Apedia

Xylem Evidence Cohesion Tension Cut Shoot Transpiration Dye Diameter

Front Describe 3 sources of evidence for cohesion-tension theory.
Back Evidence for cohesion-tension theory:
  • Poisons - if cut shoot is placed in cyanide water, uptake and transpiration continues as usual showing that transpiration does not rely on live cells and therefore isnt an active process
  • Dyes - if leafy shoot is cut and dipped into dye the dye will visibly be taken into the xylem vessels supporting that major water pathway is thru xylem
  • Diameter of tree trunk over 24 hour period is narrowest at midday and widest at midnight - cohesive forces in xylem cause negative pressure that draws tissues in and reduces diameter bc highest rate of photosynthesis is at midday & lowest around midnight

Learn with these flashcards. Click next, previous, or up to navigate to more flashcards for this subject.

Next card: Guard cells explain open/close stomata turgor low asymmetric

Previous card: Draw label annotate diagram show transport water plant

Up to card list: A-Level Biology OCR A