Bio1B-final-review - Bio 1B Section 120 May 11, 2005 Topics...

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Bio 1B Section 120 May 11, 2005 Topics to study for the Plants section of the final exam Water relations How does water flow up plant? Chain of water molecules. Driven by transpiration. Water potential : tendency of water to move from one area to another. Denoted by Ψ (psi). Water moves from an area of higher (less negative) to lower (more negative) Ψ . Ψ P : Pressure/tension, caused by mechanical forces: Can be 0, <0, or >0. Ψ Π : Osmotic potential, caused by solutes. Always ≤ 0. Ψ = Ψ P + Ψ Π (can be 0, <0, or >0) System Ψ P Ψ Π Ψ Open container of pure water 0 + 0 = 0 Open container of salty water 0 + -1 = -1 Pressurized container of pure water +1 + 0 = +1 Xylem (water sucked upward) -5 + -5 = -10 Turgid plant cells +2 + -5 = -3 Cells at incipient plasmolysis 0 + -5 = -5 We can measure the total water potential of a plant with a Scholander bomb (pressure bomb). Plants control transpiration (water loss) by opening and closing their stomata. Incipient plasmolysis is when the cell is just about to “collapse” from dehydration, i.e. the
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This note was uploaded on 04/02/2008 for the course BIO 1B taught by Professor Carlson,mischel,power during the Spring '07 term at University of California, Berkeley.

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Bio1B-final-review - Bio 1B Section 120 May 11, 2005 Topics...

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