Chapter 19 Questions

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

T4 protein and T4 DNA.

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 represents a difference between viruses and viroids?

Viruses have capsids composed of protein, whereas viroids have no capsids.

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

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 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, the virus mutates and can be transmitted to humans.

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.

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

The phage genome replicates along with the host genome.

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

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

become capable of human-to-human transmission.

What are prions?

misfolded versions of normal brain protein

Emerging viruses arise by

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.

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.