Deck 5: Viruses

Question 1

A single virus-infected cell may produce up to __________ new virions.

A)10
B)100
C)1000
D)10,000
E)one million

Answer 1

D

Question 2

A gene duplication event leads to a virus increasing the size of its genome.Which of these viruses will NOT accommodate the genome change easily?

A)tobacco mosaic virus
B)influenza A virus
C)rabies virus
D)polio virus
E)none is a correct choice

Answer 2

D

Question 3

Which feature of the Mimivirus may lead to a radical redefinition of what constitutes a virus?

A)The size of its chromosome
B)the shape of its chromosome
C)the presence of genes for anabolic functions
D)the presence of genes for catabolic function
E)none of the above

Answer 3

C

Question 4

What is the premise of the coevolution hypothesis of viral evolution?

A)Viruses appeared after the first cells were well established.
B)Viruses arose from excess DNA of cells.
C)Viruses first appeared before or at the same time as the first primordial cells.
D)Viruses first appeared about a million years ago and continue to evolve along with their hosts.
E)Viruses originated when some cells lost the ability to replicate on their own.

Question 5

Which of these findings supports the progressive hypothesis of viral origin?

A)The presence of mitochondria and chloroplast in cells.
B)The existence of obligate intracellular pathogens like Chlamydia.
C)The discovery of nucleocytoplasmic large DNA viruses.
D)The existence of eukaryal transposons or retrotransposon genetic elements.
E)The presence of a nucleus in eukaryotic cells.

Question 6

Most viruses with helical capsid symmetry contain _______ as their nucleic acid.

A)single-stranded DNA
B)single-stranded RNA
C)double-stranded DNA
D)double-stranded RNA
E)RNA/DNA dimer

Question 7

Select the correct ranking of genome sizes sizes (large to small)from the choices provided:

A)Mimivirus,Treponema,Mycoplasma,poliovirus
B)Mycoplasma,poliovirus,Mimivirus,Treponema
C)Poliovirus,Treponema,Mycoplasma,Mimivirus
D)Treponema,Mycoplasma,poliovirus,Mimivirus
E)poliovirus,Mimivirus Treponema,Mycoplasma

Question 8

The capsid of the influenza viris differs from that of the Tobacco mosaic virus because: (select all that apply)

A)there are distinct capsids for multiple chromosomal fragments
B)the chromosome is wrapped around the capsid
C)capsomeres cover each chromosomal segment
D)there is no surrounding envelope
E)the DNA is circular

Question 9

Enveloped viruses are mainly associated with which of the following?

A)plants and bacteria
B)animals
C)bacteria
D)plant and animals
E)plants

Question 10

Which of these comprises the viral genome?

A)single-stranded DNA
B)single-stranded RNA
C)double-stranded DNA
D)double-stranded RNA
E)All of these choices are seen in viruses.

Question 11

What is the premise of the progressive hypothesis of viral origin?

A)Viruses evolved from symbionts of cells.
B)Viruses evolved from self-replicating nucleic acid segments.
C)Viruses originated from cells that lost the ability to replicate.
D)Viruses were present when the first primordial cells evolved.
E)Viruses arose from fragmented DNA in a cell.

Question 12

Select the correct ranking of life form sizes (small to large)from the choices provided:

A)Mimivirus,Mycoplasma,poxvirus,picornavirus
B)Mycoplasma,poxvirus,picornavirus,Treponema
C)Treponema,Mimivirus,poxvirus,picornavirus
D)Mycoplasma,Mimivirus,picornavirus,poxvirus
E)Picornavirus,poxvirus,Mimivirus,Treponema

Question 13

What is the viral capsid composed of?

A)protein
B)nucleic acid
C)lipid
D)polysaccharide
E)glycogen

Question 14

Which choice best explains the lack of enveloped viruses infecting plants and bacteria?

A)lipid membranes from these organisms are not suited to endure environmental conditions
B)plant and bacterial viruses produce capsomeres that are not compatible with envelope formation
C)the plant viruses and bacteriophages have antigenic cappsids
D)the cell walls of plants and bacteria would prevent budding from occurring
E)none is a logical choice

Question 15

What is the most common way for enveloped viruses to enter animal cells?

A)The virion fuses itself to the cell membrane.
B)The virion directly injects its nucleic acid.
C)Endocytosis of the virion.
D)Through lysis of the cell.
E)Via a hole in the cell membrane.

Question 16

What is the most common way for non-enveloped viruses to enter animal cells?

A)The virion fuses itself to the cell membrane.
B)The virion directly injects its nucleic acid.
C)Endocytosis of the virion.
D)Through lysis of the cell.
E)Via a hole in the cell membrane.

Question 17

Which of the following is NOT a nucleocytoplasmic large DNA virus?

A)Herpes virus
B)Mimivirus
C)Chickenpox virus
D)Smallpox virus
E)Influenza virus

Question 18

Which virus has the most similarity to transposon DNA?

A)Mimivirus
B)Herpes viris
C)Mavirus
D)Influenza virus
E)Tobacco mosaic virus

Question 19

What protective structure contains the viral nucleic acid?

A)envelope
B)nucleus
C)capsid
D)endosome
E)vacuole

Question 20

How do bacteriophages invade the bacteria cell?

A)The bacteriophage fuses itself to the cell membrane.
B)The bacteriophage directly injects its nucleic acid.
C)Endocytosis of the bacteriophage.
D)Through lysis of the cell.
E)Via a hole in the cell membrane.

Question 21

What distinguishes the virus families on the top row of this figure from those on the lower row?

A)the top row families affect humans and other mammals only
B)the lower row families affect humans and other mammals only
C)the top row families contain only single stranded genomes
D)the top row families contain only DNA genomes
E)the lower row families contain only DNA genomes

Question 22

Measuring PFU has the advantage over direct virus count methods because it informs on:

A)viral structure
B)infectivity
C)enveloped versus non-enveloped anatomy
D)the burst size
E)chromosomal structure

Question 23

Which method listed below would provide the most reliable information for the identification of an unknown virus?

A)electron microscopy
B)hemagglutinin assay
C)plaque assay
D)antibody titer assay
E)viral nucleic acid analysis

Question 24

Based on the Baltimore and ICTV classification scheme information provided,which description best fits the Herpesviridae family?

A)double stranded DNA virus using DNA polymerase to replicate
B)double stranded RNA virus using an RNA polymerase to replicate
C)single stranded RNA virus using an RNA polymerase to replicate
D)single stranded DNA virus using DNA polymerase to replicate
E)none of the choices is correct

Question 25

Virus concentration requires which of the following techniques:

A)plaque assay
B)filtration
C)measurement of CPE
D)density gradient centrifugation
E)none will concentrate viruses

Question 26

The term for bacteriophage DNA that has integrated into the host cell chromosome and replicates along with the host cell chromosome.

A)a plasmid
B)a transposon
C)a prophage
D)a lysogen
E)a retrophage

Question 27

Based on the Baltimore and ICTV classification scheme information provided,which description best fits the Parvoviridae family?

A)double stranded DNA virus using DNA polymerase to replicate
B)double stranded RNA virus using an RNA polymerase to replicate
C)single stranded RNA virus using an RNA polymerase to replicate
D)single stranded DNA virus using DNA polymerase to replicate
E)none of the choices is correct

Question 28

Determination of ID₅₀ should correlate well with LD₅₀ UNLESS:

A)the virus was systemic
B)the cells used in the cell culture approach were from an organism not usually infected with the virus
C)test animals provided the cells used in the culture approach
D)ethical concerns influenced the course of the experimental approaches
E)none is a valid choice

Question 29

What is the Baltimore classification scheme for viruses based on?

A)strandedness and type of nucleic acid
B)type of virion symmetry
C)type of capsid found in the virion
D)type of host the virus infects
E)the presence or absence of an envelope

Question 30

In a serial dilution assay,a 0.1ml volume of the 10⁻⁶ dilution of a bacteriophage sample generates 24 plaques.What is the viral titer?

A)240 per ml
B)2400 per ml
C)46000 per ml
D)2)4 x10⁷ per ml
E)2)4 x 10⁸ per ml

Question 31

If morphology was the prime criterion for developing viral taxons,which two virus families (-viridae)would seem most closely related?

A)Polyoma,Parvo
B)Orthomyxo,Paramyxo
C)Rhabdo,Retro
D)Retro,Parvo
E)Bunya,Herpes

Question 32

The International Committee on Taxonomy of Viruses (ICTV)classification scheme uses all of the following criteria to classify viruses EXCEPT:

A)the host they infect.
B)the type of nucleic acid they contain.
C)ribosomal RNA sequence.
D)virion morphology.
E)presence of absence of an envelope.

Question 33

You are informed that a viral solution has 5,000 virions per milliliter and that LD50 is 2,500 virions.You infect a population of test animals with 0.5 ml doses,and observe that only 5% of the test subjects die.Which method of viral counting was NOT employed in providing your information?

A)electron microscopy
B)fluorescence antibody staining
C)hemagglutination
D)plaque or cell culture analysis
E)none is a correct choice

Question 34

Select the paired viruses which are most closely related:

A)feline infectious peritonitis virus,porcine endemic diarrhea virus
B)porcine endemic diarrhea virus,human coV 229E
C)porcine endemic diarrhea virus,feline infectious peritonitis virus
D)SARS coV,infectious bronchitis virus
E)Turkey coronavirus,mouse hepatitis virus

Question 35

Examine this figure critically.Which aspect of the figure seems unsuitable for RT-PCR of viral genomes?

A)use of reverse transcriptase
B)poly-T primer
C)use of Taq polymerase
D)use of dNTP nucleotides
E)use of multiple PCR cycles
Anwer: b

Question 36

Which Domain contains the viruses?

A)Bacteria
B)Archaea
C)Eukarya
D)It depends upon their host.
E)They are not classified at the domain level.

Question 37

All of the following methods can be used to quantify viruses EXCEPT:

A)plaque assay.
B)hemagglutinin assay.
C)viral protein assay.
D)endpoint assay to determine LD₅₀.
E)endpoint assay to determine ID₅₀.

Question 38

Term for bacteriophages that have the ability to either cause a lytic infection or integrate their genome into the host cell chromosome after entry into the host cell.

A)lysogenic phage
B)virulent phage
C)transposable phage
D)cytopathic phage
E)retro-phage

Question 39

Determining virus load by examining plant leaves for mosaicism would be considered as:

A)end point determination
B)determination of LD50
C)direct count via immunofluorescence
D)PFU count
E)None is a correct response

Question 40

What technique is usually used for the quantification of a bacteriophage suspension?

A)a direct count
B)a plaque assay
C)a protein-based assay
D)a loop dilution assay
E)a PCR assay

Question 41

Why is the human hepatitis delta virus similar to satellite viruses of plants?

A)It has a similar nucleic acid sequence.
B)It possesses capsid proteins provided by another virus
C)It requires a helper virus for replication in the cell.
D)It is enveloped
E)It is related to the retroviruses.

Question 42

In Mad cow disease,prions act in which of the following ways?

A)PrPᶜ is converted to PrPˢᶜ
B)PrPˢᶜ is converted to PrPᶜ
C)denatured proteins are refolded and then cause cell lysis
D)native proteins replicate excessively and cause cell lysis
E)none is a correct choice

Question 43

Viroids are infectious RNA particles that cause infections in:

A)plants and animals.
B)animals.
C)bacteria and plants.
D)plants
E)bacteria.

Question 44

The discovery of oncogenes in this virus group led to the discovery of proto-oncogenes in human cells and an understanding of how tumors form.

A)Poliovirus
B)Retrovirus
C)Rhinovirus
D)Orthomyxovirus
E)Paramyxovirus

Question 45

How does the structure of the influenza viris differs from that of the Tobacco mosaic virus (TMV)? (Select all that apply)

A)Tobacco mosaic virus has an envelope while influenza virus does not
B)Influenza virus has envelope fragments surrounding multiple chromosomes while TMV has a single envelope and chromosome
C)Unlike influenza virus,Tobacco mosaic virus chromosomal fragments are each associated with a viral RNA polymerase
D)Influenza virus has a single linear RNA chromosome while TMV has a circular RNA chromosome
E)None of the choices is correct

Question 46

The capsid of the influenza viris differs from that of the Tobacco mosaic virus because: (Select all that apply)

A)there are distinct capsids for multiple chromosomal fragments
B)the chromosome is enclosed by the capsid
C)capsomeres cover each chromosomal segment
D)there is no surrounding envelope
E)the DNA is circular

Question 47

Determining virus load by examining plant leaves for mosaicism might be considered as: (Select all that apply)

A)end point determination
B)determination of LD50
C)direct count via immunofluorescence
D)determination of ID50
E)None is a correct response

Question 48

Gene therapy technologies may use viruses:

A)to destroy cells that are not functioning normally.
B)as gene-carrying vectors for delivery to target cells.
C)to cause cytopathic effects in certain cells.
D)to stimulate cell destruction by the immune system.
E)to cause disease and thus boost the immune system.

Question 49

What do proto-oncogenes encode?

A)proteins that cause cell death
B)proteins that cause apoptosis in the cell
C)proteins that control cell division
D)proteins that prevent virus infection
E)retroviral proteins

Question 50

Chlamydiae have features in common with: (Select all that apply)

A)Nuclei
B)Mitochondria
C)Viruses
D)Bacteria
E)None is a correct choice

Question 51

Expression of which of these oncogenes leads to enhanced cell susceptibility to Reovirus infection?

A)Ras
B)SV40
C)T-VEC
D)CFTR
E)None is a correct response

Question 52

Prion disease could be defined as a: (Select all that apply)

A)metabolic disease
B)genetic disease
C)protein denaturation disease
D)degenerative disease
E)infectious disease

Question 53

Virophage characteristics include: (Select all that apply)

A)the ability to engage in lateral gene transfer
B)ubiquity throughout the three domains
C)an RNA genome
D)the need for a co-virus infection
E)detrimental effects on the growth of the co-virus

Question 54

What is a prion?

A)An infectious RNA particle.
B)A particle similar to a satellite virus.
C)An infectious DNA particle.
D)An infectious protein particle.
E)A type of virus.

Question 55

Which viral vector would seem most suitable for use in gene therapy to correct cystic fibrosis based upon tissue infectivity?

A)Herpesvirus
B)Reovirus
C)Poliovirus
D)SV40
E)None is suitable

Question 56

How do prions cause disease?

A)By corrupting mRNA expression in the cell.
B)By corrupting DNA replication in the cell.
C)By preventing translation from occurring in the cell.
D)By causing naturally occurring proteins in the cell to change shape.
E)By preventing proper RNA transcription termination.

Question 57

Based on the Baltimore and ICTV classification scheme information provided,which viruses seem most closely related?

A)Retro,Tetra
B)Herpes,Hepadna
C)Paramyxo,Retro
D)Toga,Asco
E)Rhabdo,Filo

Question 58

Which choice provides evidence that argues against the use of host cell RNA polymerases in replicating PSTVd RNA?

A)host cells contain DNA-dependent RNA polymerases
B)host cells contain DNA-dependent DNA plymerases
C)host cells contain RNA-dependent RNA polymerases
D)host cells contain RNA-dependent DNA polymerases
E)none is a relevant choice

Question 59

Evidence that the Mimivirus may once have been a free-living cell includes: (Select all that apply)

A)Possession of a circular DNA chromosome
B)Possession of genes encoding ribosomal RNA
C)Possession of genes encoding aminoacyl-tRNA synthetases
D)Possession of genes encoding translation initiation factors
E)Possession of genes encoding photosynthtetic electron carriers

Question 60

Which characteristics are found in viroids? (Select all that apply)

A)RNA-containing particles
B)Possess a capsid but no envelope
C)Possess capsid and envelope
D)Contain little nucleic acid
E)Possess a large genome

Question 61

The alpha coronaviruses infect the same tissue type although the host range may differ.

Question 62

Small infectious RNA molecules that are able to cause disease in plants are called ________.

Question 63

All viruses require host cell enzymes for translation.

Question 64

A bigger discrepancy between direct count and PFU estimates of virion numbers might be expected for influenza virus than for herpes virus.

Question 65

Filtration of a bacteriophage preparation replicated in E.coli will effectively separate viable cells from phage particles.

Question 66

A bacterial strain that contains a phage genome integrated into its chromosome is called a _________.

Question 67

Proto-oncogenes never play a necessary role in development and growth of an organism.

Question 68

Enveloped viruses acquire their envelope from host cell membranes.

Question 69

Viruses categorized in the same Baltimore group may possess common proteins.

Question 70

The zone of clearing as a result of a phage infection on a lawn of E.coli growing on the surface of an agar plate is called a ________.

Question 71

Genes that are involved in the normal regulation of the cell cycle and can be altered to increase probability of cancer are called ___________.

Question 72

Which characteristics are found in viroids? (Select all that apply)

A)Resistance to deoxyribonucleases
B)Resistance to ribonucleases
C)Resistance to proteases
D)Resisance to lipases
E)Possession of strong promoter sequences

Question 73

A virus which can selectively kill cancerous cells can be termed: (Select all that apply)

A)A lytic virus
B)An oncolytic virus
C)An agent for gene therapy
D)A proto-oncogenic virus
E)A temperate virus