Determining Rates of Photosynthesis Through Chloroplasts
Introduction:
1)Background=
2) Purpose= measure the rate of photosynthesis in chloroplasts.
3) The chloroplast will be subjected to two experimental conditions- light, and the absence of light, using a spectrophotometer to determine the amount of DPIP reduced at specific time intervals under each condition.
4) I predict the amount of DPIP reduced will vary for each condition and increase over the time intervals. I hypothesize under the light condition the amount of DPIP will drastically be reduced within each five minute time interval. However, under the dark condition the DPIP will not be reduced due to the fact that light is required for photosynthesis.
5) The rates of photosynthesis in each of these reactions will be measured by the amount of light reaching the photocell in the spectrophotometer. This data will be a percentage that represents the amount of DPIP reduced.
Methods
DPIP will be used to determine the rate at which the cholorplasts are being reduced. The spectrophotometer will establish the wavelength of light that penitrats the chloroplast solution in turn determining the amount of electrons reduced. In the dark reactions, the spectrophotometer will measure the amount of light passing through a darker solution of DPIP and chloroplasts. In the light reactions, the lighter solution, caused by reduction of the chloroplasts, will allow a larger amount of light to pass through to the photocell of the spectrophotometer. Thus, the spectrophotometer will prove wheter the light or dark reactions affect the rate of photosynthesis in chloroplasts. We will also be using a reference solution made of water, phosphate buffer, and active chloroplasts. The purpose of this solution will be used to set the transmittance level for the experiment. The control solution, which is different than the reference solution, is comprised of water, phosphate buffer, and DPIP. It will be used to prove that the three element of the solution do affect the results- it is strictly the chloroplasts that are subjected to the light/dark conditions.
Requirements for Test Tube Set Up
Data Collected During Time Intervals
Photosynthetic Rate for Light Reactions
0 5 10 15 20
Time Intervals
Photosynthetic Rate for Dark Reactions
0 5 10 15 20
Time Intervals
Results:
The results for the various conditions differed dramatically. As seen in the table, “Data Collected During Time Interval” the reference test tube remained at a trasmittance level of 100% for all five experimental tests. The control solution remained fairly constant for all five tests, but did vary slightly after the five minute time interval.
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This meant that this cuvette (tested under light) should display a higher decrease in DCIP due to the reduction in absorbance (dependent variable) opposed to the other cell fractions tested depending on a sixteen minute period (independent variable). The overall goal was to provide proof, through data, that the cell fractions put under the light during the sixteen minute period would indicate a higher set of chloroplast activity versus the ones put in the
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The Effect of Light Intensity on the Rate of Oxygen Production in a Plant While Photosynthesis is Taking Place
Autotrophs, can build organic compounds from simple molecules such as water and carbon dioxide and their type of feeding is called autotrophic nutrition. While they are building complex molecules, they need large amounts of energy. They are divided into two groups according to their source of energy: chemoautotrophs and photoautotrophs. Chemoautotrophs can synthesize organic compounds from CO₂ AND H₂O by using inorganic oxidation energy and they do not require sunlight. However, photoautotrophs, including green plants, produce sugar and O₂ from CO₂ and H₂O by using sunlight. The green pigment which absorbs the light is called chlorophyll and this process is called photosynthesis.
During the following lab, an aquatic plant was covered with a funnel and was placed underwater inside a beaker, with a graduated cylinder (submerged in water) was placed over the neck of the funnel. This lab tested out which source of light which is the independent variable would allow the aquatic plant to produce the most bubbles (dependent variable) and photosynthesize the fastest. This is clearly displayed because when photosynthesis is produced underwater it appears in the form of bubbles inside the water. These bubbles will travel up through the funnel and displace the water in the graduated cylinder. The dependent variable was tested by placing the four, 5cm aquatic plants in the beakers directly in front of the sources of light and observing how many bubbles were produced within the period of 10 minutes and how much water was displaced by the oxygen bubbles. The beaker in front of the light source with the most bubbles produced and with the most displaced water performed photosynthesis faster than all the other light sources. The sources of light used for this lab were sunlight, florescent, red, and yellow lamp lights, and
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Ghosh, Paramita. "Importance of Photosynthesis." Buzzle. Buzzle.com, 14 Apr. 2008. Web. 19 May 2014. .
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The purpose of the lab was to show the effect of temperature on the rate of
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