Chapter 19 - Viruses - Multiple Choice Flashcards
The study of viruses has done all of the following except
a. provide information on the molecular biology of all organisms.
b. illuminate the sexual reproductive cycles of viruses.
c. develop new techniques for manipulating genes.
d. develop an understanding of the causes of diseases.
e. show the role of mutation in the relationship between host and virus.
b. illuminate the sexual reproductive cycles of viruses.
Beijerinck concluded that the cause of tobacco mosaic disease was not a filterable toxin because
a. the infectious agent could not be cultivated on nutrient media.
b. a plant sprayed with filtered sap would develop the disease.
c. the infectious agent could be crystallized.
d. the infectious agent reproduced and could be passed on from a plant infected with filtered sap.
e. the filtered sap was infectious even though microbes could not be found in it.
d. the infectious agent reproduced and could be passed on from a plant infected with filtered sap.
Viral genomes may be any of the following except
a. single-stranded DNA.
b. double-stranded RNA.
c. misfolded infectious proteins.
d. a linear single-stranded RNA molecule.
e. a circular double-stranded DNA molecule.
c. misfolded infectious proteins.
Retroviruses have a gene for reverse transcriptase that
a. uses viral RNA as a template for making complementary RNA strands.
b. protects viral DNA from degradation by restriction enzymes.
c. destroys the host cell DNA.
d. translates RNA into proteins.
e. uses viral RNA as a template for DNA synthesis.
e. uses viral RNA as a template for DNA synthesis.
Virus particles are formed from capsid proteins and nucleic acid molecules
a. by spontaneous self-assembly.
b. at the direction of viral enzymes.
c. by using host cell enzymes.
d. using energy from ATP stored in the tail piece.
e. by both b and d.
a. by spontaneous self-assembly.
A virus has a base ratio of (A + G)/(U + C) = 1. What type of virus is this?
a. a single-stranded DNA virus.
b. a single-stranded RNA virus.
c. a double-stranded DNA virus.
d. a double-stranded RNA virus.
e. a retrovirus.
d. a double-stranded RNA virus.
Vertical transmission of a plant viral disease may involve
a. the movement of viral particles through the plasmodesmata.
b. the inheritance of an infection from a parent plan.
c. a bacteriophage transmitting viral particles.
d. insects carrying viral particles between plants.
e. the transfer of filtered sap.
b. the inheritance of an infection from a parent plan.
Bacteria defend against viral infection through the action of
a. antibiotics that they produce.
b. restriction enzymes that chop up foreign DNA.
c. their R plasmids.
d. reverse transciptase.
e. incorporating viral DNA into the bacterial chromosome.
b. restriction enzymes that chop up foreign DNA.
Drugs that are effective in treating viral infections
a. induce the body to produce antibodies.
b. inhibit the action of viral ribosomes.
c. interfere with the synthesis of viral nucleic acid.
d. change the cell-recognition sites on the host cell.
e. are vaccines that stimulate the immune system to create immunity.
c. interfere with the synthesis of viral nucleic acid.
Which of the following is true of prions?
a. They are emerging viruses.
b. They are fast-acting infectious agents.
c. They probably evolved from transposons.
d. They are infectious proteins that may convert brain proteins into misfolded forms.
e. They may be transferred between animals by sexual contact.
d. They are infectious proteins that may convert brain proteins into misfolded forms.
The replication of the genome of an RNA virus uses
a. DNA polymerase from the host.
b. RNA replicating enzymes coded for by viral genes or carried in the viral capsid.
c. reverse transcriptase to synthesize RNA.
d. RNA polymerase from the host.
e. restriction enzymes from the host.
b. RNA replicating enzymes coded for by viral genes or carried in the viral capsid.
The replication of the genome of a DNA virus uses
a. DNA polymerase from the host.
b. RNA replicating enzymes coded for by viral genes or carried in the viral capsid.
c. reverse transcriptase to make an RNA copy from the DNA.
d. RNA polymerase from the host.
e. restriction enzymes from the host.
a. DNA polymerase from the host.
