Question 1

What is approximately the largest size of a double-stranded DNA genome of a virus that infect vertebrates?

Accepted Answer

A)  25 kbp. 
B)  50 kbp 
C)  100 kbp 
D)  300 kbp 
E)  500 kbp 
A)  25 kbp. 
B)  50 kbp 
C)  100 kbp 
D)  300 kbp 
E)  500 kbp D

Question 2

Retroviruses are the only virus family known to package two copies of its genome.

Accepted Answer

A) True 
 B)False  True

Question 3

There are a number of small DNA viruses that are highly dependent on their host cells for transcription and replication enzymes.Which of the following could explain the evolutionary origins of these viruses?

Accepted Answer

A)  They originated from fragments of the genomes of larger more independent viruses. 
B)  They originated from intracellular plasmids found in bacteria. 
C)  They originated from the genomes of intracellular organelles, such as mitochondria. 
D)  They originated from fragments of cellular DNA that broke away from the cell genome. 
E)  All of the above could be correct. 
A)  They originated from fragments of the genomes of larger more independent viruses. 
B)  They originated from intracellular plasmids found in bacteria. 
C)  They originated from the genomes of intracellular organelles, such as mitochondria. 
D)  They originated from fragments of cellular DNA that broke away from the cell genome. 
E)  All of the above could be correct. D

Question 4

What distinguishes a satellite virus from a satellite nucleic acid?

Accepted Answer

A)  A satellite virus encodes its own capsid protein while a satellite nucleic acid does not. 
B)  A satellite virus packages its own replication protein while a satellite nucleic acid does not. 
C)  A satellite virus requires a helper virus while a satellite nucleic acid does not. 
D)  Genomes of satellite viruses are smaller than those of satellite nucleic acids. 
E)  Satellite viruses do not encode any proteins while satellite nucleic acids do. 
A)  A satellite virus encodes its own capsid protein while a satellite nucleic acid does not. 
B)  A satellite virus packages its own replication protein while a satellite nucleic acid does not. 
C)  A satellite virus requires a helper virus while a satellite nucleic acid does not. 
D)  Genomes of satellite viruses are smaller than those of satellite nucleic acids. 
E)  Satellite viruses do not encode any proteins while satellite nucleic acids do.

Question 5

Which of the following virus families have the ability to synthesize reverse transcriptase?

Accepted Answer

A)  Retroviruses 
B)  Caulimoviruses 
C)  Hepadnaviruses 
D)  None of the above are correct. 
E)  All of the above are correct. 
A)  Retroviruses 
B)  Caulimoviruses 
C)  Hepadnaviruses 
D)  None of the above are correct. 
E)  All of the above are correct.

Question 6

According to the RNA World hypothesis, which of the following subcellular entities may have evolved first?

Accepted Answer

A)  Retroviruses 
B)  RNA Viruses 
C)  Viroids 
D)  DNA Viruses 
E)  Bacteriophages 
A)  Retroviruses 
B)  RNA Viruses 
C)  Viroids 
D)  DNA Viruses 
E)  Bacteriophages

Question 7

Which of the following may be a factor in explaining why viral ssRNA genomes are not usually as long as the dsDNA genomes?

Accepted Answer

A)  It is much more difficult to package a large ssRNA genome into a capsid. 
B)  Long ssRNA molecules form too many secondary structures that inhibit replication. 
C)  Long RNA genomes are difficult to translate. 
D)  Long RNA genomes are difficult to transcribe. 
E)  Long pieces of RNA are easily broken by mechanical damage. 
A)  It is much more difficult to package a large ssRNA genome into a capsid. 
B)  Long ssRNA molecules form too many secondary structures that inhibit replication. 
C)  Long RNA genomes are difficult to translate. 
D)  Long RNA genomes are difficult to transcribe. 
E)  Long pieces of RNA are easily broken by mechanical damage.

Question 8

Why is the type of disease caused not the best criteria to use when classifying a virus?

Accepted Answer

The disease caused by a specific virus i

Question 9

Which of the following types of genomes is most commonly found in viruses that can infect fungi?

Accepted Answer

A)  ssDNA 
B)  dsDNA 
C)  ssRNA 
D)  dsRNA 
E)  All of the above are found. 
A)  ssDNA 
B)  dsDNA 
C)  ssRNA 
D)  dsRNA 
E)  All of the above are found.

Question 10

What is a possible explanation for why ssDNA viruses have genomes less that 10kb in size?

Accepted Answer

A)  ssDNA is not as physically stable as dsDNA. 
B)  ssDNA is not transcribed by host cells. 
C)  ssDNA can form hairpin structures because of base-pairing. 
D)  Larger pieces of ssDNA can not be replicated. 
E)  Larger pieces of ssDNA can not easily enter the host cell. 
A)  ssDNA is not as physically stable as dsDNA. 
B)  ssDNA is not transcribed by host cells. 
C)  ssDNA can form hairpin structures because of base-pairing. 
D)  Larger pieces of ssDNA can not be replicated. 
E)  Larger pieces of ssDNA can not easily enter the host cell.

Question 11

Most viruses that infect plants have the following type of genome?

Accepted Answer

A)  ssDNA, positive sense 
B)  ssDNA, negative sense 
C)  ssRNA, positive sense 
D)  ssRNA, negative sense 
E)  None of the above. 
A)  ssDNA, positive sense 
B)  ssDNA, negative sense 
C)  ssRNA, positive sense 
D)  ssRNA, negative sense 
E)  None of the above.

Question 12

There are several types of viruses with enveloped virions that can infect plants.

Accepted Answer

A) True 
 B)False

Question 13

Which of the following characteristics are NOT one of the most important criterion used to classify viruses into families?

Accepted Answer

A)  topology of genome (linear or circular) 
B)  strandedness of genome (double or single stranded) 
C)  type of nucleic acid used in genome (DNA or RN
A)  
D)  structure of virion 
E)  species of host infected 
A)  topology of genome (linear or circular) 
B)  strandedness of genome (double or single stranded) 
C)  type of nucleic acid used in genome (DNA or RN
A)  
D)  structure of virion 
E)  species of host infected

Question 14

According to the RNA World hypothesis, which of the following enzymes may have evolved first?

Accepted Answer

A)  DNA-dependent RNA polymerase 
B)  DNA-dependent DNA polymerase 
C)  RNA-dependent RNA polymerase 
D)  RNA-dependent DNA polymerase 
E)  self-replicating RNAs 
A)  DNA-dependent RNA polymerase 
B)  DNA-dependent DNA polymerase 
C)  RNA-dependent RNA polymerase 
D)  RNA-dependent DNA polymerase 
E)  self-replicating RNAs

Question 15

The family classification scheme for DNA bacteriophages is not very useful for describing the evolutionary relationships between these viruses.What is the best explanation for this?

Accepted Answer

A)  DNA bacteriophages can infect more than one host species. 
B)  DNA bacteriophages have a wide variety of virion structures. 
C)  The viral genomes are genetic mosaics due to recombination. 
D)  There are too many bacteriophages to classify into families. 
E)  These viruses do not have an evolutionary relationship to each other. 
A)  DNA bacteriophages can infect more than one host species. 
B)  DNA bacteriophages have a wide variety of virion structures. 
C)  The viral genomes are genetic mosaics due to recombination. 
D)  There are too many bacteriophages to classify into families. 
E)  These viruses do not have an evolutionary relationship to each other.

Question 16

Almost all of the viruses with positive-strand RNA genomes and enveloped virions infect which group of hosts?

Accepted Answer

A)  Bacteria. 
B)  Vertebrates 
C)  Plants 
D)  Fungi 
E)  Algae. 
A)  Bacteria. 
B)  Vertebrates 
C)  Plants 
D)  Fungi 
E)  Algae.

Question 17

Viroids do not require a helper virus in order to replicate and cause disease.

Accepted Answer

A) True 
 B)False

Question 18

The advantage of using a helical instead of an icosahedral nucleocapsid to package a ssRNA genome is…..

Accepted Answer

A)  it is more efficient to envelope a helical nucleocapsid than an icosahedral capsid. 
B)  it is easier to produce a helical nucleocapsid than an icosahedral capsid. 
C)  it better protects the genome from degradation inside the cell. 
D)  it requires a smaller protein to build than an icosahedral capsid. 
E)  it requires fewer copies of the nucleocapsid protein than an icosahedral capsid. 
A)  it is more efficient to envelope a helical nucleocapsid than an icosahedral capsid. 
B)  it is easier to produce a helical nucleocapsid than an icosahedral capsid. 
C)  it better protects the genome from degradation inside the cell. 
D)  it requires a smaller protein to build than an icosahedral capsid. 
E)  it requires fewer copies of the nucleocapsid protein than an icosahedral capsid.

Question 19

Mimivirus, which infects an amoeba, is the largest known dsDNA virus and has a genome larger than some free living bacteria and archae.Even though it encodes many of its own enzymes and even tRNAs, it still does not produce its own ribosomes.Describe the possible evolutionary origin of such a large and complex viruses.

Accepted Answer

Mimiviruses, along with poxviruses, are

Question 20

Which of the following virus families contains viruses with the longest ssRNA genomes?

Accepted Answer

A)  Picornaviruses 
B)  Coronaviruses 
C)  Flaviviruses 
D)  Togaviruses 
E)  Bromoviruses 
A)  Picornaviruses 
B)  Coronaviruses 
C)  Flaviviruses 
D)  Togaviruses 
E)  Bromoviruses

Exam 3: Virus Classification: The World of Viruses

What is approximately the largest size of a double-stranded DNA genome of a virus that infect vertebrates?

Retroviruses are the only virus family known to package two copies of its genome.

There are a number of small DNA viruses that are highly dependent on their host cells for transcription and replication enzymes.Which of the following could explain the evolutionary origins of these viruses?

What distinguishes a satellite virus from a satellite nucleic acid?

Which of the following virus families have the ability to synthesize reverse transcriptase?

According to the RNA World hypothesis, which of the following subcellular entities may have evolved first?

Which of the following may be a factor in explaining why viral ssRNA genomes are not usually as long as the dsDNA genomes?

Why is the type of disease caused not the best criteria to use when classifying a virus?

Which of the following types of genomes is most commonly found in viruses that can infect fungi?

What is a possible explanation for why ssDNA viruses have genomes less that 10kb in size?

Most viruses that infect plants have the following type of genome?

There are several types of viruses with enveloped virions that can infect plants.

Which of the following characteristics are NOT one of the most important criterion used to classify viruses into families?

According to the RNA World hypothesis, which of the following enzymes may have evolved first?

The family classification scheme for DNA bacteriophages is not very useful for describing the evolutionary relationships between these viruses.What is the best explanation for this?

Almost all of the viruses with positive-strand RNA genomes and enveloped virions infect which group of hosts?

Viroids do not require a helper virus in order to replicate and cause disease.

The advantage of using a helical instead of an icosahedral nucleocapsid to package a ssRNA genome is…..

Which of the following virus families contains viruses with the longest ssRNA genomes?

Introduction to Virology

Virus Structure and Assembly

Virus Entry

Single-Stranded RNA Bacteriophages

Microviruses

Bacteriophage

Bacteriophage Lambda

Viruses of Archaea

Cucumber Mosaic Virus

Picornaviruses

Flaviviruses

Togaviruses

Coronaviruses

Paramyxo-Viruses and Rhabdoviruses

Filovirouses

Bunyaviruses

Influenza Viruses

Reoviruses

Parvoviruses

Polyomaviruses

Papillomaviruses

Adenoviruses

Herpesviruses

Baculoviruses

Poxviruses

Viruses of Algae and Mimivirus

Retroviruses

Human Immunodeficiency

Hepadnaviruses

Viroids and Hepatitis Delta Virus

Prions

Intrinsic Cellular Defenses Against Virus Infection

Innate and Adaptive Immune Responses to Virus Infection

Antiviral Vaccines

Antiviral Chemotherapy

Eukaryotic Virus Vectors

Filters