BIOD 171 Essential Microbiology Module 6
Exam – Actual Questions with Verified
Answers (2026/2027 Updated)
Section 1: Viral Structure and Classification (12 questions)
Q1: True or False: All viruses contain both DNA and RNA genomes simultaneously.
A. True
B. False [CORRECT]
Correct Answer: B
Rationale: Viruses contain either DNA or RNA as their genetic material, never both
simultaneously. This characteristic is used to classify viruses into DNA virus or RNA
virus families.
Q2: Which two structures are considered the basic components found in all viruses?
A. Cell membrane and cytoplasm
B. Nucleus and nucleolus
C. Genomic material and a capsid [CORRECT]
D. Ribosomes and cell wall
Correct Answer: C
Rationale: All viruses possess (1) genomic material (either DNA or RNA) and (2) a
capsid (protein shell). Some viruses additionally possess an envelope, but these two
components are universal to all viruses.
Q3: A virus acquires its outer lipid bilayer containing viral glycoproteins from the host
cell's membrane during budding. This virus is classified as:
,A. Naked (non-enveloped)
B. Enveloped [CORRECT]
C. Prokaryotic
D. Capsulated
Correct Answer: B
Rationale: Enveloped viruses obtain their lipid bilayer from host cell membranes
(plasma, nuclear, or Golgi). The envelope contains viral glycoproteins (spikes) that
mediate attachment and entry into new host cells.
Q4: Fill in the blank: The individual protein subunits that assemble to form the capsid
are called __________.
[Capsomeres] [CORRECT]
Correct Answer: Capsomeres
Rationale: Capsomeres are the morphological units that arrange themselves into either
helical or icosahedral symmetries to form the complete capsid structure.
Q5: Which statement accurately describes a virus with icosahedral symmetry?
A. The capsid forms a spiral staircase-like structure around the nucleic acid
B. The capsid assembles into a roughly spherical structure with 20 triangular faces
[CORRECT]
C. It must contain single-stranded RNA
D. It cannot possess an envelope
Correct Answer: B
Rationale: Icosahedral capsids are polyhedral structures with 20 equilateral triangular
faces and 12 vertices. This geometry efficiently encloses the viral genome and is
common in many animal viruses.
Q6: True or False: The spike proteins (peplomers) projecting from viral envelopes are
composed entirely of host cell lipids.
, A. True
B. False [CORRECT]
Correct Answer: B
Rationale: While the envelope itself is derived from host cell membranes, the spike
proteins are viral-encoded glycoproteins that protrude through the lipid bilayer. These
proteins mediate attachment to specific host cell receptors.
Q7: Which characteristic definitively distinguishes viruses from bacteria?
A. Viruses lack metabolism and cannot reproduce independently outside a host cell
[CORRECT]
B. Viruses are larger than bacteria
C. Viruses contain 70S ribosomes
D. Viruses have both DNA and RNA
Correct Answer: A
Rationale: Viruses are obligate intracellular parasites lacking metabolic machinery.
Unlike bacteria, they cannot reproduce or carry out metabolic processes independently;
they require host cell machinery for replication.
Q8: Viral genomes may consist of:
A. Single-stranded DNA only
B. Double-stranded RNA only
C. Either DNA or RNA, which may be single or double-stranded [CORRECT]
D. Double-stranded DNA with histone proteins only
Correct Answer: C
Rationale: Viral genomes exhibit diversity in both nucleic acid type (DNA or RNA) and
structure (single-stranded or double-stranded). This variation is a primary basis for viral
classification systems.
Q9: Fill in the blank: Viruses that lack an envelope are referred to as __________ viruses.
Exam – Actual Questions with Verified
Answers (2026/2027 Updated)
Section 1: Viral Structure and Classification (12 questions)
Q1: True or False: All viruses contain both DNA and RNA genomes simultaneously.
A. True
B. False [CORRECT]
Correct Answer: B
Rationale: Viruses contain either DNA or RNA as their genetic material, never both
simultaneously. This characteristic is used to classify viruses into DNA virus or RNA
virus families.
Q2: Which two structures are considered the basic components found in all viruses?
A. Cell membrane and cytoplasm
B. Nucleus and nucleolus
C. Genomic material and a capsid [CORRECT]
D. Ribosomes and cell wall
Correct Answer: C
Rationale: All viruses possess (1) genomic material (either DNA or RNA) and (2) a
capsid (protein shell). Some viruses additionally possess an envelope, but these two
components are universal to all viruses.
Q3: A virus acquires its outer lipid bilayer containing viral glycoproteins from the host
cell's membrane during budding. This virus is classified as:
,A. Naked (non-enveloped)
B. Enveloped [CORRECT]
C. Prokaryotic
D. Capsulated
Correct Answer: B
Rationale: Enveloped viruses obtain their lipid bilayer from host cell membranes
(plasma, nuclear, or Golgi). The envelope contains viral glycoproteins (spikes) that
mediate attachment and entry into new host cells.
Q4: Fill in the blank: The individual protein subunits that assemble to form the capsid
are called __________.
[Capsomeres] [CORRECT]
Correct Answer: Capsomeres
Rationale: Capsomeres are the morphological units that arrange themselves into either
helical or icosahedral symmetries to form the complete capsid structure.
Q5: Which statement accurately describes a virus with icosahedral symmetry?
A. The capsid forms a spiral staircase-like structure around the nucleic acid
B. The capsid assembles into a roughly spherical structure with 20 triangular faces
[CORRECT]
C. It must contain single-stranded RNA
D. It cannot possess an envelope
Correct Answer: B
Rationale: Icosahedral capsids are polyhedral structures with 20 equilateral triangular
faces and 12 vertices. This geometry efficiently encloses the viral genome and is
common in many animal viruses.
Q6: True or False: The spike proteins (peplomers) projecting from viral envelopes are
composed entirely of host cell lipids.
, A. True
B. False [CORRECT]
Correct Answer: B
Rationale: While the envelope itself is derived from host cell membranes, the spike
proteins are viral-encoded glycoproteins that protrude through the lipid bilayer. These
proteins mediate attachment to specific host cell receptors.
Q7: Which characteristic definitively distinguishes viruses from bacteria?
A. Viruses lack metabolism and cannot reproduce independently outside a host cell
[CORRECT]
B. Viruses are larger than bacteria
C. Viruses contain 70S ribosomes
D. Viruses have both DNA and RNA
Correct Answer: A
Rationale: Viruses are obligate intracellular parasites lacking metabolic machinery.
Unlike bacteria, they cannot reproduce or carry out metabolic processes independently;
they require host cell machinery for replication.
Q8: Viral genomes may consist of:
A. Single-stranded DNA only
B. Double-stranded RNA only
C. Either DNA or RNA, which may be single or double-stranded [CORRECT]
D. Double-stranded DNA with histone proteins only
Correct Answer: C
Rationale: Viral genomes exhibit diversity in both nucleic acid type (DNA or RNA) and
structure (single-stranded or double-stranded). This variation is a primary basis for viral
classification systems.
Q9: Fill in the blank: Viruses that lack an envelope are referred to as __________ viruses.
