Cell Biology

Diffusion

• Diffusion is the spreading out of particles from an area of high concentration to an area of low concentration. 
• Takes place in both solutions and gases because the particles are free to move about randomly. 
• The bigger the concentraion gradient (the difference in concentraion), the faster the diffusion rate.
• Higher temperature = faster diffusion rate (particles have more energy so they move around faster)

Osmosis

• Osmosis is the movement of water molcules across a partially permeable membrane from a region of high water concentration to a region of low water concentration.
• Partially permeable membrane has small holes that only water molecules can pass through and bigger molecules - e.g. sucrose - can't.
• Water molecules pass both ways through the membrane. This happens because the molecules move around randomly all the time.
• Osmosis is a type of diffusion.

Active Transport

• Active Transport is the movement of molecules across a cell membrane from a region of low concentration to a region of high concentraion, which goes aainst the concentration gradient.
• Root hair takes in minerals using active transport.
• Active Transport stops us from starving.