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Unformatted text preview: Basic Ideas: 1. Water that evaporates out of the leaves pulls the rest of the water in the plant through processes known as cohesion and adhesion. 2. After being evaporated from the leaves, water is pulled up the xylem. 3. Water being pulled up the xylem pulls water in the roots causing root hairs to absorb water from the earth. It Starts with the Roots: Mycorrhizae, (a fungus that is not actually part of the plant) works with the roots to greatly increase surface area so more water can get to the plant. Root hairs are extensions of the root that absorb water and various materials that are taken to the root cortex (a part of the root that allows water to flow from the root hairs to the vascular cylinder .) The vascular cylinder consists of two tubes known as the phloem (for transporting sucrose) and xylem (for transporting water.) Water can take two different routes in order to reach the vascular cylinder : Apoplastic route (in which water travels through the air space in between cells.) and Symplastic route (in which water diffuses from cell to cell from within the cell’s membrane.) From the root hair, the water must pass through the endodermis by taking the symplastic or apoplastic route to reach the vascular cylinder. http://naturalsciences.sdsu.edu/ta/classes/lab2.1/exp1tg.html Going from roots to the Vascular Cylinder : After leaving the root hairs, the water Goes through the Epidermis (bark in trees), then the root cortex. It reaches the Endodermis (a layer of tightly packed cells which prevent water from flowing out the roots. The Casparian strip is seen as the red strip in the image. The strip is a waxy layer located between cells. Water is forced to cross the strip and is thereby filtered. All toxins are pumped out of the plant....
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This note was uploaded on 02/03/2011 for the course BIO 5A taught by Professor Zhu/cardullo/rao during the Fall '08 term at UC Riverside.
- Fall '08