OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth Chapter 13: Control of Microbial Growth * = Correct answer | 2022 latest update

OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth Chapter 13: Control of Microbial Growth * = Correct answer Multiple Choice 1. Which of the following is not an example of a fomite? A. catheter B. doorknob C. mosquitoes* D. towels Difficulty: Easy ASM Standard: 13, 14, 23 2. HEPA filters are required for which Biological Safety Level (BSL)? A. BSL 1 B. BSL 2 C. BSL 3 D. BSL 4* Difficulty: Easy ASM Standard: 14, 37 3. From a clinical perspective, aseptic technique is carried out to do which of the following? A. clean fomites B. contaminate fomites C. introduce contamination in living tissue D. prevent contamination in living tissue* Difficulty: Easy ASM Standard: 36, 37 4. The autoclave uses which of the following mechanism(s) for sterilization? A. pressure B. temperature C. pressure and temperature* D. pressure, temperature, and pH Difficulty: Easy ASM Standard: 14, 36, 37 5. Autoclaves are designed to kill which of the following heat-resistant microbes? A. endospores* B. prions C. vegetative bacterial and fungal cells Page 1 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth D. viruses Difficulty: Easy ASM Standard: 14, 36, 37 6. The decimal reduction time (D-value) is how long it takes to kill which percentage of a microbial population? A. 10% B. 50% C. 90%* D. 100% Difficulty: Moderate ASM Standard: 14 7. Which of the following actions would be most clearly considered bacteriostatic rather than bactericidal? A. autoclaving bacterial cultures B. placing a bacterial culture in the −80 C freezer* C. spraying 70% alcohol on a laboratory bench D. treating a mattress with ethylene oxide Difficulty: Moderate ASM Standard: 14 8. Microbial death follows which type of trend? A. linear B. logarithmic* C. power series D. variable Difficulty: Moderate ASM Standard: 14 9. Which of the following are the standard conditions for an autoclave? A. 100 C, 1 psi, 60 minutes B. 121 C, 1 psi, 60 minutes C. 121 C, 15 psi, 20 minutes* D. 212 C, 15 psi, 10 minutes Difficulty: Moderate ASM Standard: 14, 36, 37 10. Which of the following is not a milkborne pathogen? A. Escherichia coli O157:H7 B. Listeria monocytogenes Page 2 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth C. Salmonella enterica D. Yersinia pestis* Difficulty: Moderate ASM Standard: 23 11. For appropriate food storage in refrigerators, the temperature should be set to no higher than which of the following? A. 5 C B. 7 C* C. 9 C D. 11 C Difficulty: Easy ASM Standard: 14 12. How does pascalization control microbial growth? A. by cross-linking proteins B. by damaging DNA C. by denaturing proteins* D. by disrupting membrane integrity Difficulty: Moderate ASM Standard: 14 13. X-rays and gamma rays are examples of which type of radiation? A. beta emission radiation B. ionizing radiation* C. nonionizing radiation D. nonpenetrating radiation Difficulty: Easy ASM Standard: 14 14. Ultraviolet light is an example of which type of radiation? A. beta emission radiation B. ionizing radiation C. nonionizing radiation* D. penetrating radiation Difficulty: Easy ASM Standard: 14 15. To sterilize packaged intravenous tubing, which method would not be acceptable? A. ethylene oxide B. freezing Page 3 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth C. ionizing radiation D. nonionizing radiation* Difficulty: Moderate ASM Standard: 14, 36 16. Liquid growth media that contain antibiotics should be sterilized using which method? A. autoclaving B. boiling C. HEPA filtration D. membrane filtration* Difficulty: Easy ASM Standard: 14, 36 17. Which method of microbial control introduces double-strand breaks into DNA? A. alcohols B. autoclaving C. ionizing radiation* D. nonionizing radiation Difficulty: Easy ASM Standard: 14 18. Which method of microbial control does not rely on denaturing proteins and/or disrupting the integrity of the cell membrane? A. autoclaving B. lyophilization* C. treatment with alcohols D. treatment with phenolics Difficulty: Moderate ASM Standard: 14 19. Phenolic compounds can be found naturally in which group of organisms? A. animals B. bacteria C. fungi D. plants* Difficulty: Easy ASM Standard: N/A 20. Which phenolic compound has commonly been added to soap and raises concerns about selection for more antimicrobial-resistant bacteria? A. capsaicin Page 4 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth B. carbolic acid C. o-phenylphenol D. triclosan* Difficulty: Moderate ASM Standard: 3, 14 21. Which best describes how heavy metals can control microbial growth? A. by binding to sulfur-containing amino acids* B. by cross-linking proteins C. by introducing double-strand breaks into DNA D. by inserting pores in the cell membrane Difficulty: Moderate ASM Standard: 14 22. What is argyria? A. a buildup of silver in the body resulting in blue-gray skin* B. a form of skin necrosis due to topical use of phenolics C. inadequate blood supply resulting in chest pain D. microorganisms growing in the blood Difficulty: Moderate ASM Standard: N/A 23. Which halogen or halogen-containing compound is typically used as a form of topical antisepsis? A. bromine B. chloramine C. fluorine D. iodophor* Difficulty: Easy ASM Standard: 14, 37 24. All but which of the following may be used to disinfect water to make it potable? A. bleach B. chloramine C. fluoride D. sodium dichloroisocyanurate* Difficulty: Easy ASM Standard: 14, 23 25. Contact lens cleaners commonly use which type of chemical agent to control microbial growth? Page 5 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth A. alkylating agents B. peroxygen* C. quats D. supercritical fluid Difficulty: Easy ASM Standard: 14 26. Which of the following is not an alkylating agent? A. chlorhexidine* B. ethylene oxide C. formalin D. o-phenylphenol Difficulty: Moderate ASM Standard: 14 27. Many chemical preservatives, such as potassium sorbate, preserve food products in which of the following ways? A. by altering the pH* B. by binding to pathogens C. by changing the osmolarity D. by drying foods Difficulty: Easy ASM Standard: 14 28. Nisin is an antimicrobial peptide produced by which bacterium? A. Lactobacillus acidophilus B. Lactococcus lactis* C. Listeria monocytogenes D. Streptomyces natalensis Difficulty: Easy ASM Standard: 14, 26 29. Examine the disk-diffusion assay shown below. Which antimicrobial agent is the least effective? Page 6 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth A. A B. B C. C D. D* Difficulty: Moderate ASM Standard: 14, 28b 30. Which of the following is used to determine if a solution of disinfectant actively used in the clinical setting is contaminated? A. the disk-diffusion method B. the in-use test* C. the phenol coefficient test D. the use-dilution test Difficulty: Moderate ASM Standard: 14, 36 True/False 31. Commercial sterilization kills all microbes. Answer: False Difficulty: Easy ASM Standard: 14 32. Pasteurized foods cannot spoil. Answer: False Difficulty: Easy ASM Standard: 14 33. Autoclaves use moist heat to sterilize materials. Page 7 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth Answer: True Difficulty: Easy ASM Standard: 14 34. X-rays and gamma rays are examples of ionizing radiation and cause the formation of thymine dimers. Answer: False Difficulty: Moderate ASM Standard: 14 35. Mercury compounds may be dissolved in alcohol and used as tinctures. Answer: True Difficulty: Easy ASM Standard: 14 36. HEPA filters are able to filter many airborne virions. Answer: True Difficulty: Easy ASM Standard: 14 37. Quats are not effective against endospores and prions. Answer: True Difficulty: Difficult ASM Standard: 14 38. Quats are anionic compounds. Answer: False Difficulty: Moderate ASM Standard: 14 39. Soaps with no added ingredients are bactericidal. Answer: False Difficulty: Easy ASM Standard: 14 40. Sonication causes cavitation in cells. Answer: True Difficulty: Easy Page 8 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth ASM Standard: 14 Matching 41. Match the medical instrument to its proper classification. Note than an answer may be used more than once. A. catheter i. critical B. colonoscope ii. semicritical C. duodenoscope iii. noncritical D. sonogram probe E. sphygmomanometer (blood pressure cuff) Answers: A. i., B. ii., C. ii., D. iii., E. iii. Difficulty: Moderate ASM Standard: N/A 42. Match the microbial growth control term with its correct definition. A. antisepsis i. a technique used to prevent contamination to maintain sterility B. asepsis ii. a chemical process used to control microbial growth on body surfaces C. disinfection iii. a process that kills nonspore-forming pathogenic pathogens D. pasteurization iv. lowering microbial load to public health standards E. sanitization v. a chemical process used to control microbial growth on inanimate objects Answers: A. ii., B. i., C. v., D. iii., E. iv. Difficulty: Moderate ASM Standard: 14 43. Match the agent to its mechanism of action. A. alcohols i. physically remove a microbe from a surface B. gamma rays ii. damage DNA molecules C. heavy metals iii. bind to sulfur-containing amino acids to inhibit enzyme activity D. soaps iv. denature proteins and disrupt membrane integrity Answers: A. iv., B. ii., C. iii., D. i. Difficulty: Moderate ASM Standard: 14 44. Match the agent to the mechanism of action. A. alkylating agent i. affect proteins and nucleic acids. B. nitric acid ii. inhibit catalases and peroxidases C. quat iii. may disrupt ferredoxin in the electron transport chain D. sorbic acid iv. disrupt membrane integrity Answers: A. i., B. iii., C. iv., D. ii. Difficulty: Moderate Page 9 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth ASM Standard: 14 Fill in the Blank 45. The complete removal of vegetative cells, endospores, and viruses is known as ________. Answer: sterilization Difficulty: Easy ASM Standard: 14 46. Traditional pasteurization kills pathogens and reduces the number of ________ while maintaining food quality. Answer: spoilage-causing microbes Difficulty: Easy ASM Standard: 14, 23 47. A microbiology laboratory that works with many indigenous environmental samples would be classified as a Biological Safety Lab (BSL) ________. Answer: 2 Difficulty: Moderate ASM Standard: 37 48. ________ is the appropriate method to pasteurize milk for areas where the milk cannot be refrigerated. Answer: Ultra-high temperature (UHT) pasteurization Difficulty: Moderate ASM Standard: 14 49. Food items are irradiated using ________ radiation. Answer: ionizing (also accept gamma) Difficulty: Moderate ASM Standard: 14 50. Prior to the use of antibiotics, newborns were routinely treated with ________ upon birth as protection against bacterial infection they may have acquired during passage through the birth canal. Answer: silver nitrate Difficulty: Easy ASM Standard: 14, 23 Page 10 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth 51. Recently, the heavy metal ________ has been used in designing pots for water storage to reduce diarrheal diseases. Answer: copper Difficulty: Easy ASM Standard: 14, 23 52. ________ is a gaseous alkylating agent used to sterilize objects, like bed mattresses, that cannot be autoclaved. Answer: Ethylene oxide Difficulty: Moderate ASM Standard: 14 53. Some bacteria and other organisms produce the enzyme ________, which catalyzes the reaction H O H O + O 2 2 2 2  . Answer: catalase Difficulty: Easy ASM Standard: 14 54. A recently developed method of antisepsis that can be used on skin before transplantation is ________. Answer: scCO2 (also accept supercritical fluids) Difficulty: Moderate ASM Standard: 14 Short Answer 55. What is the difference between a disinfectant and an antiseptic? Sample Answer: Disinfectants are used on inanimate surfaces, whereas antiseptics are used on living tissue. Difficulty: Easy ASM Standard: 14 56. Which heat method (dry or moist) is more effective? Why? Sample Answer: Moist heat is more effective because moisture is able to penetrate cells better. Difficulty: Easy ASM Standard: 14 57. Name two quality-control methods/indicators used to determine if something has been autoclaved properly. Page 11 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth Sample Answer: Heat-sensitive autoclave tape, a biological indicator spore test, or a Diack tube can be used to determine if something has been autoclaved properly. Difficulty: Easy ASM Standard: 36, 37 58. Is desiccation a “-cidal” mechanism and what effect does it have on microbes? Sample Answer: Desiccation is not “-cidal.” It is “-static.” Water is removed, hence inhibiting metabolic pathways (because metabolism requires water). Difficulty: Moderate ASM Standard: 13, 14 59. Why is it rare to hear about foodborne disease outbreaks from the consumption of candy bars? Sample Answer: Candy contains a high sugar concentration, which provides an environment of high osmotic pressure. In these conditions, cells will lose water, inhibiting their metabolic pathways. Difficulty: Moderate ASM Standard: 13, 14 60. An experiment is conducted to see how many bacteria remain in a culture at different times and temperatures. The data are shown below. (a) What is the lowest temperature that represents the thermal death point? (b) What is the thermal death time at 67 C? 0 minutes 5 minutes 10 minutes 15 minutes 57 C 5 × 109 cells 3 × 107 cells 100 cells 5 cells 67 C 5 × 109 cells 1 × 103 cells 5 cells 0 cells 77 C 5 × 109 cells 100 cells 0 cells 0 cells 87 C 5 × 109 cells 0 cells 0 cells 0 cells Sample Answer: (a) 77 C; (b) 15 minutes. Difficulty: Moderate ASM Standard: 13, 14, 28b 61. How does nonionizing radiation cause mutations in DNA? Sample Answer: Nonionizing radiation causes the formation of thymine dimers between adjacent thymines in a DNA strand. If the strand is not repaired, then during DNA replication, DNA polymerase does not always incorporate the correct complementary nucleotides, thus leading to mutations. Difficulty: Moderate ASM Standard: 14 Page 12 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth 62. What is the mode of action for iodine? Sample Answer: Iodine oxidizes cellular components (including sulfur-containing amino acids, nucleotides, and fatty acids) and destabilizes macromolecules. Difficulty: Moderate ASM Standard: 14 63. What is the mode of action for alcohols? Sample Answer: Alcohols denature proteins and disrupt membrane integrity. Difficulty: Moderate ASM Standard: 14 64. Name two chemical food preservatives that are naturally produced by microorganisms. Sample Answer: Two examples of chemical food preservatives naturally produced by microorganisms are natamycin and nisin. Difficulty: Easy ASM Standard: 14, 26 65. Name one benefit of using quats. Answers will vary. Quats are stable, nontoxic, inexpensive, colorless, odorless, and tasteless. They are also active against fungi, protozoans, and enveloped viruses. They may be used as antiseptics or disinfectants. Difficulty: Moderate ASM Standard: 14 Questions 66 and 67 are based on the following experiment: Different disinfectants are soaked on sterile pads that are then placed on a lawn of bacteria. The photo below shows the results after 24 hours of incubation. Page 13 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth 66. What assay is being shown here? Sample Answer: Disk diffusion assay (also accept Kirby-Bauer) Difficulty: Easy ASM Standard: 14, 36 67. Which antimicrobial agent (A through F) is the most effective against the bacteria that were plated? Sample Answer: A Difficulty: Easy ASM Standard: 28b, 38 Questions 68 and 69 are based on the following experiment: You wish to test the efficacy of a disinfectant that has been used to clean hospital rooms. The diagram below shows the experimental setup and the results. 68. What assay is being shown here? Sample Answer: This is the in-use assay. Difficulty: Easy ASM Standard: 14, 36 69. What conclusion can you draw from the results of this experiment? Sample Answer: The disinfectant is contaminated. This is evident because of the growth of five or more colonies on either plate. Difficulty: Moderate Page 14 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth ASM Standard: 28b, 38 Brief Essay Essay Question Rubric RATING Failing Below Average Competent Advanced Criteria for evaluati on Answer does not provide an argument. Answer contains inaccuracies. Writing is poor and contains numerous grammatical mistakes and misspellings. Answer fails to provide examples to support an argument. Writing is poor and grammatical errors are common. Answer is somewhat incoherent. Answer provides an argument with one or two examples that support it. Writing is acceptable for the college level but may contain one or two grammatical mistakes or misspellings. Answer clearly provides an argument with two or more excellent examples that support it; student makes the argument clearly and eloquently. Answer is well organized and free of grammatical errors and misspellings. POINT VALUE 0 1 2 3 Assume rating/grading scale for the question ranges from 0 to 3 points. 70. A simple example of controlling microbial growth is based on how we handle our food products. Name three food preparation methods that counter microbial growth. Be sure to discuss the mode of action for each method. Answer: Student answers will vary but should include components of the following.  Heat. We cook our foods to certain temperatures to ensure that microbial growth is killed. Heat denatures proteins and disrupts membrane integrity.  Smoking. Meats are smoked with moist heat. Moist heat can easily penetrate cells. Like heating, smoking would denature proteins and disrupt membrane integrity of microbes.  Pickling. Pickling lowers the pH of food. Lowered pH inhibits enzyme activity in microbes.  Drying. Meats are cooked and dried (i.e., beef jerky). The removal of water inhibits metabolic pathways in microbes.  Salting. Similar to drying, salt removes water, inhibiting metabolic pathways in microbes. Difficulty: Difficult ASM Standard: 14 Page 15 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth 71. A company has hired you and your laboratory to test the efficacy of a new alkylating agent, “Substance X.” You prepare a culture of endospores and add Substance X. Every 5 minutes, you plate the endospores to see if they are still viable. The data from this experiment are shown below. Time (minutes) Number of viable endospores 0 50,000 5 25,500 10 5000 15 3000 20 500 25 400 30 50 35 20 40 5 A. What is the mode of action for Substance X? B. State the independent and dependent variables of this experiment. C. Prepare a graph of these data using a logarithmic scale for the y-axis and a linear sale for the x-axis. D. What is the approximate decimal reduction time (D-value) of Substance X against the endospores used? E. Would you classify Substance X as a high-, intermediate- or low-level germicide? Why? Answer: Student answers will vary but should include components of the following. A. Alkylating agents replace hydrogen atoms with alkyl groups. These chemicals cross-link proteins. B. The independent variable is time (minutes) and the dependent variable is the number of endospores. C. Graph shown below. D. It takes approximately 10 minutes to decrease 10-fold or 1 log unit. Page 16 of 17 OpenStax Microbiology Test Bank Chapter 13: Control of Microbial Growth E. Substance X is a high-level germicide because it effectively kills endospores. Intermediate-level germicides are less effective at killing endospores, and low-level level germicides are ineffective against endospores. Difficulty: Difficult ASM Standard: 14, 28b, 29, 29a, 38 72. Explain how hyperbaric oxygen therapy works. What types of bacterial infections can be treated with hyperbaric oxygen? Answer: Student answers will vary but should include components of the following. A patient is placed in a chamber with a higher oxygen concentration/pressure or is supplied pressurized oxygen through a breathing tube. This method is used to treat pathogens that are either oxygen-sensitive microbes or obligate anaerobic microorganisms (including Clostridium spp.). The increased oxygen assists with increasing the activities of certain lymphocytes like neutrophils and macrophages. The increased oxygen also produces toxic-free radicals that can target anaerobic or oxygen-sensitive pathogens. Hyperbaric therapy may also increase the effectiveness of certain antibiotics. Difficulty: Moderate ASM Standard: 13, 14, 23 73. Name two chemical preservatives and state their modes of action. Be sure to indicate whether they target bacteria and/or fungi. Answer: Student answers will vary but should include components of the following.  Sorbic acid inhibits enzyme activity by reducing intracellular pH. It also inhibits catalase/peroxidase. Acts on both bacteria and fungi.  Benzoic acid/propionic acid inhibits enzyme activity by reducing intracellular pH. It inhibits oxidative phosphorylation and acts on both bacteria and fungi.  Sulfites interfere with protein structure by disrupting disulfide bonds. They act on both bacteria and fungi.  Nitrites react with ferredoxin (an electron transport-chain carrier), preventing ATP synthesis. They act on both bacteria and fungi.  Nisin targets cell wall production against gram-positive bacteria.  Natamycin is an antifungal believed to target ergosterol in the cell membrane Difficulty: Difficult ASM Standard: 13, 14 This file is copyright 2017, Rice University. All rights reserved. Page 17 of 17