Biology 1201A Lecture Notes - Lecture 12: Abscission, Thigmotropism, Palisade Cell
2 Oct 2016
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Enter root through root hairs by osmosis. Water move through cell walls and intercellular spaces from one to another without ever enter cells. This pathway is called apoplast (nonliving portion of cells). b. Water move through cytoplasm of one cells to another (symblast-living portion) through plasmodesmata (small tubes that connect cytoplasm of adjacent cells). Once h2o reaches endodermis, it can only enter by symblast (due to casparian strips) into (stele-outer most layer is the endodermis) vascular cylinder and is selective permeable (k+ pass, Once through endodermis, apoplast pathway takes over to reach xylem: osmosis: moves from soil through root and into xylem by gradient (continuous movement of water out of root by xylem, and high [mineral] inside stele). When stomata are closed => co2 not available => cannot photosynthesize. When stomata are open => co2 can enter leaf => photosynthesize but plant risks desiccation from transpiration.
