Question

Question 41 (1 point) The initial biochemicl step at the beginning of the replication state of DNA virus reproduction is Question 41 options: is the transcription of the viral nucleic acid into mRNAs the formation of the nucleocapsid is the translation of viral mRNAs into viral enzymes. is the replication of the viral nucleic acid using the host cell nucleases.

Question 42 (1 point) Host specificity of a virus is due to Question 42 options: A) the presence of an envelope. B) particular genes that it shares with the infected cell. C) the presence or absence of a cell wall on the host cell. D) interactions between viral and cellular surface molecules. E) differences in size between the virus and the host cell.

Question 43 (1 point) When talking about viruses an infection can be classified as productive if the infection results in the formation of infectious progeny virions. Question 43 options: A) True B) False

Question 44 (1 point) All viruses cause serious and permanent damage to infected cells. Question 44 options: True False

Question 45 (1 point) The influenza viruses posess dsRNA, an envelope, and a helical nucleocapsid. Question 45 options: True False

Question 46 (1 point) Which of the following statements is correct? Question 46 options: A) the pol gene is not required for viral replication of the Rous sarcoma virus. B) Retroviruses that replicate independently within a host cell are termed defective. C) A protein kinasenecessary for malignat transformation of the host cell is coded by the src gene. D) The poxvirus genome consists of seven genes.

Question 47 (1 point) Reverse transcriptase is associated with which of the following? Question 47 options: A) retroviruses B) dsRNA viruses C) dsDNA viruses D) -ssRNA viruses E) +ssDNA viruses

Question 48 (1 point) Host specificity of a virus can be expanded due to phenotypic mixing. Question 48 options: A) True B) False

Question 49 (1 point) The phenomenon of transduction is associated with which stage of a bacteriophage life cycle? Question 49 options: A) synthesis B) attachment C) assembly D) entry E) release

Question 50 (1 point) Tropism exhibited by a viruses does not defines that virus host range. Question 50 options: True False

Question 51 (1 point) Members of the picornaviridae (polio viruses) Question 51 options: A) measure about 50 - 75 nm. B) are of binal morphology. C) are helical viruses. D) posess ssRNA. E) are enveloped.

Question 52 (1 point) How is the HIV provirus different from a lambda phage prophage? Question 52 options: A) All subsequent generations of HIV-infected cells carry the prophage. B) The HIV provirus is integrated permanently into the host cell's DNA. C) The HIV provirus is inactive inside the host cell. D) Lambda phage-infected cells produce virus slowly over time. E) All the offspring of a cell infected with a prophage will contain the virus.

Question 53 (1 point) Transcription of RNA from RNA is not a normal cellular process. Question 53 options: A) True B) False

Question 54 (1 point) At the time of Louis Pasteur and Robert Koch, the term"virus" was used to refer to: Question 54 options: anthrax etiologic agent of tuberculosis cholera etiologic agent of syphilis all of the above

Question 55 (1 point) Which of the following types of animal virus requires RNA-dependent RNA polymerase for replication? Question 55 options: A) -ssRNA viruses B) +ssRNA viruses C) dsRNA viruses D) A and B only E) A, B, and C

Question 56 (1 point) Which of the following viruses contain dsRNA genome? Question 56 options: A) orthomyxoviridae B) rhabdoviridae C) picornaviridae D) reoviridae E) paramyxoviridae

Question 57 (1 point) In order to result in a productive infection of susceptible cells, RNA tumor viruses must Question 57 options: A) Must transcribe their single-stranded genomic RNA to a double-stranded DNA that will exist as a plasmid in the cell cytoplasm. B) Integrate their RNA in the host chromosome C) Must transcribe their double-stranded genomic RNA to a double-stranded DNA that integrates in the cell chromosome. l D) Must allow their RNA to exit as a double-stranded RNA plasmi in the cytoplasm of the infected cell E) Must transcribe their single-stranded genomic RNA to a double-stranded DNA that integrates in the cell chromosome.

Question 58 (1 point) Artificial introduction of any foreign nucleic acid into a cell is known as: Question 58 options: A) Induction B) Transduction C) Zygotization D) Transfection E) Conjugation

Question 59 (1 point) The onc gene found in certain leukemia viruses is analogous to the gag gene found in the Rous sarcome virus. Question 59 options: True False

Question 60 (1 point) Microorganisms such as bacteria are measured in _________, whereas viruses are measured in __________ . Question 60 options: A) micrometers; millimeters B) inches; millimeters C) millimeters; inches D) millimeters ; micrometers E) micrometers ; nanometers

Answer 1

Solution:

41) The initial biochemical stp is the transcription of the viral nucleic acid into mRNAs . These are then translated to produce proteins that helps replicate viral genome in association with several host machinery.

42)  D) interactions between viral and cellular surface molecules. The viruses typically infects a limited number of hosts. It is due to the limit in the interaction range of proteins expressed on the surfece of virus and the receptors expressed on the surface of host cell. Many interactions between virus cell ligands and host cell receptors are specific. For example, the HIV-1 specifically binds to the chemokine receptors CXCR-4 and CCR5.

43) True. It is necessary to produce several infectious progeny virions during an infection cycle. Failure in this prossess affects the stability of viruses in their fight against host immune responses. Many viruses induce frequent mutations in their genome during the production of progeny. This forced incorporation of mutations change the antigenic molecules on the surface of progeny that helps evade the host immune system. So the production of progeny as many possible is the evolutionary stable strategy.

44) False. Eventhough many of the viral infections eventually causes the lysis of host cells and cellular machinary. Certain viruses that induce chronic persistent infections. Many persistent infections have both silent and productive periods during infection without rapidly killing or even producing excessive damage of the host cells.