bio 126L quiz 2 key

bio 126L quiz 2 key - microorganisms Methylene Blue...

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    BIO126L (Wednesday 2-5 pm) TA: Hyung Cheol Kim Date: 3/1/2006 Quiz #2 Name: Desk #.: 1-3 Answer True or False (1 point each) 1. MacConkey agar is a selective media because it does not allow growth of non-fermenting bacteria. ( F ) 2. MacConkey agar without crystal violet is NOT a differential media. ( F ) 3. Microbacterium flavescens JG-9 cannot produce its own siderophore. ( T ) 4. The four types of microbial interactions between organisms are commensalism, synergism, neutralism and antagonism. Identify the interaction involved in the following cases. (2 points) (a) Organism X requires organism Y for growth but Y does not require X for growth. ( commensalism ) (b) Organism Y inhibits the growth of organism Z. ( antagonism ) 5. Explain the role of methylene blue (1 point) and thioglycolate (1 point) in determining the O-R potential of
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Unformatted text preview: microorganisms. Methylene Blue: indicator dye turning the medium blue color at the top of the tube with oxygen. Thioglycolate: Reducing agent, causeing a gradation of oxygen. 6. These are the results of Kirby-Bauer antibiotic test for a certain bacteria with 3 antibiotics A, B and C. (a) Which antibiotic is the most effective in inhibition of bacterial growth? (2 points) A (b) Which antibiotic is the least effective in inhibition of bacterial growth? (2 points) B 7. (9 points) Zone of Inhibition (ZOI) Antibiotic Disc Antibiotic C Antibiotic B Antibiotic A Stock Concentration : 1000 Step Dilution: 0.5 0.1 0.2 Cumulative Dilution: 0.5 0.05 0.01 Sample Concentration: 500 50 10 2 mL 0.1 mL 1 mL 2 mL 0.9 mL 4 mL...
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