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Experiment to investigate the relationship between the number of stomatal pores on the upper and the lower surfacesof the leaves of a mesophyte plant and the rate of transpiration from those surfaces.

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Introduction

Experiment to investigate the relationship between the number of stomatal pores on the upper and the lower surfacesof the leaves of a mesophyte plant and the rate of transpiration from those surfaces. The aim of the experiment The aim of the experiment is to investigate how the number of stomatal pores is related to the rate at which water is lost from the leaves. A mesophyte plant is chosen and the comparison is between the upper and the lower surfaces of its leaves. Experimental hypothesis Taking into account the relative background scientific Information, it is expected to be proven that the rate of transpiration from a leaf of a plant is proportional to the number of stomatal pores on the surface of that leaf. Null hypothesis Negative results would be to establish that the transpiration rate is inversely proportional to the number of stomatal pores or is not affected by it whatsoever. Introduction Water is the universal solvent for a huge amount of chemical substances in all living organisms. Plants require water for many different reasons. It is used to uptake inorganic minerals from the ground, to transport nutrients such as amino acids and carbohydrates along their stems and to control their temperature. ...read more.

Middle

Water is also lost from the lenticles of the stems but in the leaves this takes place to a much greater extent. The rate of transpiration is affected by several environmental factors. The difference of the water potential between the leaves and the surrounding air is very important, hence humidity is one of those factors. Wind increases the rate of transpiration while temperature might have different effects on it. There are also several factors which affect the transpiration rate in an indirect way, by controlling the stomatal aperture. Although there is some evaporation from the cuticle, water, as mentioned above, is mostly lost from the stomatal pores. Therefore light intensity, carbon dioxide/oxygen ratio, water stress conditions and the biological clock effect are all closely related to the rate at which transpiration occurs. Besides the number of stomatal pores itself is proportional to the rate at which water is lost from the leaves, which is exactly what this experiment aims to prove. The experiment consists of two major parts Part 1 : Determination of the rate of transpiration on the upper and the lower surfaces of sample leaves of a mesophyte plant. ...read more.

Conclusion

2cm). Carefully place them in petridishes by means of forceps, to avoid contact with hands. Randomly choose a statistically viable number of leaves on the plant (eg. 10) and number them by attaching small labels on the stems. Insert a petridish into the microwave and heat for approximately 5 minutes. Again, by means of forceps, quickly attach the blue cobalt chloride paper on the leaf by a sellotape piece and start timing. Observe the colour change of the cobalt chloride paper as water evaporating from the leaf turns it pink from blue and for more accuracy, compare with a moist sample. Stop timing as soon as the blue colour is lost. Repeat the procedure for five times on each surface of this leaf, then proceed to another leaf until all ten are examined. Record the results into a table. Using a calculator obtain random coordinates on upper and lower surfaces of the leaves and apply a thin layer of nail polish on those sample areas. Leave to dry for 10 to 15 minutes, then remove the layer by means of forceps and transfer onto microscope slides. Count the number of stomata on a fixed area under light microscope. Record the results into a table. ...read more.

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