Answer:
This is the movement of molecules and ions from one medium to another,based on the concentration gradients, diffusion distant and area exposed. The plasma membrane is made up of phospholipid-bi-layer, to regulate what passes through.
However,because most of the molecules that diffuses across the membrane are small,non-polar, the bi -layer can not restrain their movements. O2, CO2 and lipids cross this barrier with ease by simple diffusion. However, polar molecules are restricted from passing through..
Explanation:
