Transport in plant

Transport in Plants Water Transport ∀ Ψ = ΨS + ΨP • solute pressure – result of concentration of solute in a solution • pressure potential – hydrostatic pressure Water Transport • water flows down a water potential gradient • water will move from solution with the higher (less negative) water potential to that with the lower (more negative) water potential Mineral Uptake • requires facilitated diffusion or active transport proteins • proton pump Ion Transport into Xylem • transported into the cortex • may move with water or via diffusion Water Transport into Xylem • moves into the root and into the stele because each has a more negative water potential • aquaporins • passage via: – apoplast – symplast Endodermis and Pericycle • endodermis is a selective barrier – Casparian strips • pericycle – transfer cells Transpiration-cohesiontension Mechanism • transpiration • tension • cohesion Stomata • control rate of transpiration • guard cells – open and close in response to light and daily rhythms – active transport of H+ out – K+ diffuse down electrochemical gradient into guard cells Pressure Flow Model • explains movement of phloem sap • source vs sink Pressure Flow Model • high solute concentration at source • increase in hydrostatic pressure • sugars in sink draw water out of phloem [...]... transpiration • guard cells – open and close in response to light and daily rhythms – active transport of H+ out – K+ diffuse down electrochemical gradient into guard cells Pressure Flow Model • explains movement of phloem sap • source vs sink Pressure Flow Model • 1 high solute concentration at source • 2 increase in hydrostatic pressure • 3 sugars in sink draw water out of phloem  ... Mineral Uptake • requires facilitated diffusion or active transport proteins • proton pump Ion Transport into Xylem • transported into the cortex • may move with water or via diffusion Water Transport. .. explains movement of phloem sap • source vs sink Pressure Flow Model • high solute concentration at source • increase in hydrostatic pressure • sugars in sink draw water out of phloem ... – open and close in response to light and daily rhythms – active transport of H+ out – K+ diffuse down electrochemical gradient into guard cells Pressure Flow Model • explains movement of phloem