Microbiology test bank Chapter 5,6,7, and mastering chapter 8.

Microbiology test bank Chapter 5,6,7, and mastering chapter 8. Microbiology: An Introduction, 12e (Tortora) Chapter 5 Microbial Metabolism 5.1 Multiple-Choice Questions 1) Which of the following compounds is NOT an enzyme? A) dehydrogenase B) cellulase C) coenzyme A D) β-galactosidase E) sucrase 2) Figure 5.1 Which compound is being reduced in the reaction shown in Figure 5.1? A) isocitric acid and α-ketoglutaric acid B) α-ketoglutaric acid and NAD+ C) NAD+ D) NADH E) NADH and isocitric acid 3) Which organism is NOT correctly matched to its energy source? A) photoheterotroph - light B) photoautotroph - CO2 C) chemoautotroph - Fe2+ D) chemoheterotroph - glucose E) chemoautotroph-NH3 4) Which of the following statements about anaerobic respiration is FALSE? A) It yields lower amounts of ATP when compared to aerobic respiration. B) The complete Kreb's cycle is utilized. C) It involves the reduction of an organic final electron acceptor. D) It generates ATP. E) It requires cytochromes. 5) Figure 5.2 What type of reaction is in Figure 5.2? A) decarboxylation B) transamination C) dehydrogenation D) oxidation E) reduction 6) What is the fate of pyruvic acid in an organism that uses aerobic respiration? A) It is reduced to lactic acid. B) It reacts with oxaloacetate to form citrate. C) It is oxidized in the electron transport chain. D) It is catabolized in glycolysis. E) It is converted into acetyl CoA. 7) Figure 5.3 How would a noncompetitive inhibitor interfere with a reaction involving the enzyme shown in Figure 5.3? A) It would bind to a. B) It would bind to b. C) It would bind to c. D) It would bind to d. E) The answer cannot be determined based on the information provided. 8) Figure 5.4 How is ATP generated in the reaction shown in Figure 5.4? A) glycolysis B) fermentation C) photophosphorylation D) oxidative phosphorylation E) substrate-level phosphorylation 9) Fatty acids are oxidized in A) the Krebs cycle. B) the electron transport chain. C) glycolysis. D) the pentose phosphate pathway. E) the Entner-Doudoroff pathway. 10) Figure 5.5 Which of the graphs in Figure 5.5 best illustrates the activity of an enzyme that is saturated with substrate? A) a B) b C) c D) d E) e 11) Which of the following is the best definition of oxidative phosphorylation? A) Electrons are passed through a series of carriers to O2. B) A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP. C) ATP is directly transferred from a substrate to ADP. D) Electrons are passed through a series of carriers to an organic compound. 12) Which of the following statements about substrate-level phosphorylation is FALSE? A) It involves the direct transfer of a high-energy phosphate group from an intermediate metabolic compound to ADP. B) No final electron acceptor is required. C) It occurs in glycolysis. D) The oxidation of intermediate metabolic compounds releases energy that is used to generate ATP. E) It occurs to a lesser degree in the Krebs cycle than in glycolysis. 13) Which of the following statements about photophosphorylation is FALSE? A) Light liberates an electron from chlorophyll. B) The oxidation of carrier molecules releases energy. C) Energy from oxidation reactions is used to generate ATP from ADP. D) It requires CO2. E) It occurs in photosynthesizing cells. 14) A strictly fermentative bacterium produces energy A) by glycolysis only. B) by aerobic respiration only. C) by fermentation or aerobic respiration. D) only in the absence of oxygen. E) only in the presence of oxygen. 15) The advantage of the pentose phosphate pathway is that it produces all of the following EXCEPT A) precursors for nucleic acids. B) precursors for the synthesis of glucose. C) three ATPs. D) NADPH. E) precursors for the synthesis of amino acids. 16) Which biochemical process is NOT used during glycolysis? A) substrate-level phosphorylation B) oxidation-reduction C) carbohydrate catabolism D) beta oxidation E) enzymatic reactions 17) In noncyclic photophosphorylation, O2 is released from A) CO2. B) H2O. C) C6H12O6. D) sunlight. E) chlorophyll. 18) Which of the following is the best definition of fermentation? A) the partial reduction of glucose to pyruvic acid B) the partial oxidation of glucose with organic molecules serving as electron acceptors C) the complete catabolism of glucose to CO2 and H2O D) the production of energy by oxidative-level phosphorylation E) the production of energy by both substrate and oxidative phosphorylation 19) Which of the following is NOT necessary for respiration? A) cytochromes B) flavoproteins C) a source of electrons D) oxygen E) quinones 20) Which one of the following would you predict is an allosteric inhibitor of the Krebs cycle enzyme, α-ketoglutarate dehydrogenase? A) citric acid B) α-ketoglutaric acid C) NAD+ D) NADH E) ADP 21) In green and purple bacteria, electrons to reduce CO2 can come from A) CO2. B) H2O. C) C6H12O6. D) H2S. E) chlorophyll. 22) Assume you are growing bacteria on a lipid medium that started at pH 7. The action of bacterial lipases should cause the pH of the medium to A) increase. B) decrease. C) stay the same. 23) Which of the following uses CO2 for carbon and H2 for energy? A) chemoautotroph B) chemoheterotroph C) photoautotroph D) photoheterotroph 24) Which of the following uses glucose for carbon and energy? A) chemoautotroph B) chemoheterotroph C) photoautotroph D) photoheterotroph 25) Which of the following has bacteriochlorophylls and uses alcohols for carbon? A) chemoautotroph B) chemoheterotroph C) photoautotroph D) photoheterotroph 26) Cyanobacteria are a type of A) chemoautotroph. B) chemoheterotroph. C) photoautotroph. D) photoheterotroph. 27) Which of the following statements are TRUE? 1- Electron carriers are located at ribosomes. 2- ATP is a common intermediate between catabolic and anabolic pathways. 3- ATP is used for the long-term storage of energy and so is often found in storage granules. 4-Anaerobic organisms are capable of generating ATP via respiration. 5-ATP can be generated by the flow of protons across protein channels. A) 2, 4, 5 B) 1, 3, 4 C) 2, 3, 5 D) 1, 2, 3 E) All of the statements are true. 28) Microorganisms that catabolize sugars into ethanol and hydrogen gas would most likely be categorized as A) aerobic respirers. B) anaerobic respirers. C) heterolactic fermenters. D) homolactic fermenters. E) alcohol fermenters. 29) Which of the following statements regarding metabolism is FALSE? A) Heat may be released in both anabolic and catabolic reactions. B) ATP is formed in catabolic reactions. C) ADP is formed in anabolic reactions. D) Anabolic reactions are degradative. 30) Which of the following is TRUE about this reaction? NO3-+ 2H+ NO2- + H2O Nitrate ion Nitrite ion A) This process requires O2. B) This process occurs anaerobically. C) This process requires the entire electron transport system. D) This process requires light. E) This process requires O2 and the electron transport system. 31) Which of the following statements regarding the Entner-Doudoroff pathway is TRUE? A) It involves glycolysis. B) It involves the pentose phosphate pathway. C) NADH is generated. D) ATP is generated. E) NADH and ATP are generated. 32) Assume you are working for a chemical company and are responsible for growing a yeast culture that produces ethanol. The yeasts are growing well on the maltose medium but are not producing alcohol. What is the most likely explanation? A) The maltose is toxic. B) O2 is in the medium. C) Not enough protein is provided. D) The temperature is too low. E) The temperature is too high. 33) Figure 5.6 The rates of O2 and glucose consumption by a bacterial culture are shown in Figure 5.6. Assume a bacterial culture was grown in a glucose medium without O2. Then O2 was added at the time marked X. The data indicate that A) these bacteria don't use O2. B) these bacteria get more energy anaerobically. C) aerobic metabolism is more efficient than fermentation. D) these bacteria cannot grow anaerobically. 34) An enzyme, citrate synthase, in the Krebs cycle is inhibited by ATP. This is an example of all of the following EXCEPT A) allosteric inhibition. B) competitive inhibition. C) feedback inhibition. D) noncompetitive inhibition. 35) If a cell is starved for ATP, which of the following pathways would most likely be shut down? A) Kreb's cycle B) glycolysis C) pentose phosphate pathway D) Krebs cycle and glycolysis 36) Which of the following statements regarding the glycolysis pathway is FALSE? A) Two pyruvate molecules are generated. B) Four ATP molecules are generated via substrate-level phosphorylation. C) Two NADH molecules are generated. D) One molecule of ATP is expended. E) Two molecules of water are generated. 37) Figure 5.7 The graph at the left in Figure 5.7 shows the reaction rate for an enzyme at its optimum temperature. Which graph shows enzyme activity at a higher temperature? A) a B) b C) c D) d 38) A bacterial culture grown in a glucose-peptide medium causes the pH to increase. The bacteria are most likely A) fermenting the glucose. B) oxidizing the glucose. C) using the peptides. D) not growing. 39) Gallionella bacteria can get energy from the reaction Fe2+ → Fe3+. This reaction is an example of A) oxidation. B) reduction. C) fermentation. D) photophosphorylation. E) the Calvin-Benson cycle. Figure 5.8 40) In Figure 5.8, where is ATP produced? A) a B) b C) c D) d E) e 41) Refer to Figure 5.8. In aerobic respiration, where is water formed? A) a B) b C) c D) d E) e 42) In Figure 5.8, the structure labeled "1" is A) NAD+. B) ATP synthase. C) a plasma membrane. D) a cell wall. E) cytoplasm. 43) In Figure 5.8, the path labeled "2" is the flow of A) electrons. B) protons. C) energy. D) water. E) glucose. 44) What is the most acidic place in Figure 5.8? A) a B) b C) c D) d E) e 45) A urease test is used to identify Mycobacterium tuberculosis because A) urease is a sign of tuberculosis. B) M. tuberculosis produces urease. C) urea accumulates during tuberculosis. D) some bacteria reduce nitrate ion. E) M. bovis can cause tuberculosis. 46) Researchers are developing a ribozyme that cleaves the HIV genome. This pharmaceutical agent could be described as A) an RNA molecule capable of catalysis. B) a hydrolase. C) a genetic transposable element. D) a protease inhibitor. E) a competitive inhibitor for reverse transcriptase. 47) Which statements correspond to amphibolic pathways? 1. anabolic and catabolic reactions are joined through common intermediate 2. shared metabolic pathways 3. Feedback inhibition can help regulate rates of reactions 4. both types of reactions are necessary but do not occur simultaneously A) 1 only B) 1, 2, 3 C) 1, 2, 3, 4 D) 2, 4 E) 2, 3, 4 5.2 True/False Questions 1) Catabolic reactions are generally degradative and hydrolytic. Answer: TRUE 2) The pentose phosphate pathway can be characterized as an anabolic pathway. Answer: FALSE 3) In general, ATP is generated in catabolic pathways and expended in anabolic pathways. Answer: TRUE 4) An apoenzyme that loses its coenzyme subunit will be non-functional. Answer: TRUE 5) The use of enzymes is necessary to increase the activation energy requirements of a chemical reaction. Answer: FALSE 6) Glycolysis is utilized by cells in both respiration and fermentation. Answer: TRUE 7) Carbon fixation occurs during the light-independent phase of photosynthesis. Answer: TRUE 8) Both respiration and photosynthesis require the use of an electron transport chain. Answer: TRUE 9) Both respiration and photosynthesis use water molecules for the donation of hydrogen ions. Answer: FALSE 10) Once an enzyme has converted substrates into products, the active site reverts back to its original form. Answer: TRUE Microbiology: An Introduction, 12e (Tortora) Chapter 6 Microbial Growth 6.1 Multiple-Choice Questions Figure 6.1 1) Figure 6.1, which line best depicts a facultative anaerobe in the absence of O2? A) a B) b C) c 2) In Figure 6.1,which line best depicts an obligate anaerobe in the presence of O2? A) a B) b C) c 3) In Figure 6.1, which line shows the growth of an obligate aerobe incubated anaerobically? A) a B) b C) c 4) In Figure 6.1, which line best illustrates the growth of a facultative anaerobe incubated aerobically? A) a B) b C) c 5) In Figure 6.1, which line best depicts a psychrotroph incubated at 0°C? A) a B) b C) c 6) If cells are grown in media containing amino acids labeled with radioactive nitrogen (15N), most of the radioactivity will be found in the cells' A) DNA. B) proteins. C) phospholipids. D) DNA and proteins. E) DNA and phospholipids. 7) Which of the following elements is NOT correctly matched with its cellular function? A) nitrogen — needed for amino acid synthesis B) phosphorus — incorporated into nucleic acids C) sulfur — used for synthesis of thiamin and biotin D) magnesium and potassium — required as cofactors for enzymes E) phosphorus — used for production of carbohydrates. 8) Pathogenic bacteria isolated from the respiratory or intestinal tracts of humans are A) strict aerobes that grow best in candle jars. B) capnophiles that grow best in carbon dioxide incubators. C) facultative anaerobes that require reducing media for growth. D) strict aerobes that grow best in reducing media. E) capnophiles that prefer highly oxygenated growth conditions. 9) The biosafety level (BSL) for most introductory microbiology laboratories is A) BSL-1. B) BSL-2. C) BSL-3. D) BSL-4. 10) The biosafety level (BSL) for a clinical microbiology laboratory working with potentially airborne pathogens, such as tuberculosis bacteria, is A) BSL-1. B) BSL-2. C) BSL-3. D) BSL-4. 11) A sample of milk is tested for its bacterial content in a plate count assay. A one-milliliter sample of the milk is diluted in a 1:10 dilution series. One milliliter of the third dilution tube is plated in a pour plate. After incubation, the plate has 54 colonies, indicating that the original milk sample contained A) 54 cells per milliliter. B) 540 cells per milliliter. C) 5,400 cells per milliliter. D) 54,000 cells per milliliter. E) 540,000 cells per milliliter. 12) The addition of which of the following to a culture medium will neutralize acids? A) buffers B) sugars C) pH D) heat E) carbon 13) Salts and sugars work to preserve foods by creating a A) depletion of nutrients. B) hypotonic environment. C) lower osmotic pressure. D) hypertonic environment. E) lower pH. 14) The term aerotolerant anaerobe refers to an organism that A) does not use oxygen but tolerates it. B) is killed by oxygen. C) tolerates normal atmospheric nitrogen gas levels. D) requires less oxygen than is present in air. E) requires more oxygen than is present in air. 15) Which of the following is an advantage of the standard plate count? A) can readily count cells that form aggregates B) determines the number of viable cells C) can be performed on very dilute samples, such as lake water D) provides immediate results E) can be used to count heat-sensitive bacteria 16) Which of the following is an advantage of the direct microscopic count? A) can readily count organisms that are motile B) can easily distinguish live from dead cells C) requires no incubation time D) sample volume is unknown E) requires a large number of cells 17) Most bacteria reproduce by A) aerial hyphae. B) fragmentation. C) mitosis. D) binary fission. E) budding. 18) Thirty-six colonies grew in nutrient agar from 1.0 ml of undiluted sample in a standard plate count. How many cells were in the original sample? A) 4 per milliliter B) 9 per milliliter C) 18 per milliliter D) 36 per milliliter E) 72 per milliliter Figure 6.2 19) Figure 6.2 shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture. In the figure, which section (or sections) shows a growth phase where the number of cells dying equals the number of cells dividing? A) a B) b C) c D) d E) a and c 20) Figure 6.2 shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture. In the figure, which sections of the graph illustrate a logarithmic change in cell numbers? A) a and c B) b and d C) a and b D) c and d E) a and d 21) Most bacteria grow best at pH A) 1. B) 5. C) 7. D) 9. E) 14. 22) Most fungi grow best at pH A) 1. B) 5. C) 7. D) 9. E) 14. 23) Consider a culture medium on which only gram-positive organisms such as Staphylococcus aureus colonies can grow due to an elevated NaCl level. A yellow halo surrounds the growth, indicating the bacterium fermented a sugar in the medium, decreasing the pH as a result and changing the color of a pH indicator chemical. This type of medium would be referred to as a(n) A) selective medium. B) differential medium. C) enrichment culture. D) selective and differential medium. E) differential and enrichment culture. 24) A culture medium consisting of agar, peptone, and beef heart is a A) chemically defined medium. B) complex medium. C) selective medium. D) differential medium. E) reducing medium. 25) Which of the following pairs of microbe classification terms and optimal growth temperatures is mismatched? A) psychrotroph — growth at 0°C B) thermophile — growth at 37°C C) mesophile — growth at 25°C D) psychrophile — growth at 15°C E) hyperthermophiles — growth at 85°C 26) During which growth phase will gram-positive bacteria be most susceptible to penicillin? A) lag phase B) log phase C) death phase D) stationary phase E) The culture is equally susceptible during all phases. 27) Which of the following is the best definition of generation time? A) the length of time needed for lag phase B) the length of time needed for a cell to divide C) the minimum rate of doubling D) the duration of log phase E) the time needed for nuclear division 28) Which of the following is NOT a direct method to measure microbial growth? A) direct microscopic count B) standard plate count C) filtration on a support membrane followed by incubation on medium D) metabolic activity E) most probable number (MPN) 29) Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt? A) psychrophiles B) facultative halophiles C) anaerobes D) thermophiles E) hyperthermophiles 30) Which of the following is an organic growth factor? A) glucose B) vitamin B1 C) peptone D) Mg+2 E) H2O 31) Which of the following is an example of a metabolic activity that could be used to measure microbial growth? A) standard plate count B) glucose consumption C) direct microscopic count D) turbidity E) most probable number (MPN) 32) An experiment began with 4 cells and ended with 128 cells. How many generations did the cells go through? A) 64 B) 32 C) 6 D) 5 E) 4 33) Three cells with generation times of 60 minutes are inoculated into a culture medium. How many cells are there after 5 hours? A) 900 B) 180 C) 96 D) 32 E) 15 Figure 6.3 34) In Figure 6.3, which tube shows the expected growth pattern for a microaerophile? A) a B) b C) c D) d E) e 35) In Figure 6.3, which tube shows the expected growth pattern for a facultative anaerobe? A) a B) b C) c D) d E) e 36) In one hospital, Pseudomonas aeruginosa serotype 10 infected the biliary tract of 10 percent of 1300 patients who underwent gastrointestinal endoscopic procedures. After each use, endoscopes were washed with an automatic reprocessor that flushed detergent and glutaraldehyde through the endoscopes, followed by a tap water rinse. P. aeruginosa serotype 10 was not isolated from the detergent, glutaraldehyde, or tap water. What was the source of the infections? A) bacterial cell walls in the water B) a biofilm in the reprocessor C) contaminated disinfectant D) fecal contamination of the bile ducts E) None of the answers is correct. Table 6.1 Three different culture media are shown below. Medium A Medium B Medium C Na2HPO4 Tide detergent Glucose KH2PO4 Na2HPO4 Peptone MgSO4 KH2PO4 (NH4)2SO4 CaCl2 MgSO4 KH2PO2 NaHCO3 (NH4)2SO4 Na2HPO4 37) For the three types of media in Table 6.1, which medium (or media) is/are chemically defined? A) A B) B C) C D) A and B E) A and C 38) In Table, 6.1, in which medium (or media) would an autotroph grow? A) A B) B C) C D) A and B E) A and C 39) Assume you inoculated 100 cells, with a generation time of 20 minutes, into 100 ml of nutrient broth. You then inoculated 100 cells of the same species into 200 ml of nutrient broth. After incubation for 4 hours, you can reasonably expect to have A) more cells in the 100 ml. B) more cells in the 200 ml. C) the same number of cells in both. D) The answer cannot be determined based on the information provided. 40) The source of nutrients in nutrient agar is A) agar. B) gelatin. C) peptone and beef extract. D) peptone and NaCl. E) agar and NaCl. 41) Which enzyme catalyzes the reaction: O2- + O2- + 2H+ → H2O2 + O2? A) catalase B) oxidase C) peroxidase D) superoxide dismutase Answer: D Section: 6.1 Bloom's Taxonomy: Knowledge Learning Outcome: 6.6 42) Which enzyme catalyzes the reaction: 2H2O2 → 2H2O + O2? A) catalase B) oxidase C) peroxidase D) superoxide dismutase 43) Which enzyme catalyzes the reaction: H2O2 + 2H+ → 2H2O? A) catalase B) oxidase C) peroxidase D) superoxide dismutase 44) Table 6.2 The following data show growth of two bacteria on different media. The data in Table 6.2 indicate that S. aureus is a(n) A) mesophile. B) facultative anaerobe. C) facultative halophile. D) aerobe. E) halophile. 45) Patients with indwelling catheters (long-term tubes inserted into body orifices for drainage, such as through the urethra and into the urinary bladder) are susceptible to infections because A) injected solutions are contaminated. B) their immune systems are weakened. C) infections can be transmitted from other people. D) biofilms develop on catheters. E) bacteria cause infections. 6.2 True/False Questions 1) An isolated colony on a streak plate contains millions (or even billions) of identical cells all arising from one initial cell. Answer: TRUE 2) Bacterial growth refers to an increase in the numbers of cells in a bacterial culture. Answer: TRUE 3) Pure cultures can easily be obtained on streak plates, even if the desired bacteria are present in very low concentrations in the initial culture broth. Answer: FALSE 4) Agar is used as a solidifying agent in microbiological media since few bacteria can degrade it. Answer: TRUE 5) Laboratory cultivation of obligate anaerobes requires reducing media or special growth chambers filled with inert gases. Answer: TRUE 6) Most pathogenic bacteria are thermophiles. Answer: FALSE 7) In performing a ten-fold dilutions series from a sample containing 10,000 bacteria per milliliter, the fourth tube in the dilution series will have 10 cells per milliliter. Answer: FALSE 8) Turbidity is an indirect measurement of bacterial growth that can be measured using a spectrophotometer. Answer: TRUE 9) Filtration methods, followed by growth of the bacteria trapped on the filters in growth media, are used to count bacteria present in very low concentrations, such as in lakes and streams. Answer: TRUE 10) Nitrogen-fixing bacteria, such as cyanobacteria, can use atmospheric nitrogen (N2) for their nitrogen source. Answer: TRUE Microbiology: An Introduction, 12e, (Tortora) Chapter 7 The Control of Microbial Growth 7.1 Multiple-Choice Questions 1) Which of the following is the best method to sterilize heat-labile solutions? A) dry heat B) autoclave C) membrane filtration D) pasteurization E) freezing 2) Which of the following best describes the pattern of microbial death? A) The cells in a population die at a constant rate. B) All the cells in a culture die at once. C) Not all of the cells in a culture are killed. D) The pattern varies depending on the antimicrobial agent. E) The pattern varies depending on the species. 3) Which of the following chemical agents is used for sterilization? A) alcohol B) phenolics C) ethylene oxide D) chlorine E) soap 4) Which of the following substances is used for surgical hand scrubs? A) phenol B) chlorine bleach C) chlorhexidine D) soap E) glutaraldehyde 5) Which of the following pairs of terms is mismatched? A) bacteriostatic — kills vegetative bacterial cells B) germicide — kills microbes C) virucide — inactivates viruses D) sterilant — destroys all living microorganisms E) fungicide — kills yeasts and molds 6) The antimicrobial activity of chlorine is due to which of the following? A) the formation of hypochlorous acid B) the formation of hydrochloric acid C) the formation of ozone D) the formation of a hypochlorite ion E) disruption of the plasma membrane 7) Which of the following regarding antimicrobial control agents is FALSE? A) Contaminating organic debris such as blood or sputum decrease effectiveness. B) Some agents kill by denaturing microbial cell proteins. C) Some agents affect microbial cell membranes by dissolving lipids. D) Silver is used for treating antibiotic-resistant bacteria. E) Alcohols effectively inactivate nonenveloped viruses by attacking lipids. 8) Which of the following does NOT achieve sterilization? A) dry heat B) pasteurization C) autoclave D) supercritical fluids E) ethylene oxide 9) Which of the following is a limitation of the autoclave? A) It requires an excessively long time to achieve sterilization. B) It cannot inactivate viruses. C) It cannot kill endospores. D) It cannot be used with heat-labile materials. E) It cannot be used with glassware. 10) An agent used to reduce the number of bacteria on a toilet would most accurately be called a(n) A) disinfectant. B) antiseptic. C) aseptic. D) fungicide. E) virucide. 11) Application of heat to living cells can result in all of the following EXCEPT A) breaking of hydrogen bonds. B) alteration of membrane permeability. C) denaturation of enzymes. D) decreased thermal death time. E) damage to nucleic acids. 12) Which of the following disinfectants acts by disrupting the plasma membrane? A) soaps B) aldehydes C) bisphenols D) halogens E) heavy metals 13) Oxidizing agents include all of the following EXCEPT A) chlorine. B) glutaraldehyde. C) hydrogen peroxide. D) iodine. E) ozone. 14) Disinfection of water is achieved by all of the following EXCEPT A) ozone. B) UV radiation. C) chlorine. D) copper sulfate. E) peracetic acid. 15) All of the following substances are effective against nonenveloped viruses EXCEPT A) alcohol. B) chlorine. C) ethylene oxide. D) ozone. E) None of the answers is correct; all of these are equally effective against nonenveloped viruses. 16) Which of the following methods is used to preserve food by slowing the metabolic processes of foodborne microbes? A) lyophilization B) nonionizing radiation C) freezing D) ionizing radiation E) pasteurization 17) Which concentration of ethanol is the most effective bactericide? A) 100 percent B) 70 percent C) 50 percent D) 40 percent E) 30 percent 18) All of the following factors contribute to hospital-acquired infections EXCEPT A) some bacteria metabolize disinfectants. B) gram-negative bacteria are often resistant to disinfectants. C) invasive procedures can provide a portal of entry for bacteria. D) bacteria may be present in commercial products such as mouthwash. E) None of the answers is correct; all of these factors may contribute to hospital-acquired infection. 19) Which of the following treatments is the most effective for controlling microbial growth? A) 63°C for 30 minutes B) 72°C for 15 seconds C) 140°C for 4 seconds D) They are equivalent treatments. E) None of the answers is correct. 20) Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper? A) autoclave B) gamma radiation C) microwaves D) sunlight E) ultraviolet radiation 21) Which of the following regarding antimicrobial control agents is FALSE? A) Contaminating organic debris such as blood or sputum will decrease effectiveness. B) Some agents kill by denaturing microbial cell proteins. C) Some agents affect microbial cell membranes by dissolving lipids. D) Some agents are utilized as both an antiseptic and a disinfectant. E) A true antimicrobial control agent is equally effective against both bacteria and viruses. Figure 7.1 A suspension of 106 Bacillus cereus endospores was put in a hot-air oven at 170°C. Plate counts were used to determine the number of endospores surviving at the time intervals shown. 22) In Figure 7.1, what is the thermal death time? A) 150°C B) 60 minutes C) 120 minutes D) 100°C E) The answer cannot be determined based on the information provided. 23) In Figure 7.1, the thermal death point for this culture is A) 15 minutes. B) 50°C. C) 30 minutes. D) 170°C. E) The answer cannot be determined based on the information provided 24) In Figure 7.1, the decimal reduction time (D value) for the culture, which is defined as the time to reduce a population by one log, is approximately A) 0 minutes. B) 10 minutes. C) 30 minutes. D) 40 minutes. E) 60 minutes. 25) Which of the following results in lethal damage to nucleic acids? A) heat B) radiation C) certain chemicals D) heat and radiation E) heat, radiation, and some chemicals 26) Which of the following pairs is mismatched? A) Ag — wound dressings B) alcohols — open wounds C) CuSO4 — algicide D) H2O2 — open wounds E) organic acids — food preservation Figure 7.2 Assume 109 E. coli cells/ml are in a flask. 27) Which graph in Figure 7.2 best depicts the effect of placing the culture in an autoclave for 15 minutes at time x? A) a B) b C) c D) d E) e 28) Which graph in Figure 7.2 best depicts the effect of placing the culture at 7°C at time x? A) a B) b C) c D) d E) e Table 7.1 A disk-diffusion test using Staphylococcus gave the following results: Disinfectant Zone of inhibition (mm) A 0 B 2.5 C 10 D 5 29) In Table 7.1, which compound was the most effective against Staphylococcus? A) A B) B C) C D) D E) The answer cannot be determined based on the information provided. 30) In Table 7.1, which compound was the most effective against E. coli? A) A B) B C) C D) D E) The answer cannot be determined based on the information provided. 31) In Table 7.1, which compound was bactericidal? A) A B) B C) C D) D E) The answer cannot be determined based on the information provided. 32) Table 7.2 The fate of E. coli O157:H7 in apple cider held at 8°C for 2 weeks, with and without preservatives, is shown below: Bacteria/ml Cider only 2.2 Cider with potassium sorbate 2.0 Sodium benzoate 0 Potassium sorbate + sodium benzoate 0 In Table 7.2, which preservative is most effective? A) potassium sorbate B) sodium benzoate C) potassium sorbate + sodium benzoate D) no preservative 33) An iodophor is a(n) A) phenol. B) agent that reduces oxygen. C) quaternary ammonium compound. D) form of formaldehyde. E) iodine mixed with a surfactant. 34) Ethylene oxide A) is a good antiseptic. B) is not sporicidal. C) requires high heat to be effective. D) is a sterilizing agent. E) is the active chemical in household bleach. 35) All of the following substances are used to preserve foods EXCEPT A) biguanides. B) nisin. C) potassium sorbate. D) sodium nitrite. E) calcium propionate. Table 7.3 The following data were obtained by incubating gram-positive bacteria in nutrient medium + disinfectant for 24 hr, then transferring one loopful to nutrient medium (subculturing). (+ = growth; - = no growth) 36) In Table 7.3, which disinfectant is the most effective at stopping bacterial growth? A) Doom B) K.O. C) Mortum D) Sterl E) The answer cannot be determined based on the information provided. 37) In Table 7.3, which disinfectant was bactericidal? A) Doom B) K.O. C) Mortum D) Sterl E) The answer cannot be determined based on the information provided. 38) In Table 7.3, which disinfectant was most effective against Salmonella? A) Doom B) K.O. C) Mortum D) Sterl E) The answer cannot be determined based on the information provided. 39) All of the following are effective for destroying prions EXCEPT A) boiling. B) incineration. C) NaOH + autoclaving at 134°C. D) proteases. E) None of the answers are correct; each of these will destroy prions. 40) Which of the following pairs is mismatched? A) ionizing radiation — hydroxyl radicals B) ozone — takes electrons from substances C) plasma sterilization — free radicals D) supercritical fluids — CO2 E) ultraviolet radiation — desiccation 41) All of the following are methods of food preservation EXCEPT A) desiccation. B) high pressure. C) ionizing radiation. D) microwaves. E) osmotic pressure. 42) The preservation of beef jerky from microbial growth relies on which method of microbial control? A) filtration B) lyophilization C) desiccation D) ionizing radiation E) supercritical CO2 43) If you were preparing nutrient agar at home and did not have an autoclave, what could you use to sterilize the nutrient agar? A) bleach B) boiling for one hour C) hydrogen peroxide D) oven at 121°C for one hour E) pressure cooker at 121°C for 15 minutes 44) Bone and tendons for transplant are decontaminated by A) ethylene oxide. B) glutaraldehyde. C) peroxygens. D) plasma sterilization. E) supercritical fluids. 45) Which one of the following is most resistant to chemical biocides? A) gram-negative bacteria B) gram-positive bacteria C) mycobacteria D) protozoan cysts E) viruses with lipid envelopes 46) The following is true of quarternary ammonium compounds EXCEPT A) they are non-toxic at lower concentrations. B) they are tasteless. C) they are effective when combined with soaps. D) they are stable. E) they may be an ingredient in mouthwash. 7.2 True/False Questions 1) Any process that destroys the non-spore forming contaminants on inanimate objects is sterilization. Answer: FALSE 2) Desiccation is a reliable form of sterilization. Answer: FALSE 3) The thermal death time is the time needed to kill all the bacteria in a particular culture at a certain temperature. Answer: TRUE 4) Pseudomonas has been found growing in quaternary ammonium compounds (quats). Answer: TRUE 5) Moist heat destroys organisms by denaturing proteins. Answer: TRUE 6) Some antimicrobial chemicals are considered to be disinfectants and antiseptics. Answer: TRUE 7) The pH of the medium has no effect on the activity of the disinfectant being applied. Answer: FALSE 8) Ultraviolet light (UV) causes irreversible breaks in DNA strands. Answer: FALSE 9) Autoclaving is the most effective method of moist heat sterilization. Answer: TRUE 10) Microorganisms placed in high concentrations of salts and sugars undergo lysis. Answer: FALSE Mastering for Chapter 8 Which enzyme breaks the hydrogen bonds during replication? DNA helicase How do stabilizing proteins work on the DNA? They bind to the single-stranded DNA. In which direction does the replication fork move? It moves ahead of the newly synthesized DNA What ensures that the single strands of DNA do not come back together? Stabilizing proteins What are the products of semiconservative replication for a double-stranded DNA molecule? Two double-stranded DNA molecules, each consisting of one parental strand and one daughter strand. Why is DNA replication essential for a cell? An organism must copy its DNA to pass genetic information to its offspring. What is the function of the parental DNA in replication? It serves as the template for DNA replication. What characteristic of DNA allows two connected DNA polymerases to synthesize both the leading and lagging strands? DNA is flexible. What is the function of the connector proteins? They link the leading strand DNA polymerase and the lagging strand DNA polymerase together. Which DNA strand is synthesized continuously? Leading strand Which of the following are terms associated with Okazaki fragments? Lagging strand, DNA ligase, and discontinuous Why is the DNA synthesis of the lagging strand considered discontinuous? The synthesis is moving in the opposite direction from the replication fork. Transcription produces which of the following? mRNA, tRNA, and rRNA are all produced by transcription. According to the animation, which of the following makes mRNA from the information stored in a DNA template? RNA polymerase Ribosomes contain which of the following? rRNA Which of the following is involved in bringing amino acids to the ribosomes? tRNA Which of the following can be translated into protein? mRNA What results from the process of translation? A polypeptide How is bacterial translation different from eukaryotic translation? Bacteria can begin translation before transcription has terminated. According to the animation, ribosomes move along the mRNA in which direction? 5’ to 3’ Which of the following build(s) new strands of DNA? DNA polymerases Which statement about DNA replication is CORRECT? The leading strand is built continuously, and the lagging strand is built in pieces. During DNA replication, which nucleotide will bind to an A nucleotide in the parental DNA? T The molecule that seals the gaps between the pieces of DNA in the lagging strand is DNA ligase. Which statement about DNA replication is FALSE? DNA ligase adds nucleotides to the lagging strand. Which of the following statements is FALSE? DNA replication proceeds in only one direction around the bacterial chromosome. DNA is constructed of two strands of nucleotides running in an antiparallel configuration. Which of the following is NOT a product of transcription? a new strand of DNA thymine An enzyme that makes covalent bonds between Okazaki fragments in the lagging strand of DNA being replicated is DNA ligase An enzyme that copies DNA to make a molecule of RNA is RNA polymerase Which of the following enzymes unwinds the two strands of DNA so that they can be copied during replication? helicase Which of the following is a DNA strand complementary to CGA ATC AGC? GCT TAG TCG Bacteria usually contain multiple chromosomes. False Transformation is the transfer of DNA from a donor to a recipient cell as naked DNA in solution.