carbohydrates are classified into monosaccharides, oligosaccharides and polysaccharides. monosaccharides can either be aldose or ketose depending on the functional group present. example of aldose includes glucose while example of ketose includes fructose. oligosaccharides are made up of two to ten monosaccharide units while polysaccharides are made up of more than ten monosaccharides units linked to form long chain which can be branched or unbranched.