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Transport Processes (Short-distance intercellular trasnport (guard cells…

- - - - K+ causes water potential in guard cells to become more negatvie
        
        water diffuses into guard cells
        
        guard cells swell, bend, and push apart
        
        stomatal pore opens
- - - - pressure potential equation
  - - - point at which protoplast has lost just enough water to pull slightly away from wall
    - - protoplast pulls completely away from cell wall and shrinks
      - water potential becomes more negative
- - - - all lipid/protein cell membranes
- - - - mechanism by which H2O and nutrients are moved thru phloem
      - molecular pumps and active transport
    - - sites from which H2O & nutrients are transported
      - sugars are actively transported in sieve elements (loading mechanism 1)
      - polymer trap mechanism
        
        phloem is loaded by this in some species (loading mechanism 2)
        
        monosaccharides enter, become polymers and cannot get out
      - companion cells and parenchyma important in loading
      - STM/CC complex
        
        functional unit: conducting cell & 1+ companion cells
    - - amount of sugars & nutrients transported by phloem per hour
      - excludes water
      - specific mass transfer
    - - sites that receive transported phloem sap
      - mechanisms that seal broken sieve elements
        
        P-protein/ P-protein plug
        
        callose (polymer)
  - - - cohesion
      - adhesion
      - cohesion-tension hypothesis
      - transstomatal transpiration
        
        water loss thru stomata
      - transcuticular transpiration
        
        water loss thru cuticle
      - poikilohydry
        
        body water content changes with habitat moisture
      - cavitation
        
        water columns break due to dehydration
      - embolism
        
        air bubble
      - guard cells help control water transport by opening/cloding