enzymes

Di- sulphide bonds are formed by the oxidation of two cysteine molecules resulting in a covalent sulphur-sulphur bonds.These are the strongest bonds which the last to be broken.Ionic bonds are formed by the attraction of two oppositely charged particles, in proteins they are formed form between the R groups containing amine and carboxyl groups.They can be broken by pH changes.

In competetive inhibition as the concentration of the substrate increases, the rate of reaction will increase as there will be more substrate molecules competing for the active site.Non competetive inhibition alters the shape of the active site which thus reduces the rate of reaction and therefore increase in the substrate concentration has no effect on the rate of reaction. You can differentiate between the two graphs on plotting the rate of reaction against the substrate concentration.

Hope this helps.