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Microbiology Lab Final Study guide with Answers (115 Solved Questions)

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    Microbiology Lab Final Study guide Which of the following may benefit from the identification of specific microorganisms? - Environmental bioremediation programs - Criminal investigations - Radiation treatment of produce and meats - Treatment of infectious disease - - Environmental bioremediation programs - Criminal investigations - Treatment of infectious disease _______________ identification methods examine the DNA sequence of an organism, whereas _______________ identification methods use antibody- antigen reactions to identify microorganisms. - Genotypic; immunologic Which methods used to identify a microorganism causing an infection rely on the response of the host, rather than observation of the microorganism's properties? - Immunologic methods Which of the following would be most valuable to confirm the identification of microorganisms isolated during a food poisoning outbreak? - Growth on agar plates to identify colony morphology - Gram stain to view cellular morphology - Identification of microorganisms using microscopic, cultural, and physiological characteristics - Identification of microorganisms using microscopic, cultural, and physiological characteristics

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    What three main approaches can be used by microbiologists to identify microorganisms? - Antibiotic - Atmospheric - Transgenic - Genetic - Immunologic - Phenotypic - - Genetic - Immunologic - Phenotypic Which of the following correctly describes E. coli? - Can move using its flagella - Possesses the enzyme for tryptophan breakdown - Ferments only glucose - Would be pink on MacConkey agar plate after incubation - Does not produce acids during fermentation - - Can move using its flagella - Possesses the enzyme for tryptophan breakdown - Would be pink on MacConkey agar plate after incubation What is the minimum number of media that you would need to inoculate to determine the red-circled items on this flowchart? - Three E. coli would appear _________________ in color and _________________ - shaped under microscopic examination. - Pink; rod Which of the following tests could have been used to determine that E. coli is a lactose-fermenter? - Methyl red test - KIA test

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    - MacConkey agar - SIM medium - Urease test - - KIA test - MacConkey agar The Gram stain is an example of a test that can be used to determine the ________________ characteristics of a bacterium. - Morphological A particular microorganism can be distinguished from several closely related microorganisms by determination of its preferred growth temperature. This is an example of a _______________________ characteristic that can be used for identification. - Cultural Which of the following are examples of physiological (biochemical) characteristics that could be used in the bacterial identification process? - Gram stain reaction - Growth in nutrient broth - Ability to break down lipids - Presence of specific enzyme - Cell shape - - Ability to break down lipids - Presence of specific enzyme Which of the following is an example of a morphological characteristic that could be used in the bacterial identification process? - Production of gas bubbles in broth - Oxygen requirement - Cell shape - Presence of urease enzyme - Cell shape

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    Which of the following is an example of a culturing requirement that could be used in the bacterial identification process? - Ability to ferment glucose - Cell shape - Gram stain reaction - Oxygen preferences - Oxygen preferences An organism has been shown to produce hydrogen sulfide and indole in its metabolism. These are examples of ____________________ characteristics that can be helpful in identifying the microorganism. - Physiological What is the internationally recognized reference for bacterial classification and identification? - Bergey's Manual The ninth edition of Bergey's Manual of Determinative Bacteriology was designed solely for _________________________. - Identifying bacteria that have already been cultured and phenotypically examined Before attempting to identify an unknown bacterial species, the organism must be isolated in a/an _________________ culture. - Pure Which of the following methods could be used to isolate bacteria from a mixture? - Streak plating - Serial dilution followed by spread plating - Gram staining - Smear preparation - Loop dilution pour plating - - Streak plating - Serial dilution followed by spread plating - Loop dilution pour plating

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    Bergey's Manual of Determinative Bacteriology first categorizes bacteria based upon which of the following characteristics? - Gram stain reaction - Cell shape - Presence of certain enzymes - Fermentation abilities - - Gram stain reaction - Cell shape Identification of a bacterium can not be made on microscopic morphology alone because ______________________. - Many microorganisms have a similar microscopic morphology How do you determine the strain of an unknown bacterium? - You use multiple biochemical tests and pre-existing knowledge to classify the bacteria True or False: A standard set of biochemical tests is used to identify all types of bacteria, regardless of morphological and cultural characteristics. - False Which of the following are advantages of using multitest media or systems? - Improved accuracy - Improved efficiency - Reduction in media usage - Reduction in time required for identification - - Improved efficiency - Reduction in media usage - Reduction in time required for identification

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    A ______________________ key is a flowchart that can be used to identify an organism by making a series of choices until you arrive at one possibility. - Dichotomous You have isolated a bacterial strain from a patient sample. In order to determine the identity of the bacterium, you have performed the following tests: 1. Nitrate test - Negative 2. Glucose fermentation - Negative 3. Oxidase test - Positive Based on these results, the unknown bacterium is most likely _______________. - Alcaligenes faecalis According to this flowchart, what test is most useful for distinguishing between Escherichia coli and Vibrio cholerae? - Oxidase test The name of the reference book that provides information about the staining properties, morphology, and biochemical reactions of all known bacterial species is ____________________ Manual. - Bergey's When choosing a biochemical test to perform on an unknown bacterium, you should consider which of the following? - Choose an easy, rapid test that is applicable for its main group of bacteria. Which of the following media tests can provide information on more than one biochemical characteristic? - Kligler's iron agar (KIA) - Oxidase test

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    - Gram staining - SIM tubes - - Kligler's iron agar (KIA) - SIM tubes The first choice in this dichotomous key is based on the organism's __________________________. - Gram reaction Match each image to its correct biochemical test. - Which of the following biochemical tests can be performed on a well- isolated colony and can provide immediate results without further incubation? - Glucose fermentation - Oxidase test - Nitrate reduction - Citrate test - Oxidase test Which of the following biochemical tests involve growth of an organism in a specific broth medium? - SIM test - Phenol red carbohydrate fermentation test - Nitrate reduction test - Methyl red test - Oxidase test - - Phenol red carbohydrate fermentation test - Nitrate reduction test - Methyl red test Which of the following media allows for the observation of multiple biochemical properties? - MacConkey agar

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    - SIM - Citrate medium - Urea agar - SIM Match each test name with an image depicting the test. - The oxidase test determines the presence of cytochrome oxidase enzyme. This enzyme functions as part of ______________________. - The electron transport chain Match each of the following components of citrate agar with its role. 1. Citrate 2. Ammonium salts 3. Bromothymol blue a. pH indicator b. Carbon source c. Nitrogen source - - Citrate --> Carbon source - Ammonium salts --> Nitrogen source - Bromothymol blue --> pH indicator E. coli is positive on the nitrate reduction test after the addition of the first two reagents. This means that E. coli reduces nitrate to _______________________. - Nitrite Which of the following is detected by the methyl red test? - Mixed acid fermentation - Indole production - Lactose fermentation

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    - Nitrate reduction - Mixed acid fermentation Phenol red carbohydrate broths with Durham tubes can detect ____________________________. - - Gas production - Fermentation - Acid production Which of the following is true of a bacterial species that produces dark pink colonies when grown on MacConkey agar? - They are lactose fermenters. - They ferment glucose with the production of mixed stable acids. - They reduce nitrate to nitrite. - They must be gram-negative bacilli. - They produce urease enzyme. - - They are lactose fermenters - They must be gram-negative bacilli An organism produces urease enzyme. Which of the following describes the color change expected in the test medium for this enzyme? - Changes from yellow to bright pink A KIA tube was inoculated with a bacterial isolate and incubated for 24 hours. At the end of incubation, the tube had a red slant and a yellow butt. What does this indicate about the biochemical properties of this bacterial species? - - Glucose was fermented. - Lactose was not fermented. A tube of SIM medium was inoculated and incubated for 24 hours. Following incubation, the tube was cloudy, showed black precipitate, and when Kovac's reagent was added, it turned bright pink. Which of the following is a correct interpretation of these results? - - Hydrogen sulfide production: positive

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    - Motility: positive - Indole: positive You conducted an oxidase test to detect the production of oxidase enzyme. Is the result positive or negative? - Negative This is how the MacConkey agar plate looks after 24 hours of incubation. Are these bacteria positive or negative for lactose fermentation? - Negative This is how the KIA test looks after 24h. Is the unknown bacterium positive or negative for glucose fermentation, lactose fermentation and H2S production? - Glucose Positive - Lactose Negative - H2S Negative You conducted a citrate test. Is this result positive or negative? - Negative Positive citrate test - This is how the KIA test looks after 24h. Is the unknown bacterium positive or negative for glucose fermentation, lactose fermentation and H2S production? - Glucose Positive - Lactose Negative - H2S Positive You conducted a urease test. Is this result positive or negative for urease activity? - Negative This is how the KIA test looks after 24h. Is the unknown bacterium positive or negative for glucose fermentation, lactose fermentation and H2S production? - Glucose Positive - Lactose Positive - H2S Negative You conducted a methyl red test. Is the result positive or negative? - Positive

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    This is how the SIM medium looks after 24h. Is the unknown bacterium positive or negative for H2S production, indole generation and motility? - H2S Negative - Indole Positive - Motility Positive You conducted an oxidase test to detect the production of the oxidase enzyme. Is the result positive or negative? - Positive This is how the phenol red glucose broth with a Durham tube looks after 24 hours of incubation. Is this bacterium positive or negative for glucose fermentation? - Negative The field of study in which medicine and microbiology intersect is known as ___________. - Medical microbiology Which of the following is a characteristics of members of the resident microbiota? - Resident microbiota often initiate allergic reactions. - Resident microbiota typically cause serious infections. - Resident microbiota can compete with and limit growth of harmful bacteria. - Resident microbiota are a major source of nutrients for our bodies. - Resident microbiota can compete with and limit growth of harmful bacteria. Which of the following body sites normally have large numbers of resident microbiota? - Liver - Large intestine - Blood - Throat

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