| Definition | Term |
| diffusion of water down its concentration gradient | |
| Transport of material due to random movements of particles; net movement is from areas of high concentration to low concentration | |
| atmospheric pressure exerted by the water vapor in the air; increases as the water vapor in the air increases. | |
| Measure of the water content of air relative to its content at saturation | |
| Pressure exerted by the water vapor in air that is saturated with water vapor | |
| resulting from water's tendency to adhere to the walls of containers like cell walls | |
| released during oxidation of organic molecules | |
| difference between actual water vapor pressure and the saturation water vapor pressure at a particular temperature | |
| capacity of water to do work, which is determined by its free energy content | |
| analysis of relative concentrations of stable isotopes such as carbon-13 and carbon-12 in materials; used in ecology to study flow of energy and materials through ecosystems | |
| regulation of internal salt concentration and water using a variety of anatomical structures and physiological processes; energy consuming process | |