Friday, 18 March 2011

2.54 Transpiration





  • for evaporation to occur: water (liquid) ---->  water vapour (gas).     and for this to occur you need heat. to get this heat we use sunlight

  • water is delivered in from leaf by xylem, and from there it moves through the spongy mesophyll layer and then to just above the stomatal pore. 


  • then the gas water vapour diffuses through the stomatal pore through a fairly steep diffusion gradient,  as the water vapour inside the stomatal pore is at 100% humidity and outside the leaf the humidity is less than that and the distance between them is only one cell thick. 

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