19 Jan Nitrate reduction

• Question 1

When performing the urease test, which of the following color changes is expected if the organism is positive for urease production?

Answers:

The agar changes from yellow to bright pink

The agar changes from red to yellow

The agar changes from blue to green

The agar changes from colorless to black

• Question 2

The oxidase test determines the presence of cytochrome oxidase enzyme. This enzymes functions as part of _____________

Answers:

The electron transport chain

Glycolysis

The citric acid cycle

Fermentation

• Question 3

Genotypic identification methods examine the DNA sequence of an organism

Answers: True

False

• Question 4

Which of the following would be most valuable to confirm the identification of microorganisms isolated during a food poisoning outbreak?

Answers: Growth on agar plates to identify colony morphology

Grain stain to view cellular morphology

Identification of microorganisms using microscopic, cultural, and physiological characteristics

• Question 5

Which of the following are examples of physiological (biochemical) characteristics used in the bacterial identification process?

Answers: Gram stain

Cell shape

Presence of a specific enzyme

Growth in a nutrient broth

• Question 6

Which methods used in bacterial identification usually require culturing of the unknown bacteria?

Answers: Immunologic

Genotypic

Phenotypic

Morphologic

• Question 7

If an organism produces stable acids as an end-product of glucose fermentation, the methyl red test will be red, indicating a positive result.

Answers: True

False

• Question 8

Which reagent is added to SIM medium to detect indole production?

Answers: Methyl red reagent

Phenol red

Zinc powder

Kovac’s reagent

• Question 9

In the Kligler’s Iron Agar (KIA) test, if an organism can only ferment glucose, the butt of the agar slant turns ______, and the slanted surface of the agar will be _______ after 24 hours of incubation.

Answers: black; yellow

Red; yellow

Yellow; red

Yellow; black

• Question 10

All of the following biochemical tests involve the growth of an organism in a specific liquid broth medium EXCEPT

Answers: Nitrate reduction test

SIM test

Phenol red carbohydrate fermentation test

Methyl red test

• Question 11

Which of the following is true of a bacterial species that produces dark colonies when grown on MacConkey agar.

Answers: They are glucose fermenters

They are lactose fermenters

They produce urease

They reduce nitrate to nitrite

• Question 12

The internationally recognized reference for bacterial classification and identification is called Bergey’s Manual

Answers: True

False

• Question 13

An organism has been shown to produce hydrogen sulfide and indole in its metabolism. These are examples of _____ characteristics that can be helpful in the identification of the microorganism.

Answers: Morphological

Genotypic

Physiological

Immunological

• Question 14

Which of the following types of media allows for the observations of multiple biochemical properties in one?

Answers: Urea agar

MacConkey agar

SIM media

Citrate media

• Question 15

Phenol red carbohydrate broths with Durham tubes can detect all of the following EXCEPT Answers:

Nitrate reduction

Acid production

Gas production

Fermentation