Portage Learning BIOD 171 Module 6 BIOD
UPDATED ACTUAL Exam Questions and
CORRECT Answers
True or False: viruses can be classified as prokaryotic or eukaryotic - CORRECT
ANSWER - False. Viruses are neither prokaryotic or eukaryotic
What is an obligate intracellular parasite? - CORRECT ANSWER - 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.
What is a viral capsid? - CORRECT ANSWER - a membrane-like protective structure that
contains genetic material similar to nucleus of eukaryotic cells.
What is the viral envelope, and what does the presence (or absence) of it tell you about the type
of virus? - CORRECT ANSWER - The envelope surrounds the viral capsid, is derived
from the host cell membrane and serves as an additional barrier to the external environment. The
overwhelming majority of animal viruses are enveloped whereas the majority of plant or
bacteria-infecting viruses are not.
What type of microscope would be used to study the shape of a viral capsid? - CORRECT
ANSWER - Due to its size (~30-150 nm) most viral capsids must be visualized via
electron microscopy.
How does the viral envelope both aid in cell entry as well as hide it from being detected by the
immune system? - CORRECT ANSWER - The viral envelope contains the necessary
proteins required for interaction with host cells. As the envelope is derived from the host cell
membrane, this camouflages the virus and lowers the likelihood of immune detection by making
it appear similar to the normal biological host cell.
What must happen before viral replication of its genome can occur? - CORRECT
ANSWER - For all viruses, the genome is replicated following attachment and entry,
never before.
, Describe the basic steps of the viral life cycle. - CORRECT ANSWER - 1. Attachment:
Viral receptors bind to host proteins on the surface of the cell.2. Entry: The virus fuses with the
host membrane and enters the cell3. Uncoating: (where applicable) the viral capsid
disassembles4. Replication: The viral genome provides the 'blueprint' to make copies of itself5.
Exit: New viruses are produced and leave the cell6. New infection: Newly produced viruses
leave the host cell and go on to infect new cells. The process outlined above now restarts.
What is a bacteriophage? - CORRECT ANSWER - A virus that infects bacteria
What structural aspects make bacteriophages distinct from viruses that infect either animals or
plants? - CORRECT ANSWER - Bacteriophages possess an icosahedral capsid head
group and a helical tail. Attached to the tail are fibrous extensions or 'legs' that aid in binding
host cells. Notably, this particular structural arrangement has not been observed among viruses
that infect either animals or plants.
Which viral replicative process results in the destruction of the host cell? - CORRECT
ANSWER - The lytic replication cycle occurs when a bacteriophage replicates within a
host until it ruptures, effectively destroying the host bacterial cell. The phrase lytic stems from
'lysis', meaning to rupture or disintegrate (breakdown) a cell.
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. - CORRECT ANSWER - During the
initial inoculation of virus and bacteria, the media has a high degree of turbidity (cloudiness).
However, as the lytic cycle progresses and more and more bacterial cells are destroyed, the
culture media turns from turbid to clear, as turbidity is a function of the number of intact
bacterial cells present in the media. Thus, as bacterial cell numbers decrease due to lysis, the
media becomes clearer.
To what family of viruses does rubella come from and how is it transmitted? - CORRECT
ANSWER - Rubella virus belongs to a family of viruses called Togaviridae. Rubella is
transmitted via air-borne particles such as when a person coughs.
What is the common name for rubeola, and is it a DNA or RNA virus? - CORRECT
ANSWER - Rubeola is commonly referred to as the measles and belongs to the family of
UPDATED ACTUAL Exam Questions and
CORRECT Answers
True or False: viruses can be classified as prokaryotic or eukaryotic - CORRECT
ANSWER - False. Viruses are neither prokaryotic or eukaryotic
What is an obligate intracellular parasite? - CORRECT ANSWER - 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.
What is a viral capsid? - CORRECT ANSWER - a membrane-like protective structure that
contains genetic material similar to nucleus of eukaryotic cells.
What is the viral envelope, and what does the presence (or absence) of it tell you about the type
of virus? - CORRECT ANSWER - The envelope surrounds the viral capsid, is derived
from the host cell membrane and serves as an additional barrier to the external environment. The
overwhelming majority of animal viruses are enveloped whereas the majority of plant or
bacteria-infecting viruses are not.
What type of microscope would be used to study the shape of a viral capsid? - CORRECT
ANSWER - Due to its size (~30-150 nm) most viral capsids must be visualized via
electron microscopy.
How does the viral envelope both aid in cell entry as well as hide it from being detected by the
immune system? - CORRECT ANSWER - The viral envelope contains the necessary
proteins required for interaction with host cells. As the envelope is derived from the host cell
membrane, this camouflages the virus and lowers the likelihood of immune detection by making
it appear similar to the normal biological host cell.
What must happen before viral replication of its genome can occur? - CORRECT
ANSWER - For all viruses, the genome is replicated following attachment and entry,
never before.
, Describe the basic steps of the viral life cycle. - CORRECT ANSWER - 1. Attachment:
Viral receptors bind to host proteins on the surface of the cell.2. Entry: The virus fuses with the
host membrane and enters the cell3. Uncoating: (where applicable) the viral capsid
disassembles4. Replication: The viral genome provides the 'blueprint' to make copies of itself5.
Exit: New viruses are produced and leave the cell6. New infection: Newly produced viruses
leave the host cell and go on to infect new cells. The process outlined above now restarts.
What is a bacteriophage? - CORRECT ANSWER - A virus that infects bacteria
What structural aspects make bacteriophages distinct from viruses that infect either animals or
plants? - CORRECT ANSWER - Bacteriophages possess an icosahedral capsid head
group and a helical tail. Attached to the tail are fibrous extensions or 'legs' that aid in binding
host cells. Notably, this particular structural arrangement has not been observed among viruses
that infect either animals or plants.
Which viral replicative process results in the destruction of the host cell? - CORRECT
ANSWER - The lytic replication cycle occurs when a bacteriophage replicates within a
host until it ruptures, effectively destroying the host bacterial cell. The phrase lytic stems from
'lysis', meaning to rupture or disintegrate (breakdown) a cell.
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. - CORRECT ANSWER - During the
initial inoculation of virus and bacteria, the media has a high degree of turbidity (cloudiness).
However, as the lytic cycle progresses and more and more bacterial cells are destroyed, the
culture media turns from turbid to clear, as turbidity is a function of the number of intact
bacterial cells present in the media. Thus, as bacterial cell numbers decrease due to lysis, the
media becomes clearer.
To what family of viruses does rubella come from and how is it transmitted? - CORRECT
ANSWER - Rubella virus belongs to a family of viruses called Togaviridae. Rubella is
transmitted via air-borne particles such as when a person coughs.
What is the common name for rubeola, and is it a DNA or RNA virus? - CORRECT
ANSWER - Rubeola is commonly referred to as the measles and belongs to the family of
