What are polysaccharides composed of?

Polysaccharides are complex carbohydrates that consist of long chains of sugar units, specifically monosaccharides, linked together through glycosidic bonds. The term "poly" indicates that these carbohydrates are made up of many (or multiple) sugar units, forming large and complex structures. This makes polysaccharides different from monosaccharides, which are single sugar units, and disaccharides, which consist of just two sugar molecules.

The composition of polysaccharides allows them to serve various functions in biological systems, such as energy storage (like glycogen in animals and starch in plants) and structural support (such as cellulose in plant cell walls). Understanding their structure is crucial for recognizing how they function in different living organisms.

The other options do not accurately describe polysaccharides: single sugar units refer to monosaccharides, while two sugar molecules describe disaccharides. Atoms of carbon and nitrogen do not define polysaccharides specifically, as polysaccharides are primarily composed of carbon, hydrogen, and oxygen atoms linked through sugar units. In summary, polysaccharides are characterized by their polymer chains made from many monosaccharide units, which is why the correct answer is that they are polymer chains of saccharides.