Chapter 21: Viruses

Newly released virions can infect adjacent cells.

Which statement is not true of viral replication? a. A lysogenic cycle kills the host cell. b. There are six basic steps in the viral replication cycle. c. Viral replication does not affect host cell function. d. Newly released virions can infect adjacent cells.

It transcribes RNA to make DNA.

Which statement is true of reverse transcriptase? a. It is a nucleic acid. b. It infects cells. C. It transcribes RNA to make DNA. d. It is a lipid.

bacteria

A bacteriophage can infect a. the lungs b. viruses c. prions d. bacteria

Influenza A virus

A patient presents at the clinic with an acute viral infection. Assays that analyze the viral life cycle classify the virus into Group V with a segmented genome. Which virus is the most likely diagnosis for the patient? a. Rabies virus b. Picornavirus C. HIV-1 d. Influenza A virus

Rabies virus

A scientist discovers a new virus with a linear, RNA genome surrounded by a helical capsid. The virus is most likely a member of which family based on structure classification? a. Rabies virus b. Herpesviruses c. Retroviruses d. Influenza viruses

The apple trees were infected by horizontal transmission.

An apple grower notices that several of his apple trees with fungi growing on their trunks have developed necrotic ring spots, while other trees in the orchard that lack fungi appear healthy. What is the most likely conclusion the farmer can make about the virus infecting his apple trees? a. The apple trees were infected by horizontal transmission. b. The fungi carry disease. c. The fungi attract disease-carrying insects. d. The apple trees were infected by vertical transmission.

False

Biologists have used molecular evidence to trace all viruses to a single common ancestor. True False

the use of "live" viruses as antibiotics to kill bacteria

Which is the most accurate description of phage therapy? gene editing to prevent viral infections a vaccine that contains only part of a virus the use of enzyme inhibitors to prevent a virus from attaching to host cells the use of "live" viruses as antibiotics to kill bacteria

They use the host cell's machinery to produce new copies of their genome.

Which is true of DNA viruses? a. They use the host cell's machinery to produce new copies of their genome. b. They all have envelopes. c. They are the only kind of viruses that can cause cancer. d. They are not important plant pathogens.

all of these

Which of the following can be attributed to virus evolution? all of these A virus can jump from one host species to another. New flu vaccines need to be developed every year. A virus will become less deadly to a new host species over time.

Antibiotics

Which of the following is NOT used to treat active viral disease? a. Vaccines b. Antiviral drugs c. Antibiotics d. Phage therapy

DNA

Which of the following is not associated with prions? a. Replicating shapes b. Mad cow disease c. DNA d. Toxic proteins

stimulate an immune response

Vaccines ___________. a. are similar to viroids b. are only needed once c. kill viruses d. stimulate an immune response

vary in shape

Viruses ______________. a. all have a round shape b. cannot have a long shape c. do not maintain any shape d. vary in shape

are not organized in cells, but need to use a host organism cell to survive and reproduce.

Viruses are not always considered to be life forms because they are not organized in cells, but need to use a host organism cell to survive and reproduce. do not contain proteins in their structure. do not contain a hereditary mechanism such as DNA or RNA. mutate at a much slower rate than prokaryotes and eukaryotes.

prion

Mad cow disease (BSE) is not transmitted by a virus. Its protein-based infectious particles are called

True

Most viruses that infect people evolved from viruses that infect other animal species. True False

either RNA or DNA

Oncogenic virus cores can be _________________. a. RNA b. DNA c. neither RNA nor DNA d. either RNA or DNA

Release

People with the CCR5A32 mutation of a T-cell surface protein can be exposed to some strains of HIV-1 without becoming sick. What step of the virus life cycle is likely to be inhibited with this mutation? a. Release b. Reverse transcription c. Uncoating d. Attachment

Regressive

The observation that the bacteria genus Chlamydia contains species that can only survive as intracellular parasites supports which viral origin hypothesis? a. Progressive b. Regressive c. Self-replicating d. Virus-first

both b and c

The viral __________ play(s) a role in attaching a virion to the hosts cell. a. core b. capsid c. envelope d. both b and c

During attachment, the virus attaches at specific sites on the cell surface.

Which statement is true of viral replication? a. In the process of apoptosis, the cell survives. b. During attachment, the virus attaches at specific sites on the cell surface. c. The viral capsid helps the host cell produce more copies of the viral genome d. mRNA works outside of the host cell to produce enzymes and proteins

They are single-stranded RNA particles.

Which statement is true of viroids? a. They are single-stranded RNA particles. b. They reproduce only outside of the cell. c. They produce proteins. d. They affect both plants and animals.

Viruses are acellular.

Which statement is true? a. A virion contains DNA and RNA. b. Viruses are acellular. c. Viruses replicate outside of the cell. d. Most viruses are easily visualized with a light microscope.

transposon

Which term is most relevant to the concept of horizontal gene transfer between a virus and its host? envelope capsid lysogenic cycle transposon

gene therapy with viral vectors

Which treatment holds the most promise for curing patients with hereditary disorders like Severely Compromised Immunodeficiency Disease? phage therapy antiviral drugs gene therapy with viral vectors vaccine

bacteria

Which type of host cell is targeted by a phage virus? bacteria humans plants nonhuman animals