A major benefit of bacteria with coagulase is: Select one: a. Dialating blood ve

Question

A major benefit of bacteria with coagulase is:

Select one:

a. Dialating blood vessels

b. Helping produce magic pixie dust

c. Forming a protective barrier that prevents phagocytosis

d. Making teeth whiter

What is the chromogenic reducing agent commonly used in the oxidase test?

Select one:

a. Quinone

b. Dehydrogenase

c. Cytochome c oxidase

d. Tetramethyl-p-phenylenediamine

Why is a positive control important for the oxidase test experiment?

Select one:

a. Definitely do not choose this answer

b. To distiguish a positive result from independently oxidized reagents

c. You may consider this answer, but I would advise against it

d. Do not choose this answer

If a weakly catalase-positive organism initially gives a weak positive result and is recorded as a negative because it was not verified under a microscope, this result is a:

Select one:

a. False negative from poor specificity of the test system

b. False negative from poor sensitivity of the test system

c. False positive from poor specificity of the test system

d. False positive from poor selectivity of the test system

e. False positive from poor sensitivity of the test system

"Aseptically place one or two drops of hydrogen peroxide onto the bacteria and immediately observe for the formation of bubbles." In this step, what is the rationale for using a sterile technique? Choose the most likely answer.

Select one:

a. Catalase-negative bacteria could give a false positive

b. Catalase-positive bacteria could give a false positive

c. Bacterial contamination will grow in the hydrogen peroxide

d. A stray bacterium will weaken a lot of peroxide

e. Catalase-negative bacteria could give a false negative

In which aspect of ATP production is the oxidase enzyme present?

Select one:

a. Electron transport chain

b. Kreb's Cycle

c. Lipolysis

d. Glycolysis

e. Glyconeogenesis

Catalase test: Which of the following is NOT true about the ETC?

Select one:

a. It is found in obligate anaerobes

b. Oxidative phosphorylation occurs there

c. ADP is converted to ATP there

d. Oxygen is converted to water there in aerobic respiration

e. It is found in obligate aerobes

Explanation / Answer

Please find the correct answers and reasons below:

Part a: Choice c : Coagulase is an enzyme which actively reacts with the thrombin protein of the human blood. When any bacteria with surface display of coagulase infects any person, it reacts with the protein thrombin and causes clumping of red blood cells into non-soluble fibrin thus causing clumping. This clotting reaction due to non-solubilization of fibrin prevents phagocytosis of bacteria and hence, promotes infection.

Part b: Choice d : This substrate, commonly called Wurster's blue is the commonly used reducing agent in most of the redox reactions and produces a bright and visible yellow color upon reduction in a redox reaction.

Part c: Choice b: A positive control is an experimental group which shows that the exact chemical reaction takes place even in the absence of the main experimental target. Here, a positive control in a redox reaction will be the one which undergo reduction-oxidation process even in the absence of other redox reagents.

Part d: Choice e : The experimental condition shows that the result was a false positive since only a lower or negligeble degree of color formation took place. However, the absence of positive reaction was not verified under microscopic examination as well thus suggesting poor sensitivity of the reaction since microscopic examination does reveal formation of any colored products in a biochemical reaction.

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