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Plant transport 3.1.3 - Coggle Diagram

- - - - water draining very quickly
      - Salty sand
      - Leaves exposed to very windy conditions
  - - - Con - limits photosynthesis
  - - - Store water in stems which biomes fleshy & swollen
      - Stem often ribbed or fluted so can expand when waters available
    - - Reduced SA of leaves, when total leaf SA is reduced, less water is lost by transpiration
  - - - will reduce water loss & so reduce need to take up water
    - - Achieved by maintaining high salt concentration in cells
      - Low water potential reduces evaporation of water from cell surface as water potential gradient between cells & leaf air spaces is reduced
- - - - creating a conc/proton gradient.
  - - - sucrose transported into sieve tubes => lowered water potential => water enters by osmosis => high hydrostatic pressure (= HIGH turf or pressure due to rigid cell walls) at source
    - - Sucrose leaves phloem to be used (via diffusion) => reduced sucrose conc => increased water potential in elements => water leaves tubes by osmosis => low hydrostatic pressure
    - - Companion cells have mitochondria
        .
        Translocation halted by metabolic poison of mitochondria
      - Rate of sugar flow too high to be diffusion alone
      - Aphid mouthparts take food from phloem passively
        If stylist is removed then positive pressure forces sap out
    - - Sieve plates would create a barrier to mass flow. Role unclear
      - Not all solutes in sap move at the same rate
      - Sugar travels to lots of diffusion sinks at the same rate, not just the 1 with the highest water potential/lowest conc
- - - - High water potential => low water potential
    - - https://docs.google.com/document/d/1DjJ5NUoOjnsh002o9ZoePEv09uctgPkazTuflr7kqGw/edit
  - - - = pressure asserted by water
      - If there’s a large loss of water from the spongy mesophyll cells into the atmosphere, this will reduce the hydrostatic pressure from the top of the xylem. Water gets sucked up due to the hydrostatic differences
    - - = water molecules from hydrogen bonds with each other
    - - = water molecules from hydrogen bonds the lignin in the xylem vessels
      - Adhesion & cohesion result in water exhibiting capillary action (water rises up narrow tube against gravity) Resulting in a continuous stream of water = cohesion-tension theory
    - - Active pumping of minerals into xylem results in root pressure. This gives a push up the xylem but is not the major factor.
  - - - Often they draw air in rather than ;waking water out, as water continues to move up the cut stem
    - - Broken or cut xylem stops drawing up water as the air drawn in break the transpiration stream - cohesion between water molecules
    - - At high transpiration rebates (during the day) diameter decreases due to the tension. At night, during low transpiration rate, diameter increases
  - - - Root pressure increases as temp increases & decreases as temp decreases, suggesting of an enzymes controlled chemical reaction (respiration to produce ATP)
    - - Of O2 level or respiratory substrate levels drops, root pressure decreases
    - - Cyanide stops the mitochondria from working, therefore root pressure decreases
    - - Guttation is when xylem sap is forced out of special pores at the end of leaves at night, suggesting its an active process
- - - - It is one of the substrates required for photosynthesis
      - provides support/structure through turgor pressure
      - as a solvent it is used to transport dissolved substances around the plant.
  - - - This is the movement of water through the cell wall & intercellular spaces
      - Capillary action pulls the water up the plant
        
        Capillary action = when adhesion is stronger than cohesion it causes movement
      - Faster movement of water
    - - This is the movement of water through the living spaces of the cell - cytoplasm
      - Through the plasmodesmata
      - Each cell further away from the roots has a lower water potential so water is drawn up the plant
    - - https://docs.google.com/document/d/1vBEjRFA2rDqKAM97BUMOQyW1FO1RVgnNYjwkzWvgOjE/edit
    - - Both are routes for water through the context to the stele
    - - apoplasts
        
        Water moves from cell to cell by passing along cell walls
        This route ends at the endodermis
      - symplasts
        
        Water moves into cell through vacuole/cytoplasm & into the next cell via plasmodesmata
        This route continues into the stele & supplies the xylem
  - - - Made of wax called Suberin
    - - Absence of appropriate carrier proteins
- - - - Living cells
      - No nucleus - only very thin layer of cytoplasm & few organelles
      - Joined end to end to form ‘sieve tubes’
      - End walls are like sieves (sieve plates) - lots of holes in them through which cytoplasm from adjacent cells is connected
      - ROLE - transports solutes through plant
    - - Living cells
      - Comet common plant tissue
      - -ROLE - food storage
      - Thin walls, large vacuole & intercellular space
    - - 1 companion cell for every sieve tube element
      - Very dense & active cytoplasm, many full of - many folds in cell membrane
      - ROLE - carries out living functions for both itself & its sieve tube
  - - - photosynthetic tissue, e.g. leaves
    - - eg. for
        
        Growing regions & storage sites
        
        Meristem that are actively dividing
        
        Parts that are developing foods stores
        
        Devoting seeds
        
        Storage organs
        
        Fruits
- - - - https://docs.google.com/document/d/1PC2esdygxCkAQguTYPqVo8_d62TejGkpQa1R70YWdYw/edit
    - - Water moves out of the vacuoles by osmosis
      - Outer wall is more flexible (thinner) than the inner wall (thicker), so the cell bends & closes a the stomata
    - - Guard cells pump in solutes by active transport
      - Water moves into the vacuoles by osmosis
      - Cell bends & opens the stoma
  - - - Increased temperature - water evaporates more easily
      - Light - tends to ope the stomata
      - Wind - pulls water vapour away from stomata, causing steeper concentration gradient
      - Decrease humidity - increases concentration gradient
    - - The rate of transpiration can be measured using a piece of apparatus called a potometer, which must be set up in air/water tight conditions.
      - Why is it not the case that the volume of water taken up by the plant cutting in a potometer is equal to the rate of transpiration, even though this is the assumption that we make? - because some water is used in photosynthesis
      - method
        
        Select plant to be used in experiment
        
        Underwater, make a diagonal cut, separating main plant from cutting being used
        
        Keep cutting beneath water - ensures column of water in xylem isn’t broken
        
        Fill potometer with water, be sure an air bubble is introduced to capillary tube
        
        Place whole potometer underwater & insert top of cutting into top of potometer - vital all is done underwater
        
        Exposes plant to different environmental conditions & measure rate of water uptake
        
        We’re assuming that the rate of water uptake = rate of transpiration
        
        Results can be graphed as follows: rate of water transpired (um^3 per second) against time.
      - https://docs.google.com/document/d/1BYKm2Hcjw9bu1VLYxt2Zh9KuU5ZPFbj2FnXr9grJOEA/edit