BIOL 1106 Lecture Notes - Lecture 3: Ultimate Tensile Strength, Cavitation, Phloem

• School: Virginia Tech
• Department: Biological Sciences
• Course: BIOL 1106
• Professor: Jack Evans

Document Summary

Water can move from the roots to the top of the tree using xylem: water moves unidirectly upward, carbs move bidirectly in plants. Water and dissolved minerals travel great distances in xylem: most of the source is pulling created by transpiration, cohesive and adhesive forces. Some pushing comes from pressure of water entering roots. Transport between cells: this can be done actively or passively. Once thought water moved across plasma membranes only by osmosis through lipid bilayer: osmosis is enhanced by membrane water channels called aquaporins. Water potential has 2 components: pressure potential= physical forces such as plant cell wall or gravity (ex. Solute potential= concentration of solute in each solution. Pure water has a solute potential of zero. Total water pressure = sum of these two pressures: water is what gives a plant pressure to stay turgid. Water and minerals must move across cell layers until they reach the vascular tissues.