chapter 21

Viruses_______. all have a round shape cannot have a long shape do not maintain any shape vary in shape

vary in shape

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

They are single-stranded RNA particles.

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? Rabies virus Picornavirus HIV-1 Influenza A virus

Influenza A virus

People with the CCR5Δ32 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? Release Reverse transcription Uncoating Attachment

Attachment

Which of the following is not associated with prions? Replicating shapes Mad cow disease DNA Toxic proteins

DNA

Which of the following is NOT used to treat active viral disease? Vaccines Antiviral drugs Antibiotics Phage therapy

Antibiotics

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

It transcribes RNA to make DNA.

Oncogenic virus cores can be_______. RNA DNA neither RNA nor DNA either RNA or DNA

either RNA or DNA

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

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

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

Viruses are acellular.

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? Rabies virus Herpesviruses Retroviruses Influenza viruses

rabies virus

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

regressive

Vaccines_______. are similar to viroids are only needed once kill viruses stimulate an immune response

stimulate an immune response

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

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

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

Newly released virions can infect adjacent cells.

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? The apple trees were infected by horizontal transmission. The fungi carry disease. The fungi attract disease-carrying insects. The apple trees were infected by vertical transmission.

The apple trees were infected by horizontal transmission.

A bacteriophage can infect ________. the lungs viruses prions bacteria

bacteria

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

both b and c