planttransport-lecture

planttransport-lecture - Final carbohydrates mesophyll cell...

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Final carbohydrates triose phosphates sucrose starch (amylose, amylopectin) mesophyll cell Short distance sucrose transport Phloem loading
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Long distance sucrose transport ‘pressure flow hypothesis’ of phloem P Membrane pumps actively transport sucrose into sieve element cells: 6 P Osmotic dis-equilibrium between sieve elements & surrounding cells: 6 P Protoplasm is squeezed down through sieve pores into next cell by turgor pressure P at source s... turgor pressure builds so that large amounts of material flows quickly P sink s... storage organs and rapidly-developing areas are always sinks. Long distance transport in phloem : from sources to sinks
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Water flow in xylem is counter current to phloem Long distance Long distance water transport in xylem P When stomata are open, water diffuses from intercellular spaces to atmosphere (transpiration). P A gradient of ‘ water potentials ( ψ ) ’ is established between leaves and xylem : cohesion-adhesion-tension theory Guard stomata cells
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planttransport-lecture - Final carbohydrates mesophyll cell...

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