Biochemical Tests of Bacteria

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Questions and Answers

What is the main purpose of biochemical tests in identifying bacteria?

To detect the presence of certain enzymes (correct)
To study the morphology of bacteria
To analyze the DNA structure of bacteria
To determine the shape of bacterial cells

What is the primary function of the catalase enzyme in bacteria?

To degrade hydrogen peroxide into oxygen and water (correct)
To synthesize proteins
To convert oxygen to water
To break down carbohydrates

Which of the following bacteria is likely to produce bubbles in a catalase test?

E. coli
Staphylococcus sp. (correct)
Streptococcus sp.
Salmonella sp.

What is the primary function of the oxidase enzyme in bacteria?

To oxidize TMPD reagent into a blue-coloured complex (B)

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What is the result of a negative oxidase test?

The appearance of a colourless solution (A)

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Which of the following is NOT a type of enzyme produced by bacteria?

Lipase (C)

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What is the final product of the deamination reaction catalyzed by tryptophanase?

Indole, pyruvic acid, ammonium, and energy (D)

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What is the purpose of incubating the tube of tryptone broth at 37°C for 24 to 48 hours?

To allow the growth of a pure culture (D)

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What is the function of Kovács reagent in the indole test?

To indicate the presence of indole (D)

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What is the characteristic of the color change in a positive indole test?

The solution turns from yellow to cherry red (B)

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Which of the following bacteria is known to produce indole?

All of the above (D)

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What is the principle of the Methyl Red (MR) Test?

To detect the production of acid during glucose fermentation (A)

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What is the primary purpose of the methyl red test?

To detect the production of a stable acid by bacteria (A)

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What is the pH range at which the methyl red test is typically performed?

pH 6.9 or above (C)

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What is the function of ∝-naphthol in the Voges-Proskauer test?

To convert acetylmethyl carbinol to diacetyl (D)

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What is the nature of the acid produced by bacteria in the methyl red test?

A stable acid that is produced through glucose fermentation (A)

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What is the significance of a positive reaction in the methyl red test?

The bacteria produces a stable acid from glucose fermentation (D)

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What is the primary difference between the methyl red test and the Voges-Proskauer test?

The detection of acetylmethyl carbinol (A)

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What is the primary function of citrase in the Citrate Utilization Test?

To convert citrate into oxaloacetic acid and acetic acid (A)

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What is the role of ammonium salts in the Citrate Utilization Test?

To provide a source of nitrogen for the organism (A)

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What is the primary component of the Voges-Proskauer Reagent A?

Alpha-Naphthol (D)

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What is the pH of the MRVP broth used in the Voges-Proskauer Test?

6.9 (C)

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Which of the following organisms would display a positive reaction in the Citrate Utilization Test?

Klebsiella pneumoniae (C)

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What is the indicator used to detect the alkaline pH in the Citrate Utilization Test?

Bromthymol blue (A)

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What is the purpose of the coagulase test?

To differentiate S. aureus from other coagulase-negative staphylococci (A)

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Which test is used to distinguish Streptococcus pneumoniae from other α-hemolytic streptococci?

Optochin sensitivity test (C)

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What is the result of a positive oxidase test?

Development of a dark purple color within 10 seconds (C)

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What is the function of free coagulase in S. aureus?

To cause the plasma to form a clot in the tube (B)

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What is the mode of action of optochin?

Interferes with the production of ATP in microorganisms (C)

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What is the purpose of the slide coagulase test?

To detect the presence of bound coagulase (D)

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Flashcards

Biochemical Tests Purpose

To detect the presence of certain enzymes in bacteria.

Catalase Enzyme Function

To degrade hydrogen peroxide into oxygen and water.

Catalase Test Positive Bacteria

Staphylococcus sp.

Oxidase Enzyme Function

To oxidize TMPD reagent into a blue-coloured complex.

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Negative Oxidase Test

The appearance of a colourless solution.

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Methyl Red (MR) Test Principle

To detect the production of acid during glucose fermentation

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Methyl Red Test Purpose

To detect the production of a stable acid by bacteria

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Methyl Red Test pH Range

pH 6.9 or above

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Voges-Proskauer Test Function of ∝-naphthol

To convert acetylmethyl carbinol to diacetyl

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Nature of Acid in Methyl Red Test

A stable acid that is produced through glucose fermentation

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Significance of a Positive Methyl Red Test

The bacteria produces a stable acid from glucose fermentation

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Difference Between Methyl Red and Voges-Proskauer Test

The detection of acetylmethyl carbinol

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Function of Citrase

To convert citrate into oxaloacetic acid and acetic acid

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Role of Ammonium Salts

To provide a source of nitrogen for the organism

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Voges-Proskauer Reagent A Primary Component

Alpha-Naphthol

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MRVP Broth pH in Voges-Proskauer Test

6.9

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Organism with Positive Citrate Utilization Test

Klebsiella pneumoniae

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Indicator in Citrate Utilization Test

Bromthymol blue

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Purpose of the Coagulase Test

To differentiate S. aureus from other coagulase-negative staphylococci

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Test to Distinguish Streptococcus pneumoniae

Optochin sensitivity test

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Result of a Positive Oxidase Test

Development of a dark purple color within 10 seconds

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Function of Free Coagulase in S. aureus

To cause the plasma to form a clot in the tube

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Mode of Action of Optochin

Interferes with the production of ATP in microorganisms

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Purpose of the Slide Coagulase Test

To detect the presence of bound coagulase

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Biochemical Tests of Bacteria

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Podcast

Questions and Answers

What is the main purpose of biochemical tests in identifying bacteria?

What is the primary function of the catalase enzyme in bacteria?

Which of the following bacteria is likely to produce bubbles in a catalase test?

What is the primary function of the oxidase enzyme in bacteria?

What is the result of a negative oxidase test?

Which of the following is NOT a type of enzyme produced by bacteria?

What is the final product of the deamination reaction catalyzed by tryptophanase?

What is the purpose of incubating the tube of tryptone broth at 37°C for 24 to 48 hours?

What is the function of Kovács reagent in the indole test?

What is the characteristic of the color change in a positive indole test?

Which of the following bacteria is known to produce indole?

What is the principle of the Methyl Red (MR) Test?

What is the primary purpose of the methyl red test?

What is the pH range at which the methyl red test is typically performed?

What is the function of ∝-naphthol in the Voges-Proskauer test?

What is the nature of the acid produced by bacteria in the methyl red test?

What is the significance of a positive reaction in the methyl red test?

What is the primary difference between the methyl red test and the Voges-Proskauer test?

What is the primary function of citrase in the Citrate Utilization Test?

What is the role of ammonium salts in the Citrate Utilization Test?

What is the primary component of the Voges-Proskauer Reagent A?

What is the pH of the MRVP broth used in the Voges-Proskauer Test?

Which of the following organisms would display a positive reaction in the Citrate Utilization Test?

What is the indicator used to detect the alkaline pH in the Citrate Utilization Test?

What is the purpose of the coagulase test?

Which test is used to distinguish Streptococcus pneumoniae from other α-hemolytic streptococci?

What is the result of a positive oxidase test?

What is the function of free coagulase in S. aureus?

What is the mode of action of optochin?

What is the purpose of the slide coagulase test?

Flashcards

Biochemical Tests Purpose

Catalase Enzyme Function

Catalase Test Positive Bacteria

Oxidase Enzyme Function

Negative Oxidase Test

Methyl Red (MR) Test Principle

Methyl Red Test Purpose

Methyl Red Test pH Range

Voges-Proskauer Test Function of ∝-naphthol

Nature of Acid in Methyl Red Test

Significance of a Positive Methyl Red Test

Difference Between Methyl Red and Voges-Proskauer Test

Function of Citrase

Role of Ammonium Salts

Voges-Proskauer Reagent A Primary Component

MRVP Broth pH in Voges-Proskauer Test

Organism with Positive Citrate Utilization Test

Indicator in Citrate Utilization Test

Purpose of the Coagulase Test

Test to Distinguish Streptococcus pneumoniae

Result of a Positive Oxidase Test

Function of Free Coagulase in S. aureus

Mode of Action of Optochin

Purpose of the Slide Coagulase Test

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