Archive for December 2016

This plan depicts

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This plan depicts






A) Old St. Peter's
B) St. Sernin at Toulouse
C) Chartres Cathedral
D) the Hagia Sophia






Answer: B

This object is used to store

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This object is used to store



A) perfumes and toiletries
B) human remains or ashes
C) sacred relics of a saint
D) salt or exotic spices








Answer: A

Which of the following is NOT true of this carpet?

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Which of the following is NOT true of this carpet?




A) An inscription describes the image as that of a door or portal.
B) It was made for a shrine for a Sufi saint.
C) It was designed by an artist named Muhammad ibn al-Zain.
D) It was a product of the Persian Safavid dynasty.









Answer: C

Which of the following is NOT true regarding this structure?

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Which of the following is NOT true regarding this structure?




A) It exemplifies a hypostyle hall mosque.
B) The columns were spoliated from an earlier church.
C) The mosque was built in Damascus under Umayyad rule.
D) The arches are composed of wedge-shaped blocks called voussoirs.









Answer: C

Which of the following is NOT true of this work?

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Which of the following is NOT true of this work?




A) It depicts the Byzantine emperor Justinian carrying a paten.
B) It is located in the narthex of an Early Christian basilica.
C) It was created during the 6th century CE in Ravenna.
D) It is made of tiny pieces of glass or stone called tesserae.










Answer: B

This work is a/an

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This work is a/an




A) mosaic created with tesserae
B) folio painted with tempera on velum
C) fresco wall painting with plaster
D) wooden icon with encaustic







Answer: B

This relief is from the

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This relief is from the 




A) Arch of Titus
B) Ara Pacis
C) Column of Trajan
D) Arch of Constantine








Answer: A

As evidenced by the porphyry sculpture of the Four Tetrarchs, during the late Roman empire, who divided the empire up into four parts so that it could be ruled more effectively by a tetrarchy?

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As evidenced by the porphyry sculpture of the Four Tetrarchs, during the late Roman empire, who divided the empire up into four parts so that it could be ruled more effectively by a tetrarchy? 




A) Marcus Aurelius
B) Trajan Decius
C) Diocletian
D) Justinian









Answer: C

Which of the following is now believed to be NOT true about the Flavian amphitheater?

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Which of the following is now believed to be NOT true about the Flavian amphitheater?




A) It was built using groin vaulting and arch construction.
B) It had a velarium to protect spectators from the rain and the sun.
C) It was flooded for maritime battles.
D) It was situated on a site where an emperor's private artificial lake and gardens once existed.







Answer: C

In order to identify a specific restriction fragment using a probe, what must be done?

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In order to identify a specific restriction fragment using a probe, what must be done? 





A) The fragments must be separated by electrophoresis.
B) The fragments must be treated with heat or chemicals to separate the strands of the double helix.
C) The probe must be hybridized with the fragment.
D) The fragments must be separated by electrophoresis and the fragments must be treated with heat or chemicals to separate the strands of the double helix.
E) The fragments must be separated by electrophoresis, the fragments must be treated with heat or chemicals to separate the strands of the double helix, and the probe must be hybridized with the fragment.






Answer: E

The reason for using Taq polymerase for PCR is that

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The reason for using Taq polymerase for PCR is that 






A) it is heat stable and can withstand the temperature changes of the cycler.
B) only minute amounts are needed for each cycle of PCR.
C) it binds more readily than other polymerases to primer.
D) it has regions that are complementary to primers.
E) All of these are correct.





Answer: A

Why are BACs preferred today rather than bacteriophages for making genomic libraries?

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Why are BACs preferred today rather than bacteriophages for making genomic libraries?






A) The BAC carries more DNA.
B) The BAC can carry entire genes and their regulatory elements.
C) Larger BACs are easier to store.
D) The BAC can carry entire genes and their regulatory elements, and larger BACs are easier to store.
E) The BAC carries more DNA, the BAC can carry entire genes and their regulatory elements, and larger BACs are easier to store.






Answer: E

Pax-6 is a gene that is involved in eye formation in many invertebrates, such as Drosophila. Pax-6 is found as well in vertebrates. A Pax-6 gene from a mouse can be expressed in a fly and the protein (PAX-6) leads to a compound fly eye. This information suggests which of the following?

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Pax-6 is a gene that is involved in eye formation in many invertebrates, such as Drosophila. Pax-6 is found as well in vertebrates. A Pax-6 gene from a mouse can be expressed in a fly and the protein (PAX-6) leads to a compound fly eye. This information suggests which of the following? 






A) Pax-6 genes are identical in nucleotide sequence.
B) PAX-6 proteins have identical amino acid sequences.
C) Pax-6 is highly conserved and shows shared evolutionary ancestry.
D) PAX-6 proteins are different for formation of different kinds of eyes.
E) PAX-6 from a mouse can function in a fly, but a fly's Pax-6 gene cannot function in a mouse.






Answer: C

Why is it so important to be able to amplify DNA fragments when studying genes?

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Why is it so important to be able to amplify DNA fragments when studying genes? 





A) DNA fragments are too small to use individually.
B) A gene may represent only a millionth of the cell's DNA.
C) Restriction enzymes cut DNA into fragments that are too small.
D) A clone requires multiple copies of each gene per clone.
E) It is important to have multiple copies of DNA in the case of laboratory error.






Answer: B

The major advantage of using artificial chromosomes such as YACs and BACs for cloning genes is that

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The major advantage of using artificial chromosomes such as YACs and BACs for cloning genes is that





A) plasmids are unable to replicate in cells.
B) only one copy of a plasmid can be present in any given cell, whereas many copies of a YAC or BAC can coexist in a single cell.
C) YACs and BACs can carry much larger DNA fragments than ordinary plasmids can.
D) YACs and BACs can be used to express proteins encoded by inserted genes, but plasmids cannot.
E) All of these are correct.






Answer: C

To introduce a particular piece of DNA into an animal cell, such as that of a mouse, you would find more probable success with which of the following methods?

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To introduce a particular piece of DNA into an animal cell, such as that of a mouse, you would find more probable success with which of the following methods?





A) the shotgun approach
B) electroporation followed by recombination
C) introducing a plasmid into the cell
D) infecting the mouse cell with a Ti plasmid
E) transcription and translation






Answer: B

Sequencing an entire genome, such as that of C. elegans, a nematode, is most important because

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Sequencing an entire genome, such as that of C. elegans, a nematode, is most important because






A) it allows researchers to use the sequence to build a "better" nematode, which is resistant to disease.
B) it allows research on a group of organisms we do not usually care much about.
C) the nematode is a good animal model for trying out cures for viral illness.
D) a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates.
E) a sequence that is found to have no introns in the nematode genome is likely to have acquired the introns from higher organisms.








Answer: D

A researcher needs to clone a sequence of part of a eukaryotic genome in order to express the sequence and to modify the polypeptide product. She would be able to satisfy these requirements by using which of the following vectors?

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A researcher needs to clone a sequence of part of a eukaryotic genome in order to express the sequence and to modify the polypeptide product. She would be able to satisfy these requirements by using which of the following vectors? 





A) a bacterial plasmid
B) BAC to accommodate the size of the sequence
C) a modified bacteriophage
D) a human chromosome
E) a YAC with appropriate cellular enzymes






Answer: E

Which of the following best describes the complete sequence of steps occurring during every cycle of PCR? 1. The primers hybridize to the target DNA. 2. The mixture is heated to a high temperature to denature the double-stranded target DNA. 3. Fresh DNA polymerase is added. 4. DNA polymerase extends the primers to make a copy of the target DNA.

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Which of the following best describes the complete sequence of steps occurring during every cycle of PCR?
1. The primers hybridize to the target DNA.
2. The mixture is heated to a high temperature to denature the double-stranded target DNA.
3. Fresh DNA polymerase is added.
4. DNA polymerase extends the primers to make a copy of the target DNA. 





A) 2, 1, 4
B) 1, 3, 2, 4
C) 3, 4, 1, 2
D) 3, 4, 2
E) 2, 3, 4






Answer: A

Why are yeast cells frequently used as hosts for cloning?

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Why are yeast cells frequently used as hosts for cloning? 






A) They easily form colonies.
B) They can remove exons from mRNA.
C) They do not have plasmids.
D) They are eukaryotic cells.
E) Only yeast cells allow the gene to be cloned.






Answer: D

A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using

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A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using 





A) RNA polymerase to transcribe the gene.
B) a restriction enzyme to cut the gene into shorter pieces.
C) reverse transcriptase to reconstruct the gene from its mRNA.
D) DNA polymerase to reconstruct the gene from its polypeptide product.
E) DNA ligase to put together fragments of the DNA that code for a particular polypeptide.






Answer: C

A principal problem with inserting an unmodified mammalian gene into a BAC, and then getting that gene expressed in bacteria, is that

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A principal problem with inserting an unmodified mammalian gene into a BAC, and then getting that gene expressed in bacteria, is that 






A) prokaryotes use a different genetic code from that of eukaryotes.
B) bacteria translate polycistronic messages only.
C) bacteria cannot remove eukaryotic introns.
D) bacterial RNA polymerase cannot make RNA complementary to mammalian DNA.
E) bacterial DNA is not found in a membrane-bounded nucleus and is therefore incompatible with mammalian DNA.






Answer: C

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with a recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes. III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. V. Use ligase to seal plasmid DNA to nonplasmid DNA.

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What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium?
I. Transform bacteria with a recombinant DNA molecule.
II. Cut the plasmid DNA using restriction enzymes.
III. Extract plasmid DNA from bacterial cells.
IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.
V. Use ligase to seal plasmid DNA to nonplasmid DNA. 






A) I, II, IV, III, V
B) II, III, V, IV, I
C) III, II, IV, V, I
D) III, IV, V, I, II
E) IV, V, I, II, III





Answer: C

How does a bacterial cell protect its own DNA from restriction enzymes?

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How does a bacterial cell protect its own DNA from restriction enzymes? 




A) by adding methyl groups to adenines and cytosines
B) by using DNA ligase to seal the bacterial DNA into a closed circle
C) by adding histones to protect the double-stranded DNA
D) by forming "sticky ends" of bacterial DNA to prevent the enzyme from attaching
E) by reinforcing the bacterial DNA structure with covalent phosphodiester bonds





Answer: A

Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to

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Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to 





A) insert the fragments cut with restriction enzyme X directly into the plasmid without cutting the plasmid.
B) cut the plasmid with restriction enzyme X and insert the fragments cut with restriction enzyme Y into the plasmid.
C) cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.
D) cut the plasmid twice with restriction enzyme Y and ligate the two fragments onto the ends of the DNA fragments cut with restriction enzyme X.
E) cut the plasmid with restriction enzyme X and then insert the gene into the plasmid.






Answer: C

RNA viruses require their own supply of certain enzymes because

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RNA viruses require their own supply of certain enzymes because 





A) host cells rapidly destroy the viruses.
B) host cells lack enzymes that can replicate the viral genome.
C) these enzymes translate viral mRNA into proteins.
D) these enzymes penetrate host cell membranes.
E) these enzymes cannot be made in host cells.






Answer: B

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

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A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have 






A) T2 protein and T4 DNA.
B) T2 protein and T2 DNA.
C) a mixture of the DNA and proteins of both phages.
D) T4 protein and T4 DNA.
E) T4 protein and T2 DNA.






Answer: D

To cause a human pandemic, the H5N1 avian flu virus would have to

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To cause a human pandemic, the H5N1 avian flu virus would have to 





A) spread to primates such as chimpanzees.
B) develop into a virus with a different host range.
C) become capable of human-to-human transmission.
D) arise independently in chickens in North and South America.
E) become much more pathogenic.






Answer: C

Emerging viruses arise by

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Emerging viruses arise by 




A) mutation of existing viruses.
B) the spread of existing viruses to new host species.
C) the spread of existing viruses more widely within their host species.
D) mutation of existing viruses, the spread of existing viruses to new host species, and the spread of existing viruses more widely within their host species.
E) none of these.





Answer: D

The herpes viruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex (HSV) I and II, causing facial and genital lesions, and the varicella-zoster (VSV), causing chicken pox and shingles. Each of these three actively infect nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others.

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The herpes viruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex (HSV) I and II, causing facial and genital lesions, and the varicella-zoster (VSV), causing chicken pox and shingles. Each of these three actively infect nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others. 


If scientists are trying to use what they know about HSV to devise a means of protecting other people from being infected, which of the following would have the best chance of lowering the number of new cases of infection? 

A) vaccination of all persons with preexisting cases
B) interference with new viral replication in preexisting cases
C) treatment of the HSV lesions to shorten the breakout
D) medication that destroys surface HSV before it gets to neurons
E) education about avoiding sources of infection

Answer: B

In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty." Which of the following best fits these observations? 

A) Viral capsids are needed for the cell to become infected; only the capsids enter the nucleus.
B) The viral envelope is not required for infectivity, since the envelope does not enter the nucleus.
C) Only the genetic material of the virus is involved in the cell's infectivity, and is injected like the genome of a phage.
D) The viral envelope mediates entry into the cell, the capsid entry into the nuclear membrane, and the genome is all that enters the nucleus.
E) The viral capsid mediates entry into the cell, and only the genomic DNA enters the nucleus, where it may or may not replicate.


Answer: D


In order to be able to remain latent in an infected live cell, HSV must be able to shut down what process? 

A) DNA replication
B) transcription of viral genes
C) apoptosis of a virally infected cell
D) all immune responses
E) interaction with histones


Answer: C

You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope III. culturing the substance by itself on nutritive medium, away from any plant cells IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious

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You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent.
I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious
II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope
III. culturing the substance by itself on nutritive medium, away from any plant cells
IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious 



Which treatment could definitively determine whether or not the component is a viroid? 

A) I
B) II
C) III
D) IV
E) first II and then III


Answer: A

If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities? 

A) I
B) II
C) III
D) IV
E) either II or IV


Answer: C


Which treatment would you use to determine if the agent is a prion? 

A) I only
B) II only
C) III only
D) IV only
E) either I or IV


Answer: D

Poliovirus is a positive-sense RNA virus of the picornavirus group. At its 5' end, the RNA genome has a viral protein (VPg) instead of a 5' cap. This is followed by a nontranslated leader sequence, and then a single long protein coding region (~7,000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids result in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides.

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Poliovirus is a positive-sense RNA virus of the picornavirus group. At its 5' end, the RNA genome has a viral protein (VPg) instead of a 5' cap. This is followed by a nontranslated leader sequence, and then a single long protein coding region (~7,000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids result in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. 



What part of the poliovirus would first interact with host cell ribosomes to mediate translation? 

A) the poly-A tail
B) the leader sequence
C) the VPg protein
D) the AUG in the leader sequence
E) the AUG at the start of the coding sequence


Answer: C


What conclusion is most consistent with the results of the radioactive labeling experiment?


A) The host cell cannot translate viral protein with the amino acid analogues.
B) Host cell ribosomes only translate the viral code into short polypeptides.
C) The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones.
D) The RNA is translated into short polypeptides, which are subsequently assembled into large ones.
E) The large radioactive polypeptides are coded by the host, whereas the short ones are coded for by the virus.


Answer: C

Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets.

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Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets. 



If this virus has capsomeres with 20 facets, how many proteins form each one? 

A) 1
B) 5
C) ~6
D) ~20
E) ~180


Answer: C


How many nucleotides of the genome would you expect to find in one capsid? A) 1 

B) ~6
C) ~20
D) ~180
E) ~6,300


Answer: E


If this virus has a positive RNA strand as its genome, it begins the infection by using this strand as mRNA. Therefore, which of the following do you expect to be able to measure? 

A) replication rate
B) transcription rate
C) translation rate
D) accumulation of new ribosomes
E) formation of new transcription factors


Answer: C


In a cell-free system, what other components would you have to provide for this virus to express its genes? 

A) ribosomes, tRNAs and amino acids 
B) ribosomes, tRNAs, amino acids, and GTP
C) RNA nucleotides and GTP
D) RNA nucleotides, RNA polymerase, and GTP
E) bean cell enzymes


Answer: B

Which of the following is the most probable fate of a newly emerging virus that causes high mortality in its host?

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Which of the following is the most probable fate of a newly emerging virus that causes high mortality in its host? 






A) It is able to spread to a large number of new hosts quickly because the new hosts have no immunological memory of them.
B) The new virus replicates quickly and undergoes rapid adaptation to a series of divergent hosts.
C) A change in environmental conditions such as weather patterns quickly forces the new virus to invade new areas.
D) Sporadic outbreaks will be followed almost immediately by a widespread pandemic.
E) The newly emerging virus will die out rather quickly or will mutate to be far less lethal.






Answer: E

Which of the following series best reflects what we know about how the flu virus moves between species?

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Which of the following series best reflects what we know about how the flu virus moves between species? 





A) An avian flu virus undergoes several mutations and rearrangements such that it is able to be transmitted to other birds and then to humans.
B) The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected.
C) A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans.
D) An influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this enables it to be transmitted to a human host.
E) An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, the virus mutates and can be transmitted to humans.





Answer: E

Which of the following is the best predictor of how much damage a virus causes?

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Which of the following is the best predictor of how much damage a virus causes?




A) ability of the infected cell to undergo normal cell division
B) ability of the infected cell to carry on translation
C) whether the infected cell produces viral protein
D) whether the viral mRNA can be transcribed
E) how much toxin the virus produces






Answer: A

What are prions?

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What are prions? 





A) mobile segments of DNA
B) tiny molecules of RNA that infect plants
C) viral DNA that has had to attach itself to the host genome
D) misfolded versions of normal brain protein
E) viruses that invade bacteria






Answer: D

The difference between vertical and horizontal transmission of plant viruses is that

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The difference between vertical and horizontal transmission of plant viruses is that 





A) vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant.
B) vertical transmission is the spread of viruses from upper leaves to lower leaves of the plant, and horizontal transmission is the spread of a virus among leaves at the same general level.
C) vertical transmission is the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread of viruses among plants of similar size.
D) vertical transmission is the transfer of DNA from one type of plant virus to another, and horizontal transmission is the exchange of DNA between two plant viruses of the same type.
E) vertical transmission is the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission is the spread of viruses among plants of the same species.






Answer: A

Which of the following represents a difference between viruses and viroids?

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Which of the following represents a difference between viruses and viroids? 






A) Viruses infect many types of cells, whereas viroids infect only prokaryotic cells.
B) Viruses have capsids composed of protein, whereas viroids have no capsids.
C) Viruses contain introns, whereas viroids have only exons.
D) Viruses always have genomes composed of DNA, whereas viroids always have genomes composed of RNA.
E) Viruses cannot pass through plasmodesmata, whereas viroids can.






Answer: B

Which of the following describes plant virus infections?

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Which of the following describes plant virus infections? 






A) They can be controlled by the use of antibiotics.
B) They are spread via the plasmodesmata.
C) They have little effect on plant growth.
D) They are seldom spread by insects.
E) They can never be passed vertically.






Answer: B

What is the function of reverse transcriptase in retroviruses?

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What is the function of reverse transcriptase in retroviruses? 




A) It hydrolyzes the host cell's DNA.
B) It uses viral RNA as a template for DNA synthesis.
C) It converts host cell RNA into viral DNA.
D) It translates viral RNA into proteins.
E) It uses viral RNA as a template for making complementary RNA strands.






Answer: B

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

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A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur? 





A) The plants would develop some but not all of the symptoms of the TMV infection.
B) The plants would develop symptoms typically produced by viroids.
C) The plants would develop the typical symptoms of TMV infection.
D) The plants would not show any disease symptoms.
E) The plants would become infected, but the sap from these plants would be unable to infect other plants.






Answer: C

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?

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Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory? 





A) Viruses contain either DNA or RNA.
B) Viruses are enclosed in protein capsids rather than plasma membranes.
C) Viruses can reproduce only inside host cells.
D) Viruses can infect both prokaryotic and eukaryotic cells.
E) Viral genomes are usually similar to the genome of the host cell.







Answer: E

Why do RNA viruses appear to have higher rates of mutation?

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Why do RNA viruses appear to have higher rates of mutation? 






A) RNA nucleotides are more unstable than DNA nucleotides.
B) Replication of their genomes does not involve proofreading.
C) RNA viruses replicate faster.
D) RNA viruses can incorporate a variety of nonstandard bases.
E) RNA viruses are more sensitive to mutagens.







Answer: B

Which of the following statements describes the lysogenic cycle of lambda (?) phage?

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Which of the following statements describes the lysogenic cycle of lambda (?) phage?





A) After infection, the viral genes immediately turn the host cell into a lambda-producing factory, and the host cell then lyses.
B) Most of the prophage genes are activated by the product of a particular prophage gene.
C) The phage genome replicates along with the host genome.
D) Certain environmental triggers can cause the phage to exit the host genome, switching from the lytic to the lysogenic.
E) The phage DNA is incorporated by crossing over into any nonspecific site on the host cell's DNA





Answer: C

Which of the following is characteristic of the lytic cycle?

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Which of the following is characteristic of the lytic cycle? 




A) Many bacterial cells containing viral DNA are produced.
B) Viral DNA is incorporated into the host genome.
C) The viral genome replicates without destroying the host.
D) A large number of phages are released at a time.
E) The virus-host relationship usually lasts for generations.






Answer: D

In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of the bacteriophage?

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In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of the bacteriophage? 





A) regulation via acetylation of histones
B) positive control mechanisms rather than negative
C) control of more than one gene in an operon
D) reliance on transcription activators
E) utilization of eukaryotic polymerases







Answer: C

Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of his or her life?

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Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of his or her life? 





A) re-infection by a closely related herpesvirus of a different strain
B) re-infection by the same herpesvirus strain
C) co-infection with an unrelated virus that causes the same symptoms
D) copies of the herpesvirus genome permanently maintained in host nuclei
E) copies of the herpesvirus genome permanently maintained in host cell cytoplasm






Answer: D

Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral mutation. Which of the following is the best example of a zoonosis?

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Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral mutation. Which of the following is the best example of a zoonosis? 





A) rabies
B) herpesvirus
C) smallpox
D) HIV
E) hepatitis virus




Answer: A

The host range of a virus is determined by

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The host range of a virus is determined by 





A) the enzymes carried by the virus.
B) whether its nucleic acid is DNA or RNA.
C) the proteins in the host's cytoplasm.
D) the enzymes produced by the virus before it infects the cell.
E) the proteins on its surface and that of the host.




Answer: E

Viral envelopes can best be analyzed with which of the following techniques?

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Viral envelopes can best be analyzed with which of the following techniques? 




A) transmission electron microscopy
B) antibodies against specific proteins not found in the host membranes
C) staining and visualization with the light microscope
D) use of plaque assays for quantitative measurement of viral titer
E) immunofluorescent tagging of capsid proteins







Answer: B
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