Acquisition of water and minerals

• In the absence of other forces, the movement of molecules of a substance from a place where it is more concentrated to place where it is less concentrated, due to random motion of molecules is called diffusion.
• The motion of a molecule is random, but movement of a population of molecules by diffusion is directional. 
• Therefore, diffusion takes place according to a concentration gradient, spontaneously and not using metabolic energy (ATP). Diffusion takes place across the membrane also, if the membrane is permeable to those molecules. 
• Osmosis is a special type of diffusion. The diffusion of free water molecules across a selectively permeable membrane is called osmosis.
• The physical adsorption of water molecules by hydrophilic materials is called imbibition. 
• Movement of water and hydrophilic solutes across the membranes passively with the help of transport protein that span the membrane is called facilitated diffusion