Support

• Give one piece of supporting evidence (bark)?

  • If a ring of bark (which includes the phloem but not xylem)
  • is removed from a woody stem
  • a BULGE FORMS ABOVE THE RING
  • The fluid from the bulge has a higher conc of sugars than the fluid from below ring
  • =evidence there is a downward flow of sugars
• Give one piece of supporting evidence(aphids) ?

  • Pressure in phloem can be investigated using aphids
  • The sap flows out quicker nearer the leaves
  • than further down the stem
  • evidence there is a pressure gradient
• what do aphids do?

  • pierce the phloem
  • then their bodies removed
  • leaving mouthparts behind
  • which allows the sap to flow out
• Give one piece of supporting evidence (metabolic inhibitor)?

  If a metabolic inhibitor

  • (which STOPS ATP PRODUCTION)
  • is put into the phloem,
  • then translocation stops
  • this is evidence that active transport is involved