Question 1

Prions affect the

Accepted Answer

A)   respiratory system.
B)   gastrointestinal tract.
C)   nervous system.
D)   lymphatic system.
E)   urogenital system.

Question 2

Viruses are not cultivated in

Accepted Answer

A)   live organisms.
B)   embryonated chicken eggs.
C)   tissue culture.
D)   blood agar.
E)   plants.

Question 3

What part of the E. coli T4 phage attaches to the host cell receptors?

Accepted Answer

A)   Capsid fragments around the nucleic acid.
B)   Protein fibers at the end of the phage tail.
C)   Pili of the envelope.
D)   Spikes of the envelope.
E)   Spikes of the cell wall.

Question 4

Would ID₅₀ and LD₅₀ necessarily be the same for a given virus? Why or why not?

Accepted Answer

A)   Yes, because the number of viruses that infect 50% of a test population should also kill 50% of that test population.
B)   No, because a virus may be highly infectious (very low ID50 value)  but only marginally lethal (very high LD50 value) , for example the rhinovirus (common cold virus) .
C)   No, because very few viruses are lethal, yet many are highly infectious. The two values should ALWAYS be different.
D)   Yes, because what we're actually describing here is the infection/ killing of individual cells, not of entire organisms. If a cell is infected, it will always be killed.
E)   Yes, because ID₅₀ and LD₅₀ are actually measurements of the same thing: effectiveness of a virus in entering and damaging a host cell.

Question 5

The shape of the virus is determined by its

Accepted Answer

A)   nucleic acid.
B)   capsid.
C)   envelope.
D)   tail.
E)   spikes.

Question 6

Transducing virulent phages do not lyse the cells they invade because

Accepted Answer

A)   transformation is taking place in the phage and this is transferred to the bacterium.
B)   bacterial DNA has replaced critical viral DNA in the phage.
C)   their virulence is dependent on the bacteria and virus replicating together.
D)   the lytic genes are unable to enter during penetration and are shed outside the host.
E)   viral DNA has replaced critical bacterial DNA in the phage.

Question 7

Which statement about most phages that contain single-stranded DNA is NOT True?

Accepted Answer

A)   They are extruded from the host cell.
B)   They contain a negative-sense DNA strand.
C)   Their DNA is transformed to dsDNA before replication and transcription occur.
D)   All of the choices are correct.
E)   None of the choices is correct.

Question 8

An exit method used by viruses that does not immediately destroy the host bacterium is

Accepted Answer

A)   lysis.
B)   inversion.
C)   extrusion.
D)   excising.
E)   endocytosis.

Question 9

The viral envelope closely resembles the

Accepted Answer

A)   prokaryotic cell wall.
B)   capsomere.
C)   eukaryotic cytoplasmic membrane.
D)   cytoplasm.
E)   eukaryotic cell wall.

Question 10

The approximate viral concentration of a sample may be determined by

Accepted Answer

A)   quantal assay.
B)   endpoint assay.
C)   the titer.
D)   the lysate assay.
E)   cytopathic assay.

Question 11

Which statement(s)  about cells taken from a tumor is/are True?

Accepted Answer

A)   They may be used to grow viruses.
B)   They may be used to grow bacteriophages.
C)   They divide 50 times and then die.
D)   They may be used to grow viruses AND they may be used to grow bacteriophages.
E)   They divide 50 times and then die AND they may be used to grow bacteriophages.

Question 12

An antibiotic is added to a culture of E. coli, resulting in death of the cells. Bacteriophages are then added. Would the phages replicate in the E. coli cells? Why or why not?

Accepted Answer

A)   Yes, because the cellular machinery of the bacteria is most likely still active. The bacteriophages could use that machinery to replicate new virus particles.
B)   No, because the bacteriophages would depend too much on having the active machinery of a living host cell for replication. 
C)   Yes, because bacteriophages are capable of reanimating dead cells to force them to produce more virus particles.
D)   No, because entry of the bacteriophages into the target cell is dependent on the cell being alive to conduct endocytosis of the virus.
E)   No, because dead E. coli cells do not have any receptors on their cell walls to which the bacteriophages can attach for entry into the host cell by fusion.

Question 13

Filamentous phages

Accepted Answer

A)   only infect E. coli that have pili.
B)   only infect E. coli lacking pili.
C)   infect E. coli regardless of the presence of pili.
D)   do not infect E. coli.
E)   only infect Gram-negative E. coli.

Question 14

A filamentous phage is incapable of causing a lytic infection.

Accepted Answer

A) True 
 B)False

Question 15

There are ________ major families of DNA-containing viruses that infect vertebrates.

Accepted Answer

A)   7
B)   5
C)   4
D)   2
E)   6

Question 16

A lysogenic cell contains viral DNA (a prophage) integrated into the host chromosome.

Accepted Answer

A) True 
 B)False

Question 17

Which is True of lysogenized cells?

Accepted Answer

A)   They are immune to any further infection by any virus.
B)   They are immune to infection by the same virus.
C)   They may have new properties AND they respond to infection with the SOS response.
D)   They respond to infection with the SOS response.
E)   They are immune to infection by the same virus AND may have new properties.

Question 18

Completed filamentous phages are often found in the cytoplasm of infected bacteria.

Accepted Answer

A) True 
 B)False

Question 19

Most temperate phages integrate into the host chromosome, whereas some replicate as plasmids. Which kind of relationship do you think would be more likely to maintain the phage in the host cell, and why?

Accepted Answer

A)   Plasmids; they're smaller, so they would be easier to replicate by the host cell.
B)   Integrated; the host cell would be less likely to view this DNA as "foreign" on subsequent rounds of replication, and would retain it more easily.
C)   Plasmids; these structures often carry other genes that may give the host cell a selective advantage over cells that don't have them.
D)   Integration, because plasmids are frequently lost during cell division, which could leave a daughter cell without the virus genome.
E)   Either plasmids or integration because once a virus genome is in a host cell, there is not way for that genome to be removed from the infected cell.

Question 20

You are graduating from nursing school in three months and have already lined up a new job. However, your employer informs you that before you start your job, it is mandatory for you to be vaccinated against hepatitis B, a double-stranded DNA virus that can cause the disease hepatitis. Your boyfriend, a biology major, wonders why you need to get the vaccine. You aced your microbiology class and you know a lot about both viruses and vaccines, so you understand why getting this vaccination is essential. You give your boyfriend a mini lesson on this by answering a few of his questions.
-To give more information on virus replication strategies, you explain to your friend the difference between a DNA virus and a RNA virus in terms of replication. You tell him that

Accepted Answer

A)   RNA virus replication always requires a virally encoded RNA polymerase that is an RNA-dependent RNA polymerase; this enzyme uses an RNA template to synthesize a new strand of RNA. DNA viruses use DNA-dependent DNA polymerase in replication.
B)   RNA virus replication always requires a virally encoded DNA polymerase, that is an RNA-dependent DNA polymerase; this enzyme uses a DNA template to synthesize a new strand of RNA. DNA viruses use DNA-dependent DNA polymerase in replication.
C)   RNA viruses always encode an enzyme called reverse transcriptase, which is an RNA-dependent DNA polymerase that synthesizes DNA from an RNA template. DNA viruses use DNA-dependent RNA polymerase in replication.
D)   DNA viruses replicate their genome by means of an RNA-dependent DNA polymerase that synthesizes DNA from an RNA template. RNA viruses replicate their genome by means of a virally encoded replisome.
E)   DNA viruses must always first enzymatically degrade one DNA strand before they are able to replicate the remaining strand using the enzyme DNA-dependent RNA polymerase. RNA viruses are single-stranded, so can replicate their genome directly.

Exam 13: Viruses, Viroids, and Prions

An exit method used by viruses that does not immediately destroy the host bacterium is

Correct Answer
verified

Would ID₅₀ and LD₅₀ necessarily be the same for a given virus? Why or why not?

Correct Answer
verified

Prions affect the

Correct Answer
verified

Which is True of lysogenized cells?

Correct Answer
verified

Most temperate phages integrate into the host chromosome, whereas some replicate as plasmids. Which kind of relationship do you think would be more likely to maintain the phage in the host cell, and why?

Correct Answer
verified

A lysogenic cell contains viral DNA (a prophage) integrated into the host chromosome.

Correct Answer
verified

Filamentous phages

Correct Answer
verified

A filamentous phage is incapable of causing a lytic infection.

Correct Answer
verified

Which statement(s) about cells taken from a tumor is/are True?

Correct Answer
verified

An antibiotic is added to a culture of E. coli, resulting in death of the cells. Bacteriophages are then added. Would the phages replicate in the E. coli cells? Why or why not?

Correct Answer
verified

What part of the E. coli T4 phage attaches to the host cell receptors?

Correct Answer
verified

The viral envelope closely resembles the

Correct Answer
verified

Correct Answer
verified

Viruses are not cultivated in

Correct Answer
verified

Which statement about most phages that contain single-stranded DNA is NOT True?

Correct Answer
verified

The approximate viral concentration of a sample may be determined by

Correct Answer
verified

Transducing virulent phages do not lyse the cells they invade because

Correct Answer
verified

Completed filamentous phages are often found in the cytoplasm of infected bacteria.

Correct Answer
verified

There are ________ major families of DNA-containing viruses that infect vertebrates.

Correct Answer
verified

The shape of the virus is determined by its

Correct Answer
verified

Exam 13: Viruses, Viroids, and Prions

An exit method used by viruses that does not immediately destroy the host bacterium is

Correct AnswerverifiedShow Answer

Would ID₅₀ and LD₅₀ necessarily be the same for a given virus? Why or why not?

Correct AnswerverifiedShow Answer

Prions affect the

Correct AnswerverifiedShow Answer

Which is True of lysogenized cells?

Correct AnswerverifiedShow Answer

Most temperate phages integrate into the host chromosome, whereas some replicate as plasmids. Which kind of relationship do you think would be more likely to maintain the phage in the host cell, and why?

Correct AnswerverifiedShow Answer

A lysogenic cell contains viral DNA (a prophage) integrated into the host chromosome.

Correct AnswerverifiedShow Answer

Filamentous phages

Correct AnswerverifiedShow Answer

A filamentous phage is incapable of causing a lytic infection.

Correct AnswerverifiedShow Answer

Which statement(s) about cells taken from a tumor is/are True?

Correct AnswerverifiedShow Answer

An antibiotic is added to a culture of E. coli, resulting in death of the cells. Bacteriophages are then added. Would the phages replicate in the E. coli cells? Why or why not?

Correct AnswerverifiedShow Answer

What part of the E. coli T4 phage attaches to the host cell receptors?

Correct AnswerverifiedShow Answer

The viral envelope closely resembles the

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Viruses are not cultivated in

Correct AnswerverifiedShow Answer

Which statement about most phages that contain single-stranded DNA is NOT True?

Correct AnswerverifiedShow Answer

The approximate viral concentration of a sample may be determined by

Correct AnswerverifiedShow Answer

Transducing virulent phages do not lyse the cells they invade because

Correct AnswerverifiedShow Answer

Completed filamentous phages are often found in the cytoplasm of infected bacteria.

Correct AnswerverifiedShow Answer

There are ________ major families of DNA-containing viruses that infect vertebrates.

Correct AnswerverifiedShow Answer

The shape of the virus is determined by its

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified