MCRO 251 Lab Quiz Review

What is the correct order of steps for gram staining?

• 1. Primary Stain (purple dye), 2. Mordant (iodine), 3. Decolorization (ethanol/acohol wash), 4. Counter stain (Pink Dye/safranin)

• 1. Mordant (iodine), 2.  Decolorization (ethanol/acohol wash), 3.Primary Stain (purple dye), 4. Counter stain (Pink Dye/safranin)

• 1. Primary Stain (purple dye), 2.  Decolorization (ethanol/acohol wash), 3. Counter stain (Pink Dye/safranin), 4. Mordant (iodine)

What Objective lens requires immersion oil?

• 50X

• 10X

• 100X

• All of the above

Gram Positive bacterial cell walls are:

• Thick with much peptidoglycan and polysaccharide

• Thin with little peptidoglycan

• Contain an outer lipid membrane

• Unstainable

You serially dilute a bacterial sample by transferring 1 mL of sample into 9mL of media. You plate 0.1mL of three dilutions (10^-1, 10^-2, 10^-3). After incubation, you count 68 colonies on the 10^-2 plate. What is the CFU/mL of the original bacterial sample?

• 6.8 x 10⁴ CFU/mL

• 6.8 x 10¹ CFU/mL

•  6.8 x 10³ CFU/mL

• 68 CFU/mL

You serially dilute a bacterial sample by transferring 1 mL of sample into 9mL of media. You plate 0.1mL of three dilutions (10^-1, 10^-2, 10^-3). After incubation, you count 543 colonies on the 10^-1 plate. What is the CFU/mL of the original bacterial sample?

• 5.4 x 10⁴ CFU/mL

• 54.3 CFU/mL

• 5.4 x 10⁵ CFU/mL

• You cannot determine CFU/mL from this plate because 543 is outside the countable range of colonies.

 Prolonging the time of exposure between a disinfectant and bacteria can increase the efficacy of the disinfectant.

• True

• False

Which biochemical tests rely on pH indicators to create a color change?

• Triple Sugar Iron (TSI) test

• Citrate Utilization Test

• Urease Test

• All of the above

What three characteristics does Triple Sugar Iron Media test for?

• Fermentation of glucose, lactose, sucrose (sugars). Esculin fermentation. Coagulase production

• Fermentation of Mannitol. Hemolysis. Gas production.

• Fermentation of glucose, lactose, sucrose (sugars). Production of hydrogen sulfide (H2S). Production of gas.

• Motility. ODC Production. Indole production.

What does MIO Media test for?

• Motility

• Indole Production

• ODC Production

• All of the above

What test requires Kovac’s Reagent?

• TSI Test

• MIO Test

• Urease Test

• Citrate Utilization Test