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Unformatted text preview: BILD 2 Winter 06 TA: Boris Arbit Prof. Darwin K. Berg Week 7 PLANTS (2 nd lecture) Water uptake in roots roots absorb water and minerals from the soil provide a large surface area have symbiotic relationship with fungi to reach a greater volume of soil mineral uptake followed by osmosis two routes (the goal is to deliver H20 and minerals to the vascular cylinder where they can be transported to the rest of the plant) : Apoplastic H 2 O and minerals soak into the cortex along the continuum of cell walls and extracellular spaces. As Dr. Roberto can tell you, this route will not lead to the xylem directly due to the Casparian strip . Materials must cross the plasma membrane and enter the symplast beforehand. Symplastic minerals and H 2 O that cross the plasma membrane of root hairs enter the continuum of cytosol connected by plasmodesmata. 3 mechanisms that work to get H 2 O from roots to shoots 1. Root pressure- high concentration of mineral ions in the vascular cylinder water flows in (but cannot flow out due to the endodermis), generating root pressure. Little contribution for most plants and especially trees as water is pushed only a few meter....
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