transport in plants

• lower epidermal tissue 


  apatation- contains stomata, surrounded by guard cells

  function- allows gases to diffuse in/out, guard cells open and close the stomata
• upper epidermal tissue


  adaptation- thin and transparent

  function- allows more cells to reach the palisade cells
• vascular bundles 


  adaptation- contains xylem and phloem

  function- transports water and substances around the plant
• palisade mesophyll 


  adaptation- contains lots of chloroplasts and is near the upper part of the leaf

  function- absorbs more sunlight for the process of photosynthesis
• spongy mesophyll 


  adaptation- irregularly shaped and contains many air spaces

  function- increased surface area so gases can be exchanged
• waxy cuticle 


  adaptation- waterproof layer

  function- reduces plants water loss
• toluidine blue O (TBO) will make the lignin in the walls of the xylem cells blue-green. The phloem cells and the rest of the tissue will generally appear varying shades of pink and purple.
• Water enters through root hair cells and then passes through the root cortex, including the endodermis, to reach the xylem
• • Water is drawn into the roots via osmosis.
  • The soil around roots generally has a high water potential and leaves have a lower water potential
  • This creates a water potential gradient that keeps water moving through the plant in the right direction, from roots to leaves
• transpiration 


  water evaporating from leaves
• • Xylem vessels transport the water all around the plant.
  • At the leaves, water leaves the xylem and moves into the cells mainly by the apoplast pathway.
  • Water evaporates from the cell walls into the spaces between cells in the leaf.
  • When the stomata open, water evaporates into the surrounding air space
• transpiration


  The evaporation of water from a plant's surface
• transpiration stream 


  the movement of water from roots to leaves
• Cohesion and tension help water move up plants, from roots to leaves, against the force of gravity

  1. Water evaporates from the leaves at the 'top' of the xylem (transpiration).
  2. This creates a tension (suction), which pulls more water into the leaf.
  3. Water molecules are cohesive (they stick together) so when some are pulled into the leaf others follow. This means the whole column of water in the xylem, from the leaves down to the roots, moves upwards.
  4. Water enters the stem through the root cortex cells.
• water movement up a plant

  A) transpiration

  B) tension

  C) cohesion

  D) water enters

  
• adhesion is also responsible for the movement of water as the water molecules are attracted to the walls of the xylem vessel which helps water to rise up through the vessel