Describe different types of membranes.
There are three types of membranes :

1. Permeable membranes. These membranes allow diffusion of both solvent and solute molecules or ions through them e.g. cell wall. 

2. Impermeable membranes. These membranes prevent any substance to pass through it. 

3. Semipermeable membranes. These types of membranes allow diffusion of  certain substances through it while prevent the others to pass through it. e.g. cell membrane.