Final answer:
Aggrecan is not a homopolysaccharide; it is a proteoglycan, whereas glycogen, amylopectin, cellulose, and amylose are all homopolysaccharides, composed of repeated glucose units.
Step-by-step explanation:
The term homopolysaccharide refers to a type of polysaccharide composed of a single type of monosaccharide unit. Among the options provided, aggrecan is NOT a homopolysaccharide. Glycogen, amylopectin, cellulose, and amylose are all homopolysaccharides because they are made up of repeated units of the same monosaccharide, glucose. Aggrecan, on the other hand, is a proteoglycan, a compound composed of a protein core and glycosaminoglycan chains; it does not fit the definition of a homopolysaccharide.
Other examples of homopolysaccharides include starch and its components amylose and amylopectin, as well as glycogen and cellulose. Amylose and cellulose are linear polymers of glucose, with amylose having α-1,4-glycosidic linkages and cellulose having β-1,4-glycosidic linkages. Amylopectin and glycogen are branched-chain polysaccharides also composed of glucose units with α-1,4-glycosidic bonds along the linear segments and α-1,6-glycosidic bonds at the branching points.