Question 1

All of the following are true of viroids except

Accepted Answer

A)  they are tiny,naked molecules of RNA.
B)  they are a few hundred nucleotides long.
C)  viroid nucleotide sequences resemble intron sequences in ribosomal RNA genes.
D)  they are causative agents of plant diseases.
E)  they are tiny,naked molecules DNA and proteins.F) B) and D)
G) B) and C)

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) C) and E)
G) B) and E)

Question 3

The onset of AIDS is often accompanied by

Accepted Answer

A)  a steep drop in T cell numbers.
B)  macrophage infection.
C)  a positive HIV test.
D)  lung infections and other opportunistic infections.
E)  Kaposi's sarcoma.F) C) and E)
G) A) and B)

Question 4

Outside the protein sheath,many viruses have a(n)_______ made of protein,lipid,and carbohydrate.

Accepted Answer

The answer of Outside the protein sheath,many viruses have a(n)_______...

Question 5

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) C) and D)
G) A) and B)

Question 6

Select below a unique feature of viroids compared to viruses.

Accepted Answer

A)  They consist of a circular molecule of RNA.
B)  They can only replicate when in a host cell.
C)  They are infectious.
D)  They do not code for any proteins.
E)  They use RNA as a template for RNA production.F) B) and D)
G) B) and C)

Question 7

Viruses infect every organism that has been investigated for their presence.However,viruses can only replicate in

Accepted Answer

A)  very limited conditions,depending on their capsid type.
B)  a very limited manner if they are a retrovirus.
C)  a very limited manner depending on their envelope capability with the host's cell membrane or cell wall.
D)  their lytic stage outside the host cell membrane.
E)  a very limited number of the host's cells.F) A) and E)
G) A) and D)

Question 8

Which of the following statements about TSEs (transmissible spongiform encephalopathies) is false?

Accepted Answer

A)  TSEs include scrapie in sheep,mad cow disease,chronic wasting disease in deer and elk,and kuru and variant Creutzfeldt-Jakob disease in humans.
B)  The incidence of Creutzfeldt-Jakob disease in humans increased after an outbreak of mad cow disease in England suggesting that mad cow disease may be transmitted to humans.
C)  Viroids are the likely cause of TSEs.
D)  TSEs do not seem to be affected by treatments that would eliminate nucleic acid-based diseases.
E)  Infectious TSE preparations do not seem to contain DNA or RNA.F) A) and D)
G) C) and D)

Question 9

All viruses are constructed of

Accepted Answer

A)  DNA with a protein wrapping,called a capsid.
B)  RNA with a protein wrapping,called a capsid.
C)  either DNA or RNA with a protein wrapping,called a capsid.
D)  either DNA or RNA,however many do not have the capsiD.E) None of the above
F) A) and B)

Question 10

The SARS virus is a completely new form of _______ _________.

Accepted Answer

The answer of The SARS virus is a completely new...

Question 11

Each HIV particle possesses a ___________ on its surface,called gp120,that precisely fits a cell-surface marker protein called CD4 on the surfaces of the immune system cells called macrophages and T cells.

Accepted Answer

A)  nucleic acid
B)  phospholipid
C)  polysaccharide
D)  glycolipid
E)  glycoproteinF) B) and C)
G) All of the above

Question 12

What is the name for parasitic viral DNA that has been integrated into the chromosome of its bacterial host?

Accepted Answer

A)  prophage
B)  prophase
C)  viroid
D)  virion
E)  arbovirusF) A) and C)
G) B) and D)

Question 13

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

Accepted Answer

A)  protein.
B)  monosaccharide.
C)  antigen.
D)  glycoprotein.
E)  lipoprotein.F) A) and B)
G) A) and E)

Question 14

Recently a class of infectious proteins with no associated nucleic acid have been identified.They are referred to as

Accepted Answer

A)  bacteriophages.
B)  latent viruses.
C)  viroids.
D)  prions.
E)  virions.F) C) and D)
G) A) and E)

Question 15

A scientist is studying the lysogenic cycle of the lambda 1 phage of Escherichia coli.This means that she is investigating

Accepted Answer

A)  the integration and stabilizing of the lambda 1 phase into a host cell's genome.
B)  the integration of the bacteria's genome with the viral genome outside of the bacteria's cell wall.
C)  the integration of the viral genome into the ribosomes present in the bacteria to direct protein synthesis for the capsid formation.
D)  the integration and stabilizing of a virus into its capsid,which provides protection until conditions are better for reproduction.E) B) and D)
F) C) and D)

Question 16

The following are stages in HIV infection.If arranged chronologically,which stage would be third?

Accepted Answer

A)  HIV binds to a CXCR4 receptor on a T cell.
B)  HIV binds to a CD4 receptor on a macrophage.
C)  HIV binds to a CCR5 receptor on a macrophage.
D)  Circulating levels of CD4+ T cells decline.
E)  HIV undergoes a mutation in the gene coding for its gp120 glycoprotein.F) A) and C)
G) A) and E)

Question 17

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) A) and C)
F) None of the above

Question 18

The direction of genetic information transfer in a retrovirus (such as the HIV) is

Accepted Answer

A)  DNA to mRNA to protein.
B)  RNA to DNA to mRNA to protein.
C)  DNA to protein.
D)  RNA to mRNA to protein.
E)  RNA to protein.F) A) and C)
G) A) and B)

Question 19

Viruses may cause cancer by

Accepted Answer

A)  disrupting a cancer-causing gene.
B)  inserting cancer causing genes into the cell's genome.
C)  triggering cell division through attachment to a cell surface receptor.
D)  triggering the expression of cancer-causing genes present in the genome.
E)  suppressing a gene that regulates cell division.F) A) and B)
G) B) and D)

Question 20

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) None of the above
G) A) and B)

Exam 27: Viruses

Select below a unique feature of viroids compared to viruses.

Correct AnswerverifiedShow Answer

Viruses may cause cancer by

Correct AnswerverifiedShow Answer

All viruses are constructed of

Correct AnswerverifiedShow Answer

All of the following are true of viroids except

Correct AnswerverifiedShow Answer

Viruses infect every organism that has been investigated for their presence.However,viruses can only replicate in

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

What is the name for parasitic viral DNA that has been integrated into the chromosome of its bacterial host?

Correct AnswerverifiedShow Answer

A scientist is studying the lysogenic cycle of the lambda 1 phage of Escherichia coli.This means that she is investigating

Correct AnswerverifiedShow Answer

The direction of genetic information transfer in a retrovirus (such as the HIV) is

Correct AnswerverifiedShow Answer

Outside the protein sheath,many viruses have a(n)_______ made of protein,lipid,and carbohydrate.

Correct AnswerverifiedShow Answer

The onset of AIDS is often accompanied by

Correct AnswerverifiedShow Answer

All of the following are part of phage conversion except

Correct AnswerverifiedShow Answer

The following are stages in HIV infection.If arranged chronologically,which stage would be third?

Correct AnswerverifiedShow Answer

The SARS virus is a completely new form of _______ _________.

Correct AnswerverifiedShow Answer

Which of the following statements about bacteriophage is false?

Correct AnswerverifiedShow Answer

Each HIV particle possesses a ___________ on its surface,called gp120,that precisely fits a cell-surface marker protein called CD4 on the surfaces of the immune system cells called macrophages and T cells.

Correct AnswerverifiedShow Answer

Which of the following statements about TSEs (transmissible spongiform encephalopathies) is false?

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 AnswerverifiedShow Answer

Recently a class of infectious proteins with no associated nucleic acid have been identified.They are referred to as

Correct AnswerverifiedShow Answer

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The SARS virus is a completely new form of _ ___.

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