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Transport Processes (Water potential (Metric potential (H2O adhensions to…
Transport Processes
Water potential
Metric potential
H2O adhensions to non-dissolved structures
Pressure potential
Effects pressure has on H2O
Free energy of water
Water can be heated
Pressurized or elevated
Osmotic potential
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Short distance intracellular transport
Transfer cells
Smooth outer surface wall
Finger-like outgrowths inner surface
Apoplast
Most molecules move through wall easily
as well as the intracellular spaces
Symplast
All protoplasm considered continuous mass
Guard cells
Open and close stomatal pores
Based on...
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Motor cells
Similar to guard cells
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Accumulate or expel K+
Adjusts H2O potential and turgidity
Diffusion, Osmosis, and Active Transport
Diffusion
Random movement of particles
From high to low concentraion
Technical name is Osmosis
3 Types of Membranes
Completely impermeable
No solutes diffuse
Occur isolation barriers
Freely permeable
Solutions diffues
Biological significance
Selectively permeable
Only certain substances pass
All lipid cell membranes are differntially permeable
All protein cell membranes are differentially permeable
Long distance transport
Phloem
Actively transported
sugar and spice into sieve elements
Mass transfer
sugar and nutrients transported per hour
Sinks
receiving sites of phloem sap
extremely diverse
Pressure flow hypothesis
Membrane bound molecular pumps
active transport postulated for important driving forces
Polymer trap mechanism
conduct cell plasma membranes
permeable to monosaccharides, not polysaccharides
Xylem
transcuticular transpiration
H2O lost through cuticle
cohesion tension hypothesis
Widely accepted model of process
trans stomatal transpiration
H2O lost