Question 1

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV) . The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

Accepted Answer

A)  The plants would develop some but not all of the symptoms of the TMV infection.
B)  The plants would develop symptoms typically produced by viroids.
C)  The plants would develop the typical symptoms of TMV infection.
D)  The plants would not show any disease symptoms.
E)  The plants would become infected, but the sap from these plants would be unable to infect other plants.F) A) and C)
G) None of the above

Question 2

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?

Accepted Answer

A)  Viruses contain either DNA or RNA.
B)  Viruses are enclosed in protein capsids rather than plasma membranes.
C)  Viruses can reproduce only inside host cells.
D)  Viruses can infect both prokaryotic and eukaryotic cells.
E)  Viral genomes are usually more similar to the genome of the host cell than to the genomes of viruses that infect other cell types.F) A) and B)
G) A) and E)

Question 3

Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral mutation. Which of the following is the best example of a zoonosis?

Accepted Answer

A)  rabies
B)  herpesvirus
C)  smallpox
D)  HIV
E)  hepatitis virusF) All of the above
G) A) and D)

Question 4

Which treatment could definitively determine whether or not the component is a viroid?

Accepted Answer

A)  I
B)  II
C)  III
D)  IV
E)  first II and then IIIF) A) and E)
G) A) and C)

Question 5

Which of the following is the best predictor of how much damage a virus causes?

Accepted Answer

A)  ability of the infected cell to undergo normal cell division
B)  ability of the infected cell to carry on translation
C)  whether the infected cell produces viral protein
D)  whether the viral mRNA can be transcribed
E)  how much toxin the virus producesF) B) and E)
G) B) and D)

Question 6

The difference between vertical and horizontal transmission of plant viruses is that

Accepted Answer

A)  vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant.
B)  vertical transmission is the spread of viruses from upper leaves to lower leaves of the plant, and horizontal transmission is the spread of a virus among leaves at the same general level.
C)  vertical transmission is the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread of viruses among plants of similar size.
D)  vertical transmission is the transfer of DNA from one type of plant virus to another, and horizontal transmission is the exchange of DNA between two plant viruses of the same type.
E)  vertical transmission is the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission is the spread of viruses among plants of the same species.F) All of the above
G) B) and D)

Question 7

Emerging viruses arise by

Accepted Answer

A)  mutation of existing viruses.
B)  the spread of existing viruses to new host species.
C)  the spread of existing viruses more widely within their host species.
D)  all of the above
E)  none of the aboveF) B) and D)
G) A) and E)

Question 8

Use the following information to answer the following questions.
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA.
The table below shows the results of testing five viruses for nuclease specificity, the ability of the virus to act as an mRNA, and presence (+) or absence (-) of its own viral polymerase.
 $\begin{array}{ll}
\text { Virus Nuclease } & \text { Sensitivity } &\text { Genome as mRNA}&
\text { Polymerase} \
A & \text { Dnase }&-&+ \
\mathrm{B} & \text { Rnase }&+&- \
\mathrm{C} & \text { Dnase } &-&+\
\mathrm{D} & \text { Rnase }&-&+ \
\mathrm{E} & \text { Rnase }&+&-
\end{array}$
-Based on the above table, which virus meets the Baltimore requirements for a retrovirus?

Accepted Answer

The answer of Use the following information to answer the...

Question 9

Why do RNA viruses appear to have higher rates of mutation?

Accepted Answer

A)  RNA nucleotides are more unstable than DNA nucleotides.
B)  Replication of their genomes does not involve the proofreading steps of DNA replication.
C)  RNA viruses replicate faster.
D)  RNA viruses can incorporate a variety of nonstandard bases.
E)  RNA viruses are more sensitive to mutagens.F) A) and D)
G) A) and C)

Question 10

What characteristics of electron microscopes make them most useful for studying viruses?

Accepted Answer

A)  high energy electrons with high penetrance
B)  requirement that specimens be viewed in a vacuum
C)  necessity for specimens to be dry and fixed
D)  shorter wavelengths providing higher resolution
E)  use of magnetic fields to focus electronsF) B) and D)
G) C) and D)

Question 11

What is the name given to viruses that are single-stranded RNA that acts as a template for DNA synthesis?

Accepted Answer

A)  retroviruses
B)  proviruses
C)  viroids
D)  bacteriophages
E)  lytic phagesF) A) and B)
G) A) and C)

Question 12

Use the following information to answer the following questions.
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA.
The table below shows the results of testing five viruses for nuclease specificity, the ability of the virus to act as an mRNA, and presence (+)  or absence (-)  of its own viral polymerase.
   Virus Nuclease  Sensitivity  Genome as mRNA PolymeraseA Dnase −+B Rnase +−C Dnase −+D Rnase −+E Rnase +−\begin{array}{ll}	ext { Virus Nuclease } & 	ext { Sensitivity } &	ext { Genome as mRNA}&	ext { Polymerase} \A & 	ext { Dnase }&-&+ \\mathrm{B} & 	ext { Rnase }&+&- \\mathrm{C} & 	ext { Dnase } &-&+\\mathrm{D} & 	ext { Rnase }&-&+ \\mathrm{E} & 	ext { Rnase }&+&-\end{array} Virus Nuclease ABCDE​ Sensitivity  Dnase  Rnase  Dnase  Rnase  Rnase ​ Genome as mRNA−+−−+​ Polymerase+−++−​ 
-Given Baltimore's scheme, a positive sense single-stranded RNA virus such as the polio virus would be most closely related to which of the following?

Accepted Answer

A)  T-series bacteriophages
B)  retroviruses that require a DNA intermediate
C)  single-stranded DNA viruses such as herpesviruses
D)  nonenveloped double-stranded RNA viruses
E)  linear double-stranded DNA viruses such as adenovirus F) C) and E)
G) B) and C)

Question 13

What are prions?

Accepted Answer

A)  misfolded versions of normal brain protein
B)  tiny molecules of RNA that infect plants
C)  viral DNA that has had to attach itself to the host genome
D)  viruses that invade bacteria
E)  a mobile segment of DNAF) C) and D)
G) A) and B)

Question 14

If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?

Accepted Answer

A)  I
B)  II
C)  III
D)  IV
E)  either II or IVF) A) and B)
G) D) and E)

Question 15

Which of the following series best reflects what we know about how the flu virus moves between species?

Accepted Answer

A)  An avian flu virus undergoes several mutations and rearrangements such that it is able to be transmitted to other birds and then to humans.
B)  The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected.
C)  A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans.
D)  An influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this enables it to be transmitted to a human host.
E)  An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, the virus mutates and can be transmitted to humans.F) C) and D)
G) All of the above

Question 16

Which of the following is characteristic of the lytic cycle?

Accepted Answer

A)  Many bacterial cells containing viral DNA are produced.
B)  Viral DNA is incorporated into the host genome.
C)  The viral genome replicates without destroying the host.
D)  A large number of phages is released at a time.
E)  The virus-host relationship usually lasts for generations.F) A) and B)
G) A) and C)

Question 17

Which of the following describes plant virus infections?

Accepted Answer

A)  They can be controlled by the use of antibiotics.
B)  They are spread throughout a plant by passing through the plasmodesmata.
C)  They have little effect on plant growth.
D)  They are seldom spread by insects.
E)  They can never be inherited from a parent.F) B) and D)
G) B) and C)

Question 18

Use the following information to answer the following questions.
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA.
The table below shows the results of testing five viruses for nuclease specificity, the ability of the virus to act as an mRNA, and presence (+) or absence (-) of its own viral polymerase.
 $\begin{array}{ll}
\text { Virus Nuclease } & \text { Sensitivity } &\text { Genome as mRNA}&
\text { Polymerase} \
A & \text { Dnase }&-&+ \
\mathrm{B} & \text { Rnase }&+&- \
\mathrm{C} & \text { Dnase } &-&+\
\mathrm{D} & \text { Rnase }&-&+ \
\mathrm{E} & \text { Rnase }&+&-
\end{array}$
-Based on the above table, which virus meets the requirements for a bacteriophage?

Accepted Answer

The answer of Use the following information to answer the...

Exam 19: Viruses

Correct Answer
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Which of the following is characteristic of the lytic cycle?

Correct Answer
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What characteristics of electron microscopes make them most useful for studying viruses?

Correct Answer
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Why do RNA viruses appear to have higher rates of mutation?

Correct Answer
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Emerging viruses arise by

Correct Answer
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What is the name given to viruses that are single-stranded RNA that acts as a template for DNA synthesis?

Correct Answer
verified

Which of the following is the best predictor of how much damage a virus causes?

Correct Answer
verified

Which treatment could definitively determine whether or not the component is a viroid?

Correct Answer
verified

Which of the following series best reflects what we know about how the flu virus moves between species?

Correct Answer
verified

Correct Answer
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Which of the following describes plant virus infections?

Correct Answer
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Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral mutation. Which of the following is the best example of a zoonosis?

Correct Answer
verified

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV) . The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

Correct Answer
verified

The difference between vertical and horizontal transmission of plant viruses is that

Correct Answer
verified

What are prions?

Correct Answer
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Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?

Correct Answer
verified

If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?

Correct Answer
verified

Correct Answer
verified

Exam 19: Viruses

Correct AnswerverifiedShow Answer

Which of the following is characteristic of the lytic cycle?

Correct AnswerverifiedShow Answer

What characteristics of electron microscopes make them most useful for studying viruses?

Correct AnswerverifiedShow Answer

Why do RNA viruses appear to have higher rates of mutation?

Correct AnswerverifiedShow Answer

Emerging viruses arise by

Correct AnswerverifiedShow Answer

What is the name given to viruses that are single-stranded RNA that acts as a template for DNA synthesis?

Correct AnswerverifiedShow Answer

Which of the following is the best predictor of how much damage a virus causes?

Correct AnswerverifiedShow Answer

Which treatment could definitively determine whether or not the component is a viroid?

Correct AnswerverifiedShow Answer

Which of the following series best reflects what we know about how the flu virus moves between species?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following describes plant virus infections?

Correct AnswerverifiedShow Answer

Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral mutation. Which of the following is the best example of a zoonosis?

Correct AnswerverifiedShow Answer

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV) . The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

Correct AnswerverifiedShow Answer

The difference between vertical and horizontal transmission of plant viruses is that

Correct AnswerverifiedShow Answer

What are prions?

Correct AnswerverifiedShow Answer

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?

Correct AnswerverifiedShow Answer

If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
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Correct Answer
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