Chapter 17 - Viruses Quiz

What is a virus?

• A protein shell that encloses the viral genome

• An infectious particle consisting of genes packaged into a protein coat

• A cell with a nucleic acid enclosed in a protein coat

• A type of bacteria that infects other bacteria

What are viral genomes made of?

• Double-stranded DNA or RNA

• Both double-stranded and single-stranded RNA

• Single-stranded DNA or RNA

• Both double-stranded and single-stranded DNA

What is a capsid?

• The elongated capsid head of a bacteriophage

• The membranous envelope that helps viruses infect hosts

• The protein subunit that makes up the capsid

• The protein shell that encloses the viral genome

What is the function of viral envelopes?

• To break open the host's cell wall

• To help viruses infect hosts

• To protect the viral genome

• To attach the phage to the host and inject its DNA

What is the lytic cycle of phages?

• A phage that reproduces only by the lytic cycle

• A phage replicative cycle that replicates the phage genome without destroying the host

• A phage replicative cycle that culminates in the death of the host cell

• A phage that uses both the lytic and lysogenic cycles

What is the lysogenic cycle of phages?

• A phage that uses both the lytic and lysogenic cycles

• A phage replicative cycle that replicates the phage genome without destroying the host

• A phage replicative cycle that culminates in the death of the host cell

• A phage that reproduces only by the lytic cycle

What is a provirus?

• The protein tail piece that attaches the phage to the host

• A phage that uses both the lytic and lysogenic cycles

• A phage that reproduces only by the lytic cycle

• The viral DNA molecule incorporated into the host cell's chromosome

How do bacteria defend against phages?

• By using the CRISPR-Cas system to target and degrade phage DNA

• By cutting up phage DNA using restriction enzymes

• By mutating their surface proteins to avoid recognition by phages

• By methylating their own DNA to prevent attack by restriction enzymes

What are the two key variables used to classify animal viruses?

• The nature of the viral genome and the presence or absence of viral glycoproteins

• The presence or absence of an envelope and the nature of the viral genome

• The presence or absence of an envelope and the presence or absence of a capsid

• The nature of the viral genome and the presence or absence of a capsid

How do retroviruses replicate their genetic material?

• By using viral glycoproteins to enter the host cell

• By transcribing their proviral DNA into RNA molecules

• By integrating their DNA into the host cell's chromosome

• By using reverse transcriptase to copy their RNA genome into DNA