Chapter 16 - Viruses

Viruses are not considered living organisms yet they share with living cells the ability to A) metabolize food. B) evolve. C) reproduce on their own. D) produce cell membranes. E) respond to stimuli.

B

Poliomyelitis is an RNA virus that can invade the nervous system and cause paralysis within a matter of hours. The nearly complete elimination of polio worldwide is due to A) antibiotics. B) vaccination. C) mosquito control. D) quarantine. E) improved water quality.

B

The host range of a virus is A) the geographical location in which the virus is found. B) the type of organisms or cells that a virus can infect. C) always limited to one species. D) limited by availability of its needed nutritional resources. E) the boundaries of the ecosystem in which it is found.

B

Treating a bacterial infection by inoculating the host with a bacterial virus is known as A) chemotherapy. B) phagetherapy. C) radiationtherapy. D) antibiotictherapy. E) None of the answer choices are correct.

B

What is the genetic material found in HIV? A) protein B) RNA C) DNA D) lipid E) carbohydrate

B

The human immunodeficiency virus (HIV) only affects a specific class of cells in the immune system called helper T cells, and not other types of T cells. Which is the best explanation for this observation? A) HIV can only replicate inside of helper T cells. B) Only helper T cells have reverse transcriptase. C) The helper T cells are not necessary for the immune system to fight viral infections. D) Only helper T cells have the correct receptor on their cell surface. E) HIV can only be released from helper T cells.

D

The stage of viral replication in which the virus binds a cell surface receptor is A) release. B) penetration. C) synthesis. D) attachment. E) assembly.

D

The structure of the anti-HIV drug azidothymidine (AZT) includes a phosphate group, a sugar group, and a nitrogen base, in the form of a nucleotide. Given its structure, how do you think it blocks viral replication? A) It blocks RNA synthesis by an enzyme. B) It inhibits host cells from replicating. C) It inhibits the assembly of new viruses in the cell. D) It blocks synthesis of a DNA copy of HIV's genome. E) It prevents HIV from entering the cell.

D

The type of viral infection in which a virus enters a host cell, immediately replicates, and causes the host cell to burst is a __________ infection. A) rare form ofviral B) transgenic C) lysogenic D) lytic E) systematic

D

Viral DNA inserted into the chromosome of the bacterial host cell is a A) carrier. B) phage. C) reservoir. D) prophage. E) progenote.

D

Viruses always lack which of the following? A) an envelope B) genetic material C) a proteincoat D) organelles E) None of the answer choices are correct.

D

A patient receiving a protease inhibitor and AZT is probably being treated for an infection by a A) bacterium. B) protozoan. C) DNA virus. D) retrovirus. E) fungus.

D

Drugs like aziodothymidine (AZT) work against HIV infections by inhibiting A) viral DNA from inserting into the host chromosome. B) the cleaving of proteins needed to make the protein coat of a virus. C) host cells from reproducing. D) reverse transcriptase. E) viruses from entering a host cell.

D

Human influenza viruses are usually derived from influenza viruses that infect A) horses and sheep. B) cattle and water buffalo. C) chimpanzees and gorillas. D) birds and pigs. E) a variety of primates.

D Influenza, known as "flu" for short, moves among pigs (swine flu), birds (avian flu), and humans

Our most effective weapon against viral infections is A) antibiotics. B) sulfa drugs. C) gene therapy. D) surgery. E) vaccinations.

E

Rhinovirus is an RNA virus that causes the common cold and sinus infections. The virus does not contain an envelope. Which of the following is true of a rhinovirus? A) It does not contain protein or genetic material. B) It does not contain genetic material. C) It does not contain protein. D) It does not contain lipids or protein. E) It does not contain lipids.

E

The correct sequence of the stages of viral replication is A) attachment, synthesis, penetration, assembly, and then release. B) penetration, attachment, assembly, synthesis, and then release. C) penetration, attachment, synthesis, release, and then assembly. D) attachment, penetration, assembly, synthesis, and then release. E) attachment, penetration, synthesis, assembly, and then release.

E

The shape of a virus is determined by its A) DNA. B) RNA. C) envelope. D) host. E) protein coat.

E

Viruses are smaller than A) plant cells. B) bacterial cells. C) single-celled eukaryotes. D) human red blood cells. E) All of the answer choices are correct.

E

Which of the following diseases is not caused by viruses? A) influenza B) smallpox C) polio D) warts E) diabetes

E

Many viruses are inhibited by antibiotics.

FALSE Antibiotics target bacteria not viruses.

Viruses can infect plants and animals, but no viruses are known to infect bacteria.

FALSE Viruses have a diverse set of genomes, and can often be classified by the structure of their protein coat, related to organisms they infect.

A layer of membrane outside the protein coat of some viruses is called a(n) A) envelope. B) protein coat. C) capsomere. D) capsid. E) plasmid.

A

A viral species is found to infect host fishes in isolated mountain lakes. The host range is A) the one or more infected species of fishes that exhibit the viral disease symptoms. B) the number of fish that a virus can infect before the virus dies. C) the mountainous area, in which the isolated lakes are found and mapped. D) the specific sizes and shapes of the fish tissue cells that become infected by the viruses. E) All of the answer choices are correct.

A

Hepatitis A and C contain an RNA genome, whereas hepatitis B contains a DNA genome. What is the most plausible conclusion you could draw about these strains of hepatitis? A) They do not all share a common ancestor. B) They do not all affect the liver. C) They all have the same symptoms. D) They all have the same mode of transmission. E) They all have the same rate of occurrence.

A

Human immunodeficiency virus (HIV) is classified as A) a retrovirus. B) a general mammalian infectious virus. C) responsive to antibiotics. D) a liver carcinogen. E) a skin-touch transmissable virus.

A

SIV causes symptomless infections in monkeys and apes, yet causes AIDS-like disease in chimpanzees. HIV is closely related to SIV and causes AIDS in humans. Which of the following is the best explanation for these observations? A) Monkeys, apes, and chimpanzees are all genetically very similar. B) The effects of viruses on different species is random. C) Chimpanzees and humans share a more recent common ancestor. D) SIV is most likely lytic in apes and monkeys. E) SIV is most likely latent in chimpanzees.

A

The enzyme that HIV uses to copy its RNA into DNA is A) reverse transcriptase. B) DNA polymerase. C) RNA polymerase. D) RNA integrase. E) transcriptase.

A

The stage of viral replication in which the new viruses leave the host cell is A) release. B) attachment. C) penetration. D) synthesis. E) assembly.

A

What type of cell does HIV infect? A) helper T cells B) B cells C) red blood cells D) phagocytic cells E) All of the answer choices are correct.

A

Which of the following is the suggested ancestor to HIV? A) SIV B) H5N1 C) H7N7 D) WNV E) HEV

A

The host range of a virus is determined by A) specific receptors on cells it infects. B) the type of genetic information the virus contains. C) the shape of the virus. D) the particular life cycle of the virus. E) All of the answer choices are correct.

A The host range of a virus is the types of organisms or cells that it can infect. A virus can enter only a cell that has a specific target attachment molecule, or receptor, on its surface

A host that acts as a continual source of viral infections for other host species is a A) reservoir. B) capsid. C) clade. D) bacteriophage. E) progenote.

A The reservoir of a virus is the host that acts as a continual source of the viral infection for other host species. For many viruses that infect humans, the reservoir is a host animal that may or may not show symptoms of infection

A reason given by scientists as to why viruses are not considered living organisms is that A) viruses do not contain genetic information. B) viruses do not reproduce on their own. C) viruses are all smaller than the smallest known cells. D) viruses do not contain a nucleus. E) viruses can be frozen and still survive.

B

An infectious RNA molecule is a A) virus. B) virion. C) viroid. D) prion. E) bacteriophage.

C

An infectious protein is a A) virus. B) viroid. C) prion. D) virion. E) prophage.

C

If a person is treated with a single anti-HIV drug, they often end up with a resistant strain. What is the most likely explanation for how this occurs? A) The drugs weaken the immune system, making a patient more susceptible to infection with resistant strains of HIV. B) The drug causes mutations in the HIV, making them resistant to the drug. C) The drugs kill all sensitive viruses, leaving only the preexisting resistant viruses. D) The HIV wants to avoid the drug, so it becomes resistant. E) All of the answer choices are correct.

C

The genetic information in viruses A) is single-stranded RNA. B) is double-stranded DNA. C) can be DNA or RNA, and single- or double-stranded. D) is double-stranded RNA. E) is single-stranded DNA.

C

The herpes simplex virus 1 can lie dormant in nerve cells for years. When a patient becomes stressed, the virus enters the active stage and forms cold sores on the lips. When the virus is inactive, or dormant, it is in the __________ stage. A) lytic B) symptomatic C) latent D) replicative E) infective

C

The influenza virus contains an RNA genome. Every year a flu vaccine is designed to protect against three different strains of the influenza virus. Why do scientists make a new vaccine each year? A) Our bodies develop resistance to the vaccine and it becomes less effective. B) The virus develops resistance to the vaccine. C) The virus can rapidly mutate into new strains. D) People change their habits each year and become susceptible to different strains of the virus. E) The common influenza virus can come from many species of animals, including cats and dogs.

C

The stage of viral replication in which viral nucleic acids and proteins are manufactured is A) release. B) attachment. C) synthesis. D) penetration. E) assembly.

C

Tobacco mosaic virus is most commonly introduced into plants through small wounds caused by handling and by insects chewing on plant parts. What would normally prevent most viruses from easily entering plant cells? A) the cell wall of the virus B) the plasma membrane of the plant C) the cell wall of the plant D) the plasma membrane of the virus E) the protein coat of the virus

C

Viruses that infect bacteria are A) not known toexist. B) prions. C) bacteriophages. D) composed ofprotein only. E) also capable ofcausing disease in humans.

C