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198 Cards in this Set
- Front
- Back
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1. What is the purpose of the flaming alcohol on the glass spreading rod in the spread plate isolation procedure? |
To sterilize the glass rod, as incineration does for the loop. |
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2. Effective hand washing will function to... |
... sterilize the skin. |
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3. Aseptic technique means that that you perform the preparation of media or the transfer of living microbes... |
...without introducing contamination. |
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4. Why is it best to hold the cap of a tube in your little finger during an inoculation instead of placing it on the counter top? |
To reduce contamination of the culture tube. |
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5. Open tubes should be held at an angle instead of straight up. What is the most important reason for this action? |
To reduce the amount of contamination that can fall into the tube from the air. |
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6. A mixed culture contains... |
... multiple bacteria species in a medium. |
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7. The purpose of a streak plate is to... |
... isolate a pure culture of the target organism. |
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8. What method of streak for isolation would be preferred for a sample suspected to contain a high density of cells? |
A quadrant streak. |
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9. The spread plate method of isolation is different from the streak plate method of isolation in that... |
... only spread plates will produce individual colonies (CFUs). |
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10. What is the purpose of turning the plate with either your hand or a turntable during the inoculation of a spread plate for isolation? |
To insure that the cells are spread evenly over the surface of the plate. |
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11. What would happen if flaming alcohol was to drip into the beaker of alcohol when using a glass spreading rod? |
The beaker of alcohol would catch on fire. |
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12. During the spread plate method of isolation, a few drops of the initial culture is transferred to tube A. A loop of the tube A culture is then transferred to tube B and so on until tubes A through D were produced. Which tube is expected to produce a higher number of CFUs on the plate? |
Tube A |
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13. To be ubiquitous means... |
... it can be found just about everywhere. |
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14. The ubiquity of microorganisms experiment demonstrated that microbes can be cultivated from... |
... from almost any source. |
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15. A single colony on a plate is typically composed of... |
... a visible mass of cells that originated from one cell undergoing many rounds of replication. |
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16. Smooth, rhizoid, lobate, and filamentous would be terms used to describe the ___________ of a colony. |
Texture |
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17. The description of microbial growth in broth as being turbid means that the tube appears... |
... cloudy. |
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18. A broth culture that displays a mass of cells sitting on the bottom of the tube is described as... |
... sediment. |
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19. All other factors being equal, the greater the turbidity of a broth culture of bacteria the more _____________ it contains. |
Cells |
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20. Fastidious microbes require the growth medium to supply... |
... many organic compounds. |
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21. After incubation of an agar deep stab culture, you observe growth in only in the bottom few millimeters of the tube. This organism would be classified as... |
... an obligate anaerobe. |
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22. After incubation of an agar deep stab culture, you observe abundant growth throughout the whole depth of the tube. This organism would be classified as... |
... an aerotolerant anaerobe. |
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23. After incubation of an agar deep stab culture, you observe that growth did not occur in the stab, but instead appears on the surface of the agar. This organism would be classified as... |
... an obligate aerobe. |
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24. Facultative anaerobes will grow more abundantly in the presence of oxygen than without it. Why is this so? |
Aerobic respiration is more efficient than fermentation or anaerobic respiration. |
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25. How would the growth of your culture be affected if resazurin was omitted from your Fluid Thioglycollate Medium? |
The growth would not be affected. |
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26. Although Fluid Thiogycollate Medium allows for the growth of microbes in all aerotolerance categories, it is more commonly used for the growth of anaerobes and microaerophiles because... |
... it contains ingredients that prevent oxygen from becoming equally diffused throughout the whole tube. |
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27. Why does a microaerophilic organism grow only in the middle depth region of a Fluid Thioglycollate Medium tube? |
The tube has a gradient of dissolved oxygen and the organism requires intermediate levels. |
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28. How does the gas generator envelope function to remove oxygen from the anaerobic jar? |
It catalyzes a reaction between hydrogen and oxygen creating water. |
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29. Why must an anaerobic jar be used to culture anaerobic bacteria? |
Anaerobes do not grow in the presence of oxygen. |
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30. You inoculate two plates with the same organism and incubate them at the same temperature for the same amount of time but one of the plates is grown in the anaerobic jar. The resulting growth is evident on both plates however it appears less dense on the anaerobic plate. What kind of organism is this? |
Facultative Anaerobe. |
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31. Human pathogens are... |
... Mesophiles. |
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32. An organism with an optimal growth temperature around 65°C would be called a... |
... Thermophile. |
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33. Organisms that are able to grow in boiling geothermal pools would be called... |
... Hyperthermophiles. |
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34. The cardinal temperatures describe the... |
... range of temperatures that allow growth and survival of an organism. |
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35. The pH scale functions to represent the molar concentration of... |
... Hydrogen ions in solution. |
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36. If an organism grows best at a pH of 6.5, it is described as being...
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... a neutrophile. |
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37. A solution with a pH of 3 is _________ _________ than a solution with a pH of 6. |
more acidic |
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38. The net movement of water through a semi-permeable membrane is always towards the higher concentration of... |
... solutes. |
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39. An organism that grows very well in broth containing 15-20% NaCl but very poorly or not at all in broth containing 0-10% NaCl would be called... |
... a halophile. |
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40. If a method of microbial control functions to reduce the number of pathogens to a safe level, the method would be called a... |
... decontamination. |
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41. What about the physiology of Bacillus, Geobacillus, and Clostridium makes these organisms heat tolerant and able to survive many disinfection methods? |
The ability to produce resistant endospores. |
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42. What is the difference between a disinfectant and an antiseptic? |
Antiseptics are used on people whereas disinfectants are used on objects. |
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43. In the chemical germicides: disinfectant and antiseptics experiment, what is the logic in choosing Staphylococcus epidermidis and Escherichia coli as the test organisms? |
They are both pathogens. |
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44. In the chemical germicides: disinfectant and antiseptics experiment, if there is growth in the control #2 tube the experiment results cannot be interpreted. Why does growth in this tube prevent the use of the other results and interpretation of the effectiveness of the agents? |
It indicates that the broth being used throughout the experiment was likely contaminated. |
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45. In the chemical germicides: disinfectant and antiseptics experiment, what is the purpose of the control #4? |
To demonstrate that the beads being used were sterile. |
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46. Why is it important to center an object you are analyzing in the field of view of the microscope before switching to a higher power lens? |
As magnification increases, field diameter decreases and objects at the periphery will no longer be in the visible field. |
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47. Most microscopes are parfocal. This means that the distance from the nosepiece opening to the focal plane of each lens has been standardized. What does this mean to you with regard to how you use the microscope? |
Once the specimen is in focus under a low power lens, the microscope can be switched to a higher power lens without moving the stage and the image will be in or nearly in focus no matter what lens is used. |
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48. If the ocular micrometer is a ruler, why does it need to be calibrated? |
Because the gradations are unspecified and will change with the magnification of the objective lens being used. |
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49. How is the stage micrometer different from the ocular micrometer? |
The stage micrometer has gradations of known size. |
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50. The resting or survival stage of a protozoan is called... |
... a cyst. |
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51. When comparing prokaryotic cells and eukaryotic cells, prokaryotes are _____________ and _____________ than eukaryotes. |
smaller, simpler |
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52. Fungi are heterotrophs which means that they... |
... digest organic food sources and absorb the resulting products. |
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53. Common modes of locomotion for protoza include... |
... flagella, cilia, and psuedopods. |
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54. Cyanobacteria can be differentiated from algae, as cyanobacteria are...
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... larger and more grass green in color. |
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55. Green algae... |
Are unicellular, multicellular, and filamentous. [All the above] |
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56. Diatoms are... |
... photosynthetic, unicellular, and golden brown in color. |
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57. The term coccus describes a bacterial shape that is _______________. |
spherical |
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58. During the simple stain procedure, why is it necessary to heat fix the cells? |
To adhere them to the slide. |
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59. When preparing a bacterial smear for staining, why is it important to air dry the slides before heat-fixing? |
To prevent boiling during the heat-fix that would damage the cells. |
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60. Negative staining is preferable to simple staining when... |
... determining the accurate size is crucial. |
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61. In the Gram stain procedure, the primary stain crystal violet functions to... |
... stain only the thicker peptidogylcan cell walls. |
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62. In the Gram stain procedure, Gram-negative, but not Gram-positive, cell wall structures are decolorized because... |
... the alcohol removes the lipids of the Gram-negative wall making the wall more porous. |
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63. Differential stains function to... |
... highlight differences between cells or parts of a cell. |
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64. Upon completion of the acid-fast stain, cells with mycolic acid in the cell wall will appear... |
... purple. |
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65. In the acid-fast staining procedure, why is the carbolfuchsin stain left in contact with the cells for five minutes? |
To allow the stain to penetrate the waxy wall of the cell. |
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66. In the acid-fast procedure, why is the sample counterstained with methylene blue or brilliant green rather than safranin which is used as the counterstain in the Gram stain procedure? |
Safranin is pink like carbolfuchsin and would not allow one to differentiate between the cell types. |
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67. If you failed to perform the decolorization step during the acid-fast staining procedure... |
... all the cells would appear pink. |
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68. The capsule stain involves the use of both... |
... basic stain and acidic stain. |
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69. Upon completion of the capsule staining procedure, the capsule will appear... |
... unstained. |
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70. The capsule of a bacterial cell is located... |
... outside the wall. |
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71. The capsule stain is... |
... a differential stain. |
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72. Why is water, rather than alcohol sufficient for the destaining step in the endospore staining procedure? |
Malachite green has a low affinity for cellular material. |
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73. Endospores are produced by bacteria... |
... to survive poor environmental conditions. |
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74. Endospores are resistant to heat and chemicals because of... |
... a thick outer covering of protein. |
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75. Upon completition of the endospore staining procedure, the endospore will appear... |
... green. |
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76. How does true motility differ in appearance from Brownian motion? |
With motility, cells will each exhibit independent movement over greater distances. |
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77. Why must bacterial flagella be stained in order to observe them? |
Because unstained they are more narrow than the resolution limit of the microscope. |
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78. An arrangement of flagella on both ends of the bacterial cell would be described as... |
... amphitrichous. |
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79. An arrangement of flagella all over the surface of the bacterial cell would be described as... |
... peritrichous. |
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80. Phenylethyl Alcohol Agar is... |
... selective for Gram-positive bacteria. |
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81. Phenylethyl Alcohol Agar plates are commonly used to isolate... |
... Staphylococci and Streptococci. |
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82. Phenylethyl Alcohol Agar plates inhibit growth of Gram-negative organisms by... |
... damaging the DNA. |
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83. E. coli plated on Phenylethyl Alcohol Agar plates... |
... will not grow at all. |
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84. Columbia CNA plates are particularly good at inhibiting the growth of... |
... coliforms. |
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85. If an organism grows well and clears the blood from the agar of a Columbia CNA plate you can conclude that it is... |
... Gram-positive and beta-hemolytic. |
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86. The substances in Columbia CNA plates that inhibit Gram-negative organisms are... |
... colistin and nalidixic acid. |
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87. An organism that produces a thick growth with a greening of the medium on Columbia CNA plates could be... |
... an alpha-hemolytic Staphylococcus. |
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88. A positive result for esculin hydrolysis on Bile Esculin Agar appears as...
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... a darkening around the growth. |
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89. The Bile Esculin test is common used to identify... |
... Enterococci. |
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90. Of what benefit would it be for an organism to have enzymes to hydrolyze esculin? |
To produce glucose for use in glycolysis. |
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91. You have been given an unknown culture that you have narrowed down to be a Streptococcus or Enterococcus through various assays. In the latest test it has not produced a brown pigment on a bile esculin plate. Which of the following organisms could it be? |
Streptococcus Pyogenes. |
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92. Growth of an organism on Mannitol Salt Agar plates indicates that the organism... |
... ferments mannitol. |
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93. When a Mannitol Salt Agar plate turns yellow, this indicates... |
... an acidic pH. |
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94. The mannitol in the Mannitol Salt Agar plate serves as... |
... a selective agent. |
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95. You have isolated some bacteria from your skin. In a Gram stain, the cells appear as purple cocci, many in grape-like clusters. On a Mannitol Salt Agar plate, the organism grows well and turns the plate yellow. A likely suspect is... |
... Staphylococcus Aureus. |
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96. MacConkey Agar is a selective and differential medium. It selects for ________________ while differentiating between those that can and cannot __________. |
Gram-negative, ferment lactose. |
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97. The neutral red dye in the MacConkey Agar functions... |
... as a pH indicator. |
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98. MacConkey Agar is often used to isolate and differentiate bacteria in the group... |
... Enterobacteriaceae. |
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99. You have isolated an organism from a fecal sample that has produced abundant pink growth on MacConkey Agar. This organism is likely... |
... a coliform. |
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100. The peptone in the Eosin Methylene Blue Agar serves as... |
... a nutrient source. |
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101. Eosin Methylene Blue Agar is a selective and differential medium. It selects for ________________ while differentiating between those that can and cannot __________. |
Gram-negative, ferment lactose. |
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102. If a Gram-negative organism is a vigorous fermenter of lactose, it will produce ____________ colonies on an Eosin Methylene Blue Agar plate. |
dark purple |
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103. What could you conclude about the lactose fermenting abilities of a Gram-positive organism plated on Eosin Methylene Blue Agar? |
Gram-positives will not grow, so no conclusion can be made. |
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104. Hektoen Enteric Agar is used to isolate... |
... Salmonella and Shigella. |
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105. In Hektoen Enteric Agar, the ferric ammonium citrate serves to produce a visible reaction with ______________ that would be produced by the bacteria. |
sulfide |
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106. Colonies that produce alkaline waste on Hektoen Enteric Agar will turn... |
... blue-green. |
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107. Colonies that produce hydrogen sulfide on Hektoen Enteric Agar will turn... |
... yellow. |
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108. In Xylose Lysine Desoxycholate Agar, the desoxycholate serves to... |
... inhibit Gram-positive cells. |
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109. Xylose is... |
... a carbohydrate. |
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110. A yellow colony on Xylose Lysine Desoxycholate Agar indicates that organism... |
... ferments Xylose. |
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111. An organism that produces red colonies on Xylose Lysine Desoxycholate Agar... |
... produces hydrogen sulfide. |
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112. Common products of microbial fermentation include... |
Acid, Alcohol, and Gas. [All of the above] |
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113. What is the purpose of the inclusion of a Durham tube in differential culture media? |
To visualize the production of gas during growth. |
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114. Following incubation of an organism in a tube of phenol red glucose broth, you observe the tube to be yellow with a bubble in the Durham tube. What can you reasonably conclude about this organism? |
It ferments glucose to both acid and gas products. |
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115. Following incubation of an organism in a tube of phenol red glucose broth, you observe the tube to be red with no visible bubbles in the Durham tube. What can you reasonably conclude about this organism? |
It does not ferment glucose. |
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116. The methyl red test is intended to detect organisms that are capable of... |
... performing mixed acid fermentation of glucose. |
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117. The Voges-Proskauer test is intended to detect organisms that are capable of... |
... converting acid products of fermentation into acetoin and 2,3-butanediol. |
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118. A positive result in the methyl red test will appear... |
... Red. |
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119. A positive result in the Voges-Proskauer test will appear... |
... Red. |
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120. Why is ONPG used to distinguish late lactose fermenting bacteria from non-lactose fermenting bacteria? |
It does not require a transporter to enter the cell. |
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121. Beta-galactosidase typically reacts with lactose to produce... |
... glucose and galactose. |
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122. Catalase is an enzyme that functions to... |
... convert hydrogen peroxide into water and gaseous oxygen. |
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123. A positive result in the catalase test is indicated by... |
... bubbles upon addition of hydrogen peroxide. |
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124. You have a human isolate unknown culture that appears as Gram-positive cocci. It demonstrates bubbling upon the addition of hydrogen peroxide. Which of the following is a likely candidate to suspect? |
Staphylococcus Epidermidis. |
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125. Why is it important to place the organism on the slide first when performing the catalase test? |
The metal loop can catalyze a false-positive reaction. |
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126. The oxidase test will yield positive results for organisms that... |
... utilize cytochrome c oxidase. |
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127. A positive result in the oxidase test will appear as... |
... purple on the bacterial cells. |
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128. In the Oxidase test, why is it important that the results of the test are scored rapidly upon application of the reagent? |
The reagents can oxidize without enzymatic activity resulting in false positive readings. |
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129. The presence of gas in the Durham tube in a nitrate reduction test indicates that the organism... |
... has performed denitrification. |
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130. What is the function of the zinc powder in the nitrate reduction test? |
To act as a catalyst. |
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131. When all the possible steps of the nitrate reduction test are complete and the culture tube still fails to produce a color change, this indicates the organism... |
... is capable of nitrate reduction. |
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132. In the nitrate reduction test, sulfanilic acid and naphthylamine will combine with ___________ to produce nitrous acid, which will result in a red color change. |
Nitrite |
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133. Why do organisms that have the capacity to utilize citrate as the sole carbon source tend to produce an alkaline reaction in Simmons citrate agar? |
The organism will also utilize ammonium phosphate as a nitrogen source resulting in alkaline waste. |
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134. Why is it important to use a light inoculum when preparing a Simmon's citrate agar slant? |
A heavy inoculum of inactive cells can be mistaken for new growth post incubation. |
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135. Citrate is utilized in which step of cellular respiration? |
Fermentation. |
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136. Organisms with the enzyme citrate-permease can... |
... can absorb citrate. |
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137. The enzyme succinate dehydrogenase functions in the citric acid cycle to... |
... oxidize succinate to fumarate while reducing FAD to FADH2. |
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138. A positive reaction in the malonate broth test will produce a _____________ color in the tube. |
Blue |
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139. A yellowing of the pH indicator in the malonate test indicates... |
... the organism is fermenting glucose into acid. |
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140. If an organism is negative for malonate utilization... |
... Malonate will inhibit succinate dehydrogenase, thus killing the cell.
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... the malonate broth culture will be green or greenish-yellow post incubation.
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141. Enzymes that catalyze the removal of the carboxyl group of an amino acid are called... |
... Decarboxylases. |
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142. Decarboxylation of amino acids results in the accumulation of ____________ end products. |
Alkaline |
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143. The enzyme that functions to remove the amino group from the amino acid phenylalanine is called... |
... Phenylalanine Decarboxylase. |
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144. The formation of a dark green product when ferric chloride is added to a culture incubated in phenylalanine deaminase test medium, indicates the presence of... |
... phenylpyruvic acid. |
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145. A yellow reaction in the phenylalanine deaminase test indicates that the organism is... |
... negative for phenylalanine deaminase. |
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146. The decarboxylation and deamination tests are often used to differentiate... |
... members of the Enterobacteriaceae. |
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147. If an organism produces the enzymes alpha-amylase and oligo-1,6-glucosidease, the organism will be able to hydrolyze... |
... Amylose and Amylopectin. |
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148. A positive result for a starch hydrolysis test performed on a starch agarplate will appear... |
... as a clear halo. |
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149. The function of the iodine in the starch hydrolysis test is to... |
... make starch visible. |
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150. In the urea hydrolysis test, if the tube is orange at 24 hours and pink at 48 hours, the organism is described as demonstrating... |
... slow urea hydrolysis. |
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151. In the urea hydrolysis test, if the tube is orange throughout the duration of the experiment, the organism is described as demonstrating... |
... no urea hydrolysis. |
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152. The enzyme necessary to hydrolyze urea into ammonia and carbon dioxide is... |
... Urease. |
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153. In the urea hydrolysis assay, the phenol red indicator will turn pink when... |
... the media has become alkaline. |
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154. The protein that gives milk its white color is... |
... Casein. |
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155. In a milk agar plate, when casein is hydrolyzed into individual amino acids... |
... the medium becomes transparent. |
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156. The enzyme casease functions to... |
... hydrolyze casein. |
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157. Gelatinases function to... |
... hydrolyze gelatin into amino acids. |
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158. Why does the solid medium become liquefied for an organism that produces gelatinases in the nutrient gelatin medium? |
The gelatin serves as the solidifying agent. |
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159. A positive result in the gelatin hydrolysis assay... |
... is liquefaction of the nutrient gelatin. |
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160. How would the results of a gelatinase assay be impacted if the organism was capable of producing gelatinases, but not secreting them as exoenzymes? |
It is unlikely that the culture would be able to liquefy the gelatin. |
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161. The DNA hydrolysis test can be used to distinguish...
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... Staphylococcus Aureus from other Staphylococcus species. |
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162. Deoxyribonuclease function to... |
... hydrolyze the bonds in the backbone of the DNA molecule. |
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163. A positive result in DNA hydrolysis test will produce... |
... a zone of clearing on the plate. |
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164. The methyl green dye in the DNAse test agar plate functions... |
... to allow visualization of DNA hydrolysis. |
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165. Enzymes that function to hydrolyze fats are called... |
... Lipases. |
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166. Lipid hydrolysis tests are performed on tributyrin agar plates. What purpose does the tributyrin serve in the assay? |
It is the substrate for the reaction. |
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167. A positive result in the lipid hydrolysis test will produce... |
... a clear zone around the bacterial growth. |
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168. Lipases will function to hydrolyze triglycerides into... |
... glycerol and fatty acids. |
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169. The PYR test is used for presumptive identification of... |
... group A streptococci. |
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170. A positive result in a PYR test will appear... |
... Red. |
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171. Which organism will produce a positive result in the PYR test? |
Enterococcus Faecalis.
& Streptococcus Pyogenes.
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172. An orange result in the PYR test indicates... |
... the organism is negative for L-pyrrolidonyl arylamidase. |
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173. SIM medium will assay for... |
Sulfur Reduction, Indole production, and Motility.
[All of the Above] |
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174. If the addition of Kovac's reagent produces a floating red layer on a SIM medium culture, this indicates the organism is... |
... positive for tryptophanase. |
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175. The ferrous ammonium sulfate in the SIM medium functions to... |
... produce a visible result when hydrogen sulfide is produced. |
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176. If you were to check on the Kligler iron agar tube of an organism that ferments glucose but not lactose at about 10 hours of incubation, what would you expect to see? |
The media would be all yellow. |
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177. If an organism is capable of reducing sulfur and producing hydrogen sulfide, the result that is expected in a Kligler iron agar slant is... |
... black precipitate. |
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178. In the lysine iron agar assay, if the incubated culture produces a red slant and yellow butt, the organism... |
... is positive for lysine deamination. |
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179. In the lysine iron agar assay, if the incubated culture tube has a yellow butt, the organism... |
... ferments glucose. |
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180. Assays in which the intent is to detect hydrogen sulfide production use media recipes that include ferric ions because... |
... the iron will combine with the hydrogen sulfide and produce a visible precipitate. |
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181. A bluing reaction of the litmus milk medium after incubation indicates that the organism... |
... partially digested the casein and produced ammonia. |
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182. A culture that has been incubated in litmus milk medium produces a tube that appears pink throughout. This indicates that the organism... |
... ferments lactose. |
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183. In order for an organism to be deemed sensitive to the antibiotic bacitracin, the zone of inhibition must be... |
... 10 mm or greater in size. |
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184. If an organism is sensitive to bacitracin this means... |
... growth of the organism can be prevented by bacitracin. |
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185. In order for an organism to be considered sensitive to a particular antibiotic, it must... |
... display a zone of inhibition of a certain size. |
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186. On a blood agar plate, the complete destruction of red blood cells and hemoglobin, resulting in a clearing of the medium around the colonies, is... |
... beta-hemolysis. |
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187. Why must a blood agar plate be stabbed to properly determine the hemolysis pattern, particularly for streptococci? |
The hemolysins produced by streptococci are produced or function maximally under anaerobic conditions. |
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188. After incubation on blood agar plate, the medium surrounding the organism is observed to have a greenish discoloration. The organism would be described as... |
... alpha-hemolytic. |
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189. If an organism that is grown on a Blood Agar plate does not cause any visible change to the blood in the agar, the pattern is called... |
... gamma-hemolysis. |
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190. The CAMP test is used to differentiate... |
... Streptococcus Agalactiae from other Streptococcus species. |
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191. In the CAMP test, Staphylococcus aureus must be cultures on the test plate along with the organism to be tested because... |
... the reaction requires synergism with beta-hemolysin from S. Aureus. |
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192. The CAMP test must be performed on a blood agar plate because... |
... this assay tests for hemolysis of red blood cells. |
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193. A positive result on the CAMP test will appear as... |
... an arrowhead pattern of hemolysis where the test organism is close to the S. Aureus. |
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194. The coagulase test is typically used to differentiate... |
... Staphylococcus Aureus from other Gram-positive cocci. |
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195. Rabbit plasma tubes being used for the tube coagulase test need to be analyzed for results within 24 hours of incubation because... |
... a positive coagulation can revert to a liquid after 24 hours. |
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196. Coagulase production can give a pathogenic organism an advantage during infection because it allows the microbe to... |
... surround itself with fibrin to prevent phagocytosis. |
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197. Why is it important to perform your streak for isolation from a fresh mixture culture of the two organisms for your “Bacterial Unknowns Project”? Why should the culture not be allowed to incubate while mixed for a long period of time before your prepare your plates? |
One organism may overgrow, inhibit, or kill the other, making isolation of both very difficult. |
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198. Why is the Gram stain a good beginning step with pure cultures in the “Bacterial Unknowns Project”? |
It will provide information about morphology and cell wall structure that will help to limit the potential suspects. |
