Please enable JavaScript.

Coggle requires JavaScript to display documents.

WATER RELATIONS - Coggle Diagram

- - - - MEMORIZE HOFLER DIAGRAM INTERPRETATION
    - - FAMILIARIZE WITH VOLUMETRIC ELASTIC MODULUS
- - - - water molecules interact with nieghboring water molecules
        
        pure water takes on quasi-crystalline structure due to weak H-bonds between molecules
        
        cohesion--water molecules have an affinity for other water molecules due to H-bonding
        
        water experiences adhesion, an affinity for other molecules or sufaces due to H-bonding with other molecules, forming a shell of hydration around solutes and drawing them into the solutoin
    - - makes evaporatoin good cooling technique
  - - - required for cell enlargement, gas exchange, phloem transport, and membrane transport
      - aids rigidity of tissue and mechanical stability of nonlignified cells
      - Intracellular pressure, expressed as Pressure Potential
- - - - psychrometer
    - - governs water transport across membranes
      - Indicator of plant water status
  - - - MEMORIZE VAN'T HOFF'S EQN
    - - psychrometer
      - osmometry
  - - - pressure bomb
      - pressure probe
- - - - Pressure Potential
        
        soil, xylem, leaf cell walls
      - water potential
        
        roots, leaf internal gas spaces, outside atmosphere
  - - - sand composed of large particles with low surface area per gram and large spaces
      - clay composed of small particles with high surface area per gram and small spaces
    - - saturation occurs when water fills all air spaces in the soil and moves through it by gravity, water potential = 0 MPa due to excess water
      - Field Capacity is the water in soil after excess is removed by gravity, water potential = -0.05 to -0.1 MPa
      - permanent wilting point occurs when the soil water content is too low to rehydrate the plant and the plant loses turgor even when transpiration = 0
        
        water potential of soil < water potential of plant
  - - - the large the pore size, the lower the hydraulic conductivity
      - the lower the water potential, the lower the hydraulic conductivity
    - - permits water to move in from adjacent soil
      - water removed form pores first
      - menisci form as water recedes into pores
        
        FAMILIARIZE WITH EQN
  - - - apoplast
      - symplast
      - transmembrane
    - - guttation
- - - - midrib is major vein along center of leaf
      - major veins branch off midrib
      - minor veins branch from major veins
        
        diffusion operates effectively
  - - - movement of water by capillary action
      - mesophyll cells in contact with intracellular spaces
    - - water enters leaf via xylem
      - water moves into leaf through cell walls
      - water enters vapor phase into internal air spaces
      - Water exits leaf as a gas
      - MEMORIZE
      - water moves in pathway by diffusion
      - primary resistances include leaf stomatal resistance, boundary layer resistance
  - - - FAMILIARIZE WITH RELATIVE HUMIDITY EQN
      - changes in RH around leaf can drive water movement
  - - - provides a low resistance pathway
      - the greater the stomatal aperture, the greater the transpiration rate
        
        aperture regulated by plant
      - stomata regulate transpiration
        
        balance CO2 uptake and water loss
        
        rapid, short term response mechanism
        
        stomata structure:
        
        two guard cells surrounding a pore
        
        kidney shaped guard cells found in dicots, gymnosperms, mosses, and ferns; subsidiary cells may be present
        
        dumbbell-shaped guard cells found in monocots and flanked by subsidiary cells; functions like beams with inflatable ends
        
        cell wall structure of guard cells permit control of stomatal aperture
        
        guard cell wall structure directs control of stomatal aperture
        
        cellular expansion in response to pressure potential of cells
        
        inflated guard cells curve outward from pore
        
        increased turgor pressure of GC leads to open stomatal aperture
        
        decreased turgor pressure of GC leads to closed stomatal aperture
        
        Guard Cell Metabolism and Mechanism of Stomatal Opening
        
        uptake of K+ and Cl- coupled to malate synthesis leads to open stoma
        
        accumulation of sucrose from starch hydrolysis leads to open stoma
        
        accumulation of sucrose from apoplast leads to open stoma
        
        stomatal aperture tracks daily photosynthesis and responds to light
        
        blue light induces stomatal opening
        
        blue light stimulates guard cell swelling
        
        blue light stimulates H+ pumping
        
        ABA antagonizes blue light stimulated H+ pumping
    - - physical constraint on diffusion due to unstirred air surrounding leaf
      - can inhibit transpiration rate
      - reduced by high wind speed velocity
      - affected by leaf anatomical features
- - - - osmosis
        
        movement of water through selectively permeable membrane driven by concentration gradients and pressure gradients
      - diffusion
        
        water molecules intermingle due to thermal energy and move from high to low distribution
        
        water moves according to Fick's Law
        
        BECOME FAMILIAR WITH EQUATION
        
        good over short distances, bad over long distances
        
        FAMILIARIZE WITH TIME REQUIRED FOR MOVEMENT EQN
    - - more violent in high temperatures
      - movement of molecules in fluid depends on molecular collisions
      - direction of movement is result of the sum of the forces acting on a molecule due to molecular collisions
      - mean free path is the linear distance a molecule moves between collisions
        
        gasses--relatively large mean free path
        
        liquids--relatively short mean free path
  - - - if radius increases 2x, flow increases 16x
      - FAMILIARIZE WITH POSISSULE EQN
- - - - tracheids
        
        bordered pits
      - Vessel elements
        
        simple pits
    - - low resistance pathway
      - negative pressure in xylem drives transport
      - cohesion-tension theory of sap ascent
      - inherent problems with negative pressure
    - - vulnerability curves estimate susceptibility to cavitation
        
        FAMILIARIZE WITH CURVE CHART
      - decreases conductivity
      - amelioration
        
        pitted walls permit water movement around embolism
        
        embolism may be dissolved