Lab study guide for midterm fall 2022 student copy

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Miami Dade College, Miami *

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2010L

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Biology

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Feb 20, 2024

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MCB2010 Lab HW for midterm Exercises 1, 2, 3, 4.1, 6.4, 6.5, 4.2, 4.3, 5.1, 5.2, 5.3, 6.1, 6.2, 6.3, 5.4, 5.9 Exercises 5.5, 5.6, 5.7, 5.8, 6.6, 6.7, 6.8, 6.9, 6.10, 6.11, 7.1, 7.2, 7.3, 7.4, 7.5 Exercise1 1. All of the organisms we work with are pathogenic A. TRUE B. FALSE 2. All of the organisms we work with should be handled as if they are pathogenic A. TRUE B. FALSE 3. All of the organisms we work with should be handled as if they are opportunistic A. TRUE B. FALSE 4. Wash hands with disinfectant and wipe bench tops with soap and warm water before starting any lab exercise and after all work has been completed. A. TRUE B. FALSE 5. The following are not allowed in the lab: A. food B. drink C. children D. smoking E. All of the above 6. In the lab long hair must be tied back and loose clothing should be worn A. TRUE B. FALSE 7. Inoculation loops and needles are flamed before and after use. A. TRUE B. FALSE 8. Aerosols created by splattering of cultures are caused by improper flaming and cooling of needles and loops before use. A. TRUE 1

B. FALSE 9. The mouth of test tubes and other culture vessels are to be flamed before use A. TRUE B. FALSE 10. Everything going into the incubator must be labeled with name, microbial content and other data, using black marking tools. A. TRUE B. FALSE 11. Non-contaminated waste goes into the autoclavable bags. Contaminated disposable waste goes into the waste basket. A. TRUE B. FALSE 12. Never lay tubed media down vertically, at anytime—it will spill. A. TRUE B. FALSE Exercise2 13. Aseptic techniques are any techniques employed to encourage contamination. A. TRUE B. FALSE 14. Methods to prevent contamination include: A. flaming B. autoclaving C. sterilizing D. use of steam under pressure E. all of the above 15. An axenic culture is a mixed culture of organism of interest. A. TRUE B. FALSE 16. Typically growth media is sterilized by flaming A. TRUE B. FALSE 17. An autoclave sterilizes by using halogenated gases A. TRUE B. FALSE 2

18. Flame inoculating tools using the Bunsen burner until they are red hot in order to sterilize A. TRUE B. FALSE 19. Blow on the sterilized inoculating tools to cool them A. TRUE B. FALSE 20. Test tubes are fitted with loose caps that will not come off, so you can hold the tube by the cap A. TRUE B. FALSE 21. Contents of tubes will spill if you lay the tube on the table or invert it A. TRUE B. FALSE 22. Hold the tube in your nondominant hand (right-handed people should hold the tube in their left hand) and the inoculating loop in your dominant hand. A. TRUE B. FALSE 23. When handling a petri dish with agar tilt the lid up to open it, do not completely remove it A. TRUE B. FALSE 24. Airborne microorganisms can contaminate sterile media and inoculating tools A. TRUE B. FALSE 25. Most bacterial cultures will be incubated at 55°C for 24 to 48 hours A. TRUE B. FALSE Exercise3 26. Define colony: A. Macroscopic bacterial growth on solid media B. Microorganisms all originating from a single mother cell 3

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C. Bacterial clones D. Genetically identical bacteria E. All of the above 27. Define ubiquitous A. Present everywhere B. Present nowhere C. All of the above D. None of the above 28. Characteristics of a pure culture include: A. All colonies have the same textures B. All colonies have different margins C. All colonies have the same elevations D. All colonies have different pigment E. None of the above 29. Cultural characteristics include size, form, margin, elevation, opacity, color A. TRUE B. FALSE Exercise 4.1 30. One of the most important steps in identifying a new bacteria or one isolated from a patient's specimen is noting colony morphology A. TRUE B. FALSE 31. Colony morphology is described as how the colony or clone of cells looks on the agar surface. A. TRUE B. FALSE 32. Colony morphology is identical between various microbial species A. TRUE B. FALSE 33. Colony morphology does not vary with microbial growth conditions A. TRUE B. FALSE 4

34. Nutrients present in various media or incubation conditions may contribute to altered colony size or appearance. A. TRUE B. FALSE 35. Increased or specific carbohydrate content may result in more pronounced bacterial capsule synthesis, leading to very mucoid colonies. A. TRUE B. FALSE 36. Some temperatures may be restrictive or stimulating to growth of specific species. A. TRUE B. FALSE 37. Mycobacterium, Mycoplasma, Chlamydia, and Rickettsia are not pathogens A. TRUE B. FALSE 38. Species of Rickettsia can cause pneumonia, urogenital and other infections and are normally found in normal mucous membrane microflora A. TRUE B. FALSE 39. Mycobacterium, Mycoplasma, Chlamydia, and Rickettsia are not classified as true bacteria A. TRUE B. FALSE 40. Mycobacterium, Mycoplasma, Chlamydia, and Rickettsia are extremely large and cannot be cultured by ordinary methods. A. TRUE B. FALSE 41. Mycoplasma are pleomorphic because they have no cell wall. A. TRUE B. FALSE 42. Mycoplasmas can be opportunistic pathogens. A. TRUE B. FALSE 43. Mycoplasmas can pass through sterilizing filters, and do not 5

stain with ordinary stains. A. TRUE B. FALSE 44. Mycoplasmas are susceptible to the antibiotics which act by inhibiting cell wall synthesis. A. TRUE B. FALSE 45. A type of colony morphology form includes A. Raised B. Convex C. Flat D. FILAMENTOUS E. UMBONATE 46. A type of colony morphology margin includes A. Raised B. Convex C. Flat D. FILAMENTOUS E. UMBONATE 47. Types of colony morphology elevation include A. Crateriform B. Umbonate C. Flat D. All of the above E. None of the above 48. Rickettsiae are very small bacteria that can only grow and multiply intracellularly, as they are obligate parasites. A. TRUE B. FALSE 49. Rickettsiae have a cell wall that cannot be stained. A. TRUE B. FALSE 50. Rickettsiae must be grown in cell culture or intact animals. A. TRUE B. FALSE 51. Most Rickettsiae are transmitted by arthropods like bats 6

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A. TRUE B. FALSE 52. Pathogenic Rickettsiae include the causative agents for typhus and Rocky Mountain spotted fever. A. TRUE B. FALSE 53. Chlamydiae are motile, coccoid, obligate intracellular parasites. A. TRUE B. FALSE 54. Chlamydiae have three life forms, or stages, known as the elementary body, primary body and the reticulate body. A. TRUE B. FALSE 55. Chlamydiae must grow and multiply inside another cell; then they are released to infect new cells. A. TRUE B. FALSE 56. There are two species of Chlamydiae responsible for human disease: psittaci (parrot fever) and trachomatis (STD, trachoma, LGV). A. TRUE B. FALSE 57. Psittaci and trachomatis can only be studied in cultured cells or intact animals A. TRUE B. FALSE Exercise 6.5 58. Microbial colonies can be colored/pigmented because of loss of nutrients and carbohydrates to the growth media A. TRUE B. FALSE 59. If the organism produces an extracellular pigment the media turns colorless A. TRUE B. FALSE 60. Both the media and the colonies may be colored if the bacteria produces an intracellular pigment and an extracellular pigment A. TRUE 7

B. FALSE 61. There are different degrees of opacity. A. TRUE B. FALSE 62. In colony morphology, ‘size’ relates to the size of the bacterial cell A. TRUE B. FALSE 63. To examine size, observe colonies in the most densely populated quadrant of the plate (e.g., first quadrant) A. TRUE B. FALSE 64. Size distinctions to be made include pinpoint, small, medium, and large. A. TRUE B. FALSE 65. In colony morphology, ‘margin’ refers to what the edge of the colony looks like A. TRUE B. FALSE 66. To observe elevation, it is best to look at the bottom of your plate A. TRUE B. FALSE 67. To observe elevation, it is best to look at the top of your plate A. TRUE B. FALSE 68. In colony morphology, ‘transparency’ is how much light is able to pass through the colony. A. TRUE B. FALSE 69. To observe opacity, hold the plate obliquely to the overhead light or place the plate over the writing of your textbook/notebook/handout. A. TRUE B. FALSE 70. Transparent colonies allow all of the light to pass through them. A. TRUE B. FALSE 8

71. Translucent colonies allow most of the light to pass through them; some light is blocked. A. TRUE B. FALSE 72. Opaque colonies block none of the light. A. TRUE B. FALSE 73. If the bacteria produce an intracellular pigment that is retained by the cell, the colony becomes colored. A. TRUE B. FALSE 74. If the bacteria produce an extracellular pigment that is excreted by the cell, the medium becomes colored. A. TRUE B. FALSE 75. If the organisms are translucent, the colored media will show through the colonies, and the colonies will appear to have the same color as the media. A. TRUE B. FALSE 76. White colonies or translucent colonies that take on the color of the straw-colored media are termed “pigmented” A. TRUE B. FALSE Exercise 4.2 77. Characteristic surface or internal components that are of value in identifying organisms include: A. Endospores B. Capsules C. Flagella D. All of the above E. None of the above 78. Special stains are available for characteristic surface or internal components as well as for other cell components to aid in the study of microbes. A. TRUE B. FALSE 9

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79. The acid-fast stain is a differential stain for Mycobacterium and related bacteria. A. TRUE B. FALSE 80. Mycobacterium is a genus that includes the causative ages of leprosy and tuberculosis A. TRUE B. FALSE 81. It is useful clinically to have a stain for rapid identification of Mycobacterium in sputum or skin scrapings. A. TRUE B. FALSE 82. Mycobacterium are unusual in that the cell wall has a mixture of waxy lipids called mycolic acids, that prevent the bacterium from staining by simple and gram stains. A. TRUE B. FALSE 83. Fatty lipids called mycolic acids also prevent drying of the microbe. A. TRUE B. FALSE 84. In the acid-fast stain, a green stain (carbolfuchsin) is cooked into the waxy cell wall, and cannot be removed with acidified alcohol. A. TRUE B. FALSE 85. A stain that is cooked into the waxy cell wall, and cannot be removed with acidified alcohol is acid-fast. A. TRUE B. FALSE 86. Non acid fast bacterium and tissue background will lose the carbolfuchsin stain when washed with acid-alcohol, becoming colorless. A. TRUE B. FALSE 87. A counterstain (methylene blue) is used to see them non acid fast bacterium A. TRUE 10

B. FALSE 88. The genus Mycobacterium contains some pathogens and many saprophytic species, found in soil and water, and also on human skin and mucous membranes. A. TRUE B. FALSE 89. Mycobacterium grows very fast in the laboratory on a complex media. A. TRUE B. FALSE 90. Often it will take 9 weeks for visible growth of Mycobacterium in culture. A. TRUE B. FALSE 91. Acid-fast stain is important for quick diagnosis because some strains of Mycobacterium, such as M. leprae, cannot yet be grown in culture. A. TRUE B. FALSE 92. Capsules are found on some bacteria (and fungi) A. TRUE B. FALSE 93. Capsules may actually relate to pathogenicity in some strains, such as Streptococcus pneumoniae, Klebsiella pneumoniae, and Clostridium perfringens. A. TRUE B. FALSE 94. Small capsules can protect the microbe from host defense mechanisms, especially phagocytosis. A. TRUE B. FALSE 95. Capsules are often identified immunologically, but can also be visualized with a simple gram stain. A. TRUE B. FALSE 96. In a negative stain technique, material such as India ink or Congo red is used to coat the slide but not penetrate the cell or capsule. 11

A. TRUE B. FALSE 97. A stain can be used to color the cells, and then the capsule is seen as a clear region surrounding the cells against the dark background. A. TRUE B. FALSE 98. There are direct and indirect methods of staining capsules. A. TRUE B. FALSE 99. Flagella are tiny hairlike organelles for pathogenicity. A. TRUE B. FALSE 100. Flagella have a carbohydrate structure requiring a special staining technique A. TRUE B. FALSE 101. The number of flagella and their arrangement can be defined as: A. Monotrichous B. Amphitrichous C. Lophotrichous D. Peritrichous E. All of the above 102. A stain and mordant react with the flagella, increasing its diameter to allow viewing in the microscope. A. TRUE B. FALSE 103. Endospore formation is most characteristic of two genera of bacteria, Bacillus and Mycobacterium A. TRUE B. FALSE 104. Endospores provide a resistant form for survival of the organism in unfavorable conditions. A. TRUE B. FALSE 105. Because of the weak spore coating, they are not readily stained and may appear as empty “holes” in simple or gram-stained bacteria. A. TRUE 12

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B. FALSE 106. A special staining technique must be used to drive dye into endospores. A. TRUE B. FALSE 107. Usually malachite green is heated to stain the endospores, and then the vegetative bacteria are counterstained with safranin. A. TRUE B. FALSE 108. Endospores appear blue in red bacterial cells. A. TRUE B. FALSE 109. Boiling water is used in the process of staining an endospore A. TRUE B. FALSE 110. 15-20 minutes of steam is used in the process of staining an endospore A. TRUE B. FALSE 111. Cooking safranin into the resistant endospore wall is used in the process of staining an endospore A. TRUE B. FALSE 112. During the process of staining an endospore, running water washes the green stain out of the vegetative cells and sporangia, and they become colorless. A. TRUE B. FALSE 113. The counterstain then dyes the vegetative cells red. A. TRUE B. FALSE 114. Vegetative cells are dormant A. TRUE B. FALSE 115. Endospores are reproductive germinating cells A. TRUE B. FALSE 13

116. What is the clinical value of an acid-fast stain? A. Rapid identification of Clostridium B. Rapid identification of Bacillus C. Rapid identification of Mycobacterium D. All of the above E. None of the above 117. Why is a capsule stain useful in the lab? A. To identify bacterium with a flagella B. To identify bacterium with an endospore C. Because encapsulated bacteria cannot be stained D. To identify whether or not a bacterium has a capsule E. None of the above 118. What is the importance of the different arrangements of flagella? A. Pathogenicity B. Attachment C. Speed D. Virulence E. Locomotion 119. Why must the spore stain include a heating step? A. Cooking safranin into the resistant endospore allows its visualization B. Cooking congo red into the resistant endospore allows its visualization C. Cooking malachite green into the resistant endospore allows its visualization D. Cooking malachite green into the resistant endospore prevents its visualization E. None of the above 120. What would happen if the heating step were omitted from the spore stain? A. The endospore would be green B. The endospore would be blue C. The endospore would be black D. The endospore would be red E. The endospore would be clear Exercise 4.3 121. The science of taxonomy provides us with a system for classifying and naming organisms. 14

A. TRUE B. FALSE 122. The currently accepted taxonomic system places all organisms into one of five Domains: Eukarya, Archaea, Bacteria, Fungi, Animalia A. TRUE B. FALSE 123. Domains Archaea and Bacteria contain all organisms with cells that are prokaryotic A. TRUE B. FALSE 124. Prokaryotic cells have chromosomes that are contained in a true membrane-bound nucleus. A. TRUE B. FALSE 125. Within each of the domains, a hierarchical taxonomic system places similar species into the same kingdom A. TRUE B. FALSE 126. Within each of the domains, a hierarchical taxonomic system places similar similar genera into the same family A. TRUE B. FALSE 127. Within each of the domains, a hierarchical taxonomic system places similar similar families into the same order A. TRUE B. FALSE 128. Within each of the domains, a hierarchical taxonomic system places similar similar orders into the same class A. TRUE B. FALSE 129. Within each of the domains, a hierarchical taxonomic system places similar and similar classes into the same phylum A. TRUE B. FALSE 130. There are seven phyla of the Domain Bacteria. A. TRUE 15

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B. FALSE 131. Firmicutes and Actinobacteria are two bacterial A. Families B. Genera C. Classes D. Orders E. Phyla 132. Firmicutes and Actinobacteria are generally Gram negative A. TRUE B. FALSE 133. Firmicutes and Actinobacteria differ from each other in the percentage of Guanine and Cytosine (G + C) bases (relative to Adenine and Thymine) in their DNA. A. TRUE B. FALSE 134. Firmicutes contains five key genera A. TRUE B. FALSE 135. Bacillus, Clostridium, Lactobacillus, Staphylococcus and Streptococcus are genera of: A. Actinobacteria B. Proteobacteria C. Cyanobacteria D. Streptomyces E. Firmicutes 136. Actinobacteria contains two key genera including Mycobacterium and Streptomyces A. TRUE B. FALSE 137. Gram-negative phyla include A. Proteobacteria B. Cyanobacteria C. Chlamydiae D. All of the above E. A and B 138. Chlamydiae has the most genera (> 300) of any other bacterial phylum 16

A. TRUE B. FALSE 139. Proteobacteria contains five key genera: Escherichia, Pseudomonas, Rhizobium, Salmonella, and Spirillum. A. TRUE B. FALSE 140. The members of phylum Cyanobacteria, including the ke genus Anabaena, are unique in their metabolic strategy, utilizing oxygenic photosynthesis to obtain energy and organic carbon molecules. A. TRUE B. FALSE 141. Many of the Cyanobacteria also use nitrogen fixation (in specialized cells called heterocysts) to convert gaseous nitrogen into a form they can use A. TRUE B. FALSE 142. Rhizobium of the Proteobacteria use carbon fixation (in specialized cells called heterocysts) to convert gaseous carbon dioxide into a form they can use. A. TRUE B. FALSE 143. Phylum Chlamydiae is unique among bacteria in that its members have an abundance of peptidoglycan in their cell walls A. TRUE B. FALSE 144. Phylum Chlamydiae bacteria do not have genes for production of peptidoglycan. A. TRUE B. FALSE 145. There are no disease-causing species of the genus Chlamydia A. TRUE B. FALSE 146. Mycobacterium and Streptomyces are genera of: A. Cyanobacteria B. Proteobacteria C. Actinobacteria D. Streptomyces 17

E. Firmicutes, 147. Escherichia, Pseudomonas, Rhizobium, Salmonella and Spirillum are genera of: A. Actinobacteria B. Proteobacteria C. Cyanobacteria D. Streptomyces E. Firmicutes 148. Which phylums have one genera? A. Cyanobacteria B. Chlamydiae C. Anabaena D. None of the above E. A and B 149. Phylum Cyanobacteria contains genera Anabaena which utilizes heterocysts for nitrogen-fixation A. TRUE B. FALSE 150. Wasserblüthe is a German word meaning ‘water fall” A. TRUE B. FALSE 151. When looking at a slide of Wasserblüthe, you will observe many different types of Cyanobacteria.’ A. TRUE B. FALSE 152. The dominant metabolic strategy of all five major phyla in the domain bacteria is oxygenic photosynthesis A. TRUE B. FALSE 153. Actinobacteria have a low G + C content in DNA A. TRUE B. FALSE 154. Firmicutes have a low G + C content in DNA A. TRUE B. FALSE Exercise 5.2 18

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155. Crystal violet is a ______ stain. A. negative B. neutral C. basic D. positive E. C and D 156. The following is a bacterial stain A. safranin B. methylene blue C. crystal violet D. malachite green E. All of the above 157. Bacterial cells have a positive charge A. TRUE B. FALSE 158. Congo red and India ink are ____stains A. negative B. neutral C. basic D. positive E. C and D 159. Staphylococcus sp. is arranged as chains and is rod shaped A. TRUE B. FALSE 160. Bacillus sp. is a rod shaped microbe that divides only along 1 axis A. TRUE B. FALSE Exercise 5.3 161. A/an ______ is a small glass disc with uniformly spaced lines etched on it. 19

A. microscope B. ocular micrometer C. stage D. objective E. binocular 162. The smallest object you can possibly see (as a barely-visible dot under the oil-immersion lens) with a light microscope is about ____ A. 0.1 μm B. 0.4 μm C. 2 μm D. 0.2 μm E. 0.3 μm Exercise 6.1 163. E. binocular A. 0.1 μm B. 0.4 μm C. 2 μm D. 0.2 μm E. 0.3 μm Exercise 6.2 164. _____ is/are bacterial flagellar arrangements that are polar A. monotrichous B. amphitrichous C. lophotrichous D. peritrichous E. A, B, and C 165. The following is/are methods to examine flagella provide motility to the cell. A. negative stain B. electron microscopy C. Ryu stain D. B and C E. A, B, and C 20

166. The two commonly used methods to determine if a bacterium is motile are wet-mount preparation (microscopic) and motility media (mac-roscopic) A. TRUE B. FALSE 167. Brownian motion is the ordered moving of particles resulting from their collisions with atoms or molecules in the water. A. TRUE B. FALSE 168. 0.005% triphenyltetrazolium chloride (TTC) TTC can be utilized by bacteria as an electron acceptor and in its reduced form turns red. A. TRUE B. FALSE Exercise 6.3 169. The purpose of making a smear is to adhere/fix the bacteria to the slide to prevent the sample from being lost during the staining process. When using a liquid culture, one loopful of culture is smeared onto a glass slide and allowed to air dry. The cells in the dried smear are then “fixed” to the slide by briefly heating. This process is known as heat fixation. A. TRUE B. FALSE 170. When using growth from an agar medium to make a smear, a loopful of water is placed on the slide, and a very large amount of culture is mixed with the water to separate and suspend the bacteria. The suspension is then spread out, air dried, and heat fixed. In a good smear, the bacteria are evenly spread out on the slide and individual organisms are visible microscopically. A. TRUE B. FALSE 21

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171. Bacteria have rigid cell walls that function to maintain a constant shape. A. TRUE B. FALSE 172. There are five basic bacterial shapes: cocci, bacilli, rectangle, star and spiral. A. TRUE B. FALSE Exercise 5.4 173. The most common clinically used methods of differential staining are the Gram stain and the Acid-fast stain. A. TRUE B. FALSE 174. What is true of gram negative organisms A. stain blue/purple B. have thick peptidoglycan C. do not have an outer membrane D. clear when decolorized E. none of the above 175. Old cultures tend to decolorize more easily than younger cultures. A. TRUE B. FALSE 176. The acid fast stain receives its name because certain bacteria, particularly the Mycobacteria, have a tendency to resist decolorization by acids. A. TRUE B. FALSE 177. Gram stained Mycobacteria appear blue/purple A. TRUE B. FALSE 22

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178. Acid fast organisms have a high content of fat or lipid and mycolic acids in their cell walls. A. TRUE B. FALSE 179. Two types of acid fast stains include Ziehl-Neelsen (Z-N) and Method Kinyon Method A. TRUE B. FALSE Exercise 5.9 180. The correct order of the gram stain procedure is: A. crystal violet-iodine-ethanol-safranin B. safranin-crystal violet-iodine-ethanol C. iodine-safranin-crystal violet-ethanol D. crystal violet-ethanol-iodine-safranin E. crystalviolet-iodine-safranin-ethanol 181. Crystal violet is used as the primary stain in the gram stain procedure because it contains an anionic ion that binds to the cell wall of both gram-positive and gram negative cells because the cell walls of both are negatively charged. A. TRUE B. FALSE 182. Ethanol is thought to extract the lipid from the gram-negative cell wall and dehydrate the cell wall of the gram-positive organism A. TRUE B. FALSE 23

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Lab study guide for midterm fall 2022 student copy

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