AP Biology Chapter 17
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?
9
What is the function of reverse transcriptase in retroviruses?
It uses viral RNA as a template for DNA synthesis.
Why do RNA viruses appear to have higher rates of mutation?
Replication of their genomes does not involve proofreading.
Which of the following is the most probable fate of a newly emerging virus that causes high mortality in its host?
The newly emerging virus will die out rather quickly or will mutate to be far less lethal.
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?
The plants would develop the typical symptoms of TMV infection.
Which of the following describes plant virus infections?
They are spread via the plasmodesmata.
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?
control of more than one gene in an operon
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?
copies of the herpesvirus genome permanently maintained in host nuclei
Emerging viruses arise by
all of the above
Which of the three types of viruses shown in Figure 17.1 would you expect to include a capsid(s)?
all three
Viral envelopes can best be analyzed with which of the following techniques?
antibodies against specific proteins not found in the host membranes
In order to be able to remain latent in an infected live cell, HSV must be able to shut down what process?
apoptosis of a virally infected cell
RNA viruses require their own supply of certain enzymes because
host cells lack enzymes that can replicate the viral genome.
Which of the following characteristics, structures, or processes is common to both bacteria and viruses?
genetic material composed of nucleic acid
Which of the following can be effective in preventing the onset of viral infection in humans?
getting vaccinated
Which viruses have single-stranded RNA that acts as a template for DNA synthesis?
retroviruses
The host range of a virus is determined by
the proteins on its surface and that of the host.
Based on Table 17.1, which virus meets the requirements for a bacteriophage?
A
Which of the following is characteristic of the lytic cycle?
A large number of phages are released at a time.
Which of the following series best reflects what we know about how the flu virus moves between species?
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.
Based on Table 17.1, which virus meets the Baltimore requirements for a retrovirus?
D
Which of the three types of viruses shown in Figure 17.1 would you expect to include glycoproteins?
I and II only
If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?
III
A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced will have
T4 protein and T4 DNA.
Which of the following statements describes the lysogenic cycle of lambda (λ) phage?
The phage genome replicates along with the host genome.
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?
The viral envelope mediates entry into the cell, the capsid enters into the nuclear membrane, and the genome is all that enters the nucleus.
Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?
Viral genomes are usually similar to the genome of the host cell.
Which of the following is the best predictor of how much damage a virus causes?
ability of the infected cell to undergo normal cell division
A human pandemic is
an epidemic that extends around the world.
If you already knew that the infectious agent was either a viroid or a prion, which treatment would allow you to distinguish between these two possibilities?
either I or IV
In Figure 17.2, at the arrow marked II, what enzyme(s) are being utilized?
host cell DNA polymerase
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?
interference with new viral replication in preexisting cases
Antiviral drugs that have become useful are usually associated with which of the following properties?
interference with viral replication
In Figure 17.2, when new viruses are being assembled (IV), what mediates the assembly?
nothing; they self-assemble
The difference between vertical and horizontal transmission of plant viruses is that
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.