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How does light intensity affect photosynthesis?

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Introduction Photosynthesis is a very important process in nature. Photosynthesis is a biochemical reaction used to produce glucose using light energy, water and CO2 (Carbon Dioxide). A bye product of the reaction, photosynthesis, is Oxygen. It takes place in all green plants, which use the green chlorophyll, held in chloroplasts in the leaves, to trap light. The main site of photosynthesis is the palisade mesophyll cells in the leaf of a plant. It is these cells that contain the green chloroplasts and are very well adapted to do their task. They are near the upper side of the leaf where they can obtain the maximum amount of light, they are packed very closely together and as already mentioned contain green chloroplasts clustered towards the upper side too. Plants photosynthesise to produce food chemicals that are needed to allow them to grow. The main reaction is to produce oxygen and glucose to be changed into energy during respiration. Glucose is stored in the form of starch which is insoluble and does not affect the osmosis taking pace in the plant. As plants respire both day and night this starch is often used up during the night when photosynthesis cannot take place. The uses of glucose within the plant are for active transpiration, cell division, the production of protein and the production of cellulose. ...read more.


The optimum temperature for the enzymes to work is at roughly about 30-40 degrees, when enzymes are exposed to temperatures higher than this they are denatured and make the enzymes unable to perform at all. Variables in this experiment: The independent Variable is Light intensity. The dependant Variable is the rate of photosynthesis. To make sure this experiment is kept fair other variables are kept the same. Limiting Factors * Water. x * Light energy. x * Carbon Dioxide Concentration. x * Temperature (room temperature). V * Chlorophyll. V My experiments limiting factors will be Chlorophyll and Temperature. In my experiment water shall not be a limiting factor as the plant with be submerged in the water, this will not affect the plant in a bad way since the plant I am using is pond weed. Light energy will not be a limiting factor since it is our Independent variable. Carbon Dioxide will not be a limiting factor as I will put sodium bicarbonate into my water this will make a solution, which allows the water to make CO2 (carbon dioxide). Apparatus list * Beaker. * Flannel. * 1 metre ruler. * Elodea - also known as Canadian pond weed. * Pleistocene. * Stopwatch. * Lamp. * Sodium Bicarbonate. * Water. Method. * Set up apparatus. * Start up the lamp 100 cm away from plant in dark room. ...read more.


My results show me that 3 steps of results are in close arrangement and I would say that they are reliable. To make my results more reliable I could have recorded results for every 1cm as this would have been more reliable because it would have allowed me to make more accurate calculations of bubbles per minute of this experiment. Extension. I theorise that there are 3 primary light frequencies for white light (red blue green). I predicted that the chlorophyll absorbs the red and blue light and reflects the green light. Rate of Photo- synthesis R G B W No Frequency of Light Light Apparatus * Flannel. * 1 metre ruler. * Elodea - also known as Canadian pond weed. * Pleistocene. * Stopwatch. * Lamp. * Sodium Bicarbonate. * Water. * Syringe. * Beaker x2. * Different colour filters. Method. * Set up apparatus. * Start up the lamp 100 cm away from plant in dark room. * Switch lamp on. * Leave it in place for 2 minutes so it can adjust to the different light intensity. * Count number of bubbles produced by plant in one minute. * Record Results. * Move lamp forward 5cm. * Leave it for 2 minutes for plant to adjust to amount of light energy. * Count number of bubbles for 1 minute. * Repeat steps 4, 5, 6 and 7 until lamp is 5cm away from beaker. * Record 3 sets of results and repeat experiment with blue and red filters. Zaka Ahmad 11m 1 ...read more.

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