Diffusion and Osmosis. Passive Transport Passive transport- movement of molecules across a cell...
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Transcript of Diffusion and Osmosis. Passive Transport Passive transport- movement of molecules across a cell...
Diffusion and Osmosis
Passive TransportPassive transport- movement of molecules
across a cell membrane without energy inputRefresh:
SoluteObject being dissolved
SolventObject doing the dissolving
DiffusionDiffusion: movement of molecules from areas of
high concentration to areas of low concentrationConcentration: number of molecules of a
substance in a given volumeConcentration gradient: difference of
concentration of a substance from one location to another
OsmosisOsmosis: Diffusion of water
Water moves across a semipermeable membrane from an area of high water concentration to an area of low water concentration
Types of SolutionsIsotonic: cell has same concentration of
dissolved particles as cellWater moves into and out of cell at equal rates
and cell size remains constant
Types of Solutions Cont.Hypertonic: Solution has a higher concentration
of dissolved particles than a cellWater concentration is higher in cell than outside
Water flows out of cell, cell shrivels
Types of Solutions Cont.Hypotonic: solution has lower concentration of
dissolved particles than a cellWater concentration is higher outside cell than
inside cellWater flows into the cell, cell swells
Cell may burst, this is called lysed
Plant CellsPlant cells prefer a hypotonic solution
Cell wall provides more support and are less likely to lyse
Plant cells at isotonic solutions are flaccidPlant cells at hypertonic solutions under-go plasmolysis
The cytoplasm and plasma membrane begin to pull away from the cell wall
Plant cell swells to point where it exerts a backward pressure, called turgor pressure This pressure prevents further uptake of water