Transpiration and Translocation

• Translocation:

  • made of columns of elongated living cells with small pores in the end walls to allow cell sap to flow through
  • they transport food substances made in the leaves to the rest of the plant for immediate use for storage
  • the transport goes both directions
• 1. the movement of water from the roots through the xylem and out of the leaves is called the transpiration stream
• 2. caused by the evaporation and diffusion of water from a plants surface. most transpiration happens at the leaves
• 3. this evaporation creates a slight shortage of water in the leaf, and so more water is drawn up from the rest of the plant through the xylem vessels to replace it
• 4. this in turn means more water is drawn up from the roots and so there's a constant transpiration stream of water through the plant
• 5. this is a side effect of the way leaves are adapted for photosynthesis. They have stomata in them sogases can be exchanged easily because there's more water inside the plant than in the air outside, the water escapes from the leaves through the stomata by diffusion