Ap Bio Lab Report

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Jonah Meesig
Ms. Raffay
Ap Biology
15 March, 2011

“The effect of environmental variable, light, on the rate of transpiration in plants”
Contrary to what most may think, the majority of water a plant absorbs isn’t used in daily plant functioning. Instead it is lost in the process of transpiration, a manner similar to evaporation. It is described as water vapor being lost through the leaf/ stomata by means of guttation, almost like sweating. The rate of transpiration is directly related to the evaporation of water from stomates on leaves. This stomatal transpiration accounts for the significant amount of water loss by a plant. By adding certain environmental changes a change in the transpiration rate will occur.

I this relationship exists, then when the plants exposure to a variable such as constant heat lamp increases the rate of transpiration in turn will increase. For Transpiration:
The materials used were a small amount of water, an electric scale, a calculator, string, scissors, a clear plastic bag, pencil, paper, a light source, and a plant.

For the Stem Structure:
Materials used were a nut- and- bolt microtome, plant stems, a single blade razor, paraffin, blue stain, 50%ethanol, distilled water, 50% glycerine, a microscope slide and cover slip, pencil, paper, light microscope.

Methods for transpiration lab; the plant was generously watered then covered the pot with a clear plastic bag, tied at the stem with string. The plant was then weighed prior to being put under light the first day and weighed every day at the beginning of the period from then on. Measurements were written down on paper. This went on for 5 days without watering and then massed one final time.

Methods for the structure of stem portion were first making a microtome out of a nut and bolt leaving a small space for the plant stem. The stem was placed in the center of the space and melted paraffin was poured around it. After cooling time for the paraffin was allowed the...
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