Bio Transpiration Paper

Topics: Evaporation, Water, Leaf Pages: 5 (1729 words) Published: March 7, 2013
Hannah Baumann
Bio 212
Lab: Thurs 10:00

Transpiration Laboratory

Transpiration is affected by many things including temperature and humidity; we were interested in seeing what other factors influence the rate that transpiration occurs. The purpose of this experiment was to explore how paint effects transpiration. I hypothesized that the rate of transpiration would decrease with the addition of paint to the bottom or the Laurel twig’s leaves. After collecting and analyzing the data I learned that transpiration rate actually increased with the addition of the paint, the transpiration rate for the control was 2.516 and the transpiration rate for the experiment was 2.904. The relationship between the control and the experiment was significant, meaning the null hypothesis was rejected. Introduction:

Plants require CO2 to perform functions like photosynthesis. Stomata on the bottom of leaves open and close in order to allow CO2 to diffuse into the plant and O2 to exit them. Transpiration is essential for maintaining the plants water cycle but it is a byproduct of opening and closing the stomata. Transpiration starts in the roots where water uptake occurs, water is then moved up through the plant via the xylem. When the water reaches the leaves evaporation occurs, the water forms a meniscus between the mesophyll cells and the lower pressure potential in this meniscus allows for the evaporation to occur. This evaporation creates a force that pulls water up the plant (Carrier). The stomata control the rate of evaporation and the absorption of CO2. Transpiration have many factors that can affect how fast transpiration can occur, temperature, humidity, light, and air movement are just a few things that can affect transpiration. Studying transpiration is interesting because we can manipulate factors like these to control the plants water cycle and transpiration. This could be beneficial when trying to move minerals and nutrients up from the roots quickly so the plant and grow faster, when trying to cool a plant down, and when trying to increase or decrease the rate of photosynthesis (Carrier). In our experiment we wanted to test the effect of paint on the leaves. I hypothesized that the rate of transpiration will decrease after the paint is applied to the bottom of the leaves. Since more stomata are located on the underside of the leaves, painting the bottom of the leaf will have the greatest effect. When humid days transpiration decreases because water usually diffused from higher concentrations to lower concentrations and since there is more water in the air the water from the plant doesn’t diffuse as easily. Because of this fact I think that after the leaves are painted, transpiration will decrease because there is water in the acrylic paint. I think that the water in the paint will be at a higher concentration then inside the plant so less water will diffuse out. Jay Anderson performed research with taramax chinensis twigs to determine factors control transpiration and photosynthesis. Anderson looked at the effect of humidity and temperature, he found that photosynthesis and transpiration decreased as humidity and temperature increases. He hypothesized that is because of the stomatal response to humidity but there was no definitive evidence (Anderson, 55). Paint contains water and by placing the paint onto the leaves, the play may observe this moisture as something similar to humidity and have the same stomatal response as the twig would have if there were high levels of humidity. Methods:

The procedure for this experiment fairly easy, we collected 20 twigs and placed the stems in water while making sure the leaves did not get wet because if they were wet it could affect the outcome of the experiment. Each twig was then was placed in an apparatus, which was hooked up to the logger pro software to measure the transpiration rate. After everything was set up, the initial pressure was measured and...
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