General

• Transport system of plants

  • multicellular organism - small SA:V ratio
  • relatively big - high metabolic rate, direct diffusion is too slow
  • transporting water, minerals, sugars and waste
• Lenticels


  • porous tissue
  • allows for direct gas exchange with tissues
  • good for woody plants
• Vascular system


  • xylem and phloem
  • present in roots, stems, and leaves
  • different structures

  
• Root structure


  • xylem in the centre
  • xylem surrounded by phloem to provide support as the root pushes through the soil
• Stem structure


  • xylem and phloem around the outside
  • provide 'scaffolding' to prevent bending
• Leaf structure


  • xylem and phloem make up a network of veins
• Xylem - transpiration (water and mineral ions)

  • dead cells, no cytoplasm
  • long, tube-like structures
  • no end walls
  • LIGNIN and CELLULOSE- prevent collapse
  • bordered pits to allow water to move laterally
  • parenchyma for support
  • small diameter - assist capillary action
  • thick walls
• Phloem - translocation (solutes e.g. sugars)

  • sieve tube elements - living cells with no nucleus, thin cytoplasm, few organelles, thin cell walls, supported by companion cells
  • companion cells - lots of mitochondria to support themselves and sieve tube elements in terms of energy for active transport of solutes
  • sieve plates - support, allow solutes to pass between cells