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Microbiology Lab Quiz 6

Terms in this set (12)

As explained in the lab manual, after inoculating a bacterial species into gelatin tube, incubating overnight, then cooling the tube in the refrigerator or on ice, bacteria that have secreted the exoenzyme gelatinase (collagenase) will cause the gelatin to:
remain liquid
Microbial production of gelantinase, or collagenase, is likely to be involved with which of these processes? Select all correct answers:
1. Breaking down connective tissue in animal host
2. Decomposition of dead animals
3. Decomposition of dead plants
4. Conversion of H2O2 to water and oxygen
1. Incorrect
2. Correct
3. Incorrect
4. Incorrect
SIM medium can be used to detect the production o f indole from the breakdown of tryptophan, which is a(n)
amino acid
Assume this SIM test was inoculated with a pure culture, incubated 48 hours, and Kovac's reagent was added. Select ALL correct interpretations:
1. H2S was produced:
2. The bacteria produced tryptophanase
3. The bacteria are motile
4. The bacteria produce betagalactosidase
1. Incorrect
2. Correct
3. Correct
4. Incorrect
For each bacterial metabolic process that can result in production of H2S, select "true." for metabolic processes that do not produce H2S, select "false."
1. Aerobic Respiration
2. Anaerobic Respiration
3. Catabolism of sulfur-containing amino acids (cysteine)
4. Fermentation of urea
1. False
2. True
3. True
4. False
In a positive test for urease, the agar will turn pink in color (as shown). What specific biochemical activity is being detected?
The ability of some bacteria to produce urease, which breaks down urea to ammonia and CO2
As mentioned in lab, for the clinical test for urease activity in which patients drink radioactive urea, what is actually being measured in the patient's breath?
radioactive CO2
The breath test in the previous question is used to help diagnose infection with which bacterium?
H. Pylori
What is the substrate for the enzyme catalase?
H2O2
Suppose you are performing a catalase test and after adding the appropriate reagent tot he bacteria you see bubbles forming (as shown). The bubbles are:
O2
True or false: Hydrogen peroxide (H2O2) is actually generated within phagocytic cells of the immune system to help kill microbes they can ingest.
True
The oxidase test detects the presence of a component of which of these?
electron transport chain
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