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TRANSPORT IN PLANTS

TRANSPORT IN PLANTS. 2 types of transport tissue: XYLEM & PHLOEM. Vascular Cambium. creates new xylem cells on the inside, and new phloem cells on the outside. XYLEM & PHLOEM anatomy:. sieve cells. companion cells. plasmodesmata. XYLEM~ moves water and minerals.

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TRANSPORT IN PLANTS

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  1. TRANSPORT IN PLANTS

  2. 2 types of transport tissue:XYLEM & PHLOEM

  3. Vascular Cambium creates new xylem cells on the inside, and new phloem cells on the outside.

  4. XYLEM & PHLOEM anatomy: sieve cells companion cells plasmodesmata

  5. XYLEM~ moves water and minerals • Acts like a bundle of straws • functions via. negative pressure • “sucking” • http://www.youtube.com/watch?v=Ir9bm3fli90

  6. XYLEM cells (transport water & dissolved minerals) ~2 kinds of cells: Tracheid= single cell, elongated, tapered ends (wall composed of cellulose) * Pits (holes) between and surrounding these~ * Dead & hollow at maturity * Conifers, have only these

  7. XYLEM cells~ 2 kinds: VesselElement = numerous elongated cells make up this tube. (typically smaller in length than tracheids, but wider in diameter) * Have “pits” or openings on their ends and are stacked to create one long “pipe” * Carry more water than tracheids * Dead & hollow at maturity * Conifers do not have these

  8. XYLEM ~ water movement b/c of 2 forces: • Transpirational pull- via. negative pressure as water is evaporated out of the stomata http://www.youtube.com/watch?v=EKyHbanzYnI&feature=related

  9. XYLEM ~ water movement b/c of 2 forces: • Transpirational pull- via. negative pressure

  10. 2) Root Pressure- morenegative water potential in the root as compared to the outside soil

  11. 2) Root Pressure- water moves from the soil… into the root

  12. PHLOEM~ has 2 types of cells: companion cells sieve tube cells

  13. PHLOEM companion cells: nucleus sieve tube cells: no nucleus both types are alive

  14. .. How do solutions move through the PHLOEM ~ Ernst Munch 1933PRESSURE FLOW HYPOTHESIS

  15. .. How do solutions move through the PHLOEM ~ Ernst Munch 1933PRESSURE FLOW HYPOTHESIS Solutes move through plants as a result of pressure gradients, not negative pressure (aka. pulling)

  16. SOURCE = area of excess sugar supply aka. leaf in the summer • SINK = area of storage aka. roots in the summer & winter

  17. SINK = area of storage aka. leaf are in the spring • SOURCE = area of excess sugar supply aka. roots in the spring.

  18. TRANSPORT OF SAP (Photosynthesizing cell) sugar source Phloem companion cell 1) @ SOURCE, sucrose moves from mesophyll cells into companion cells via. active transport

  19. TRANSPORT OF SAP Photosynthesizing cell Photosynthesizing cell sugar source Phloem companion cell 2) Companion cells move sap into SIEVE TUBE CELLS via. active transport

  20. Mineral absorption • Proton pumps • active transport (ATP) of H+ ions out of cell • chemiosmosis • H+ gradient • creates membranepotential • difference in charge • drives cation uptake • creates gradient • cotransport of othersolutes against theirgradient ATP H+ H+ H+ H+ H+ H+ H+ H+ H+ sugar

  21. TRANSPORT OF SAP sugar source Phloem companion cell 3) Sugar accumulates in SIEVE TUBES, thus decreasing (lowering) water potential (aka. making more negative)

  22. TRANSPORT OF SAP H2O sugar source Phloem companion cell 4) WATER then, moves in from the XYLEM (as a result)… thus increasing turgor pressure in SIEVE TUBES -->

  23. Maple sugaring

  24. TRANSPORT OF SAP H2O sugar source Phloem companion cell 5) thus moving sugar to areas of lower pressure (the sink).

  25. TRANSPORT OF SAP sugar source Phloem companion cell 6) @ sink, sugar is unloaded from sieve tubes, thus INCREASING water potential...

  26. TRANSPORT OF SAP H2O sugar source Phloem companion cell 7) Water moved back into xylem… and UP via. negative pull

  27. Pressure Flow Hypothesis

  28. Don’t get mad… Get answers!! Ask Questions! Do you think a fruit is a source or a sink?

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