Transport213-page8

Transport213-page8 - Root hairs increase the surface area...

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Transport in Plants - 8 Moving Water – the Mechanisms We need to answer the following in our discussion of water movement mechanisms: 1. How does water enter and move through the plant when plants have no pumps? 2. How does a plant move water upward as much as 300 feet above the ground against the force of gravity? Water and other substances move into and within the plant root in a variety of ways: Apoplastic movement is movement of water through intercellular spaces and cell walls Transmembrane movement moves water from cell to cell via membrane transport Symplastic movement is movement of water through plasmodesmata from cell to cell, once water has entered a cell (Transmembrane and symplastic movement are sometimes considered to be the same.)
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Unformatted text preview: Root hairs increase the surface area for absorption, and soil particles with their surrounding water films adhere to root hairs to promote a diffusion gradient. Root hairs may also use active transport for uptake. Mycorrhizae associates absorb both water and minerals and transfer them into the roots. Once through the root cortex, substances pass into the cells of the endodermis (protected by the casparian strip) and from root stele parenchyma cells into xylem tissue for upward movement throughout the plant. Dilute minerals also move with water. In spring, even very dilute solutes can move with water through the xylem. The substances that move through xylem are called sap....
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This note was uploaded on 01/08/2012 for the course BIO 213 taught by Professor Makina during the Fall '09 term at SUNY Stony Brook.

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