Osmosis is the spontaneous net movement of solvent molecules through a semi-permeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides.It may also be used to describe a physical process in which any solvent moves across a semipermeable membrane (permeable to the solvent, but not the solute) separating two solutions of different concentrations.Osmosis can be made to do work.
Osmotic pressure is defined as the external pressure required to be applied so that there is no net movement of solvent across the membrane.
Pepsin is an enzyme that breaks down proteins to polypeptides so if you add pepsin to aprotein it will break it down into smaller molecules of polypeptides
I think that carbon dioxide/pollution could be a massive change in the environment. You can find more information here
http://www.theworldcounts.com/stories/How-Pollution-Affects-the-Environment