What type of chemical reaction synthesizes long-chain molecules, like polysaccharides, through the formation of new bonds?

The answer would be Dehydration Synthesis

Dehydration Synthesis is the process where water is removed from the bonds of these polysaccharides, so they can be combined to make a coherent whole of new bonds.

Hydrolysis is the opposite of Dehydration Synthesis. This process adds water to the process, which in turn hydrolyzes the polysaccharide breaking it down to its monomers or dimers (disaccharide or monosaccharide).

A covalent bond formed between two monosaccharides by a dehydration reaction. A polymer of many monosaccharides, formed by dehydration reactions. A storage polysaccharide in plants, consisting entirely of glucose monomers joined by α glycosidic linkages.