The Effect of Stomata Opening on Plant Transpiration

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The Effect of Covered Stomata on Plant Transpiration

Nezar Alsaeedi

IB Biology Higher Year 1

Mr. Connors

May 7, 2005

Abstract:

        The purpose of this study is to find the effect of covered stomata on plant transpiration. The experiment was designed to examine the changes in texture of four Devil’s Ivy leaves (Epipremnum aureus) affected by covered stomata and rate of transpiration. One leaf was completely coated with Vaseline gel. The second leaf was coated only on the front surface, while the third leaf was coated on the back surface with gel. The fourth leaf was left uncoated as a control variable. The four leaves were hung on a rope (50cm. long), 10cm. apart from each other. The leaves were exposed to the same amount of sunlight, temperature (32 degrees Celsius), and humidity (about 70 percent). The changes in the texture of the four leaves were observed over a one-week interval. The results showed slight loss of turgidity for the completely coated leaf, moderate flexibility and folding edges in partially covered leaves (front-surface and back-surface coated leaves), and tremendous flexibility, softness, and complete inward folding of the edges of the uncoated leaf. According to the results, it is concluded that the uncoated leaf with uncovered stomata had the higher rate of transpiration than the other completely and partially coated leaves.

Introduction:

        Transpiration is the loss of water through stomata openings on the surfaces of plant leaves. It is crucial for the survival of plants since it aids in water transport through roots, stems, and leaves, creating a suction force. The stomata, minute pores controlled by guard cells, are also essential for gas exchange. Carbon dioxide enters these pores, and oxygen exits as a product of photosynthesis. Stomata generally open at daytime and close at nighttime. Many environmental factors also affect stomata openings for transpiration. These factors include low humidity, wind, high temperature, and light, which increase the rate of transpiration. During dry conditions, cold weather, and high humidity, the plant decreases the rate of transpiration in order to preserve its water supply and keep its turgidity. Many plants have adapted to their environments by controlling the amount of water loss. Desert plants, such as cactus plants, have a waxy coating on the epidermal surface of their leaves to decrease water loss. Cactus plants open their stomata pores during the night where the air is cool and close their pores during the hot day. Without these adaptations, the plants will wilt and shrivel, losing an ample supply of water.

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        How do the covered stomata affect the rate of transpiration? The hypothesis of this experiment is if the stomata are uncoated and open, then the rate of transpiration will be higher than the coated stomata. The experiment was designed to observe the changes occurring in leaf texture affected by covered stomata and the rate of transpiration. Four healthy Devil’s Ivy leaves (Epipremnum aureus) were cut and hung on a rope with the two ends tied around two poles. The first leaf was coated with Vaseline gel on the front and back surfaces. The second leaf was coated with the gel at ...

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