OUTLINE-chap43-1

OUTLINE-chap43-1 - 1 How does the plant control the...

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How does the plant control the swelling of guard cells? By osmosis. -Plants can move potassium into (active transport) and out of (diffusion) guard cells. -When the potassium (K + ) concentration is high, water moves in, and the stoma opens. -When potassium leaves the guard cells, the stomata close. Three important triggers to open or close stoma: 1) Light reception (opens) - Plants need CO 2 during photosynthesis. When light strikes certain pigments in guard cells they trigger a pumping of potassium into guard cells (opening stomata). At night, potassium diffuse back out, closing the stomata. 2) Low carbon dioxide concentration (opens) - Plants use CO 2 (in photosynthesis) and produce CO 2 (in cellular respiration). During the daytime the use of CO 2 is much faster than its production. This leads to low CO 2 and triggers potassium pumping into the guard cells, opening the stoma. 3) Water loss (closes) - If water vapor leaves the stomata faster than it can be replaced from xylem, the leaf will wilt. This causes the mesophyll cells to release a hormone (
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This note was uploaded on 03/17/2011 for the course PHYSICS 2001 taught by Professor Young during the Spring '08 term at LSU.

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OUTLINE-chap43-1 - 1 How does the plant control the...

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