Deck 27: Viruses

Question 1

Phages are viruses that can infect

A)humans.
B)plants.
C)insects.
D)farm animals.
E)bacteria.

Answer 1

E

Question 2

Viruses that cause lysis of their hosts are called

A)lethal.
B)potent.
C)temperate.
D)virulent.
E)latent.

Answer 2

D

Question 3

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

A)phage
B)latent
C)transforming
D)benign
E)inducible

Answer 3

B

Question 4

Virulent viruses multiply within infected cells and eventually

A)cause an alternation of generations in the host cell,releasing new viruses.
B)cause the transformation of the host cell,releasing new viruses.
C)cause lysis of the host cell,releasing new viruses.
D)cause the transduction of the host cell,releasing new viruses.
E)cause a transfer of material from the host cell,releasing new viruses.

Question 5

Viruses are _______-coated fragments of DNA or RNA that have become detached from the genomes of cells and have the ability to replicate themselves within cells.

Question 6

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

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

Question 7

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

Question 8

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

Question 9

The integration of a virus into a cellular genome is called _________.

Question 10

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

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

Question 11

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

Question 12

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.

A)nucleic acid
B)phospholipid
C)polysaccharide
D)glycolipid
E)glycoprotein

Question 13

_____________ infects the CD4 + T cells,which are required for normal immunity.

Question 14

Isometric viruses are _________ in basic structure,which contains 20 equilateral triangular surfaces.

Question 15

Viruses are characterized by all of the following except

A)being found in every organism investigated so far.
B)being specific to the hosts they infect.
C)being capable of independent reproduction.
D)having either a helical or isometric structure.
E)being acellular.

Question 16

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

A)lethal.
B)potent.
C)temperate.
D)virulent.
E)latent.

Question 17

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

Question 18

All of the following are diseases caused by viruses except

A)strep throat.
B)AIDS.
C)polio.
D)small pox.
E)measles.

Question 19

The viruses that infect bacteria are called ____________.

Question 20

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

A)capsid.
B)casing.
C)envelope.
D)membrane.
E)viroid.

Question 21

A scientist is investigating the lytic cycle of the T4 phage virus.This means she is examining the

A)method used by the T4 phage to kill a bacterial cell.
B)method used by the T4 phage to replicate proteins.
C)method used by the T4 phage to replicate its DNA.
D)method used by the T4 phage to enter a eukaryotic cell.
E)method used by the T4 phage to begin protein synthesis on the bacterium's ribosomE.

Question 22

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

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

Question 23

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

A)attachment.
B)entry.
C)replication.
D)immediately killing the host cell.
E)viral DNA integrates into the host chromosomE.

Question 24

Viruses may cause cancer by

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.

Question 25

Activation of a latent herpes virus is responsible for

A)fever blisters.
B)AIDS.
C)syphilis.
D)Alzheimer's disease.
E)dental caries.

Question 26

Which of the following is not a part of a potential HIV treatment?

A)AZT
B)protease inhibitors
C)elimination of susceptible host cells
D)chemokines and CAF
E)defective nef gene

Question 27

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

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.

Question 28

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

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.

Question 29

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

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.

Question 30

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

A)CD4+
B)gp120 -T
C)CCR5-T
D)CXCR4-T
E)CD8-T

Question 31

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

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.

Question 32

All viruses are constructed of

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.

Question 33

All of the following are true of viroids except

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.

Question 34

Prions are

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.

Question 35

Mad cow disease is caused by a

A)bacterium.
B)virus.
C)viroid.
D)virion.
E)prion.

Question 36

HIV studies revealed that it is closely related to

A)smallpox virus.
B)ebola virus.
C)herpes virus.
D)a chimpanzee virus.
E)mad cow diseasE.

Question 37

Which of the following is a virus with an icosahedral head,a capsid that contains primarily three proteins,a connecting neck with a collar and long whiskers,a long tail and a complex base plate?

A)influenza virus
B)measles virus
C)T2 bacteriophage
D)HIV
E)tuberculosis

Question 38

The onset of AIDS is often accompanied by

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.

Question 39

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

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

Question 40

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

A)the host cell to reject the virus.
B)the host cell to shrink because of the loss of cytoplasm that has been used in the synthesis of viral DNA.
C)the host cell to burst because there will be so many viral particles present.
D)the host cell to replicate itself at a higher than normal frequency.
E)the host cell to initiate an attack on the virus.

Question 41

Choose the letter of the best match from the following:
A.virion
B.viroid
C.virus
D.prion
E.phage
Infectious,naked RNA.

Question 42

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

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.

Question 43

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

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.

Question 44

Which of the following statements about bacteriophage is false?

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.

Question 45

Which of the following statements about emerging viruses is false?

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 completely new form of corona virus.
E)The stable genome of the SARS virus makes it an unlikely candidate for vaccine development.

Question 46

The enormous genetic diversity of HIV has made it especially difficult to create a vaccine against the virus.This genetic diversity is largely the result of

A)its large variety of capsid proteins.
B)the great variety of HIV in the environment.
C)alternate splicing of exons.
D)the high error rate of reverse transcriptase.
E)the high sensitivity of the virus to UV radiation.

Question 47

Which matching of HIV drug therapy and proposed mode of action is incorrect?

A)AZT-blocks viral replication
B)protease inhibitor-inhibitor of reverse transcriptase
C)defective nef gene-incorporation into a vaccine
D)chemokines-block HIV binding to CD4⁺ cells
E)CAF-block viral replication

Question 48

All of the following are part of phage conversion except

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.

Question 49

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

A)transformation.
B)induction.
C)latency.
D)phage conversion.
E)injection.

Question 50

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

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.

Question 51

Which of the following statements about the types and subtypes of the influenza (flu)virus is false?

A)Of the three major types of flu virus (A,B,and C),only Type A can occur in humans,other mammals,and birds.
B)Flu subtype is determined by the kinds of proteins representing the H and N protein spikes making up the capsid of the virus.
C)The A(H2N2)and the A(H3N2)strains of the virus require different vaccines.
D)High mutation rates create more diversity in strains of flu than does genetic recombination.
E)Genetic recombination between flu strains from different species is common.

Question 52

Choose the letter of the best match from the following:
A.virion
B.viroid
C.virus
D.prion
E.phage
RNA or DNA enclosed in protein.

Question 53

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

A)prophage
B)prophase
C)viroid
D)virion
E)arbovirus

Question 54

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

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.

Question 55

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

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.

Question 56

Select below a unique feature of viroids compared to viruses.

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.

Question 57

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

A)protein capsid
B)RNA
C)reverse transcriptase
D)viral envelope
E)complementary DNA

Question 58

An RNA virus that is temperate (lysogenic)would necessarily have to involve all of the following except

A)the enzyme reverse transcriptase.
B)a prophage.
C)a lysogen.
D)oncogenes.
E)induction.

Question 59

Which of the following statements about the CCR5 and the CXCR4 receptors used by HIV to recognize and enter macrophages is false?

A)The smallpox virus and HIV share the co-receptor CCR5.
B)Cytokines inhibit HIV infection by binding to CCR5 and CXCR4.
C)Only HIV with mutated gp120 glycoproteins can bind to CXCR4 receptors on T cells.
D)Individuals with few CXCR4 receptors should be more resistant to HIV infection.
E)Individuals with a genetic resistance to smallpox may be more susceptibility to HIV infection.

Question 60

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?

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

Question 61

Choose the letter of the best match from the following:
A.virion
B.viroid
C.virus
D.prion
E.phage
Viral particle.

Question 62

Choose the letter of the best match from the following:
A.virion
B.viroid
C.virus
D.prion
E.phage
Bacterial virus.

Question 63

Choose the letter of the best match from the following:
A.virion
B.viroid
C.virus
D.prion
E.phage
Infectious protein.