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Ecology - (06) Water Relations

Molles, Cahill - Chapter 6
alluvial groundwater
water that is derived from a surface stream in contrast to groundwater that is derived from underground streams and high water tables. -Page 155
rapid formation of air bubbles within the xylem of plants. -Page 155
transport of material due to the random movement of particles; net movement is from areas of high concentration to areas of low concentration. -Page 146
referring to organisms with body fluids with a higher solute concentration than the external environment (e.g. most freshwater fishes) -Page 146
referring to organisms with body fluids with lower solute concentration than the external environment (e.g. most marine bony fishes) -Page 146
matric forces
water's tendency to adhere to the walls of containers such as cell walls or the soil particles lining a soil pore; adhesion and cohesion due to hydrogen bonds -Page 148
metabolic water
water released during oxidation of organic molecules (e.g. six molecules of water are produced during the oxidation of one glucose molecule) -Page 151
movement of water across a semi-permeable membrane from an area of high water concentration (low solutes) to an area of low water concentration (high solutes) -Page 146
relative humidity
a measure of the water content of air relative to its content at saturation; ratio of actual water vapour density to saturation water vapour density. -Page 145
saturation water vapour pressure
the pressure exerted by the water vapour in air that is completely saturated (cannot hold any more water vapour) -Page 145
stable isotope analysis
analysis of the relative concentrations of stable isotopes in materials (e.g. 13C and 12C; used in ecology to study the flow of energy and materials through ecosystems. -Page 165
vapour pressure deficit (VPD)
the difference between the actual water vapour pressure and the saturation water vapour pressure at a particular temperature. -Page 145
water potential
the free energy content of water (capacity to do work); water moves from positions of higher free energy to positions of lower free energy; increases as solute concentration decreases -Page 147
water vapour pressure
the atmospheric pressure exerted by the water vapour in air; increases as the water vapour in air increases. Page 145
referring to organisms with body fluids with the same solute concentration as the external environment (e.g. most marine invertabrates) -Page 146
concentration gradients
___ influence hte movement of water between an organism and its environment
___ organisms regulate their internal water by balancing water acquisition against water loss.
___ organisms use complementary mechanisms for water and salt regulation.