Xylem and Phloem

• Xylem -> transport water and dissolved mineral up the plant tp the leaves

  Phloem -> translocate sucrose around the plant to respiring cells
• Xylem

  • Made of dead cells whcih are located on the inner section of the stem
  • no cytoplasm and no nucleus
  • No end wall so the top and bottom cell walls have disintegrated to create a long tube
  • Their cells haven been thickened with hard rings of lignin which provide support
• Phloem

  • Made out of living cells which are located on the outer section of the plant
  • Phloem -> translocate sucrose
  • little cytoplasm and no nucleus so there is more space to translocate sucrose
  • Phloem vessels have sieve plates in between one cell and the next to allow translocation of sucrose
• Companion cell

  -> Adaptation is it has lots of mitocondria. Mitocondria is the site of respiration and they release energy

  Companion cell:

  -> actively pump sucrose into sieve cells

  -> This increases the pressure in sieve cells causing the bulk movement of sucrose up and down a plant