Photosynthesis.pdf - Light Intensity Elena Tamez(827007877...

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Light Intensity Elena Tamez (827007877) October 24, 2018 Biology 111-564 Yau Adamu
Tamez 1 Introduction When a scientist or experimenter changes NADPH with DPIP, one can measure the effect of light intensity on photosynthesis. Light intensity and light wavelength affect the rate of photochemical reactions and since oxygen is a product of these reactions, one could measure the rate of photosynthesis when measuring the oxygen that is produced. If there is a reduction of DPIP, this means there is a higher absorbance when it is measured with a spectrophotometer. Hypothesis If the light treatment that was used on a tube was 49 cm, then it will have a higher absorbance. Null HypothesisNo matter what the light treatment was, each tube will have the same absorbance. Methods First, thespectrophotometer was turned on and the wavelength was set to 605 nm. By using an ice bath, the tubes were kept cold. Then the instrument was zeroed. DPIP was added to tube 1 and then wipe with a Kimwipe, covered with Parafilm, and inverted to mix the solution. Then, the tube was inserted and the zero time absorbance was taken. Then tube 1 was covered in foil to keep it in the dark. The remaining tubes (2-4) were tested in the same way, however tubes 2-4 were not wrapped in foil. Every lab table tested a different light intensity. A tube was placed in the rack at each light set up. Tube 1 was kept in foil and in the dark. The light intensity‘s that were tested were: Table 1: 24 cm = 30.5 x 1000 microwatts/cm2 Table 2: 30 cm = 20.0 x 1000 microwatts/cm2 Table 3: 49 cm = 10.0 x 1000 microwatts/cm2 The tubes were inverted at five minute intervals and measured. Then the absorbance values were recorded and two one was re-wrapped in foil between each measurement. Results Table 7-3. Absorbance values for each tube that indicate a photochemical reaction rate. Minutes Dark 24 cm 30 cm 49 cm 0 .583 .557 .543 .529 5 .559 .495 .523 .516 10 .506 .494 .490 .487 15 .503 .347 .454 .532 20 .537 .403 .386 .460 25 .553 .388 .485 .483
Tamez 2 30 .549 .448 .457 .493 Discussion and Conclusion The hypothesis was correct and the null hypothesis was rejected. The absorbance values

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