01:119:116 Lecture Notes - Lecture 10: Casparian Strip, Apoplast, Endodermis
15 Mar 2016
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Document Summary
Cortex: loosely packed parendymo cells, large intracellular spices. Endodermis: inner layer of cortex, single layer of cells, boundary between cortex and stele. Stele- vascular tissue: regulates movement of water and minerals into xylem, casparian strip. Single layer of parenchyma cells: xylem, phloem, fig 35. 14. Mycorrhizae: indirectly increase surface area of roots (cid:1) Osmosis: diffusion of free water across membrane. Water potential: psi, free energy of water, measured relative to reference point. Pure water in container open to atmosphere at sea level. Psi = 0 mpa (megapascals: higher psi = more potential energy, psi decreases when solutes dissolved in water. Psi reduced to negative : water moves from region of higher (less negative) psi. To region of lower (more negative) psi. Uptake of water and minerals by roots. Dry: relatively more solute, hypertonic, psi very low. Movement of water: dry soil, soil hypertonic relative to root, water does not move from soil into. Diffusion movement of water over smaller scales.
