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Questions: 1. (2pts) Explain the purpose of Cuvette #1. 2. (2pts) Explain the pu

ID: 63335 • Letter: Q

Question

Questions: 1. (2pts) Explain the purpose of Cuvette #1. 2. (2pts) Explain the purpose of Cuvette #2. 3. (2pts) include an Excel graph of your data from Cuvettes 2, 3, and 4. Your x-axis should be time and your y-axis should be CHANGE in Absorbance (this is the ''rate of photosynthesis''). You should have labeled axes and a clear title on your graph. 4. (2pts) Explain the reaction that is taking place in Cuvettes #3 and #4. Also, compare your data from Cuvettes #3 and #4. Did you see any difference? Why? 5. (2pts) Were there any errors in your technique that cause you to be concerned about your data? Explain any potential sources of error.

Explanation / Answer

Photosynthetic organisms are able to capture light energy and use it to form carbohydrates and free oxygen. The overall equation for the hill reaction of photosynthesis is as follows:  

2,000 Kcal light energy  

plants and algae  

6 CO2   +  12 H2O   ------------------------------------->   C6H12O6   +   6 O2   +   6 H2O

chlorophyll

Various dyes can be used as the artificial electron acceptor (A) so that the general equation, known as the Hill Reaction can be written as follows:  

(blue)                        (colorless)  

                                            H2O        +        A  ----------------------> AH2       +        1/2O2  

The photoreduction of an electron acceptor by the hydrogens of water, with the evolution of oxygen is known as the HIll reaction.

Since you have not provide the data pertaining to your specific experiment and what chemicals and their concentrations you have used, I will give you an example.

Cuvette Number   Tris-NaCl     DCIP                 Dist H2O         Chloroplast Stock

Buffer     (4 x 10-4)                                       Suspension  

   1 (blank)         3.5 ml              ----                     1.0 ml                  0.5 ml  

   2*                  3.5 ml              0.5 ml                0.5 ml                  0.5 ml  

   3                    3.5 ml              0.5 ml                0.5 ml                  0.5 ml

If the above are the 3 sets of reactions that you have set up, then:

Cuvette 1 - is a control where you have no DCIP(2,6-dichlorophenolindophenol) therefore their will be no change in the color from blue (oxidized form) to colorless (reduced form).

Cuvette 2 - is a nonilluminated control as it will be covered by Aluminium.

Cuvette 3 - is your actual reaction set where all the prerequisite reactions will occur and the data obtained will be adjusted according to the values obtained in the controls in cuvettes 1 and 2.