Define the following: 1. Osmosis 2. Transpiration 3. Transpiration stream 4. Diffusion

1. Osmosis: Osmosis is the process by which water molecules move from a weaker  solution into a stronger solution through a partially permeable membrane.  

2. Transpiration: Transpiration is the loss of water in vapour form from the leaves  into the air.  

3. Transpiration stream: The continuous flow of water from roots to the leaves (via  xylem vessels) where it evaporates into the air by transpiration is called  transpiration stream.  It can be summarised as:  Soil —> root hair —> xylem vessels —> leaves —> air.  

4. Diffusion: Diffusion is the movement of particles from a high concentration to a  low concentration until they are spread out evenly.