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An experiment to investigate the water loss from leaves through stomata.

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An experiment to investigate the water loss from leaves through stomata In the experiment I intend to find out which of the four leaves will lose the most water and why. Method For the experiment to be carried out the following materials will be needed: * Four leaves which approximately have the same mass and surface area * Petroleum jelly * String * Four paperclips * Two clamps * Electronic balance Four leaves were chosen with approximately the same mass and volume. Petroleum jelly was put on three of the four leaves using the finger. On leaf 1, petroleum jelly was smeared on both the upper side of the leaf and the also the bottom side of leaf. On leaf 2, petroleum jelly was then put on the upper side only. Petroleum jelly was then put on the underside of leaf 3. On leaf 4, the controlled leaf, no petroleum jelly was put on. The leaves were then weighed on an electro balance (the results were recorded in a table). The four leaves would then hang on a string, which were tied to the poles of two clamps. ...read more.


and then again at the end of the experiment. This will tell us the total amount of weight loss, which will give us an indication of how much water loss there has been. Results that have been taken must be reliable. Also all calculations that have been performed will also be done twice. This will reduce the chance of a mistake. Background Knowledge Water is lost through small pores found in the underside of the leaf called stomata. The water is lost through a process called Active Transpiration. The water turns into water vapour and then it diffuses into the air. It happens mainly inside the leaves in the cellulose wall. The stomata are open throughout the day to allow carbon dioxide to pass through (this lets water escape too). In order for the leaves to transpire the leaves will need to be in light at all times (otherwise the stomata would close up). Diagram Obtaining evidence To obtain evidence we weighed the leaves. This was done again after 24 hours for seven days. Then the original mass of the leaves was taken away from the mass of leaves at the end of the experiment. ...read more.


This may have happened because the leaves may have not have had the same amount of water in them at the beginning of the test. Also the leaves themselves may not have had equal surface areas. Also the amount of petroleum jelly may not have covered the whole leaf (this may have given unfair advantage to one of the leaves). The readings were not repeated when any of the values did not fit in with the pattern. The readings, which were taken, were far enough to make a firm conclusion. However the experiment could have improved. In the experiment the size and mass of the leaves were approximately the same but more accurate measurements could have been such as weighing the leaves at the start on an electro balance (before the petroleum jelly was added) to make sure the leaves had the same mass. Also the perimeter of the leave could have been measured to make sure the surface area was the same. To make the test more accurate it could've been done twice. Also when petroleum jelly was added there may have been gaps in between (so water vapour could have diffused), this should have been checked. To take the experiment further it could have been repeated with different specie of leaf to see if the results were the same. ...read more.

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