Micro Chapter 6 Exam Questions And Answers Verified 100% Correct

Micro Chapter 6 Exam Questions And Answers Verified 100% Correct 1. Which of the following is most true of a viral DNA genome? A. It uses the same four nitrogenous bases found in prokaryotic and eukaryotic DNA. B. It may have the normal bases found in prokaryotic and eukaryotic DNA, or it may have one or more unusual bases. C. It is usually composed of unusual bases unique to viruses. D. Viruses do not use DNA for their genome. - ANSWER B. It may have the normal bases found in prokaryotic and eukaryotic DNA, or it may have one or more unusual bases. 2. Virion size ranges from A. 1-40 nm. B. 10-400 nm. C. 600- 1,000 nm. D. 1,000-10,000 nm. - ANSWER B. 10-400 nm. 3. Viral capsids are generally constructed without any outside aid once the subunits have been synthesized. This process is called A. facilitated assembly. B. self-assembly. C. spontaneous maturation. D. self-maturation. - ANSWER B. self-assembly. 4. In which of the following stages of the viral infectious cycle do enveloped viruses usually acquire their envelopes? A. penetration B. component biosynthesis C. assembly D. release - ANSWER D. release 5. Most enveloped viruses use the host __________ membrane as their envelope source. A. plasma B. nuclear C. mitochondrial D. none of these - ANSWER A. plasma 6. Poliovirus receptors are found A. in cells of all tissues. B. in spinal cord anterior horn cells only. C. in nasopharynx, gut, and spinal cord anterior horn cells. D. in gut cells only. - ANSWER C. in nasopharynx, gut, and spinal cord anterior horn cells. 7. Nonenveloped viruses most often gain access to eukaryotic host cells by A. fusion with the host cell plasma membrane followed by entrance of the nucleocapsid into the cytoplasm. B. endocytosis. C. pinocytosis. D. nucleic acid injection through the plasma membrane. - ANSWER B. endocytosis. 8. Which of the following represent(s) the way(s) in which enveloped viruses acquire their envelopes? A. Budding through the plasma membrane. B. Budding through internal cellular membranes. C. Viral enzymes are responsible for production of the envelope. D. For some viruses, a is correct; for other viruses, b is correct. - ANSWER D. For some viruses, a is correct; for other viruses, b is correct. 6. Which of the following has been associated with a form of liver cancer? A. Human papilloma virus. B. Hepatitis B virus. C. Human T-cell lymphotropic virus. D. Hepatitis A virus. - ANSWER B. Hepatitis B virus. 9. Animal viruses have been cultivated in A. suitable host animals. B. embryonated eggs. C. tissue cultures (monolayers of animal cells). D. all of the choices - ANSWER D. all of the choices 10. Which of the following can be used to cultivate plant viruses? A. Cultures of separated plant cells. B. Whole plants. C. Plant protoplast cultures. D. All of these can be used to cultivate plant viruses. - ANSWER D. All of these can be used to cultivate plant viruses. 51. 0.2 mls of a 10-4 dilution of a virus preparation yields 90 plaques. What is the number of PFU per ml in the undiluted virus preparation? A. 9.0 105 B. 4.5 106 C. 4.5 107 D. 9.0 108 - ANSWER B. 4.5 106 52. A ________ assay is most useful for determining the viability of a viral preparation? A. direct (electron microscopic) count B. hemagglutination C. plaque D. PCR - ANSWER C. plaque 53. Hemagglutination is A. the clumping together of red blood cells in the presence of a viral suspension. B. the binding of iron in the process of a viral suspension. C. the clumping together of infected cells in the presence of a viral suspension. D. none of the choices - ANSWER A. the clumping together of red blood cells in the presence of a viral suspension. 57. Which of the following is not a mechanism by which viruses cause cancer? A. They carry a cancer-causing gene into the cell. B. They encode proteins that bind to and inactivate host cell proteins known as tumor suppressor proteins. C. They produce defective interfering particles. D. An expression of viral proteins results in abnormal expression of genes that regulate cell growth and reproduction. - ANSWER C. They produce defective interfering particles. 58. Which of the following is not true regarding the human hepatitis D virusoid? A. Its genome is a circular, single-stranded RNA molecule. B. It needs a helper virus to infect host cells. C. It produces one protein called the delta antigen. D. All of the statements are true. - ANSWER D. All of the statements are true. 59. Which of the following is not true of viroids? A. Viroids are small circular ssRNA molecules. B. Viroids have no protein capsids. C. Viroid RNA does not serve as mRNA nor does it direct the synthesis of mRNA. D. Extracellular viroids have a lipid bilayer envelope. - ANSWER D. Extracellular viroids have a lipid bilayer envelope.