Exam 3 Notes

7bd osmosisthediffusionofwateracrossa

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Unformatted text preview: occurs on three scales o Transport of water and solutes by individual cells o Short­distance transport of substances from cell to cell at the level of tissues and organs o Long­distnace transport (bulk­flow) within xylem and phloem Selective permeability of Membranes o Plasma membrane controls movement of solutes into and out of the cell Passive transport: movement across membrane down concentration gradient; requires energy Active transpoert: pumping solutes across membrane against concentration graditent; requires energy Transport proteins integral membrane proteins that carry out transport Proton Pumps o Creat a H+ gradient that is a form of potential energy o Helps produce a voltage known as a membrane potential o Figure 36.7a 22 Solute Transport in Pant Cells o Transport of many solutes drive by proton gradients o Cotransport: transport proteins couple passage of one solute with passage of another Uptake of NO3 Uptake of sucrose Figure 36.7b­d Osmosis: the diffusion of water across a selectively permeable membrane o Affected by solute concentration and pressure Factors Affecting Water Potential o Water potential (ψ) affected by Solute potential (ψs): proportional to concentration of dissolved molecules Pressure potential: (ψp): physical pressure on a solution Ψ = ψs + ψ,p Analysis of Water Potential o Figure 36.8 23 Water Potential in Plant Cells o Figure 36.9 24 Transpiration drives the transport of water and minerals from roots to shoots via the xyle...
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This note was uploaded on 02/03/2014 for the course BIOL 1202 taught by Professor Gregg during the Spring '08 term at LSU.

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