BIO 373 Lecture Notes - Lecture 9: Tonicity, Water Potential, Water Balance
Document Summary
Lecture 9: importance of water for organisms: it"s the medium in which all biochemical reactions necessary for physiological functioning occur. Pressure/turgor potential: energy assoc with exertion of pressure. Matric potential: energy assoc with attractive forces on surfaces of large molecules inside cells or on surfaces of soil particles. Important in determining amt of water in soil. i. sand particles are bigger, vs clay particles are smaller, so has higher matric potential which can capture more water. 0 for pure water, and negative for water with solutes: water balance in plants: Pressure potential is important because of cell walls. Plants take up water from sources with water potential higher than their own. freshwater: hyperosmotic, more solutes in external environment than internal. i. marine: isosmotic, plants synthesize solutes similar to external environment. ii. terrestrial: acquire water from soil through roots and associations with fungi. Finer roots can take up water, while older roots with waxy coating can"t absorb water as well.
