Biology 2601A/B Lecture Notes - Lecture 15: Root Cap, Amyloplast, Water Potential
10 Jan 2015
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Get roots down to promote growth, anchor down the plant into the ground. Attract bacteria to bring nutrients on the surface of the root. Not very permeable to water; only for growth. Plants have brains in the root cap, deciding which direction to grow. Growth is towards: gravity amyloplasts sediment in columella cells. Amyloplasts fall towards gravity to tell which direction to go; if you flip the plant, then amyloplasts move: water unknown mechanism wp: water potential; white=dry. Extend b/w soil grains into films of water. Create more surface area to increase access to water. Diversity: some plants have big above-ground part but sm amt of root, other plants have vice versa. Casparian band (or strip): ensures that the plant can control what goes in or out. Hypothesis: creating positive pressure, short plants can prevent cavitation. In saline soils, plants have to make their solute concentration a lot lower to bring the water in.
