No color change in the allotted amount of time for the oxidase test suggests: Se

Question

No color change in the allotted amount of time for the oxidase test suggests:

Select one:

a. Negative result

b. Materials were not sterilized

c. Culture was not pure enough

d. Too much time was allowed

e. Positive result

Catalase test: Which of the following samples used in the slant test would likely produce bubbles?

Select one:

a. More than one of these is likely to produce bubbles

b. Unincoculated control

c. Staphylococcus epidermidis

d. Enterococcus faecalis

Cytochrome C oxidase is an enzyme that:

Select one:

a. Uses ATP in glycolysis

b. Transfers electrons to oxygen

c. Leads to no color change when present

d. Causes false negative results

e. Produces ATP in the Krebs cycle

Catalase test: In the slide test, what does the positive control confirm?

Select one:

a. Quality of your slide

b. Quality of your unknown sample

c. Quality of your hydrogen peroxide

d. Quality of your sterile technique

e. Quality of the agar

Explanation / Answer

Answer:

1). a. Negative result

Explanation:

This chemical takes the place of oxygen as a recipient for the electrons from the oxidasecytochrome. The additional electrons turn the oxidase reagent from colorless to purple. If oxidase is not present, no color change is observed.

2). c. Staphylococcus epidermidis

Explanation:

A positive result is the rapid evolution of oxygen (within 5-10 sec.) as evidenced by bubbling. A negative result is no bubbles or only a few scattered bubbles. The catalase test is primarily used to distinguish among Gram-positive cocci: members of the genus Staphylococcus are catalase-positive, and members of the genera Streptococcus and Enterococcus are catalase-negative.

3). b. Transfers electrons to oxygen

Explanation:

Cytochrome C oxidase receives an electron from each of four cytochrome c molecules, and transfers them to one oxygen molecule, converting molecular oxygen to two molecules of water.

4). c. Quality of your hydrogen peroxide

Explanation:

The catalase test demonstrate the presence of catalase, an enzyme that catalyses the release of oxygen from hydrogen peroxide (H2O2). It is used to differentiate those bacteria that produces an enzyme catalase, such as staphylococci, from non-catalase producing bacteria such as streptococci.

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.