BIOL 1002 Lecture : Bio Notes 2
Document Summary
K+ is actively transported into and out of guard cells: postasium is actively transported, pumps up with water pops up making a small core, co2 in the leaf. When k+ is low the amount of h20 is low and guard cells close stomata. Low co2 stimulates the uptake of k+ by guards cells, opening stomata. Moves form sources (things that make sugar, like leaves) to sinks (thing that use up sugar, like fruits) In the phloem it can move up, down, left, or right. Just depends on the time of day, season, or disease in the plant. Sugars manufactured in leaves diffuse to phloem companion cells. Companion cells actively transport sugars into sieve-tube members (elements) Food (sugars) are then translocated from sources to sinks according to the pressure flow theory: Water follows by osmosis from source cells and xylem; this creates high pressure. Water may be taken up by the transpiration stream in the xylem.
