Chapter 13 Osmosis Flashcards
3 types of permeability
Permeable- everything in and out
Semi-permeable- lets some things in and out
Impermeable- lets nothing in or out.
Diffusion Def.
Movement of molecules from a region of higher concentration to a region of lower concentration across a concentrated gradient.
-passive
examples of diffusion
animal: CO2 out of body cells
O2 into body cells.
vice versa in plants.
Osmosis def.
movement of water molecules from high water concentration to low water concentration across a semi permeable membrane.
-Passive
Active transport def
Movement of molecules from low concentration to high concentration with the use of energy against a concentrated gradient.
Solute is..
the substance dissolved in the solvent.
Solvent is..
the substance that dissolves the solute.
concentrated solution
High solute
Low solvent
Osmosis:
Animal cells in same concentration
Water moves in and out at same rate.
Cell remains intact.
Osmosis:
Animal cells in less concentrated
Water moves into cell.
Bursts and dies.
Osmosis:
Animal cells in more concentrated
Water leaves cell.
Shrivel and dies.
Plant cells in less concentrated solution.
Water enters cytoplasm and vacuole.
Vacuole gets bigger and Cytoplasm swells.
Cell mem. pushed out.
Described as turgid. Causes turgor pressure.
Importance of Turgor Pressure
Gives plants strength.
Would wilt otherwise.
eg. Lettuce, house plants.
Plants in more concentrated solution.
Water leaves cell.
Cell wall same. Cell mem. shrivels away from cell wall.
Described as plasmolysed cells. Process called plasmolysis.
How does osmosis preserve food?
Coated in salty/ sugary solution. Higher concentration than fungi/bacteria so causes the cells to lose water and shrivel and die.
Eg. Salty: Meat and fish
Sugary: Jams, tinned fruit.
