Osmosis , diffusion , and active transport

• Osmosis is the movement of water particles from an area of high water concentration to an area of low water concentration across a partially permeable membrane
• A partially permeable membrane has tiny holes in it, allowing small molecules to pass through it, but not karge molecules
• 1. Water moves from a high water concentration, outside the cell, to a low water concentration, inside the cell, by osmosis, across a partially permeable membrane, causing the cell to expand
• 2. Water moves from a high water concentration inside the cell, to a low water concentration outside the cell, by osmosis, across a partially permeable membrane, causing the cell to shrink
• Diffusion is the net movement of particles from an area of high concentration to an area of low concentration.
• Diffusion is a passive process, which means it doesn't require energy
• Diffusion takes place in liquids and gases - because particles move randomly
• The concentration gradient : the bigger the difference in concentration, the faster the rate of diffusion
• The surface area to volume ratio : a larger surface area in proportion to the volume will increase rate of diffusion
• The distance : the shorter the distance, the faster the rate of diffusion
• The temperature : the higher the temperature, the faster the rate of diffusion
• Active transport is the movement of particles from a low concentration to a higher concentration
• Active transport moves UP or against the concentration gradient
• Active transport requires energy from respiration, in the form of ATP
• Mineral ions are taken up from the soil by active transport, from a low concentration to a high concentration using energy
• Carrier proteins in the cell membrane are needed to get molecules e.g. mineral ions into the cells. This process requires energy