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64 Cards in this Set
- Front
- Back
What is resolving power?
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the ability to distinguish between two points
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What is human body temperature?
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37C
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What color would a human cell be in a gram stain? Gram + or - ?
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Red, gram -
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What is the decolorizing agent in a gram stain?
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ethanol
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What is the decolorizing agent in an acid-fast stain?
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acid alcohol
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What diseases are diagnosed using the acid-fast procedure?
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Mycobacterium caused disease.
tuberculosis, leprosy, and other pulmonary diseases |
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What is the purpose of the paper in the acid-fast stain?
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Keeps it from drying out
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How would the appearance of a 24hr bacillus culture and a 72hr culture differ? How do you account for this?
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spores will be released in the 72hr culture, as times goes by they produce waste and then die off and produce spores.
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What genus of organism seems to be the one that can lower the pH enough to dissolve tooth enamel?
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streptococcus
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What is the indicator used in the snyder test?
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bromcresol green
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What is the color of the control in the synder test?
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green
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What color will the indicator turn if the pH becomes more acidic?
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yellow
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Why are bile salts and crystal violet added to MacConkey agar?
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they inhibit gram + organisms
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What chemicals are added to EMB to prevent gram + growth?
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Eosin, methylene blue
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Is MacConkey agar selective or differential?
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both
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Is EMB selective or differential?
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both
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Is the blood agar used for the hemolysin test a differential or selective medium?
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differential
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What does TSI stand for?
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triple sugar iron
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Which nutrient is in short supply in a TSI slant
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glucose
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What color will the slant and butt turn if the organism can use glucose but not lactose?
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red slant, yellow butt
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What happens when an organism uses peptones in the TSI agar?
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Ammonia is produced, pH is raised. Changes to dark red. When it runs out of glucose it starts aerobically eating peptones on top of slant
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What happens to the color of the slant and butt if the organism can ferment lactose in TSI agar?
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Both yellow
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Why would the tube look black in a TSI agar slant?
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Organism produces H2S gas, reacting to make FeS which is black
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What is the reaction for the production of black in a TSI agar tube?
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H2S + Fe ==> FeS + H2
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Why should you not analyze results too early in a TSI test?
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Organism may have only eaten glucose and will be yellow, hasnt had time to go on to other things yet.
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Why should you not analyze results too late in a TSI agar test?
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Organism can eat all sugar and move to proteins, turning tube completely red.
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What is the exoenzyme in starch hydrolysis?
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amylase
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What is a positive test that casease exoenzyme is secreted?
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clear halo around organism
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What organic compound is gelatin?
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protein
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Why is agar used as a solidify agent instead of a gelatin?
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agar is not nutritive
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what would you find in the liquid of hydrolyzed gelatin
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amino acids
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nutrient gelatin is incubated at 35C. What would have to be done to determine hydrolysis after incubation?
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Cool it down to resolidify
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what is a positive test for lipid hydrolysis?
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makes clear halo
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Is the carbohydrate test selective or differential?
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differential
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What is a positive test for fermentation?
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yellow
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What is a negative test for fermentation?
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red
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Why does the indicator turn yellow when fermentation occurs?
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sugars ferment and make acid, changes indicator yellow.
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What is an alkaline swing?
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after 1st 24hr it changes yellow (acidic) after all sugars are used. After 2nd 24hr it changes back to red (alkaline) as it starts using proteins
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What is a positive test for urease production?
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pink
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What is the source of urea in the body?
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proteins, amino acids brokedown
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What is the formula for hydrogen peroxide hydrolysis with catalase?
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H2O2 ==> H2O + O2
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In the catalase test, what gas is in the bubbles?
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O2
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What types of organisms produce catalase?
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aerobic
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What does CFU stand for?
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colony forming unit
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Why should hamburger meat be cooked more thoroghly than steak or roast?
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hamburger meat has more surface area, which the bacteria grows on. Steak or roast only has the outside of the meat for growing the bacteria.
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Is the test for milk a qualitive or quantitative measurement?
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quantitative
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Milk is considered to be contaminated when the bacteria count rises above ____.
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20,000/mL
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What range of bacterial colonies on a plate should be used for counting?
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25-250
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What stain is used in the simple stain? How long is it applied?
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Methylene blue. 60sec
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What is the primary stain, counterstain and mordant in the gram stain?
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Crystal violet
Safranin Iodine |
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What color is gram +?
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purple
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What color is gram -?
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pink
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What is the primary and counterstain in the acid-fast?
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Carbolfuschsin
methylene blue |
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What are the stains in the spore stain?
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malachite green
safranin |
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What is the name of the agar used in the salival test in experiment #4?
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Snyder agar
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What is a positive test on MSA agar? Negative?
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Yellow
Red |
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What is a positive test on MacConkey agar? Negative?
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Red/pink
agar color, white/colorless |
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What is a positive test on EMB agar? Negative?
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Red, if alot, shiny-green metallic
agar color |
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What is the name of the test in lab #7
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Antimicrobial susceptibility test
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What is the name of the agar used in the antimicrobial susceptibility test?
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mueller-hinton agar
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What are the organisms used in the hemolysis test? What were their results?
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E. coli - gamma-hemolysis
S. pyogenes - beta-hemolysis Throat - alpha-hemolysis |
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In starch agar test what is a positive test? Negative?
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Clear halo around organism where iodine doesnt stick
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What is the enzyme that breaks down milk protein?
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casease
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What is a positive test for gelatin hydrolysis?
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It is liquid when cooled
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