ap bio chapter 17: viruses

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

c. 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, and the virus mutates and can be transmitted to humans

which of the following characteristics, structures, or processes in common to both bacteria and viruses?

c. genetic material composed of nucleic acid

RNA viruses require their own supply of certain enzymes because

c. host cells lack enzymes that can replication the viral genome

based on table 17.1, which virus meets the requirements for a bacteriophage?

a. a (nuclease sensitivity: DNase; genome as mRNA: -; polymerase: -)

a human pandemic is

a. an epidemic that extends around the world

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

a. apoptosis of a virally infected cell

the herpesviruses 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 virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV), causing chicken pox and shingles. each of these three actively infects 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. interference with new viral replication in preexisting cases

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. t4 protein and t4 DNA

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. the viral envelope mediates entry into the cell, the capsid mediates entry into the nuclear membrane, and the genome is all that enters the nucleus

which of the following responses correctly lists the order of events in a generalized viral replicative cycle?

a. the virus enters the cell, host enzymes replicate the viral genome, enzymes transcribe the viral genome into mRNA

which viruses have single-stranded RNA that acts as a template for DNA synthesis?

e. retroviruses

which of the following statements correctly describes one characteristic of the lyric cycle of viral replication?

b. a large number of phages are released at a time

which of the following processes can be effective in preventing the onset of viral infection in humans?

b. getting vaccinated

why do RNA viruses tend to have unusually high rates of mutation?

b. replication of their genomes does not involve proofreading

which of the following statements correctly describes the lysogenic cycle of lambda phage?

b. the phage genome replicates along with the host genome

which of the following characteristics determine a virus's host range?

b. the proteins on its surface and that of the host

which of the following statements correctly describes one difference between vertical and horizontal transmission of plant viruses?

b. 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

some viruses can be crystallized and their structures analyzed. one such virus is yellow mottle virus, which infects beans. this virus has a single-stranded RNA genome containing about 6,300 nucleotides. its capsid is 25-30 nm in diameter and contains 180 identical capsomeres. if the yellow mottle virus capsid has 20 facets, how many proteins form each facet?

c. 9

which of the following statements correctly describes the best predictor of how much damage a virus causes?

c. ability of the infected cell to undergo normal cell division

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

c. iii only

what is the function of reverse transcriptase in retroviruses?

c. it uses viral RNA as a template for DNA synthesis

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?

c. the plants would develop the typical symptoms of TMV infection

which of the following statements accurately describes plant virus infections?

c. they are spread via the plasmodesmata

emerging viruses arise by

d. all of the above (ribosomes, cell division, genetic material composed of nucleic acid)

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

d. antibodies against specfic proteins not found in the host membrane

which of the following is why someone who has had a herpesvirus-mediated cold sore or genital sore may have flare-ups for the rest of his or her life?

d. copies of the herpesvirus genome remaining as mini-chromosomes in some host cell nuclei

based on table 17.1, which virus meets the baltimore requirements for a retrovirus?

d. d (nuclear sensitivity: RNase; genome as mRNA: -; polymerase: +)

antiviral drugs that have become useful are usually associated with which of the following properties?

d. interference with viral replication

in figure 17.2, when new viruses are being assembled (iv), what mediates the assembly?

d. nothing; they self-assemble (sorry idk how to explain the picture)

which of the following statements correctly describes the most probable fate of a newly emerging virus that causes high mortality in its host?

d. the newly emerging virus will die out rather quickly or will mutate to be far less lethal

most molecular biologists think that viruses originated from naked bits of cellular nucleic acid. which of the following observations supports this theory?

d. viral genomes are usually similar to the genome of the host cell

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 if you already knew that the infectious agent was a prion, which treatment would allow you to distinguish this?

e. either i or iv

in figure 17.2, at the arrow marked ii, what enzyme(s) are being utilized?

e. host cell DNA polymerase (idk how to explain the picture sorry guys)

which of the three types of viruses shown in figure 17.1 would you expect to include glycoproteins as part of their overall structure?

i and ii only (adenovirus, influenza virus; respectively)

which of the three types of viruses shown in figure 17.1 would you expect to include a capsid(s) as part of their overall structure?

i, ii, iii: all three (adenovirus, influenza virus, bacteriophage)