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6.1 - 6.11B (Plants (Phloem (transports food substances(mainly sucrose)…

- - - - gives it a massive surface are therefore increasing rate of active transport and osmosis.
  - - - this process is called "translocation" and it uses energy from respiration
        
        "translocation" goes in both direction
  - - - strengthened by a material called "lignin"
    - - movement of water from roots,through xylem and out of leaves is called "transpiration stream", this is caused by evaporation and diffusion.
      - loss of water ; creates slight shortage of water in leaf ; more water drawn from plant through xylem vessel to replace it
        
        more water drawn from the roots therefore bringing dissolved mineral ions with it ; this creates a constant stream of water and mineral ions through the plant
  - - - allow CO₂ and O₂ to to diffuse in and out of a leaf ; allow water vapour to escape during transpiration
        
        surrounded by guard cells ; change shape to control size of pore
        
        turgid (swollen with water) -stomata are open
        
        flaccid (low on water and limp) - stomata are closed
  - - - broad ; so large surface area exposed to light ; needed for photosynthesis
      - palisade layer has lots of chloroplasts ; positioned near top of leaf to maximise sunlight
      - upper epidermis is transparent to allow light to pass through palisade layer
      - xylem and phloem form a network of vascular bundles
        
        provide leaf with water for photosynthesis ; take away the glucose produced
        
        also help support the structure
      - epidermal tissue covered with waxy cuticle ; helps reduce water lose water loss by evaporation
      - tissues of leaves are adapted for efficient gas exchange
- - - - 6H2O(l) + 6CO2(g) == sunlight ==> C6H12O6(aq) + 6O2(g)
  - - - if too low, enzymes needed for photosynthesis function more slowly.
      - if too high, enzymes denature so photosynthesis stop(usually around 45°c).
        
        quite hot for outdoors but can happen in greenhouses :
    - - as light increases, so does the rate of photosynthesis(steadily)
      - till it reaches a certain point, beyond which increasing light won't make a difference
      - L=1/d²
        
        light intensity is inversely proportional to distance squared
        
        this means that when the light is moved twice as far from the plant it will receive a quarter of the energy.
    - - as concentration increases, so does the rate of photosynthesis(steadily)
      - till it reaches a certain point, beyond which increasing concentration won't make a difference
  - - - change the distance between the lamp and the pondweed and count number of bubbles produced
        
        light intensity is the independent variable and the number of bubbles is the dependent variable.
        
        rate of photosynthesis - rate that pond weed produces bubbles
        bubbles released-oxygen(a waste product of photosynthesis)