Exam #9

Question 1

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

Answer 1

Antibodies against specific proteins not found in the host membranes

Question 2

The host range of a virus is determined by

Answer 2

The proteins on its surface and that of the host

Question 3

Which of the following accounts for someone who has had a herpes virus- mediated cold sore or genital sore getting flare - ups for the rest of his or her life?

Answer 3

Copies of the herpes virus genome permanently maintained in host nuclei

Question 4

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 bacteriophage?

Answer 4

Control of more than one gene in an operon

Question 5

Which of the following is characteristic of the lytic cycle?

Answer 5

A large number of pages are released at a time.

Question 6

The phage genome replicate along with the host genome describes which of the following phases of the lambda (Y) phage ?

Answer 6

Lysogenic phase

Question 7

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?

Answer 7

Viral genomes are usually similar to the genome of the host cell.

Question 8

A researcher loses a cell that contains nucleic acid molecules and capos merges 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?

Answer 8

The plants would develop the typical symptoms of TMV infection

Question 9

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

Answer 9

Retroviruses

Question 10

What is the function of the reverse transcriptions in retro viruses ?

Answer 10

It uses viral RNA as a template for DNA synthesis.

Question 11

Why do RNA viruses appear to have higher rates of mutation?

Answer 11

Replication of their genomes does not involve proofreading.

Question 12

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

Answer 12

Getting vaccinated

Question 13

Which of the following describes plant virus infections?

Answer 13

They are spread via the plasmodesmata

Question 14

Which of the following is the best predictor of how much damage a virus causes?

Answer 14

Ability of the infected cell to undergo normal cell division

Question 15

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

Answer 15

Interferences with viral replication

Question 16

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

Answer 16

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

Question 17

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

Answer 17

Genetic material composed of nucleic acid

Question 18

Emerging viruses arise by

Answer 18

All

• mutation of existing viruses
• the spread of existing viruses more widely within their host species
• the spread of existing viruses to a new host species

Question 19

A human pandemic is

Answer 19

An epidemic that extends around the world

Question 20

RNA viruses require their own supply of certain enzymes because

Answer 20

Host cells lack enzymes that can replicate the viral genome