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Conducting an experiment to find out what effect the surface area has on the rate of transpiration.

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Introduction: �In my investigation I plan on conducting an experiment to find out what effect the surface area has on the rate of transpiration. �Plants are autotrophic i.e. they make there own food (energy) through the process of photosynthesis. 6CO2 + 6 H2O --> C6H12O6 + 6O2 �For the above process plants require carbon dioxide and water as well as sunlight. They get the carbon dioxide from the air and water is absorbed from the soil through the process of osmosis. �Plants add considerable volume of moisture to the atmosphere. After absorbing water trough their roots, the water travels up the stem to the leaves where over 90% of the absorbed water is lost through the process named transpiration. The sun provides the energy required turning the water in the leaves to vapour, and then vaporised water diffuses out of the plant in to the atmosphere through stomata in the leaves. The diffusion of water out of plant reduces the pressure at the top of the plant, but a high pressure is created at the bottom of the plant so the water moves up the stem into region where it is needed. The loss of water vapour from the plants is called Transpiration. It is a passive process. ...read more.


There was a choice of two potometre: a simple potometer and a complex one with more syringes. Both were used in the pilot but simple potometre was preferred as it gave the reliable result and it was simple to set up. The pilot was carried out by the following procedure. 1. First of all a small branch with few leaves was cut and put in water so the xylem tunes don't become dried. A potometer was filled with water. 2. A small piece was cut from the stalk of the branch so damage or dried xylem tubes can be removed. Then the stalk was attached to the potometer under water. Making sure there were no air bubbles present in the potometer. 3. One bubble was introduced this will be used as a marker. The distance for the air bubble to move was set at 5 mm at first trial. Time for air bubble to move this distance be recorded. Then one leaf was removes and same procedure was repeated and time was recorded. Number of leaves Distance moved (mm) Time taken for the distance to move (s) 1st trial 2nd trial 9 5 157.5 157.3 8 5 162.4 162.7 9 1 31.0 32.0 8 1 45.1 44.5 9 2 ...read more.


Water up take I roughly the same as transpiration. �The graph shows a positive correlation but the line is not straight passing through the origin, meaning it is not directly proportional as predicted. I will explain why the results desired were not obtained as I analyse the data. Summary tables. Number of leaves on the shoot Average time taken (to move 2mm) (secs) 9 71.0 8 57.6 7 55.0 6 50.8 5 56.9 4 62.8 3 71.0 2 75.4 1 82.0 Area of the leaves (m2) Number of leaves Rate of transpiration (1/s) 0.017 9 0.014 0.015 8 0.017 0.013 7 0.018 0.012 6 0.020 0.010 5 0.018 0.008 4 0.016 0.006 3 0.014 0.004 2 0.013 0.002 1 0.012 I said in my prediction that bigger the surface area of the leaves faster the rate of transpiration due to the more stomata available. But this was found not be true as we can see in the above summary table that when there were nine leaves and area was 0.017m2 the transpiration was slower than when there were six leaves on the shoot and total leaves surface area was 0.012m2. So the part of the graph marked A can be considered uncharacteristic. But we can also prove that these three readings (A) are true. �Leaves are plants food producing organ. ...read more.

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