What does polysaccharide mean?
It means that polysaccharides are composed of many simple sugar molecules, called monosaccharides, which are chemically bonded.
The word polymer means many parts, and the word monomer means a single part. Monosaccharides, such as glucose, are the monomers of the polysaccharides.
Three examples of polysaccharides that are composed of glucose molecules are cellulose, starch, and glycogen (animal starch).
In the image below, notice that the way the glucose molecules in cellulose are bonded differently than the bonds between the glucose molecules in starch and glycogen. Because of this difference, humans are unable to digest cellulose because we lack an enzyme that can break the bonds between the glucose molecules. Also notice that glycogen contains branched chains of glucose, which is the difference between plant starch and glycogen.