Question 1

Benign Vibrio cholerae becomes pathogenic by all of the following steps except

Accepted Answer

A)  a bacteriophage introduces a gene coding for the cholera toxin.
B)  the cholera toxin gene is incorporated into the benign Vibrio cholerae chromosome.
C)  the benign host is transformed into a disease-causing agent by the toxin.
D)  the cholera toxin gene is translated.
E)  a bacteriophage binds only to benign Vibrio cholerae without pili.F) B) and D)
G) All of the above

Question 2

If a virus enters the lytic phase in a host's cell,it will cause the host cell to

Accepted Answer

A)  reject the virus.
B)  shrink because of the loss of cytoplasm that has been used in the synthesis of viral DNA.
C)  lyse due to the action of enzymes.
D)  replicate itself at a higher than normal frequency.
E)  initiate an attack on the virus.F) B) and D)
G) B) and C)

Question 3

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) B) and E)
G) B) and D)

Question 4

HIV infects cells by recognizing the cell-surface markers with its own

Accepted Answer

A)  DNA.
B)  glycoproteins.
C)  reverse transcriptase.
D)  capsid protein.
E)  enzymes.F) B) and C)
G) C) and D)

Question 5

The HIV virus is considered a(n) ________ virus,because after getting integrated into the host cell chromosomes,it does not begin replicating immediately.

Accepted Answer

A)  phage
B)  latent
C)  transforming
D)  benign
E)  inducibleF) B) and C)
G) A) and B)

Question 6

The SARS virus is a member of the family of viruses called ________.

Accepted Answer

The answer of The SARS virus is a member of...

Question 7

Which of the following statements about emerging viruses is false?

Accepted Answer

A)  Emerging viruses are able to "jump" from one species to another.
B)  Hantavirus,which causes a hemorrhagic-type fever,originates in deer mice.
C)  Ebola is an emerging virus of unknown origins that can have a mortality rate in excess of 50%.
D)  The emerging virus SARS is a coronavirus.
E)  The stable genome of the SARS virus makes it an unlikely candidate for vaccine development.F) C) and D)
G) B) and E)

Question 8

Each HIV particle possesses a ________ on its surface,called gp120,that precisely binds to a protein,called CD4,that is found 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) None of the above
G) C) and D)

Question 9

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

Question 10

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 11

Which of the following is a unique feature of viruses that separates them from bacteria?

Accepted Answer

A)  They are generally smaller.
B)  They are often highly toxic.
C)  They lack proteins.
D)  They have different nucleotides in their hereditary material.
E)  They cannot exist outside of a host cell.F) A) and D)
G) D) and E)

Question 12

Tetracycline is effective against viruses because it disrupts the action of the viral ribosomes.

Accepted Answer

A) True 
 B)False

Question 13

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) B) and D)

Question 14

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) All of the above
G) None of the above

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

Question 16

The direction of genetic information transfer in a retrovirus (such as 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) B) and E)
G) B) and C)

Question 17

Viruses that become established as stable parts of the host cell genome are called

Accepted Answer

A)  lethal.
B)  potent.
C)  temperate.
D)  virulent.E) None of the above
F) A) and D)

Question 18

Gardasil is marketed as a cervical cancer vaccine,but it is actually a human papilloma virus (HPV) vaccine.Why is this done?

Accepted Answer

A)  The virus multiplies more rapidly in cancerous cells.
B)  Cancer cells are particularly susceptible to viral infection.
C)  Genital warts is a sign of cancer.
D)  HPV in the cervical epithelial cells may cause the cells to become cancerous.E) All of the above
F) None of the above

Question 19

Viruses can ________ only after they have entered a host cell,and only by using the host's cellular machinery.

Accepted Answer

The answer of Viruses can ________ only after they have...

Question 20

While they are simple relative to cells,viruses often have a very diverse collection of components.Which one of the following choices is LEAST likely to be found as part of a virus?

Accepted Answer

A)  proteins with functional binding sites
B)  membrane components
C)  single-stranded DNA
D)  ribosomes
E)  glycoproteinsF) A) and B)
G) B) and D)

Exam 26: Viruses

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

Correct AnswerverifiedShow Answer

If a virus enters the lytic phase in a host's cell,it will cause the host cell to

Correct AnswerverifiedShow Answer

Which of the following is a unique feature of viruses that separates them from bacteria?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Viruses that become established as stable parts of the host cell genome are called

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The SARS virus is a member of the family of viruses called ________.

Correct AnswerverifiedShow Answer

Gardasil is marketed as a cervical cancer vaccine,but it is actually a human papilloma virus (HPV) vaccine.Why is this done?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Viruses can ________ only after they have entered a host cell,and only by using the host's cellular machinery.

Correct AnswerverifiedShow Answer

Each HIV particle possesses a ________ on its surface,called gp120,that precisely binds to a protein,called CD4,that is found on the surfaces of the immune system cells called macrophages and T cells.

Correct AnswerverifiedShow Answer

HIV infects cells by recognizing the cell-surface markers with its own

Correct AnswerverifiedShow Answer

The onset of AIDS is often accompanied by

Correct AnswerverifiedShow Answer

Benign Vibrio cholerae becomes pathogenic by all of the following steps except

Correct AnswerverifiedShow Answer

The HIV virus is considered a(n) ________ virus,because after getting integrated into the host cell chromosomes,it does not begin replicating immediately.

Correct AnswerverifiedShow Answer

Which of the following statements about emerging viruses is false?

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

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

Correct AnswerverifiedShow Answer

Tetracycline is effective against viruses because it disrupts the action of the viral ribosomes.

Correct AnswerverifiedShow Answer

While they are simple relative to cells,viruses often have a very diverse collection of components.Which one of the following choices is LEAST likely to be found as part of a virus?

Correct AnswerverifiedShow Answer

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