Transpiration is the process that allows plants to release H20 in the form of water vapor into the atmosphere. This process mostly occurs during the time the stomata, the microscopic pores on the surface of a leaf, are open for the passage of CO2 and O2. Transpiration plays a huge role for plants, as 90% of the water that enters the plant is through transpiration. It also allows the plant to receive key nutrients and minerals in order to survive. By transpiring, or evaporating, it causes the plant to suck up more water from its roots, causing a constant flow of water through the plant, which is optimal for survival. If transpiring were to terminate, then the plant would continue ...view middle of the document...
Water is then lost to the air from these mesophylls, causing a great negative pressure in the air-water interface. In order to reduce this pressure, water molecules from the more hydrated parts of the plants are pulled upwards toward this area to lessen the tension. Once water lost from the air reaches the leaves, it diffuses through tiny whole called stomata, which allow the plants to breathe. As more water escapes, more water is drawn up from the xylem by suction pressure.In order to defy such gravity pulling within the plant, there must be special properties that allow it to do so. Such special properties lie within water. Its special properties include cohesion, adhesion, as well as surface area. Cohesion is due to hydrogen bonding, making it possible to pull without the water molecules breaking. As water molecules exit the xylem, it tugs on adjacent water molecules, as it is repeated molecule by molecule, causing an endless chain of molecules sticking to each other as it pull upward. Another property of water is the property of adhesion, which is the ability of a substance to stick to another substance other than itself. Since the walls of the xylem walls are hydrophilic, the hydrogen bonds within water attach itself strongly to these walls, allowing it to stick and travel upwards. Surface tension of water also plays a role in this upward pull. Surface tension is a measure of how difficult it is to break or stretch the surface of a liquid. Since water has such a high surface tension due to hydrogen bonding, they are arranged orderly, hydrogen-bonded to one another and to the water below. All these factors enable water to defy gravity and flow upward in the plant in order to reach the leaf.Many factors contribute to the process of transpiration in a very important way. However, one of the most important factors is the ability for plants to regulate themselves. If regulation did not occur, and evaporation took place too often, the plant would release to much water and lack water within the plant, causing it to die. Or if the plant did not transpire enough, the plant would hold too much water causing too much pressure in many areas, also causing it to die. Plants control water gain and loss by opening and closing their stomata. The stomata have two guard cells surrounding it, which opens or closes depending on whether it is becoming more or less turgid. When these guard cells take in water from neighboring cells, they become more turgid and bowed. It is oriented in such a way that the guard cells buckle outwards when turgid, causing the size of the pore to increase. When cells lose water and become flaccid, the are less bowed and the pore closes. Turgor pressure, wh...
