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The aim of my experiment is to show how light intensity effects the rate of photosynthesis in the Canadian pondweed called Elodea.

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The aim of my experiment is to show how light intensity effects the rate of photosynthesis in the Canadian pondweed called Elodea. We will be using elodea because it is cheap and readily available, it is an under water plant therefore it is easy too see photosynthesis when it occurs. I predict that the closer the light the higher amount of bubbles but as the experiment goes on I would expect to see a few anomalies because the pond weed will have been used a lot.. The way we will carry out this experiment is by counting the number of bubbles of oxygen, which leave the stem of the weed from where it has been cut. Method - I will take 60mm of water and place the fresh pondweed in it with the paper clip attached to make sure the elodea stays underwater. I will then add the sodium hydrogen carbonate and stir to make sure it dissolves in to the water. I will then measure the light intensity at every point along the meter rule in 5 cm gaps from 5 to 100. ...read more.


Photosynthesis, which is the process that converts energy in sunlight to chemical forms of energy that can be used by biological systems. Photosynthesis is carried out by many different organisms, ranging from plants to bacteria. All these organisms convert CO2 (carbon dioxide) to organic material by reducing this gas to carbohydrates in a rather complex set of reactions. Energy for this process is provided by light, which is absorbed by pigments (primarily chlorophylls and carotenoids). Chlorophylls absorb blue and red light and carotenoids absorb blue-green light ,but green and yellow light are not effectively absorbed by photosynthetic pigments in plants; therefore, light of these colors is either reflected by leaves or passes through the leaves. This is why plants are green. Other photosynthetic organisms, such as cyanobacteria (formerly known as blue-green algae) and red algae, have additional pigments called phycobilins that are red or blue and that absorb the colors of visible light that are not effectively absorbed by chlorophyll and carotenoids. Yet other organisms, such as the purple and green bacteria (which, by the way, look fairly brown under many growth conditions), contain bacteriochlorophyll that absorbs in the infrared, in addition to in the blue part of the spectrum. ...read more.


Here are the results from the proper exerpiment a fresh pond weed was used and every result possible was recorded and temperature of water was recoreded alond with the room temperature; <<<<<<< temperature >>>>>>>> No. bubbles Distance Before During After Average Per 30 s Light intensity % 5 22 24 24 23.3 38 96 10 24 24 25 24.3 30 95 15 25 25 24.5 24.8 28 95 20 24.5 25 24 24.5 20 95 25 24 25 25 24.6 20 95 30 25 25 25.5 25.2 14 94 35 25.5 25 25 25.2 13 94 40 25 26 26 25.7 12 94 45 26 25 25 25.3 11 93 50 25 25 25 25 7 93 55 25 25 25 25 7 92 60 25 25 24.5 24.8 6 92 65 24.5 25 25 24.8 5 91 70 25 25.5 25 25.2 4 91 75 25 25.5 26 25.5 4 90 80 25.5 25.5 25.5 25.6 3 90 85 26 26 26 26 1 89 90 26 26 26 26.2 2 88 95 26.5 26 26.5 26 0 88 100 25.5 26 26 25.8 1 87 room temperature = 22 From this we can draw many conclusions and present them in graphs asin the following; ...read more.

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