Absorbtion of Spinach Essay Sample

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  • Word count: 789
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  • Category: light

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Introduction of TOPIC

In the photosynthesis system, plants and other photosynthesizing creatures they use light of the sun as energy by absorbing some specific wavelength. A prepared sample of the chloroplast from spinach was used during this experiment. In order to observe the absorbance of chloroplast, a sample of the 7 mL chloroplast was prepared by pipetting the 7 mL amount of the chloroplast in to the clean, dry cuvette. A spectrophotometer was warmed up from the beginning of the lab to get prepared for the actual testing. A blank sample which contained 7mL sorbitol buffer was used to celibate the device between each different wavelength. the result shown on the spectrophotometer was recorded. Filters


In order to observe the activity of the chloroplast in different wavelength of the light, a system that contained a light source, 100mL beaker filled with tap water and the 250 mL beaker covered separately with three different light filter was used. its been shown in the figure.1. The distance between light source and the 250 mL was measured by 20 centimeter ruler and the beaker was taped in its place. Three light filters were used to cover the 250mL beaker. 1000mL


Figure.1 the system of the wavelength of light

The blank cuvette was used to calibrate the device each time in this section of the experiment. DCPIP is the blue color substance that usually been used as a concentration indicator in the chloroplast. A 50μL of this substance was measured carefully by using 200μ micrometer and transferred it to the three different clean cuvettes. A three separate 7mL of chloroplast was measured by 10mL pipette and was transferred to each prepared cuvette. The solutions were swirled and mixed by vortexing. Cover the 250mL beaker with blue filter and insert one of the prepar

ed cuvette. Zero the spectrophotometer by the blank cuvette and transfer the cuvette at T=0 . It’s

important to transfer the cuvette as soon as the cuvette taken out of the beaker with filter or each try, The spectrophotometer reading was recorded right after it was inserted to the device Then the absorbance for the interval time T=3 was recorded for each specific color filters.. This procedure was repeated two more times for the two more light filters. The spectrophotometer was zeroed before each test. All the 3used materials were cleaned up after the experiment finished. Table.1 absorbance of chloroplast in different wavelength

Wavelength(nm)| Absorbance| Wavelength(nm)| Absorbance| | 400| 1.857| 560| .884| |
420| 2.146| 580| .888| |
440| 2.303| 600| .912| |
460| 2.062| 620| .977| |
480| 2.052| 640| 1.054| |
500| 1.772| 660| 1.342| |
520| 1.163| 670*| 1.10| |
540| .912| 680| 1.892| |
| | 700| .855| |

It absorbance of the chloroplast was observed for the different wavelength. Of light. The first wavelength of 400nm was observed to be 1.857. The absorbance stayed constant from 400 to 540 nm wavelength. From the wavelength of 540nm, absorbance reduced to .912 and stayed the same till the wavelength of 620nm. The absorbance in the range of 640nm until 680nm it keep raising until it rich 700 nm that plunged to .855. The observance for the 670nm point observed to be 1.710. Chloroplast absorbance shows that the light absorbance is higher in two area of the examined absorbance. Those two areas with high absorbance will provide the highest energy for the plant. Table .1 summarizes this section of the lab. The graph was drawn to show the high area of the absorbance for the chloroplast which represents the high energy capture.

Figure.2 changes of the absorbance in chloroplast by wavelengths

After all three cuvette were located in the three different filter and the absorbance was noted for T=0 and time interval of each 3 for each of the cuvette, two observance were subtract to find the A620 which is the interval value to the photosynthesis value. Figure .3 represents the result for three different filters. The result shows that the blue color has the least interval for the choloroplast ,red is the second one, and finally green colur is the green c Figure.3 thee different filter result of absorbance for choloroplast in standard A620 Conclusion:

1: according to the figure.2 wavelength reached its highest absorbance when it was between 400nm to 480nm wavelength. Also there was two section in the graph at 2.303 and 1.857 that absorbance start to rose and then plunged back to lower value. This area is the value for the green light transition of light. 2: absorption of the light in the photosynthesis is very important. The wavelength that causes to see trees with in green color is the green color with least absorbance. According to figure.3, red color which has a .07 absorbance is the most effective in photosynthesis.

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