Deck 16: Viruses

Question 1

Figuer:
Five different virus species are shown and labeled arrows indicate structures.
The virus structure indicated by the arrow labeled A is the

A) genetic material, DNA or RNA.
B) the bacteriophage.
C) the bacterial membrane.
D) the lipid-rich envelope.
E) the protein coat, or capsid.

Answer 1

A

Question 2

The correct sequence of the stages of viral replication is

A) penetration, attachment, synthesis, release, and then assembly.
B) attachment, penetration, synthesis, assembly, and then release.
C) attachment, synthesis, penetration, assembly, and then release.
D) attachment, penetration, assembly, synthesis, and then release.
E) penetration, attachment, assembly, synthesis, and then release.

Answer 2

B

Question 3

Viruses can infect all higher life forms such as plants and animals,but cannot infect bacteria.

Answer 3

False

Question 4

Which of the following diseases is not caused by viruses?

A) the common cold and influenza
B) aids and warts
C) diabetes
D) polio and rabies
E) smallpox and mononucleosis

Question 5

Viruses

A) consist of multiple cells.
B) are smaller than cells.
C) contain a nucleus.
D) contain ribosomes.
E) consist of only a single cell.

Question 6

The shape of a virus is determined by its

A) RNA.
B) coat protein organization.
C) envelope.
D) DNA.
E) host.

Question 7

Most viruses

A) infect only a few closely related species.
B) only infect plant cells.
C) cannot infect living cells.
D) only infect animal cells.
E) infect a wide variety of organisms.

Question 8

A friend of yours,as a biology major,has prepared microscope specimens from a rat that had been found dead for unknown reasons.Viewing the prepared slide with a light microscope,your friend points out many small round objects,each about 1/10th the diameter of the nearby rat cells,identifying those round objects as viruses,the likely reason for the rat's death.You can interpret from the observations that

A) the viruses your friend identified were likely received as an infection from another organism.
B) these are more likely bacteria, being too large for viruses.
C) they are indeed viruses, likely received from another organism, and are also specifically common bacteriophages.
D) they are probably specialized bacteriophages that commonly infect mammals.
E) they are capsids, which have evolved as a transition between viruses and bacteria.

Question 9

When a lab technician collects viruses,grinds them,and then stains the extract for proteins,they are studying the

A) RNA molecule of the virus.
B) lipid coat of the virus.
C) DNA molecule of the virus.
D) space inside the virus where its genetic information is located.
E) capsids of the virus.

Question 10

Figuer:
Five different virus species are shown and labeled arrows indicate structures.
The virus structure indicated by the arrow labeled C is the

A) genetic material, DNA or RNA.
B) the bacteriophage.
C) the bacterial membrane.
D) the lipid-rich envelope.
E) the protein coat, or capsid.

Question 11

Many viruses are inhibited by antibiotics.

Question 12

Most scientific evidence points to the HIV viruses originating in Africa.

Question 13

The host range of a virus is

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

Question 14

The influenza viruses,that infect human beings,are usually derived from a type that infects

A) birds and pigs.
B) chimpanzees and gorillas.
C) horses and sheep.
D) a variety of primates.
E) cattle and water buffalo.

Question 15

A layer of membrane outside the protein coat of some viruses is called a(n)

A) capsid.
B) protein coat.
C) envelope.
D) capsomere.
E) plasmid.

Question 16

The site,in nature,where viruses exist before they infect humans,is the

A) capsid.
B) reservoir.
C) clade.
D) bacteriophage.
E) progenote.

Question 17

The genetic information in viruses

A) is found in the nucleus of the virus.
B) is a specialized capsid protein.
C) is always DNA.
D) is always RNA.
E) can be DNA or RNA.

Question 18

A species is found to infect host fishes in isolated mountain lakes.The host range is

A) impossible to determine, because the isolated lakes don't allow tests for the infection of other fishes.
B) All of these definitions are applied by researchers, depending on the particular viruses of concern.
C) the mountainous area, in which the isolated lakes are found and mapped.
D) the one or more infected species of fishes that exhibit the viral disease symptoms.
E) the specific sizes and shapes of the fish tissue cells that become infected by the viruses.

Question 19

Viruses that infect bacteria are

A) prions.
B) bacteriophages.
C) also capable of causing disease in humans.
D) not known to exist.
E) composed of protein only.

Question 20

Figuer:
Five different virus species are shown and labeled arrows indicate structures.
The virus structure indicated by the arrow labeled B is the

A) the bacterial membrane.
B) genetic material, DNA or RNA.
C) the bacteriophage.
D) the lipid-rich envelope.
E) the protein coat, or capsid.

Question 21

Hepatitis A and C contain an RNA genome,while hepatitis B contains a DNA genome.What is the most plausible conclusion you could draw about these strains of hepatitis?

A) They all have the same mode of transmission.
B) They do not all share a common ancestor.
C) They all have the same symptoms.
D) They all have the same rate of occurrence.
E) They do not all affect the liver.

Question 22

Our most potent weapon in the fight against viruses is

A) gene therapy.
B) surgery.
C) sulfa drugs.
D) antibiotics.
E) vaccinations.

Question 23

An infectious RNA molecule is a

A) virion.
B) prion.
C) viroid.
D) virus.
E) bacteriophage.

Question 24

A patient receiving a protease inhibitor and AZT is probably being treated for an infection by a

A) DNA virus.
B) protozoan.
C) fungus.
D) bacterium.
E) retrovirus.

Question 25

Human immunodeficiency virus (HIV)is classified as

A) a skin-touch transmissable virus.
B) a general mammalian infectious virus.
C) a liver carcinogen.
D) a retrovirus.
E) responsive to antibiotics.

Question 26

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) lysogenic
B) rare form of viral
C) systematic
D) transgenic
E) lytic

Question 27

A trait that is not shared by lytic and lysogenic viruses is

A) lysis of the host cell occurs soon after the infection.
B) a protein capsid specialized for attachment to the host cells.
C) dependence on the metabolism and synthesis processes of the host cell for replication.
D) None of the answer options are correct; lytic and lysogenic viruses share all these listed traits.
E) DNA or RNA is the nucleic acid responsible for storage of the genetic information.

Question 28

The stage of viral replication in which the host cell produces viral nucleic acids and proteins is

A) attachment.
B) release.
C) penetration.
D) assembly.
E) synthesis.

Question 29

Since viruses have no active methods of entering plant cells,they must rely upon mechanically caused wounds,vegetative propagation of plants,grafting,seed,pollen,and being carried on the mouth parts of chewing insects.Tobacco mosaic virus is most commonly introduced into plants through small wounds caused by handling and by insects chewing on plant parts.What would prevent most viruses from easily entering plant cells?

A) the cell wall on the virus
B) the plasma membrane on the plant
C) the protein coat on the virus
D) the plasma membrane on the virus
E) the cell wall on the plant

Question 30

An infectious protein is a

A) prion.
B) virion.
C) virus.
D) prophage.
E) viroid.

Question 31

Oral infections with herpes simplex virus 1 can lie dormant in nerve cells for years.When a patient becomes stressed,the virus is released,forming cold sores on the lips.While lying dormant,the virus is in which of the following states?

A) infective
B) latent
C) replicative
D) symptomatic
E) lytic

Question 32

The stage of viral replication in which the virus binds a cell surface receptor is

A) attachment.
B) release.
C) assembly.
D) synthesis.
E) penetration.

Question 33

Viruses are not considered to be alive,yet they share with living cells the ability to _____.

A) metabolize food
B) evolve
C) reproduce on their own
D) produce cell membranes
E) synthesize proteins

Question 34

A reason(s)given by scientists as to why viruses are not considered living organisms include

A) viruses do not contain a nucleus.
B) viruses do not reproduce on their own.
C) viruses can be frozen and still survive.
D) viruses do not contain genetic information.
E) viruses are all smaller than the smallest known cells.

Question 35

The stage of viral replication in which the new viruses leave the host cell is

A) release.
B) synthesis.
C) penetration.
D) assembly.
E) attachment.

Question 36

The enzyme that HIV uses to copy its RNA into DNA is

A) reverse transcriptase.
B) RNA polymerase.
C) RNA integrase.
D) DNA polymerase.
E) transcriptase.

Question 37

Treating a bacterial infection by inoculating the host with a bacterial virus is

A) chemotherapy.
B) phage therapy.
C) None of the answer choices are correct.
D) radiation therapy.
E) antibiotic therapy.

Question 38

Viral DNA inserted into a chromosome of the host is a

A) phage.
B) reservoir.
C) prophage.
D) carrier.
E) progenote.

Question 39

If a physician diagnoses that a person has a viral infection,antibiotics are not considered an appropriate,effective means of treating viruses for which main reason?

A) Antibiotics inhibit ribosome production of proteins.
B) Antibiotics inhibit synthesis of cell walls.
C) Antibiotics destroy DNA and RNA.
D) All of these answer options except the destruction of DNA and RNA are common means of antibiotic action.
E) Antibiotics inhibit enzymes.

Question 40

Two basic mechanisms by which antibiotics fight infections are in the inhibition of cell wall synthesis,and in the alteration of cell membranes,so

A) viruses are controlled more effectively than other bacteria because of their smaller size.
B) the replication of the viral DNA or RNA is inhibited when the capsid is damaged by the antibiotic.
C) None of the answer options are correct.
D) viruses are not affected at all, because they do not produce their own cell walls or cell membranes.
E) bacteriophages have evolved to rapidly reconfigure their cell wall and membrane to counteract the damage.

Question 41

Figuer:
Based on the figure from the section on HIV replication,why could researchers use PCR to amplify viral DNA from the chimp Marilyn's tissues?

A) HIV uses DNA as its genetic material.
B) Some of the HIV will be stuck to the outside of a cell.
C) PCR uses a reverse transcriptase and can thus detect RNA.
D) PCR can amplify any genetic material.
E) HIV is converted to DNA and integrated into a cell's chromosome.

Question 42

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 inhibits host T cells from replicating.
B) It blocks RNA synthesis by an enzyme.
C) It prevents HIV from entering the cell.
D) It inhibits the assembly of new viruses in the cell.
E) It blocks host cell DNA synthesis by an enzyme.

Question 43

In studies designed to determine the origin of HIV,how did the researchers first know that Marilyn the chimp may be infected with HIV?

A) She had HIV DNA in her tissues.
B) She had tested positive antibodies against HIV.
C) She had been used in HIV research.
D) She had HIV RNA in her blood.
E) She had symptoms of HIV infection, or AIDS.

Question 44

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) quarantine.
B) vaccination.
C) antibiotics.
D) mosquito control.
E) improved water quality.

Question 45

Oral infections with herpes simplex virus 1 can lie dormant in nerve cells for years.When a patient becomes stressed,the virus is released,forming cold sores on the lips.Why is the cold sore adaptive to the virus?

A) Cold sores allow the virus to move to another part of the body.
B) Cold sores warn other people that the host is infected.
C) Cold sores allow the virus to avoid the immune system.
D) Cold sores allow the virus to spread to a new host.
E) Cold sores allow the virus to mutate and survive antibiotic treatments.

Question 46

Figuer:
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) SIV is most likely lytic in apes and monkeys.
B) SIV is most likely latent in chimpanzees.
C) Chimpanzees and humans have a more recent common ancestor.
D) The effects of viruses on different species is random.
E) Monkeys, apes, and chimpanzees are all genetically very similar.

Question 47

Figuer:
Based on the figure,which of the following is true of HIV?

A) It is an enveloped virus.
B) It replicates in the nucleus of cells.
C) It contains DNA as its genetic material.
D) It uses reverse transcriptase from the cell to make DNA.
E) It lyses cells when it is released.

Question 48

A vaccine against the influenza virus would result in production of antibodies against which of the following?

A) proteins in the envelope
B) the protein coat
C) lipids in the envelope
D) viral DNA
E) viral RNA

Question 49

Smallpox is an enveloped virus with a DNA genome.We have eliminated this once deadly virus through an aggressive worldwide vaccination program.Why might a vaccine be successful with smallpox,but not with HIV?

A) Host cells have RNA in them, and thus do not raise antibodies against RNA.
B) Viruses with DNA genomes must replicate inside a host cell.
C) Smallpox is an enveloped virus.
D) RNA is more stable than DNA, and is less likely to be destroyed by the vaccine.
E) DNA genomes mutate less rapidly than RNA genomes.

Question 50

Viruses always lack which of the following?

A) an envelope
B) None of these answer options are correct, because viruses have all of these structures.
C) organelles
D) genetic material
E) a protein coat

Question 51

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 lipid.
B) It does not contain lipid or protein.
C) It does not contain protein or genetic material.
D) It does not contain protein.
E) It does not contain genetic material.

Question 52

Drugs like aziodothymidine (AZT)work against HIV infections by inhibiting

A) host cells from reproducing.
B) viral DNA from inserting into the host chromosome.
C) viruses from entering a host cell.
D) the cleaving of proteins needed to make the protein coat of a virus.
E) reverse transcriptase.

Question 53

Oral infections with herpes simplex virus 1 can lie dormant in nerve cells for years.When a patient becomes stressed,the virus is released,forming cold sores on the lips.Where will the virus be while dormant in the nerve cell?

A) floating in the nerve cell cytoplasm
B) integrated in the nerve cell chromosomes
C) in the nerve cell membrane
D) floating outside of the nerve cell, waiting to reinfect it
E) in the blood

Question 54

If a person is treated with a single anti-HIV drug,they often end up with a resistant strain.How does this occur?

A) The drugs kill all sensitive viruses, leaving only the preexisting resistant viruses.
B) The HIV wants to avoid the drug, so it becomes resistant.
C) The drug causes mutations in the HIV, making them resistant to the drug.
D) The drugs weaken the immune system, making a patient more susceptible to infection with resistant strains of HIV.

Question 55

It has been difficult to generate drugs to treat AIDS for which reason?

A) The only way to kill a virus is with a vaccine, not with drugs.
B) People with HIV infections die very rapidly, before the drugs have a chance to cure them.
C) HIV does not use any enzymes that can be targeted by drugs.
D) HIV mutates rapidly among infected humans.
E) HIV does not cause AIDS.

Question 56

The influenza virus contains an RNA genome.Every year the common flu vaccine is designed to protect against three different strains of the influenza virus.Why do scientists typically have to make a new vaccine every year?

A) The virus can rapidly mutate into new strains.
B) The common influenza virus can come from many species of animals, including cats and dogs.
C) Our bodies develop resistance to the vaccine and it becomes less effective.
D) People change their habits each year and become susceptible to different strains of the virus.
E) The virus develops resistance to the vaccine.

Question 57

Figuer:
The human immunodeficiency virus (HIV)only affects a specific class of cells in the immune system called T helper cells,and not other types of T cells.Which is the best explanation for this observation?

A) The T helper cells are not necessary for the immune system to fight viral infections.
B) HIV can only replicate inside of T helper cells.
C) Only T helper cells have the correct receptor on their cell surface.
D) Only T helper cells have reverse transcriptase.
E) HIV can only be released from T helper cells.

Question 58

What is the genetic material found in HIV?

A) lipid
B) carbohydrate
C) DNA
D) RNA
E) protein

Question 59

Figuer:
Based on the figure,which of the following statements is most likely accurate?

A) HIV arose more than once.
B) HIV and SIV are not genetically related.
C) SIV only arose once.
D) HIV groups M, N, and O will be more similar to each other than to SIV.
E) The SIV strains will all have more sequence similarity with each other than with any of the HIV groups.