reproduce independently
Rationale: Viruses are not living organisms; they lack cellular structure and cannot reproduce
independently. They require a host cell's machinery to replicate. Viruses contain either DNA or RNA,
never both, and are neither prokaryotic nor eukaryotic.
**2. The two essential components of every virus are:**
A) A cell wall and a nucleus
B) Genomic material and a capsid
C) A capsid and an envelope
D) DNA and RNA
Correct Answer: Genomic material and a capsid
Rationale: All viruses possess nucleic acid (either DNA or RNA) as their genomic material and a protein
capsid that surrounds and protects the genome. Not all viruses have an envelope; some are considered
"naked" viruses and lack this outer lipid layer.
**3. The protein coat that surrounds the viral genome is called the:**
A) Envelope
,B) Nucleocapsid
C) Capsid
D) Matrix protein
Correct Answer: Capsid
Rationale: The capsid is the protein coat that surrounds and protects the viral genome. The capsid is
composed of protein subunits called capsomeres. The nucleocapsid refers to the capsid together with
the enclosed nucleic acid. The envelope is an outer lipid layer found in some viruses.
**4. A virus that infects bacteria is called a:**
A) Viroid
B) Prion
C) Bacteriophage
D) Retrovirus
Correct Answer: Bacteriophage
Rationale: A bacteriophage (or phage) is a virus that specifically infects and replicates within bacteria.
Bacteriophages are important tools in molecular biology and have been studied extensively for their lytic
and lysogenic life cycles. Viroids and prions are subviral agents, and retroviruses are a type of RNA virus.
**5. A bacteriophage contains a ______-sided polygon capsid.**
A) 12
B) 20
C) 24
D) 30
Correct Answer: 20
, Rationale: Bacteriophages typically have an icosahedral capsid, which is a 20-sided polygon structure.
The icosahedral shape is one of the most common capsid geometries found in viruses, providing a stable
structure that maximizes internal volume while minimizing the amount of protein needed.
**6. True or False: Highly infectious viruses undergo genome replication prior to viral attachment and
entry.**
A) True
B) False
Correct Answer: False
Rationale: Viral replication cannot occur before attachment and entry because the virus must first attach
to a host cell and deliver its genome into the cell. The correct sequence is: attachment, entry, uncoating,
replication, assembly, and release. Replication occurs after the virus has entered the host cell.
**7. Which of the following is a step in the viral life cycle that occurs immediately after entry?**
A) Attachment
B) Replication
C) Uncoating
D) Assembly
Correct Answer: Uncoating
Rationale: After entry into the host cell, the viral capsid is removed during uncoating, releasing the viral
genome. Replication occurs after uncoating, followed by assembly and release. Attachment is the first
step before entry.
**8. The correct order of the viral life cycle is:**
A) Entry → Attachment → Uncoating → Replication → Assembly → Release
B) Attachment → Entry → Uncoating → Replication → Assembly → Release
C) Attachment → Uncoating → Entry → Replication → Assembly → Release
