Differential and Structural Stains
Which of the following is true about differential stains?
A. It detects differences between organisms
B. It uses one dye to stain all cells present
C. It includes the gram stain and acid fast stain
D. A and C
E. All of the Above
D. A and C
True or False: A pure culture contains a single microbial species.
True
What is the dilution factor formula?
A. B/(A+B)
B. A/B
C. A/(A+B)
D. B/A
C. A/(A+B)
True or False: Starch agar tests for the enzyme starchase while milk agar tests for caseinase.
False.
Starch agar tests for AMYLASE
A positive oxidase test turns what color?
A. Red
B. Cerise
C. Yellow
D. Black/Blue
E. Green
D. Black/Blue
Which of the following is incorrectly matched?
A. Primary Dye- Crystal Violet
B. Gram's Iodine- Decolorizer
C. Safranin- Secondary Dye
D. Safranin- Counterstain
B. Gram's Iodine- Decolorizer
Which of the following are true? Select all that apply:
A. General purple media support the growth of a variety of microorganisms
B. Selective media use inhibitors to prevent growth of certain organisms
C. Differential medial allow growth of many microbes, but differentiation is seen by indicators that detect changes
D. Combination media are a combination of both selective and differential media
All of the answers are correct
A. General purple media support the growth of a variety of microorganisms
B. Selective media use inhibitors to prevent growth of certain organisms
C. Differential medial allow growth of many microbes, but differentiation is seen by indicators that detect changes
D. Combination media are a combination of both selective and differential media
What is the countable range on a viable plate?
A. 10 to 100 colonies
B. 30 to 100 colonies
C. 100 to 300 colonies
D. 30 to 300 colonies
D. 30 to 300 colonies
Which of the following would be seen in a PR Sugar Fermentation Broth if the organism ferments?
A. Yellow color change with a bubble
B. Yellow color change
C. Cerise color change
D. A and B
E. All of the above
D. A and B
In a positive test for gelatinase, what will happen?
A. The gelatin will solidify
B. The gelatin will not solidify
C. The gelatin will slightly change color
D. A and C
E. B and C
B. The gelatin will not solidify
When performing a gram stain for E.coli, the final result showed gram positive bacilli. However, E. coli is a gram negative organism. What could've happened?
A. The primary dye was left on for too long
B. Not enough Grams iodine was added
C. The 95% ethanol step was skipped
D. A and B are possibilities
E. B and C are possibilties
C. The 95% ethanol step was skipped
Which of the following reagents are incorrectly matched with their inhibitors?
A. PEA - Phenylethyl alcohol
B. Mac- Crystal violet and bile salts
C. EMB- Eosin and methylene blue
D. B and C
E. None of the above are incorrectly matched
E. None of the above are incorrectly matched
A. mL
B. CFU/L
C. CFU/mL
D. mL/L
C. CFU/mL
Which of the following are indicators in a KIA test? Select all that apply:
A. Phenol red
B. Tetrazolium chloride
C. Bromothymol blue
D. Ferric ammonium citrate
E. Methylene blue
A. Phenol red
D. Ferric ammonium citrate
What does a red color after zinc indicate in nitrate reduction?
A. Positive nitrate reduction
B. Negative nitrate reduction
C. Presence of ammonia
D. Nitrate was used and broken down to nitrogen gas
E. A and D
B. Negative Nitrate reduction
Acid Fast Staining is also known as the:
A. Ziehl-Neelsen Method
B. Schaeffer-Fulton Method
C. Hans-Christian Method
D. None of the above
A. Ziehl-Neelsen Method
What type of organism does PEA select for?
A. Gram negative rods
B. Fungi
C. Gram positive cocci
D. Acid fast bacteria
C. Gram positive cocci
Which of the following is true about the total tube dilutions?
A. It is the total dilution of the final sample in each of the tubes
B. The product comes from multiplying the combined dilution of the previous tube by the dilution factor of the transfer
C. It is the total dilution of the original sample in each of the tubes
D. A and B
E. B and C
E. B and C
In the litmus milk test, what causes the milk to turn clear?
A. Casein degrading
B. pH rising
C. pH lowering
D. Protein denaturation
A. Casein degrading
What pathway does the VP test detect?
A. Mixed acid fermentation
B. Butanediol fermentation
C. Lactic acid fermentation
D. Alcohol fermentation
E. A and B
B. Butanediol fermentation
Which of the following is the reagents needed for structural stains?
A. Malachite Green, Safranin, Acid Alcohol
B. Carbol Fuchsin, Acid Alcohol, Methylene Blue
C. Carbol Fuchsin, Water, Malachite Green
D. Malachite Green, Water, Safranin
D. Malachite Green, Water, Safranin
Motility media contain soft agar, or a lower agar concentration. A dye indicator can sometimes be used to aid in detecting motility. Which dye indicator can be used?
A. Neutral Red
B. Tetrazolium Chloride
C. Methylene Blue
D. Phenol Red
E. Spirit Blue
B. Tetrazolium Chloride
You are performing a serial dilution. You start with a sample of E. coli and transfer 0.1 mL into a 9.9 mL tube, labelled as Tube 1. What is the total dilution of the original culture in Tube 1?
A. 1/100
B. 0.1/100
C. 10/100
D. 1/10
E. None of the above
A. 1/100
Which of the following are correctly matched with their positive result? Select all that apply:
A. Litmus = Pink
B. PR Sugar Fermentation = Phenol Red
C. KIA = Yellow
D. KIA = Black
E. Milk Agar = No color(clearing)
A. Litmus = Pink
C. KIA = Yellow
D. KIA = Black
E. Milk Agar = No color(clearing)
Match the reagents to the test:
Tests:
1. Oxidase Test
2. Nitrate Reduction
3. Phenylalanine Slant
4. MR-VP Broth
5. Tryptone Broth
6. Simmons Citrate Slant
Reagents:
A. Ferric Chloride
B. Bromothymol blue
C. Methyl red + Barritt's reagents
D. Dimethyl-p-phenylenediamine hydrochloride
E. Sulfanilic acid + dimethyl-alpha-naphthylamine
F. Kovac's reagent
1 - D
2 - E
3 - A
4 - C
5 - F
6 - B