Biochemical Tests Lab QUIZ

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York Technical College *

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225

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Chemistry

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Dec 6, 2023

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BIOCHEMICAL TESTS LAB QUIZ HIGHLIGHT OR COLOR OR BOLD YOUR ANSWERS AND SUBMIT THIS QUIZ TO THE PROPER DROPBOX. 1. Which of the following best describes the action of catalase? a. Catalase combines water and oxygen to produce hydrogen peroxide. b. Catalase transports electrons out of the respiratory reaction. c. Catalase enables oxygen to accept electrons at the end of the electron transport respiratory chain. d. Catalase converts hydrogen peroxide into water and oxygen. e. Catalase reduces thiosulfate anion to hydrogen sulfide. 2. Which of the following best describes the action of cytochrome c oxidase? a. Cytochrome c oxidase combines water and oxygen to produce hydrogen peroxide. b. Cytochrome c oxidase transports electrons out of the respiratory reaction. c. Cytochrome c oxidase enables oxygen to accept electrons at the end of the electron transport respiratory chain. d. Cytochrome c oxidase converts hydrogen peroxide into water and oxygen. e. Cytochrome c oxidase reduces thiosulfate anion to hydrogen sulfide. 3. What is the purpose of including phenol red in triple sugar iron (TSI) medium? a. Phenol red undergoes fermentation. b . Phenol red is a pH indicator. c. Phenol red can be reduced to hydrogen sulfide. d. Phenol red ferments the sugars. e. Phenol red inhibits catalase. 4. Which statement about the sugar content of triple sugar iron (TSI) medium is correct? a. TSI medium contains equal amounts of glucose, lactose, and sucrose. b. TSI medium contains high amounts of glucose, and small amounts of lactose and sucrose. c. TSI medium contains a small amount of glucose, and high amounts of lactose and sucrose. d. TSI medium contains small amounts of glucose and lactose, and a high amount of sucrose. e. TSI medium contains high amounts of glucose and lactose, and a small amount of sucrose.

5. What is indicated by the formation of a black precipitate in a tube of triple sugar iron (TSI) medium? a. bacterial production of hydrogen peroxide b. bacterial fermentation of glucose, lactose, and sucrose c. bacterial fermentation of glucose only d. bacterial production of catalase e. bacterial production of hydrogen sulfide 6. Which is the correct interpretation of a tube of triple sugar iron (TSI) medium that develops a yellow slant and a yellow butt? a. fermentation of glucose only b. no fermentation of sugar; aerobic and anaerobic protein catabolism c. no fermentation of sugar; aerobic protein catabolism d. fermentation of glucose, plus lactose and/or sucrose e. nonexistent growth 7. Which is the correct interpretation of a tube of triple sugar iron (TSI) medium that develops a red slant and red butt? a. fermentation of glucose only, with gas production b. no fermentation; aerobic and anaerobic protein catabolism c. nonexistent growth d. fermentation of glucose only; aerobic protein catabolism e. fermentation of glucose, plus lactose and/or sucrose, with sulfur reduction 8. How does a pH indicator enable one to determine if fermentation has occurred?  Organic acid is produced when fernentation occurs so the acid will cause a change of color in the indicator. 9. What is the preferred energy source used by most bacteria? What alternatives may bacteria use if the preferred energy source is depleted?  Glucose- preferred energy source  Break down proteins- alternative energy source 10. Why perform multiple tests in order to identify an unknown bacterium, instead of a single biochemical test?  Performing mulitple tests in order to identify an unknown bacterium will help to accurately determine the biochemical characteristics to distinguish a given species. One test is not enough to make a conclusion.

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