What are chemical process in which larger compounds are broken down into their monomers using water to break the bonds?
This is known as hydrolysis, which literally means "to take apart with water".
It is often not the water that causes the molecules to break apart. This is usually carried out by some other factor such as a catalyst (enzymes for example) or a strong mineral acid.
However, once the molecules has been broken up, the unbonded "ends" of the fragments are completed by adding a H atom to one and OH to the other.
This is especially common in organic chemistry. An example would be an ester being broken into an alcohol and organic acid:
This process is used for example to break proteins into amino acids, to synthesize vitamin A from beta-carotene, in the digestion of sugars and breaking down of fats during digestion, so lots of biochemical applications.
Have a look at this site for a quite detailed example: