Viruses

Which of the following characteristics, structures, or processes is common to both bacteria and

viruses?

• cell division

• genetic material composed of nucleic acid

• ribosomes

• metabolism

RNA viruses require their own supply of certain enzymes because ...

• these enzymes translate viral mRNA into proteins.

• these enzymes penetrate host cell membranes.

• host cells rapidly destroy the viruses.

• host cells lack enzymes that can replicate the viral genome.

Which of the following statements correctly describes one characteristic of the lytic cycle of viral replication?

• Viral DNA is incorporated into the host genome.

• Many bacterial cells containing viral DNA are produced.

• The viral genome replicates without destroying the host.

• A large number of phages are released at a time.

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

• lytic phages

• retroviruses

• proviruses

• bacteriophages

• viroids

What is the function of reverse transcriptase in retroviruses?

• It uses viral RNA as a template for DNA synthesis.

• It converts host cell RNA into viral DNA.

• It hydrolyzes the host cell's DNA.

• It uses viral RNA as a template for making complementary RNA strands.

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

• RNA viruses can incorporate a variety of nonstandard bases.

• Replication of their genomes does not involve proofreading.

• RNA viruses replicate faster.

• RNA nucleotides are more unstable than DNA nucleotides.

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

• applying antiseptics

• taking antibiotics

• getting vaccinated

• taking vitamins

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

• Sporadic outbreaks will be followed almost immediately by a widespread pandemic.

• The new virus replicates quickly and undergoes rapid adaptation to a series of divergent hosts.

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

• It is able to spread to a large number of new hosts quickly because the new hosts have no immunological memory of them.

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

• A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans.

• 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.

• An avian flu virus undergoes several mutations and rearrangements such that it is able to be transmitted to other birds and then to humans.

• The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected.

At the arrow marked II, what enzyme(s) is (are) being utilized?

• viral DNA polymerase

• host cell DNA and RNA polymerases

• reverse transcriptase

• host cell RNA polymerase

• host cell DNA polymerase