Lab 25: Oxidase Test Assignment

Data and Observations

Post Lab Questions

1. Where is the reagent in this test?

2. The fact that the CRA will spontaneously give up its electrons after a certain amount of time whether or not cytochrome c oxidase is present can be described as poor in the test system. How does the protocol minimize this possibility for error?

3. Suppose you perform this test on E. coli and after you add cells to the reaction card, your partner asks you to help them find cells under the microscope. When you return to the reaction card after 10 minutes, you notice the dark color and record a positive result in your data table. You have recorded a false _____________. This an example of poor _____________.

Suppose you perform this test on Pseudomonasaeruginosa and after you add the cells to the card and wait for 20 seconds, you do not see a color change. After you help your partner find cells under the microscope, you return to see that the reagent has turned dark color.

4. How should you record your result as an ethical scientist?

5. This result is a false ______________.

6. This is an example of poor _______________.

7. What could have caused this result? List at least two possibilities. Be concise.

8. Why is “contamination” NOT a possible cause?