Assignment Problem:
The experiments using catechol oxidase may be quantified by measuring results using a Spectronic 20. Modify the instructions in Exercises 4.1 and 4.2 according to the following instructions.
a. Rather than using three experimental tubes, use four cuvettes, and label them B (the blank), 1, 2, and 3.
b. Prepare the solutions in cuvettes as directed for test tubes 1, 2, and 3, omitting catechol until ready to take the reading. The blank will contain 5 mL of distilled water, 20 drops of distilled water, and 10 drops of potato extract only. Do not add catechol to the blank.
c. Design a table to record your data.
d. Record the absorbance of the solutions in the four cuvettes. (For steps 1-3 following, see the diagram of the Spectronic 20D+ and details of its operation in Appendix C. Steps 4-6 are self-explanatory.)
(1) Set the wavelength at 540 nm.
(2) Zero the instrument.
(3) Calibrate the instrument.
(4) Add the catechol to the appropriate cuvettes.
(5) Insert cuvette 1 into the sample holder and record absorbance in your data table. Immediately repeat with cuvettes 2 and 3.
(6) Continue to take readings at 5-minute intervals for 30 minutes or an appropriate time.
Experimental Design
Based on the above information, come up with your own question for this experiment. Answer questions 1-8. Question 10 asks for an outline of the materials and methods section; you may type this up on a separate document and attach it as part of your assignment. Question 11 needs to be changed from "X, Y, Z" to the proper treatment levels you answered in Question 8. Use the data provided in question 12 to answer Question 13.
Question 1: A statement of the question being asked
Question 2: A statement of the hypothesis
Question 3: A statement of the prediction
Question 4: Independent variable
Question 5: Dependent variable
Question 6: Controlled variables
Note: Remember that each test tube must contain the same total volume (6 mL total) for quantitative comparisons. How will you maintain this constant volume?
Question 7: Control
Question 8: Levels of treatment (3) - list out treatment levels
Question 9: Experimental replications = 7 total
Question 10: Outline of the experimental methods section for your paper. Use this information and information from the PowerPoint over Cellular Respiration and Fermentation to write up the materials and methods section of your rough draft. Refer to Figure 2. Investigative extensions #3 for the format of the outline. If needed, write it in a separate document and include it with your submission.
A. Spectrophotometer calibration
- Spec 20 D+ Emulation
- 540 nm
- 100 % transmittance
B. Practice Round
- Test tube prep (parafilm/kimwipe)
- Don't add catechol until ready!
- 5 min interval for 10 min
- Clean test tubes
C. Experimental Round
- Test tube prep (parafilm/kimwipe)
- Don't add catechol until ready!
- 5 min interval for 20 min
- Clean test tubes
D. Record Data
- Data conversion form (%T -> A)
- Calculations
Question 11: Table of test tube contents for blank tube(s), control tube, and tubes for each treatment level. This table may be used in your rough draft to show how the test tubes were filled out. Make sure you know what the X,Y, and Z placeholders are for and adjust the table accordingly.
Question 12: Table for inputting absorbance values. Use this data to create a graph for question 13.
Question 13: Graph relating the average change in absorbance to time. Make sure to properly title and label the graph. You may create the graph by handor use Excel. (One line for control tube, one line for each treatment level)
Attachment:- Independent Experimental Design Setup.rar