Microbiology chapter 5 example questions

Which statement is TRUE? A) All viruses contain their own nucleic acid polymerases. B) RNA viruses contain their own nucleic acid polymerases. C) Viruses do not contain their own nucleic acid polymerases. D) The origins of the nucleic acid polymerases used by viruses are eukaryotic.

A) All viruses contain their own nucleic acid polymerases

In a natural population of diverse slow-growing prokaryotic cells, what type of viruses would you expect to be most common? A) Lytic bacteriophages B) Enveloped viruses C) Icosahedral viruses D) Temperate bacteriophages

A) Lytic bacteriophages

Reverse transcriptase is a(n) A) RNA-dependent DNA polymerase. B) DNA-dependent DNA polymerase. C) RNA-dependent RNA polymerase. D) DNA-dependent RNA polymerase.

A) RNA-dependent DNA polymerase

Which of the following are the hosts for most enveloped viruses? A) Bacteria B) Animals C) Archaea D) Fungi

B) Animals

T4 genes are transcribed by host RNA polymerase, yet this transcription is carefully controlled so that groups of T4 genes are transcribed in a specific order after infection. How is this accomplished? A) Early T4 genes encode for proteolytic enzymes that destroy the host RNA polymerase. Subsequently, a viral polymerase is created that transcribes the middle and late genes in the correct order. B) Early and middle T4 genes encode for RNA polymerase-modifying proteins so that only phage promoters are recognized. C) Each group of T4 genes has a different promoter that indicates the order in which they should be transcribed based on the affinity of the promoter for the host RNA polymerase. D) Rolling circle replication of the viral genome ensures that the genes are available for transcription in the correct order.

B) Early and middle T4 genes encode for RNA polymerase-modifying proteins so that only phage promoters are recognized

A prophage replicates A) along with its host while the lytic genes are expressed. B) along with its host while the lytic genes are not expressed. C) independently of its host while the lytic genes are expressed. D) independently of its host while the lytic genes are not expressed.

B) along with its host while the lytic genes are not expressed

For a virus to cause a latent infection, it must possess A) ssDNA. B) dsDNA. C) dsRNA. D) Any type of viral genome can lead to a latent infection.

B) dsDNA

When a virus enters a host cell in which it can replicate, the process is called a(n) A) insertion. B) infection. C) prophage. D) excision.

B) infection

When a solution composed of bacteria and infectious virions are mixed and spread on an agar plate, ________ form where viruses lyse the host cells. A) insertion sequences B) plaques C) prophages D) colonies

B) plaques

The use of ________ is the easiest and most effective way of studying many animal and plant viruses. A) bacterial cultures B) tissue or cell culture C) live hosts D) prophages

B) tissue or cell culture

The general steps of the viral life cycle are similar in most viruses. One major exception, however, is entry into the host cell. How does this step differ between an animal cell and E coli? A) The entire virion is taken into an animal cell, but only the viral genome enters E coli. B) The entire virion enters E coli, but only the nucleic acid is taken up by animal cells. C) The virion fuses to the bacterial cell membrane of E coli, while the genome is injected into an animal cell. D) The virion randomly attaches to E coli, but viral binding to a specific receptor is required for entry into animal cells.

A) The entire virion is taken into an animal cell, but only the viral genome enters E coli

All viral particles A) are metabolically inert. B) are smaller than bacterial cells. C) contain an envelope to prevent its degradation outside of a host. D) exhibit cell lysis under a particular condition.

A) are metabolically inert

For bacteriophages and animal viruses ________ is the step in the viral life cycle that determines host cell specificity. A) attachment B) penetration C) synthesis D) assembly

A) attachment

Regarding the viral membrane of an enveloped virus, the lipids are derived from the ________, and the proteins are encoded by ________. A) host's cell membrane / viral genes B) virion / viral genes C) host's cell membrane / host's genes D) virion / host's genes

A) host's cell membrane / viral genes

Viral replication is A) independent of the host cell's DNA but dependent on the host cell's enzymes and metabolism. B) independent of both the host cell's DNA and the host cell's enzymes and metabolism. C) dependent on the host cell's DNA and RNA. D) dependent on the host cell's DNA, RNA, enzymes, and metabolism.

A) independent of the host cell's DNA but dependent on the host cell's enzymes and metabolism

Viral replication occurs A) intracellularly. B) extracellularly. C) both intracellularly and extracellularly. D) either intracellularly or extracellularly, depending on the virus involved.

A) intracellularly

The T4 bacteriophage could not infect Staphylococcus aureus because this bacterium does NOT possess a A) lipopolysaccharide outer membrane. B) teichoic acid outer membrane. C) pili. D) flagella.

A) lipopolysaccharide outer membrane

A virus that kills its host is said to be A) lytic or virulent. B) temperate. C) lysogenic. D) virulent or lysogenic, but not temperate.

A) lytic or virulent

A cell that allows the complete replication cycle of a virus to take place is said to be a A) permissive host. B) viral cell. C) dead cell. D) lytic cell.

A) permissive host

Viral proteins are categorized as early, middle, and late. Early proteins typically are necessary for A) production of viral mRNA. B) packaging of DNA into the nucleocapsid. C) copying the viral genome. D) production of viral mRNA and copying the viral genome.

A) production of viral mRNA

The majority of many important human viral diseases are caused by A) ssRNA viruses. B) ds RNA viruses. C) ss DNA viruses. D) ds DNA viruses.

A) ssRNA viruses

The growth of viruses in a culture is described as a one-step growth curve, because A) virion numbers show no increase during intracellular replication and can only be counted after the virions burst from the host cell. B) there is only one step in the viral life cycle which leads to only one replicative cycle in a culture. C) assembly and release actually occur in one step. D) the eclipse phase prevents the plating and enumeration of virions although new virions are produced at a steady rate during the eclipse phase.

A) virion numbers show no increase during intracellular replication and can only be counted after the virions burst from the host cell

What would be the consequence of deleting the late T4 genes? A) The T4 genome would not be copied. B) T4 mRNA would not be produced. C) T4 capsid proteins would not be made. D) ATP would not be produced and the T4 genome would not be packaged into the capsid.

C) T4 capsid proteins would not be made

Restriction is A) the viral process whereby a host's DNA ceases normal functioning. B) the viral process whereby the virus prevents other viruses from entering the cell. C) a general host mechanism to prevent the invasion of foreign nucleic acid. D) a general host mechanism to prevent virus particles from further infective action.

C) a general host mechanism to prevent the invasion of foreign nucleic acid

The term ʺphageʺ is generally reserved for the viruses that infect A) animals. B) plants. C) bacteria. D) multiple species.

C) bacteria

Enveloped viral membranes are generally ________ with associated virus-specific ________. A) lipid bilayers / phospholipids B) protein bilayers / lipids C) lipid bilayers / proteins D) glycolipid bilayers / phospholipids

C) lipid bilayers / proteins

Some bacteriophage possess an enzyme similar to ________, which makes a small hole in the bacterial cell wall, allowing the viral nucleic acid to enter. A) peptidoglycanase B) infectase C) lysozyme D) nuclease

C) lysozyme

Viral size is generally measured in A) micrometers. B) picometers. C) nanometers. D) centimeters.

C) nanometers

When packaged in the virion, the complete complex of nucleic acid and protein is known as the virus A) capsid. B) concatemer. C) nucleocapsid. D) envelope.

C) nucleocapsid

The concentration of infectious plaque forming units (pfu) per volume of fluid is known as the viral A) infectivity. B) virulence. C) titer. D) fluid infectivity.

C) titer

Which of the following statements is FALSE? A) Lambda is a temperate phage that infects Escherichia coli. B) Lambda is a linear double-stranded DNA phage. C) Lambda is replicated by the rolling circle mechanism. D) Lambda always circularizes upon entering the host cell.

D) Lambda always circularizes upon entering the host cell

What are the possible consequences of viral infection of an animal cell? A) Rapid lysis or latent infections B) Lysogeny followed by eventual lysis C) Lysis or lysogeny D) Outcomes vary from rapid lysis to persistent infections, latent infections, or cancer.

D) Outcomes vary from rapid lysis to persistent infections, latent infections, or cancer

Which of the following enzymes would you expect to find in the virion of a retrovirus, but NOT in a bacteriophage? A) Lysozyme B) Methylase C) Restriction enzymes D) Reverse transcriptase

D) Reverse transcriptase

All of the following can act as receptors for various bacteriophages EXCEPT A) iron transport proteins. B) flagella. C) sugar transporters. D) cilia.

D) cilia

Cellular receptors may be composed of A) proteins. B) carbohydrates. C) lipids. D) combinations of proteins, carbohydrates, and/or lipids.

D) combinations of proteins, carbohydrates, and/or lipids

Bacteriophages' genomes are typically composed of A) single-stranded RNA. B) single-stranded DNA. C) double-stranded RNA. D) double-stranded DNA.

D) double-stranded DNA

The size and shape of viral particles is largely governed by the size and packaging of the viral A) envelope. B) enzymes. C) prophage. D) genome.

D) genome

As a consequence of infection by a temperate bacteriophage such as lambda, the host cell A) lyses as a result of bacteriophage release. B) never lyses but continues to divide and replicate both itself and the prophage. C) divides faster at moderate temperatures. D) may lyse or may continue to divide and replicate both itself and the prophage.

D) may lyse or may continue to divide and replicate both itself and the prophage

Viruses infecting ________ are typically the easiest to grow in the laboratory. A) plants B) animals C) fungi D) prokaryotes

D) prokaryotes

Retroviruses are medically important viruses because A) they include the poliovirus. B) they include the influenza virus. C) they include all human pathogenic viruses. D) they include some viruses that cause cancer and HIV.

D) they include some viruses that cause cancer and HIV