Bio Exam 4 (CB CH19)
which of the following is characteristic of the lytic cycle?
a large number of phages are released at a time
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
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 anew species such as a bird, the virus mutates and can be transmitted to humans
viral envelopes can best be analyzed with which of the following techniques?
antibodies against specific proteins not found in the host membranes
which of the following can be effective in preventing the onset of viral infection in humans?
getting vaccinated
antiviral drugs that have become useful are usually associated with which of the following properties?
interference with viral replication
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?
rabies
why do RNA viruses appear to have higher rates of mutation?
replication of their genomes does not involve proofreading
which viruses have single-stranded RNA that acts as a template for DNA synthesis?
retroviruses
viral genomes vary greatly in size and may include from four genes to several hundred genes. Which of the following viral features is most apt to correlate with the size of the genome?
size and shape of the capsid
which of the following is the most probable fate of a newly emerging virus that causes high mortality in it's host?
the newly emerging virus will die out rather quickly or will mutate to be far less lethal
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
what is the function of reverse transcriptase in retroviruses?
it uses viral RNA as a template for DNA synthesis
what are prions?
misfiled versions of normal brain protein
which of the following statements describes the lysogenic cycle of lambda phage?
the phage genome replicates along with the host genome
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
the host range of a virus is determined by...
the proteins on it's surface and that of it's host
which of the following describes plant virus infections?
they are spread via the plasmodesmata
the difference between vertical and horizontal transmission of plant viruses is that...
vertical transmission is transmission of a virus from a parent plant to it's progeny, and horizontal transmission is one plant spreading the virus to another plant
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 represents a difference between viruses and viroids?
viruses have capsids composed of protein, whereas viroids have no capsids