Biology 2601A/B Lecture 15: Lecture 15 – Water
3 Dec 2016
School
Department
Course
Professor
Document Summary
Lecture 15 water & fluid transport in plants: xylem & phloem 1. Animals use positive pressure generated by contractions in muscles of heart tissue to push fluids through veins and arteries. Plants use negative pressure to achieve same thing: pulls fluids through one type of vascular tissue called the xylem. Plants have bidirectional movements of fluids transpiration streme, movement of water in solutes, translocated proteins and other substances using phloem: dependent on osmotic pressure => positive pressure. Movements of fluids from higher to lower pressure down the pressure gradient: movement through arteries or phloem. Diffusion and bulk flow are not the same thing: diffusion relies on movement of solutes in cells, bulk flow movement of medium (water) that carries solutes. Movement of solutes from high concentration to low concentration individual solutes separated by a semi permeable membrane: movement through concentration gradient. Osmotic potential is in relation to that, total solutes in system.
