Microbiology 250 Lab Practical exam questions with answers

Microbiology 250 Lab Practical exam \| \| \| \| \|




questions with answers \| \|




brom cresol purple - CORRECT ANSWERS ✔✔indicator in MIO media that
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tests for decarboxylation of ornithine
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positive result is a lavender-purple color
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A



hydrogen peroxide - CORRECT ANSWERS ✔✔H2O2
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used to test for organism's possession of catalase
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copious amounts of bubbles are evidence for release of O2 as peroxide is
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broken down \| \|




2H2O2 + O2 \| \|




iodine - CORRECT ANSWERS ✔✔indicates the presence or absence of starch
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agar - CORRECT ANSWERS ✔✔solidifying agent purified from marine algae
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,colonial morphology - CORRECT ANSWERS ✔✔size, color, shape, elevation,
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consistency, form, margin, surface, optical characteristics
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should only be observed on isolated colonies
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YA10SC - CORRECT ANSWERS ✔✔yeast agar loaded with 10% sucrose
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(table sugar)
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encourages the growth of streptococcus organisms such as Streptococcus
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salivarius and Streptococcus mutans
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dental caries - CORRECT ANSWERS ✔✔result of bacterial fermentation of
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sugar, commonly sucrose
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Streptococcus mutans and Lactobacillus acidophilus are main microbes
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responsible for production of acid that causes these
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demineralization - CORRECT ANSWERS ✔✔as sugars are fermented an acid
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is made that dissolves the hard calcium layer of enamel of the tooth
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dental plaque - CORRECT ANSWERS ✔✔dense mass of bacteria
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dental caries are formed under this
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,difficult to remove \| \|




microbes involved in advanced tooth decay - CORRECT ANSWERS
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✔✔Actinomyces



Nocardia



fermentation - CORRECT ANSWERS ✔✔the chemical action of yeast on
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sugars



ubiquitous - CORRECT ANSWERS ✔✔term referring to the fact that
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microorganisms are found virtually everywhere \| \| \| \|




SMA plate - CORRECT ANSWERS ✔✔standard methods agar
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used to assess viable bacterial growth of a sample
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microscopic morphology - CORRECT ANSWERS ✔✔also known as cellular
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morphology



aids in the observation of microbial traits such as a cell shape, size,
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arrangement, stain reactions, endospores \| \| \|




primary shapes of bacteria - CORRECT ANSWERS ✔✔rod - Bacillus
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, sphere - coccus\| \|




spiral - Spirillum
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parfocal - CORRECT ANSWERS ✔✔property of microscope which allows
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objectives to be changed without having to refocus
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refraction - CORRECT ANSWERS ✔✔the bending of light as it passes from
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one material to another
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immersion oil - CORRECT ANSWERS ✔✔addition of this minimizes the
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amount of light that is refracted or lost
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size of coccus cell - CORRECT ANSWERS ✔✔about 1 micrometer on 100x
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size of bacillus cell - CORRECT ANSWERS ✔✔about 4 micrometers on 100x
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size of spiral cell - CORRECT ANSWERS ✔✔about 15 micrometers on 100x
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size of average bacteria - CORRECT ANSWERS ✔✔0.2 micrometers to 3.0
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micrometers



can reach a length of 10 micrometers
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