GCSE AQA Biology 3 Water Flow Through Plants

GCSE AQA Biology 3 Water Flow Through Plants

1. Vessels in flowering plants

   • Phloem
     • Made of columns of living cells with small holes in ends - allow stuff to flow through
     • Transport food substances (mainly dissolved sugars) made in leaves to growing regions & storage organs
     • Transport goes in both directions
   • Xylem
     • Made of dead cells joined end to end, with no end walls & hole down middle
     • Carry water & minerals from roots to stem & leaves in transpiration stream
     • Transport is up only

2. Transpiration - the loss of water from the plant

   • Caused by the evaporation & diffusion of water from inside leaves
     • Creates slight shortage of water in leaf so more water is drawn up from rest of plant through xylem to replace it
       • More water drawn up from roots - constant transpiration stream of water through plant
   • Side-effect of way leaves are adapted for photosynthesis - have stomata in them so gases can be exchanged easily
     • There's more water inside plant than outside - water escapes from leaves through stomata