Name: 
 

Chapter 18 Review



Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

 1. 

Which of the following is (are) true about viruses?
a.
Viruses are classified below the cellular level of biological organization.
b.
A single virus particle contains both DNA and RNA.
c.
Even small virus particles are visible with light microscopes.
d.
Only A and B are true.
e.
A, B, and C are true.
 

 2. 

Which of the following is a characteristic of all viruses?
a.
a nucleic acid genome
b.
a protein capsid
c.
a viral envelope
d.
A and B only
e.
A, B, and C
 

 3. 

The host range of a virus is determined by
a.
the proteins on its surface.
b.
whether its nucleic acid is DNA or RNA.
c.
the proteins on the surface of the host cell.
d.
the enzymes produced by the virus before it infects the cell.
e.
both A and C
 

 4. 

What is the function of the single-stranded RNA in certain animal viruses?
a.
It can serve directly as mRNA.
b.
It can serve as a template for mRNA synthesis.
c.
It can serve as a template for DNA synthesis.
d.
Only A and C are correct.
e.
A, B, and C are correct.
 

 5. 

The membrane making up the viral envelope can come from
a.
the virus itself, using enzymes encoded by the virus.
b.
the nuclear membrane of an infected cell.
c.
the plasma membrane of an infected cell.
d.
both A and B
e.
both B and C
 

 6. 

The simplest infectious biological systems are
a.
bacteria.
b.
viruses.
c.
viroids.
d.
both A and B
e.
both B and C
 

 7. 

Which of the following can be effective against viral diseases?
a.
vaccination
b.
nucleoside analogs that inhibit DNA synthesis
c.
antibiotics
d.
A and B only
e.
A, B, and C
 

 8. 

RNA viruses appear to have higher rates of mutation because
a.
RNA nucleotides are more unstable than DNA nucleotides.
b.
replication of their genomes does not involve the proofreading steps of DNA replication.
c.
RNA viruses replicate faster.
d.
RNA viruses can incorporate a variety of nonstandard bases.
e.
RNA viruses are more sensitive to mutagens.
 

 9. 

Which of the following contributes to the emergence of viral disease?
a.
production of new virus strains through mutation
b.
spread of existing virus from one host species to another
c.
transformation from lytic to lysogenic activity
d.
A and B only
e.
A, B, and C
 

 10. 

The difference between vertical and horizontal transmission of plant viruses is that
a.
vertical transmission refers to the transmission of a virus from a parent plant to its progeny, and horizontal transmission refers to one plant spreading the virus to another plant.
b.
vertical transmission refers to the spread of viruses from upper leaves to lower leaves of the plant, and horizontal transmission refers to the spread of a virus among leaves at the same general level.
c.
vertical transmission refers to the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission refers to the spread of viruses among plants of similar size.
d.
vertical transmission refers to the transfer of DNA from one type of plant virus to another, and horizontal transmission refers to the exchange of DNA between two plant viruses of the same type.
e.
vertical transmission refers to the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission refers to the spread of viruses among plants of the same species.
 

 11. 

In biotechnology, genes are commonly introduced into bacterial cells by incubating the cells together with DNA and high concentrations of calcium ions. This is an example of
a.
transformation.
b.
translocation.
c.
transduction.
d.
conjugation.
e.
transposition.
 

 12. 

A scientist is studying a strain of bacteria that commonly transfers genes to other bacteria. Which of the following would provide evidence that the genes are being transferred through specialized transduction?
a.
Transmission of the genes is always accompanied by transfer of the F plasmid.
b.
Transmission of the genes is always accompanied by transfer of the R plasmid.
c.
The same one or several gene(s) are always transferred.
d.
The transmission of the genes is dramatically enhanced in the presence of calcium.
e.
The bacterial strain is often infected by a virulent phage.
 

 13. 

What does the operon model attempt to explain?
a.
the coordinated control of gene expression in bacteria
b.
bacterial resistance to antibiotics
c.
how genes move between homologous regions of DNA
d.
the mechanism of viral attachment to a host cell
e.
horizontal transmission of plant viruses
 

 14. 

The lactose operon is likely to be transcribed when
a.
there is more glucose in the cell than lactose.
b.
the cyclic AMP levels are low.
c.
there is lactose but no glucose in the cell.
d.
the cyclic AMP and lactose levels are both high within the cell.
e.
both C and D
 

 15. 

Transcription of the structural genes in an inducible operon
a.
occurs all the time.
b.
starts when the pathway's substrate is present.
c.
starts when the pathway's product is present.
d.
stops when the pathway's product is present.
e.
does not produce enzymes.
 



 
Check Your Work     Reset Help