BIOL 225 Lecture Notes - Lecture 9: Sieve Tube Element, Water Potential, Cell Membrane
11 Mar 2018
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Document Summary
No transport system for water and nutrients. Plants get sugar from photosynthesis & absorb water form the soil. Plants move water from down up water potential is higher at the roots (water moves from high to low potential) Water and minerals are absorbed in the roots thanks to root hairs increase surface available for water and mineral absorption. Water can pass across cells walls and membranes transmembrane route. Water is transported to the endodermis where they must cross the plasma membrane. When stomata open: water evaporates and negative potential/ negative tension cause water to be transported upwards. Water can thus move in several directions and the direction of sugars is variable. Sieve tube element transport sugar but companion cells transfer wtv the sieve tube needs to survive. Photosynthesis usually happens in mature leaves source of sugar. Sugar sink: developing leaves, flowers or other that need energy sink. Sugar must move from lower concentration to higher concentration environments.
