Starch hydrolysis is detected by adding _____ to the starch medium a. Barritt\'

Question

Starch hydrolysis is detected by adding _____ to the starch medium a. Barritt' s reagent A and B b. Gram' s iodine c. 10% ferric chloride d. zinc dust e. Kovac' s reagent The degradation of tryptophan by the bacterial enzyme tryptophanase can be detected with a. Barritt' s reagent A and B b. Gram' s iodine c. 10% ferric chloride d. zinc dust e Kovac' s reagent Which of the following Gram negative enteric bacteria is/are urease positive? a. Proteus b. Providencia c. Morganella d. all of the above e. none of the above Gram negative bacteria such as Proteus, Morganella, and Providencia can oxidatively deaminate the aminoacid phenyl alanine to produce a. phenyl pyruvic acid and ammonia b. pyruvic acid and indole c. ammonia and CO_2 d. none of the above The enzyme phenylalanine deaminase can be detected in a bacterial culture by addition of a. 3% hydrogen peroxide b. 10% alpha naphtol c. KOH d. none of the above Butter become rancid because a. bacteria oxidize casein producing volatile and odoriferous organic acids b. bacteria oxidize butter fat producing volatile and odoriferous organic acids c. of the decomposition of triglycerides and the breakdown of the fatty acids into short chains volatile organic acids d. of none of the above A skim milk agar plate is inoculated with B. subtilis. After incubation at the optimum temperature for 24-48 hours, a clear zone is observed adjacent to the growth of B. subtilis. This is evidence of: a. fat hydrolysis b. casein hydrolysis c. starch hydrolysis d. tryptophan hydrolysis Which of the following sentences is false? a. some gram negative enteric bacteria produce the enzyme urease b. when urease is produced by an organism, alcohol is released. c. urea is a waste product excreted in urine by animals d. urease splits urea molecule into carbon dioxide and ammonia The advantage of MSA medium over SM10 is that a. It favors colony pigmentation by different strains of S aureus b. It favors color change as mannitol is fermented

Explanation / Answer

ANSWER:

34) e

Bacteria that have the enzyme tryptophanase, can convert the amino acid, tryptophane to indole. Indole reacts with added Kovac’s reagent to form rosindole dye which is red in color

35) a

Proteus mirabilis is a Gram-negative, facultatively anaerobic, rod-shaped bacterium. It shows swarming motility and urease activity. The bacteria can be found throughout the stones, andthese bacteria lurking in the kidney stones .Tryptophan test-negative; Urea test- positive

36) a

Gram-negative bacteria can oxidatively deaminate the amino acid phenylalanine to produce phenylpruvic acid and ammonia. Proteus vulgaris motility positive, swarming on blood agar plate.

37) d

10% ferric chloride and five drops of 0.1N HCl are added.

38) c

Butter becomes rancid when these chains break down into smaller components, like butyric acid and diacetyl.

39) c

Casein hydrolysis is tested by growing an organism on a skim milk agar plate (providing nutrients and the casein) and then checking the plates for hydrolysis.

40) b is a false sentence.

41) a

Mannitol Salt Agar (MSA) is a selective, differential and indicator medium which is used to isolate and identify Staphylococcus aureus from the clinical specimen.

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