Consider trafficking for example. The oligos on the protein play a part in govern the direction a protein will go during trafficking. Polysaccharides can exist as free molecules. This is a storage form of energy in plants. Some plants can branch the polymer by adding glc1-6.
Branched starch is called amylopectin.
Animals also store energy as polymerized, highly branched glc called glycogen. Intestinal microbes in termites and ruminants can digest so it can be used symbiotically in these animals. Also, adjacent chains can form intermolecular H bonds. This results in cellulose fibers having high tensile strength. See fig 9-17 p. 307.