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91 Cards in this Set
- Front
- Back
Mannitol Salt agar is both ________ and ____________.
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Selective and Differential media. Selective is based on the ability to grow in the presence of 7.5% NaCl. (Halotolerence). The media is differential in that it indicates the use of mannitol by changing the phenol red indicator from red to yellow as the pH drops.
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Halotolerent organisms include the ________ and _______.
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Staphylococci and micrococci
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Mannitol
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a sugar alcohol
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Mannitol Salt Agar
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Salt resistant - ( upper left side of plate), Salt resistant mannitol + (yellow section on plate), Salt sensitive, unknown mannitol reaction ( lower )
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Eosin Methylene Blue Agar is both _________ and _________.
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Selective and differental
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Eosin Methylene Blue Agar is selective against?
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Gram positive organisms because of the eosin Y and methylene blue dyes in the media.
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Why is Eosin Methylene Blue Agar differential?
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It is differentail because it seperates the Gram negative organisms into those that ferment lactose and sucrose from those that cannot.
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As the degree of fermentation increases the fermentors colors range from _________to______to dark_______ or even ________ with a metallic green sheen.
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pink, red, purple or even black.
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What is an example of a fast fermentor in Eosin Methylene Blue Agar?
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Escherichia coli
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Give an example of a slow fermenter in Eosin Methylene Blue Agar.
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Enterobacter aerogenes
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Staphylococcus epidermidis
(Eosin Methylene Blue Agar) |
Gram positive - inhibited - no growth
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Eosin Methylene Blue Agar
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Escherichia coli fast fermenter ( upper left corner)
Enterobacter aeogenes slow fermenter ( lower right ) Staphylococcus epidermidis - gram postive- inhibited - no growth ( upper right corner) |
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Pseudomonas Isolation Agar
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designed for the selection of Pseudomonas species by the inclusion of the phenolic compond Triclosan.
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Pseudomonas species often produce ___________ pigments. Often ________ or __________ in color and sometimes pigments which fluoresce under ultraviolet light.
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Diffusible
Green or blue-green |
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Pseudomonas Isolation Agar
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P.fluorescens ( upper left corner)
P aeruginosa ( upper right corner) E. coli , no growth ( lower ) |
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PEA means
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Phenylethyl Alcohol agar
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PEA contains the inhibitory substance called?
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Phenylethyl alcohol
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PEA is a ____________ media.
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Selective in that is grows slow or prevents the growth of gram negative bacteria while allowing Gram positive organisms to grow.
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Example of Gram negative bacteria
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E. aerogenes
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Example of gram positive organism
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B. subtilis and E. faecalis
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Phenylethyl Alcohol agar
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Bacillus subtilis ( upper left corner)
Enterococcus faecalis ( upper right corner) Enterobacter aerogenes ( lower ) |
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A unique characteristic of the PEA agar is?
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It gives off a rose odor caused by the substance phenylethyl.
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DNAse Agar
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Weak + (upper left corner)
Strong + ( upper right corner) negative (lower) |
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DNAse contains?
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Free DNA in the media
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Which enzyme, released by some organisms, breaks down the DNA into free nucleotides which can be taken up by the cell?
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Exonuclease
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The indicator in DNAse is?
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Methyl Green
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How can you tell if an organism has used some of the DNA in the DNAse agar?
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There will be a zone of clearing around the areas of growth because methyl green is ONLY green when bound to DNA.
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Blood Agar
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alpha (partial ) hemolysis (upper left)
Gamma (no) hemolysis (upper right) beta (complete) hemolysis ( lower) |
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Blood agar is a selective or differential media?
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differential which seperates organisms based on a hemolytic ability.
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Organisms that completely lyse red blood cells are?
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B-hemolytic
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B-hemolytic leave a ________ ________ around a colony.
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clear zone
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a-hemolytic organisms ___________ ___________ red blood cells.
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partially lyse
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In Blood agar a greenish zone around the colonies is caused by?
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partially lysed red blood cells
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Organisms showing no hemolysis are sometimes called?
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y-hemolytic
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Skim Milk Agar
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If the casein is broken down into amino acids (peptonization) a clear zone will be visable around the areas of growth.
Upper half is negative. Lower half is positive (note the clearing area) |
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What does Casein hydrolysis agar plates test for?
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It tests for the organisms's ability to release an exoenzyme ( casease) which breaks down the milk protein (casein) in the skim milk plates.
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Skim milk agar tests for the ability of an organism to release the exoenzyme
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casease
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The three primary physical parameters for describing a colony are:
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shape (configuration), margin and elevation
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MPN analysis is performed using tubes of _____ broth.
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lactose
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Kirby-Bauer (antibiotic disk-diffusion assays) are carried out using _____ plates
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Mueller-Hinton agar
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A positive MR test indicates the following end product(s):
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mixed acids
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MR-VP broth performs two tests that relate to the breakdown of:
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glucose
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What would you expect to see if you streaked a culture of Enterobacter aerogenes (a gram-negative organism) on phenylethyl alcohol agar?
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no growth
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Identify the organism growing on this Petri plate that is positive for starch hydrolysis
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A
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Bubbling of hydrogen peroxide placed on colony growth is a sign of the presence of the enzyme catalase. This is due to the production of:
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oxygen gas
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A positive starch test can be confirmed after adding Lugol's reagent. It is indicated by:
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a zone of clearing that is colorless to golden
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DNAse agar contains free DNA which can be broken down by the exoenzyme:
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exonuclease
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The reagent used in the catalase test is
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hydrogen peroxide
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The main substrate available for hydrolysis in skim milk agar is:
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casein
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The pH indicator found in Mannitol Salt agar is:
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phenol red
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The selective agent(s) in Eosin methylene Blue agar is/are:
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eosin Y and methylene blue
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Blood agar is able to distinguish between different types of organsims based on ____ ability?
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hemolysis
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The selective agent in Pseudomonas Isolation agar is:
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triclosan
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Looking at this Petri plate of organisms growing on Pseudomonas Isolation agar what can you conclude about Organism C?
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It is not a Pseudomonas
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Which of the following organisms plated onto the phenylethyl alcohol agar plate shown above is most likely Gram-positive
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Organism A and Organism B
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The potential end products that can be readily detected by observation of sugar (carbohydrate} broth tubes is/are:
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acid and gas
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The indicator present in Simmon's citrate media is:
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bromthymol blue
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The pH indicator present in a phenylalanine deaminase slant is:
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there is no pH indicator in this media
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. Which test is not determined by use of SIM media?
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mixed acids from glucose
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Which of the following tubes show a positive test for urease activity in urea broth?
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Tube B
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The reagent used to perform the MR test is:
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methyl red
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MR-VP broth performs two tests that relate to the breakdown of:
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glucose
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The MPN value for the sample shown above is:
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15
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Which of the following circles shown above represents a positive reaction for Stapylococcus aureus in the Staphyloslide test?
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#2
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In a positive oxidase test a _____ color should be seen within 30 seconds of applying bacteria to oxidase paper.
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dark blue or violet
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The oxidase test checks for the presence of cytochrome c oxidase an enzyme found in certain ______ bacteria.
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aerobic
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Before a stach hydrolysis test can be interpreted the following reagent must be added to the Petri plate:
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Lugol's
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DNAse agar contains free DNA which can be broken down by the exoenzyme
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exonuclease
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The chemical reaction catalysed by catalase is:
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hydrogen peroxide --> water to oxygen
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Organisms that produce clear halos around colony growth on Blood agar plates are said to be _____ hemolytic.
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beta
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The enzyme activity responsible for the visible reaction seen in this SIM tube is:
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cysteine desulfurase
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Pseudomonas Isolation agar is:
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selective
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What would you expect to see if you streaked a culture of Enterobacter aerogenes (a gram-negative organism) on phenylethyl alcohol agar?
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no growth
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The end product that is detected by the added reagents in a VP test is
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acetoin
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Which of the tubes pictured shows a negative VP test?
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Tube A
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Look at this nitrate broth. No gas was seen in the Durham tube. Nitrate A and Nitrate B have been added. What was the fate of the nitrate?
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reduced to nitrite
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Given the following information: The disk shown is for the antibiotic Ampicillin; the organism on the plate is Escherichia coli; The organism is most likely ____ to the antibiotic.
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resistant
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DNAse agar contains the indicator reagent ____ which allows for detection of the breakdown of DNA by microorganisms.
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Methyl green
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The reagent used in the catalase test is:
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hydrogen peroxide
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Phenylethyl alcohol agar is used to:
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select against Gram-negative organisms
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The potential end products that can be readily detected by observation of sugar (carbohydrate} broth tubes is/are:
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acid and gas
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Which of the following organisms placed on Simmon's citrate slants is positive for citrate utilization?
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Organism A
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Which of the phenylalanine tubes (above) show breakdown of phenylalanine to Phenylpyruvic acid and ammonia?
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Tube B
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Looking at the two SIM tubes shown here you can clearly determine that the organism is both:
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Indole+, sulfide+
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The type of aggltination test used in the lab where an antibody is attached to a latex particle to enhance visibility of the reaction is known as ___ agglutination.
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indirect
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What would be the logical explanation if tube B were clearly pink compared to tube A?
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ammonia was produced from amino acids
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Tube A shows a tube after nitrate reagents and zinc powder were added. The conclusion would be:
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nitrate was reduced to ammonia
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. The source of information used to create the dichotomous keys in the lab manual and for the species tables kept in the lab drawets is:
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Bergey's Manual
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The pH in a positive Simmon's citrate test is:
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basic
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Phenylalanine is broken down to form _____ and ammonia which can be detected on a pheylalanine slant using the reagent ferric chloride.
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phenylpyruvic acid
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Which of the following SIM tubes shows a non-motile organism?
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Tube A
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