Transpiration/Translocation

• Translocation


  Plants transport sugars made through photosynthesis in leaves to rest of plant
• Phloem cells


  Arranged end to end to form long columns called phloem tubes to transport cell sap (water and sugar)
• Phloem tubes


  • Have small pores/gaps between adjacent cells to enable movement of cell sap
  • Can transport substances in either direction (up or down the plant)
• Transpiration


  Movement of water from roots to leaves driven by evaporation of water from leaves
• Transpiration stream


  Chain of water molecules pulled up the plant as water evaporates from leaves
• Increased light intensity


  More photosynthesis, more stomata open, higher rate of transpiration
• No photosynthesis at night

  Stomata closed, very little transpiration
• Increased temperature


  Higher rate of transpiration (water particles have more energy, more likely to evaporate)
• High airflow


  Water molecules quickly blown away, higher concentration gradient, increased transpiration
• High humidity


  Lower concentration gradient, decreased transpiration