front 1 Which of the following statements concerning viruses is FALSE? A) Viruses never contain both DNA and RNA. B) Viruses enter a cell to complete the replication they have begun extracellularly. C) Some viruses have an outer membrane called an envelope. D) Viral capsids can assume one of three basic shapes. E) Tobacco mosaic virus was the first virus to be discovered and characterized. | back 1 B) Viruses enter a cell to complete the replication they have begun extracellularly. |
front 2 The outermost layer of a virion fulfills which of the following functions of the virus? A) protection B) recognition C) replication D) protection and recognition E) recognition and replication | back 2 D) protection and recognition |
front 3 During the intracellular state, a virus exists as A) a lipid. B) a protein. C) a nucleic acid. D) both a protein and a nucleic acid. E) both a lipid and a nucleic acid. | back 3 C) a nucleic acid. |
front 4 Viruses are primarily classified according to their A) type of nucleic acid. B) type of life cycle. C) number of chromosomes. D) shape. E) size. | back 4 A) type of nucleic acid. |
front 5 Host specificity of a virus is due to A) particular genes that it shares with the infected cell. B) the presence of an envelope. C) differences in size between the virus and the host cell. D) the presence or absence of a cell wall on the host cell. E) interactions between viral and cellular surface molecules. | back 5 A) particular genes that it shares with the infected cell. |
front 6 Who was the first person to demonstrate the existence of viruses? A) Stanley B) Rous C) Lacks D) Ivanowsky E) Prusiner | back 6 D) Ivanowsky |
front 7 How are fungal viruses different from viruses that infect other organisms? A) They have no extracellular state. B) They have only DNA for genetic material. C) They have no capsid. D) They have no intracellular state. E) They cannot pass through a filter. | back 7 A) They have no extracellular state. |
front 8 Which of the following infectious particles do NOT have protein in their structure? A) bacteriophages B) prions C) animal viruses D) viroids E) both prions and viroids | back 8 D) viroids |
front 9 Which of the following would NOT be found as a component of a bacteriophage? A) envelope B) icosahedral capsid C) DNA D) tail fibers E) base plate | back 9 A) envelope |
front 10 Which of the following statements regarding virus taxonomy is true? A) Viruses are classified on the basis of the taxonomy of their host organisms. B) Virus classes are well established. C) Some virus family names are derived from the name of an important member of the family. D) The species epithet is a Latin descriptor of the virion structure. E) Virus classes are based on the domain of the host organism. | back 10 C) Some virus family names are derived from the name of an important member of the family. |
front 11 Which of the following statements comparing virus classification and taxonomy of organisms is true? A) Both viruses and organisms are organized into classes. B) The common names of viruses are their genus and species epithet, as they are with organisms. C) Both viruses and organisms are organized into domains. D) Genus and specific epithet are used in both classification systems. E) Only families are common to both viral classification and organism taxonomy. | back 11 D) Genus and specific epithet are used in both classification systems. |
front 12 Put the following stages of a lytic replication cycle in order, from earliest to latest stages: I. Synthesis II. Assembly III. Attachment IV. Release V. Entry A) III, V, I, II, IV B) III, II, V, I, IV C) V, III, II, IV, I D) I, III, V, II, IV E) I, II, III, V, IV | back 12 A) III, V, I, II, IV |
front 13 13) Which of the following is associated with the attachment of a bacteriophage to a bacterial cell? A) random collisions B) chemical attractions C) receptor specificity D) chemical attractions and receptor specificity E) random collisions, chemical attractions, and receptor specificity | back 13 E) random collisions, chemical attractions, and receptor specificit |
front 14 14) The enzyme lysozyme is critical for which of the stages of a bacteriophage T4 infection cycle? A) entry B) assembly C) entry and release D) synthesis E) attachment | back 14 C) entry and release |
front 15 The phenomenon of transduction is associated with which of the stages of a bacteriophage infection cycle? A) attachment B) assembly C) release D) synthesis E) entry | back 15 B) assembly |
front 16 Which of the following events occurs in the lytic cycle of bacteriophage T4 infection but NOT in the lysogenic cycle? A) attachment B) entry C) digestion of host DNA D) viral protein synthesis E) both digestion of host DNA and viral proteins synthesis | back 16 C) digestion of host DNA |
front 17 Why is lysogeny advantageous to a bacteriophage? A) It speeds up the viral infection cycle. B) The genetic material of the bacteriophage can be passed on to future generations of cells. C) It allows the bacteriophage to infect cells it would not normally infect. D) It allows the bacteriophage to destroy the host cell's DNA. E) It enables the bacteriophage to take over the cell. | back 17 B) The genetic material of the bacteriophage can be passed on to future generations of cells. |
front 18 Which of the following agents is capable of inducing conversion of a prophage back to a lytic phage? A) UV light B) X rays C) presence of +ssRNA D) UV light and X rays E) UV light and +ssRNA | back 18 D) UV light and X rays |
front 19 Zones of clearing in cell cultures that are the result of virus infection are called plaques. Sometimes "cloudy plaques" are seen on bacterial cultures infected with bacteriophage. What type of viral infection might cause this appearance? A) lytic B) lysogenic C) prion D) viroid E) transducing | back 19 B) lysogenic |
front 20 Which of the following is matched INCORRECTLY? A) poliovirus — direct penetration B) herpesvirus — endocytosis C) adenovirus — membrane fusion D) measles virus — membrane fusion E) HIV — membrane fusion | back 20 C) adenovirus — membrane fusion |
front 21 Reverse transcriptase is associated with which of the following? A) dsDNA viruses B) +ssRNA viruses C) -ssRNA viruses D) retroviruses E) dsRNA viruses | back 21 D) retroviruses |
front 22 The genome of which of the following types of animal virus can act directly as mRNA? A) retroviruses B) +ssRNA viruses C) -ssRNA viruses D) ssDNA viruses E) dsRNA viruses | back 22 B) +ssRNA viruses |
front 23 Which of the following types of animal virus requires RNA-dependent RNA transcriptase to be replicated? A) +ssRNA viruses B) ssDNA viruses C) -ssRNA viruses D) retroviruses E) dsDNA viruses | back 23 C) -ssRNA viruses |
front 24 In contrast to most dsDNA animal viruses, the poxviruses replicate solely in the cytoplasm of the host cell. This fact implies that the viral genome may encode A) reverse transcriptase. B) a DNA polymerase. C) RNA-dependent RNA transcriptase. D) ribosome components. E) reverse transcriptase and RNA-dependent RNA transcriptase. | back 24 B) a DNA polymerase. |
front 25 Which of the following membranes can give rise to a viral envelope? A) the nuclear membrane B) the cytoplasmic membrane C) the endoplasmic reticulum D) the nuclear and cytoplasmic membranes E) the nuclear and cytoplasmic membranes and the endoplasmic reticulum | back 25 E) the nuclear and cytoplasmic membranes and the endoplasmic reticulum |
front 26 The majority of cases of infant diarrhea are caused by what kind of virus? A) dsDNA viruses B) dsRNA viruses C) +ssRNA viruses D) retroviruses E) -ssRNA viruses | back 26 B) dsRNA viruses |
front 27 How is the HIV provirus different from a lambda phage prophage? A) The HIV provirus is integrated permanently into the host cell's DNA. B) All subsequent generations of HIV-infected cells carry the provirus. C) All the offspring of a cell infected with a prophage will contain the virus. D) The HIV provirus is inactive inside the host cell. E) Lambda phage-infected cells produce virus slowly over time. | back 27 A) The HIV provirus is integrated permanently into the host cell's DNA. |
front 28 Which of the following individuals discovered prions? A) Lacks B) Iwanowsky C) Prusiner D) Stanley E) Rous | back 28 C) Prusiner |
front 29 One mechanism by which viruses may cause cancer is to interrupt the genetic regulatory sequences of repressor proteins. Which of the following types of viruses is most likely to be involved in causing cancer by this mechanism? A) +ssRNA viruses B) dsRNA viruses C) -ssRNA viruses D) retroviruses E) +ssRNA and -ssRNA viruses | back 29 D) retroviruses |
front 30 Tumors invade other organs and tissues in a process called A) neoplasia. B) a plaque assay. C) latency. D) budding. E) metastasis. | back 30 E) metastasis. |
front 31 Plaque assays are used for A) evaluating the cancer-causing ability of a virus. B) estimating the number of phages in a culture. C) the study of prions. D) cultivating viruses that cannot be grown any other way. E) counting the number of latent phages in a cell. | back 31 B) estimating the number of phages in a culture. |
front 32 Diploid cell cultures and continuous cell cultures differ in which of the following ways? A) longevity B) source of cells C) convenience of use D) longevity and convenience of use E) longevity and source of cells | back 32 E) longevity and source of cells |
front 33 Viroids infect A) bacteria. B) plants. C) fungi. D) plants and animals. E) all organisms. | back 33 B) plants. |
front 34 How are prions different from all other known infectious agents? A) They cannot reproduce outside a cell. B) They act as slow viruses. C) They cause neurological problems. D) They can be destroyed by incineration. E) They lack nucleic acid. | back 34 E) They lack nucleic acid. |
front 35 The infectious particles of fungi have RNA genomes and lack a capsid. They are therefore similar to A) bacteriophages. B) enveloped viruses. C) prions. D) viroids. E) lysogens. | back 35 D) viroids. |
front 36 A lipid membrane is present A) only in viruses. B) in both cells and viruses. C) only in cells. D) only in prions. E) in both prions and viroids. | back 36 B) in both cells and viruses. |
front 37 Double-stranded DNA genomes are found A) only in viroids. B) only in cells. C) only in viruses. D) in both cells and viruses. E) in both viruses and viroids. | back 37 D) in both cells and viruses. |
front 38 Double-stranded RNA genomes can be found A) only in cells. B) in both cells and viruses. C) only in viruses. D) in prions. E) in both prions and viruses. | back 38 C) only in viruses. |
front 39 Cytoplasm is a characteristic of A) cells only. B) viruses only. C) both cells and viruses. D) viroids only. E) both viroids and viruses. | back 39 A) cells only. |
front 40 Proteins are present in A) cells only. B) viruses only. C) viroids only. D) both cells and viruses. E) cells, viruses, and viroids. | back 40 D) both cells and viruses. |
front 41 Viruses are shed slowly and steadily during A) lytic replication. B) budding. C) oncogenesis. D) persistent infection. E) latency. | back 41 D) persistent infection. |
front 42 During __________, viruses remain dormant in a cell. A) budding B) latency C) lytic replication D) persistent infection E) oncogenesis | back 42 B) latency |
front 43 Virus replication results in the death of the cell in a(n) __________ infection. A) lytic B) latent C) persistent D) oncogenic E) both latent and persistent | back 43 A) lytic |
front 44 Virus infection results in cancer in the process of A) lytic replication. B) budding. C) oncogenesis. D) persistent infection. E) latency. | back 44 C) oncogenesis. |
front 45 is a mechanism of release for enveloped viruses. A) Lytic replication B) Persistent infection C) Oncogenesis D) Latency E) Budding | back 45 E) Budding |
front 46 Viruses cause most human cancers. | back 46 FALSE |
front 47 Most viruses cannot be seen by light microscopy. | back 47 TRUE |
front 48 Protozoa are susceptible to viral attack. | back 48 TRUE |
front 49 Many diseases of plants are caused by infectious RNA molecules lacking capsids. | back 49 TRUE |
front 50 Bacteriophages are cheaper and easier to culture than animal viruses. | back 50 TRUE |
front 51 Assembly of new viruses is a process that usually requires the direction of a variety of viral and cellular enzymes. | back 51 FALSE |
front 52 Bacteriophage release is a gradual process in which small numbers are released at a time. | back 52 FALSE |
front 53 Poxvirus is assembled in the cytoplasm of the cell instead of in the nucleus, as is the case for the majority of dsDNA viruses. | back 53 TRUE |
front 54 Transcription of RNA from RNA does not occur in uninfected cells. | back 54 TRUE |
front 55 Virus vaccines are always cultured in embryonated chicken eggs. | back 55 FALSE |
front 56 The combination of a virus's protein coat and nucleic acid core is called the __________. | back 56 Answer: nucleocapsid |
front 57 Viral capsids are composed of subunits called __________. | back 57 Answer: capsomeres |
front 58 A(n) __________ is a 20-sided polyhedral capsid. | back 58 Answer: icosahedron |
front 59 Bacteriophages use the enzyme __________ to breach the bacterial cell wall. | back 59 Answer: lysozyme |
front 60 The number of new bacteriophages released from each infected cell is called the __________ size. | back 60 Answer: burst |
front 61 The process in which viral capsids are removed within the infected cell is called __________. | back 61 Answer: uncoating |
front 62 Virus RNA that can act directly as mRNA is __________-strand RNA. | back 62 Answer: positive |
front 63 RNA viruses such as HIV require the activity of reverse __________ to become proviruses. | back 63 Answer: transcriptase |
front 64 In enveloped viruses, virus-encoded __________ proteins are required for the assembly of the envelope around the capsid. | back 64 Answer: matrix |
front 65 Genes that play a role in proper cell division but may also play a role in some types of cancer are called __________. | back 65 Answer: protooncogenes |
front 66 A(n) __________ is a clear zone on a bacterial lawn where cells have been killed by the activity of a bacteriophage. | back 66 Answer: plaque |
front 67 Three __________ represent the highest level of taxonomic rank used in classifying viruses. | back 67 Answer: orders |
front 68 Prions are composed of a single protein called __________. (Be sure you use proper capitalization.) | back 68 Answer: PrP |
front 69 An animal virus that does not have an envelope is described as a(n) __________ virion. | back 69 Answer: naked |