transport in plants

• xylem

  1. one long tube made from dead cells
  2. strengthened by lignin
  3. transport water and mineral ions to leaves
• transpiration 


  evaporation of water from the leaves

  water reaches the leaves via the xylem
• factors that effect rate of transpiration

  1. temperature ( warmer = water particles have higher energy = more likely to evaporate)
  2. air flow ( high air flow quickly blows evaporated water particles away = concentration gradient is high = more transpiration)
  3. light intensity (more light =more photosynthesis = stomata open to let carbon dioxide in = water can also evaporate through open stomata )
  4. humidity ( humid air will decrease transpiration = decreased concentration gradient )
• why does transpiration happen ?

  When the plant opens its stomata to let in carbon dioxide, water on the surface of the cells of the spongy mesophyll and palisade mesophyll evaporates  and diffuses out of the leaf. This process is called transpiration.
• The phloem moves food substances that the plant has produced by photosynthesis
• phloem

  1. sieve tubes - have pores that connect to each cell and allow sugars and sap to pass through
  2. companion cell gives energy