Flowering Plants Nutrition and Transport Transport of water and solutes in plants 1 Across the cell membrane osmosis diffusion membrane transport 2 Short distance tissue level membrane transport and other mechanisms 3 Long distances xylem and phloem pressure driven bulk flow diffusion of water down concentration gradient via transport no energy required across a selectively permeable membrane Turgid more water in than out Flaccid equal amount of water leaving and absorbing Plasmolyzed pulling away from the cell wall Osmosis Passive vs active transport of other molecules Simple diffusion Facilitated diffusion help molecules through the proteins Active move against the concentration Movement across membranes hydrophobic CO2 O2 1 Simple Diffusion passive direct movement across membrane down concentration gradient usually small 2 Facilitated Diffusion passive transport proteins required down concentration used for hydrophilic molecules 3 Active transport transport of proteins required against concentration gradient required ATP used for any molecule against its concentration gradient Solute Concentration and physical pressure affect movement Water moves from regions of higher water potential to regions of lower water potential o Solutes cell wall o Water potential solute potential negative pressure potential Water potential ideal MPa is 0 0 Transport at the cell membrane 1 Passive simple or facilitated diffusion 2 Active requires ATP either directly or indirectly Transport at the tissue level Radial or Lateral o Transmembrane Symplastic Apoplastic Root endodermis goes around the tissue and root Casparian Strip Checkpoints whether ions will do harm or good No heavy metals Al3 Long Distance Travel Bulk Flow mass movement of liquid due to pressure gravity and both Applies to movement in xylem and phloem Xylem flows up Phloem flows up down depending on the season Xylem Phloem Cohesion tension theory Transpiration causes tension negative pressure H boning cohesion adhesion moves column of water Water moves from regions of higher water potential to regions of lower water potential Pressure flow hypothesis sugars flow from a source to sink via difference in pressure High concentration to low concentration Load the phloem with sugar fill with water xylem flows to developing fruit sink and leaf source Water entry increases pressures causing sap to flow