FREE AND STUDY GAMES ABOUT MICROBIOLOGY 211

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FREE AND STUDY GAMES ABOUT MICROBIOLOGY 211

EXAM QUESTIONS

Actual Qs and Ans Expert-Verified Explanation

This Exam contains:

-Guarantee passing score -65 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation Question 1: Give an example of the hydrolysis of small molecules used to acquire carbon compounds for metabolic purposes.

Answer:

Tryptophane is split into pyruvate and indole by the enzyme tryptophanase. The pyruvate is metabolized but the indole ring accumulates in the growth medium because it cannot be broken down.Question 2: Bacteria that hydrolyze starch produce ____ that degrade the starch molecule into molecules of ___, ___, ___.

Answer:

Amylases. Maltose, glucose, and dextrins.

Question 3: How is the degradation of tryptophan by the enzyme detected?

Answer:

Kovac's reagent, which forms a deep red color if indole is present.Question 4: What type of medium is used for the Casein hydrolysis test, and how can you indicate whether it has tested positive for caseinase?

Answer:

Skim milk agar, the clear zone surrounding the bacterial growth shows where proteolysis of casein has occurred.

Question 5: What illustrates a positive starch hydrolysis result? (Positive amylase)

Answer:

Clear zone along streak indicates starch hydrolysis.Question 6: Which organisms tested positive for caseinase in the Casein Hydrolysis Test?

Answer:

Bacillus subtilis and S. aureus.

Question 7: Proteolysis

Answer:

The process in which enzymes called proteases degrade protein moleculessuch as casein into peptides and amino acids.Question 8: Why are bacteria unable to surround and engulf their food by the process of phagocytosis?

Answer:

Bacteria have rigid cell walls.

Question 9: How is the phenylalanine deamination reaction catalyzed?

Answer:

Catalyzed by the enzyme phenylalanine deamninase, a flavoprotein oxidase.Question 10: Which bacteria tested positive for amylase in the Starch Hydrolysis Test? How can you tell?

Answer:

Bacillus subtilis. (Clear zone)

Question 11: How can phenylalanine deamninase be detected?

Answer:

By the addition of 10% ferric chloride, which forms a green colored complex with alpha-keto acids, such as phenylpyruvic acid.Question 12: What type of exoenzyme degrades triglycerides into fatty acids and glycerol?

Answer:

Lipase

Question 13: Which bacteria can oxidatively deaminate the amino acid phenylalanine to produce phenylpyruvic acid and ammonia?

Answer:

Gram-negative bacteria such as Proteus, Morganella, and Providencia.

Question 14: Urea

Answer:

Waste product of animal metabolism that is broken down by a number of bacteria.Question 15: The PPA Test (Phenylalanine deamninase) exhibits a positive reaction if it turns:

Answer:

Green.Question 16: Some bacteria hydrolyze ___ to produce carbon dioxide and ammonia, thereby causing the pH to become alkaline.

Answer:

Urea

Question 17: How is urease produced?

Answer:

By some of the gram-negative enteric bacteria such as Proteus, Providencia, and Morganella, which can be differentiated from other gram-negative enteric bacteria by the Urea Hydrolysis test.Question 18: If starch is degraded, a ___ area will occur next to the growth of the organism.Areas on the plate where no starch hydrolysis has occurred will be ___.

Answer:

Clear, blue.Question 19: Phagocytosis is a characteristic of:

Answer:

Higher cells.

Question 20: Amylopectin

Answer:

A large branched polymer of glucose on the starch macromolecule.

Question 21: Some bacteria do not completely hydrolyze all the fatty acids from the tributyrin, so what happens as a result in the Lipid (Fat) Hydrolysis Test? What would oil droplets indicate?

Answer:

The pH is not sufficiently lowered to give a dark blue precipitate. In this case, all you notice may be simply the depletion of fat or oil droplets in the agar to indicate lipase activity (therefore, that would it is positive).

Question 22: Which bacteria produces amylases that degrade starch?

Answer:

Bacillus subtilis.

Question 23: What materials are needed for the Starch hydrolysis test?

Answer:

Gram's iodine and starch agar plates.Question 24: Urea is unstable and is broken down under steam pressure at __ psi.

Answer:

15 Question 25: The PPA Test (Phenylalanine deamninase) exhibits a negative reaction if it turns:

Answer:

Remains yellowish, colorless.Question 26: What illustrates a negative starch hydrolysis result? (Negative amylase)

Answer:

No clear zones along streak indicates that no hydrolysis of starch occurred.

Question 27: How is the urea medium prepared for the Urea Hydrolysis Test?

Answer:

The urea medium is prepared by adding filter-sterilized area to the base medium after autoclaving it.Question 28: Which exoenzymes degrade starch and cellulose into simple sugars that are then transported into the cell where they are metabolized by fermentation or oxidation?

Answer:

Amylase degrades starch, Cellulase degrades cellulose.