Transport across cell membrane Flashcards
What is the definition of selectively permeable ?
only certain molecules selected depending on size are able to pass though the membrane
What is diffusion?
The movement of molecules down a concentration gradient from a higher to a lower concentration
What are examples of passive transport?
Diffusion, osmosis as they don’t require energy
Why is diffusion important
As oxygen, amino acids and glucose can enter, carbon dioxide and other waste products can leave the cell
What is active transport?
Movement of molecules/ ions against a concentration gradient from lower to higher concentration, requires energy
What is osmosis?
Movement of water molecules from a high water concentration to a lower water concentration through a selectively permeable membrane.
Plant cells and osmosis- high sugar/ salt concentration?
Water concentration outside the cell is lower than the concentration inside the cell, water moves out of the cell, the vacuole gets smaller, the cell membrane pulls away from the cell wall, plasmolysed
Animal cells and osmosis- low sugar/salt concentration
Water concentration of the solution outside the cell is the same as the water concentration inside the cell, water moves in and out by osmosis, the cells remain their usual size and shape.
Animal cells and osmosis- high sugar/salt solution
Water concentration of the solution outside the cell is lower than the water concentration inside the cell, water moves out of cell by osmosis, cells shrink and shrivel.
Plant cells and osmosis- 100% water?
Water concentration outside the cell is higher than the water concentration inside the cell, water moves into cell by osmosis, vacuole gets larger, the cell wall is pushed outwards slightly, turgid.
Plant cells and osmosis- water concentration same as cell sap
Water concentration outside the cell is the same as the water concentration inside the cell, water moves in and out of cell, is not turgid or plasmolysed.
Animal cells and osmosis- 100% water?
Water concentration outside the cell is higher than the water concentration inside the cell, water moves into the cell by osmosis, the cells swell and burst.
