diffusion and osmois

• diffusion is the movement of substances from an area of high concentration to an area of low concentration
• Diffusion is a passive process - means that it does not need energy to occur
• examples of diffusion - co2 duffusing out of cell
• The movement of salts, glucose, amino acids into and out of cells is strictly controlled because an imbalance of these molecules in the body can kill cells.
• Osmosis is the movement of water molecules from an are of high water concentration to an area of low water concentration across a selectively-permeable membrane
• osmosis is a passive process
• lots of solvent + little solute = dilute
• little solvent + lots solute = concentrated
• solute + solvent = solution
• turgor pressure is the pressure of the vacuole and cytoplasm the cell wall
• if animal cells are placed in a very concentrated solutions, water will pass out of the cells - the cells will lose shape and become shrivelled - dehyradtion
• if animal cells are placed in very dilute solutions, water will enter the cells due to osmosis - the cells will expand and may burst as they do not have a cell wall to restrain them - drinking too much water too quickly
• Plant cells with contents that are more concentrated than their surroundings will swell, and the cell membrane will be forced against the cell wall. The cell is now much firmer dur to this turgor pressure
• plants cells with contents that are less concentrated than their surroundings will lose turgor pressure and become much weaker - cells said to be plasmolyed
• if plant cells lose turgur - the plant will wilt
• plasmolysis occurs in plants on hot days or when the soil dries out resulting in the plant drooping/wilting