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Transport Processes, Water Potential can be defined as the chemical…
Transport Processes
Short -Distance Transport
distances of a few cell diameters or less
Long-Distance transport
distance between cells that are not close together.
Diffusion
the random movement of particles in solution causes them to move from areas where they are in relatively high concentration to areas of low concentration.
Osmosis
diffusion through a membrane.
Freely Permeable
membranes that allow solutes to diffuse through them and have little biological significance.
Completely Impermeable
membranes do not allow anything to pass through and occur as isolation barriers.
Differentially/ Selectively Permeable
allow only certain substances to pass through: all lipid/protein cell membranes are differentially permeable.
Aquaporins
protein channels that water molecules rapidly move through.
Molecular Pumps
use the energy of ATP to force molecules across the membrane, even if that type of molecule is extremely concentrated on the receiving side
Active Transport
the receiving side that receives molecules from molecular pumps
Intracellular Transport
vesicles migrate through the cytoplasm and fuse with another organelle.
The Water Available in Water
Eutrophication
As algae die, they sink and are decomposed by bacteria. this process uses up enough oxygen.
The Water Available in Air
Incipient Plasmolysis
the point at which the protoplast has lost just enough water to pull slightly away from the wall
Plasmolyzed
the point where the cell has lost very little water, so its volume change and osmotic potential change
Short Distance Intercellular Transport
Symplast
all of the protoplasm of one plant can be considered one continuous mass
Apoplast
most small molecules can move easily through both the wall and the intercellular spaces.
Motor Cells
joint cells, that can accumulate or expel potassium and tus adjust their water potential and turgidity.
Transfer Cells
the walls are smooth on the outer surface but have numerous finger-like and ridgelike outgrowths on the inner surface.
Long-distance Transport; Phloem
Pressure Flow Hypothesis
membrane bound molecular pumps and active transport are postulated to be the important driving force.
Sources
sites from which water and nutrients are transported
P-protein
found as a fine network adjacent to the plasma membrane inner surface of uninjured sieve elements.
P-protein plug
when the p-protein is too large to pass through the sieve it forms a mass
Callose
polymer found within an uninjured phloem..
Actively Transported
sieve tube members in angiosperms, sieve cells in plants other than angiosperms.
Polymer trap mechanism
conducting cell plasma membranes are permeable to monosaccharides and disaccharides but not to polysaccharides.
STM/CC complex
composed of a conducting cell and one or several companion cells.
Mass Transfer
the actual amount of sugars and other nutrients besides water transported by phloem per hour.
Specific Mass Transfer
to make comparisons easier, mass transfer can be divided by the cross-sectional area of phloem .
Sinks
are the sites that receive transported phloem sap and they are extremely diverse.
Long-Distance Transport: Xylem
Cohesive
any force acting on one molecule acts on all neighboring ones as well.
Cohesion-tension hypothesis
most widely accepted model of the process.
Adhesive
molecules interact with many other substances.
poikilohydry
having a body of water content that changes with habitat moisture.
Cavitation
hydrogen bonding is broken over a large region and the water column breaks.
Embolism
between two portions of space.
Transstomatal Transpiration
when water potential is as low as -50.0MPa
Transcuticular Transpiration
how some water is lost directly through the cuticle.
Drought Avoidance
alternatives by which plants adapt to dry habitats.
Drought Tolerance
plants adaptation to wet climates.
Water Potential
can be defined as the chemical potential of water.
Pressure Potential
the effect that pressure has on water potential.
Megapascals (MPa)
how potential is measured in units of pressure.
Osmotic Potential
the effect that solutes have on water potential.
Matric Potential
water's adhesion to nondissolved structures such as cell walls, membranes and soil particles.
