Biochemical Tests of Bacteria

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) Signup and view all the answers

What is the result of a negative oxidase test?

The appearance of a colourless solution (A) Signup and view all the answers

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

Lipase (C) Signup and view all the answers

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

Indole, pyruvic acid, ammonium, and energy (D) Signup and view all the answers

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) Signup and view all the answers

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

To indicate the presence of indole (D) Signup and view all the answers

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

The solution turns from yellow to cherry red (B) Signup and view all the answers

Which of the following bacteria is known to produce indole?

All of the above (D) Signup and view all the answers

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

To detect the production of acid during glucose fermentation (A) Signup and view all the answers

What is the primary purpose of the methyl red test?

To detect the production of a stable acid by bacteria (A) Signup and view all the answers

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

pH 6.9 or above (C) Signup and view all the answers

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

To convert acetylmethyl carbinol to diacetyl (D) Signup and view all the answers

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) Signup and view all the answers

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

The bacteria produces a stable acid from glucose fermentation (D) Signup and view all the answers

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

The detection of acetylmethyl carbinol (A) Signup and view all the answers

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

To convert citrate into oxaloacetic acid and acetic acid (A) Signup and view all the answers

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

To provide a source of nitrogen for the organism (A) Signup and view all the answers

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

Alpha-Naphthol (D) Signup and view all the answers

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

6.9 (C) Signup and view all the answers

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

Klebsiella pneumoniae (C) Signup and view all the answers

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

Bromthymol blue (A) Signup and view all the answers

What is the purpose of the coagulase test?

To differentiate S. aureus from other coagulase-negative staphylococci (A) Signup and view all the answers

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

Optochin sensitivity test (C) Signup and view all the answers

What is the result of a positive oxidase test?

Development of a dark purple color within 10 seconds (C) Signup and view all the answers

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

To cause the plasma to form a clot in the tube (B) Signup and view all the answers

What is the mode of action of optochin?

Interferes with the production of ATP in microorganisms (C) Signup and view all the answers

What is the purpose of the slide coagulase test?

To detect the presence of bound coagulase (D) Signup and view all the answers