Question 1

Diseases such as scrapie in sheep,"mad cow" disease in cattle,and Creutzfeldt-Jakob disease in humans are known as

Accepted Answer

A)  viroids.
B)  viruses.
C)  retroviruses.
D)  TSEs (transmissible spongiform encephalopathies) .
E)  emerging viruses,for example Ebola.F) A) and D)
G) C) and E)

Question 2

The specific white blood cells that HIV attaches to are the ________ cells.

Accepted Answer

A)  CD4+
B)  gp120-T
C)  CCR5-T
D)  CXCR4-T
E)  CD8-TF) All of the above
G) C) and D) A

Question 3

The infection cycle of HIV includes all of the following steps except

Accepted Answer

A)  attachment.
B)  entry.
C)  replication.
D)  immediately killing the host cell.
E)  viral DNA integrates into the host chromosome.F) A) and B)
G) B) and E)

Question 4

Prions are

Accepted Answer

A)  strands of nucleic acids encased in a protein coat.
B)  viral nucleic acids integrated into the host chromosomes.
C)  viral-infected cells.
D)  infectious proteins with no associated nucleic acid.
E)  proteins coded by genes.F) B) and E)
G) B) and D)

Question 5

A layer of lipoprotein and glycoprotein that covers the outer surface of some viruses is the

Accepted Answer

A)  capsid.
B)  casing.
C)  envelope.
D)  membrane.
E)  viroid.F) None of the above
G) D) and E)

Question 6

Viruses are characterized by all of the following except

Accepted Answer

A)  being found in every organism investigated so far.
B)  being specific to the hosts they infect.
C)  being capable of independent reproduction.
D)  being acellular.E) A) and B)
F) C) and D)

Question 7

Check all of the correct statements regarding the use of metagenomics to describe viral diversity.

Accepted Answer

A)  Most samples are obtained from animals and plants.
B)  During sample collection,the actual virus needs to be isolated for analysis.
C)  Metagenomics has identified thousands of new viral species.
D)  Samples with the viruses are first analyzed by PCR.E) B) and C)
F) A) and D)

Question 8

Which of the following statements about bacteriophage is false?

Accepted Answer

A)  Bacteriophages do not have a viral envelope.
B)  A temperate phage can have its DNA integrated into the host chromosome as a prophage.
C)  Ultraviolet radiation can cause induction.
D)  A prophage is replicated with the bacterial chromosome and passed to the two new daughter cells.
E)  Late genes are only expressed during the lysogenic cycle.F) D) and E)
G) C) and D)

Question 9

What best describes whether a virus is likely to infect a particular cell?

Accepted Answer

A)  Viruses infect the first cells they encounter.
B)  If a host cell is weakened,viruses are likely to infect it.
C)  A virus will only infect host cells with the correct surface receptors.
D)  Viruses only attack epithelial cells,such as the cells lining the lungs.
E)  The initial choice is random but once a cell type is chosen it becomes the preferred host.F) A) and B)
G) B) and D)

Question 10

The enormous genetic diversity of HIV has made it especially difficult to create a vaccine against the virus.We can attribute this genetic diversity to

Accepted Answer

A)  mutation hotspots in the hemagglutinin (H) molecule.
B)  mutation hotspots in the CD4+ molecule.
C)  the high error rate of reverse transcriptase.
D)  the high sensitivity of the virus to UV radiation.E) A) and B)
F) B) and D)

Question 11

One way in which retroviruses differ from all other types of viruses is that retroviruses

Accepted Answer

A)  possess an RNA genome.
B)  possess only single-stranded nucleic acids.
C)  can create a prophage.
D)  have single-strained RNA that serves as viral mRNA.
E)  have the enzyme reverse transcriptase.F) A) and D)
G) A) and E)

Question 12

All of the following are part of phage conversion except

Accepted Answer

A)  injection of phage gene into host.
B)  transcription and translation of phage gene.
C)  induction of phage.
D)  expression of phage gene by host.
E)  integration of phage gene to form a prophage.F) All of the above
G) A) and B)

Question 13

Most viruses form a capsid around their nucleic acid core.This capsid is composed of

Accepted Answer

A)  proteins.
B)  monosaccharides.
C)  glycoproteins.
D)  lipoproteins.E) A) and B)
F) All of the above

Question 14

Integrase inhibitors work by:

Accepted Answer

A)  Agglutinating the reverse transcriptase inhibitors
B)  Degrading the viral envelope
C)  Preventing the incorporation of the viral DNA into the genome
D)  Blocking the final viral assemblyE) A) and C)
F) B) and C)

Question 15

Scientists have demonstrated that the cholera bacteria,Vibrio cholerae,can exist as a rather harmless form or,by phage conversion,can exist as a disease-causing,virulent form.This conversion is caused by

Accepted Answer

A)  the phage entering the cholera bacterium genome and causing the bacterium's cell to lyse.
B)  the phage introducing a gene into the bacterium's chromosome that codes for the cholera toxin that can cause death in humans.
C)  the phage altering the cell wall of the cholera bacterium that produces a toxin that can cause death in humans.
D)  the phage alters the host cell,which permits direct entry of the cholera bacterium into the host cell leading to death in humans.E) None of the above
F) A) and B) B

Question 16

Which of the following would NOT be a component of a newly produced HIV virus particle?

Accepted Answer

A)  protein capsid
B)  RNA
C)  reverse transcriptase
D)  viral envelope
E)  complementary DNAF) B) and E)
G) B) and C)

Question 17

A mutation in the gene encoding the integrase enzyme renders the protein non-functional.How would this affect-the HIV infection cycle?

Accepted Answer

A)  The gp120 glycoprotein would not be able to bind the CCR5 receptor.
B)  Reverse transcription would not be possible.
C)  The viral DNA would not be able to integrate the viral genome into a chromosome.
D)  Cutting and assembling the capsid would be halted.E) B) and D)
F) C) and D)

Question 18

If the gp120 glycoprotein were damaged as a result of a mutation,HIV would have difficulty:

Accepted Answer

A)  binding to a host cell.
B)  leaving a macrophage.
C)  inserting its genes into the host cell's genome.
D)  assembling the capsid.
E)  attaching its RNA to a host cell's ribosome.F) C) and E)
G) A) and C)

Question 19

A ________ can contain DNA or RNA as its genetic material,but not both.

Accepted Answer

virus

Question 20

The switch from a lysogenic prophage to a lytic cycle is called

Accepted Answer

A)  transformation.
B)  induction.
C)  latency.
D)  phage conversion.
E)  injection.F) C) and D)
G) None of the above

Exam 26: Viruses

Diseases such as scrapie in sheep,"mad cow" disease in cattle,and Creutzfeldt-Jakob disease in humans are known as

Correct AnswerverifiedShow Answer

The specific white blood cells that HIV attaches to are the ________ cells.

Correct AnswerverifiedA

The infection cycle of HIV includes all of the following steps except

Correct AnswerverifiedShow Answer

Prions are

Correct AnswerverifiedShow Answer

A layer of lipoprotein and glycoprotein that covers the outer surface of some viruses is the

Correct AnswerverifiedShow Answer

Viruses are characterized by all of the following except

Correct AnswerverifiedShow Answer

Check all of the correct statements regarding the use of metagenomics to describe viral diversity.

Correct AnswerverifiedShow Answer

Which of the following statements about bacteriophage is false?

Correct AnswerverifiedShow Answer

What best describes whether a virus is likely to infect a particular cell?

Correct AnswerverifiedShow Answer

The enormous genetic diversity of HIV has made it especially difficult to create a vaccine against the virus.We can attribute this genetic diversity to

Correct AnswerverifiedShow Answer

One way in which retroviruses differ from all other types of viruses is that retroviruses

Correct AnswerverifiedShow Answer

All of the following are part of phage conversion except

Correct AnswerverifiedShow Answer

Most viruses form a capsid around their nucleic acid core.This capsid is composed of

Correct AnswerverifiedShow Answer

Integrase inhibitors work by:

Correct AnswerverifiedShow Answer

Scientists have demonstrated that the cholera bacteria,Vibrio cholerae,can exist as a rather harmless form or,by phage conversion,can exist as a disease-causing,virulent form.This conversion is caused by

Correct AnswerverifiedB

Which of the following would NOT be a component of a newly produced HIV virus particle?

Correct AnswerverifiedShow Answer

A mutation in the gene encoding the integrase enzyme renders the protein non-functional.How would this affect-the HIV infection cycle?

Correct AnswerverifiedShow Answer

If the gp120 glycoprotein were damaged as a result of a mutation,HIV would have difficulty:

Correct AnswerverifiedShow Answer

A ________ can contain DNA or RNA as its genetic material,but not both.

Correct Answerverifiedvirus

The switch from a lysogenic prophage to a lytic cycle is called

Correct AnswerverifiedShow Answer

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