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To continue maintaining the concentration gradient between this, the plant will take up eater from the soil by the roots and to the air space Of the leave through xylem vessels. And we will use the light instead of the sun and the fan instead of the wind in the atmosphere in the experiment to measure the rate of transpiration of the plants under those conditions. Results & Discussion After the experiment, we obtain the decreasing graph as the pressure decrease to pull the water up through the xylem. We have determined the rate of transpiration with 4 stages. Each stage required 10 minutes to measure the rates respectively.
Without any conditions, using the fan only, sing the light only and using both light and fan are the four stages respectively. And we have observed that different conditions give the different rates by calculating the slope. For the first stage, we obtain the smallest slope compared with others, nearly about -0. 9286 kappa/min. As in this stage, we haven’t use any conditions that make the stomata more widen to further exchange of the water vapor, the water uptake is maintained in the normal speed in the room temperature, therefore the rate of transpiration is the smallest for the first ten minutes.
For the second stage, the condition we have used is the fan. The slope in this is higher than the previous 10 minutes, we have get the -1 . 206 kappa/min. That indicate the transpiration have been increased. The reason for this result is that the fan is instead of the windy conditions. The wind continues blowing the water vapor in the air space of the leaves to the air. As mentioned before, to maintain the concentration gradient between the leaves and the air, water is needed for the this process continually, therefore the rate of transpiration increases and the more steeper slope we have resulted.
For the next, the light is used to measure the rate. The slope in this case is more steeper than the previous two. The slope is -1. 424 kappa/min. In this case, the light is instead of the sunlight. When the plant is placed on the light intensity, the guard cells surrounding the stomata will absorb the light and make the stomata more wider as regulator, thus more water vapor is diffused out to the air and so the rate of water uptake is higher, that why the rate of transpiration in light is higher than in wind as the wind just blow away the water vapor but not widening the opening the stomata.
With the both light intensity and the fan, the slope among these four stages is the highest, with -1. 697 kappa/min. The stomata in the leaves still open wider to let more water vapor to diffuse out, and with the wind add on, more water vapor diffuses out to the air. As there is a hugely difference of the concentration gradient between air and the leaves, the amount of water uptake is more than the previous conditions and hence the rate of transpiration in this case is the highest. To explain the way of water uptake from the soil to the leaves, here is the reason for it.
The water molecules that evaporate from cells to the air space and then to air are replaced by other water molecules from the xylem. As Water molecules are cohesive, transpiration exerts a pulling force called transpiration pull to draw the water to replace the water lost, therefore we know that why the concentration gradient sill be maintained after the lost of water vapor to the air Conclusion With the wind and the light intensity, the rate of transpiration in 2-4 stages are higher than the rate in the first stage. With the help of the transpiration pull, water molecules are replaced to maintain the concentration gradient.