Monosaccharides are classified into aldoses (containing an aldehyde group) and ketoses (containing a keto group). Aldoses have an aldehyde group, while ketoses have a keto group.

Glucose is found freely in nature and in combined forms. It is present in sweet fruits, honey, and ripe grapes, where it occurs in large amounts.

Monosaccharides are classified into aldoses (containing an aldehyde group) and ketoses (containing a keto group). The nomenclature reflects the presence of these functional groups, with aldoses having an aldehyde and ketoses having a keto group.

Reducing sugars are those that can reduce Fehling’s solution and Tollens’ reagent. All monosaccharides, whether aldose or ketose, are considered reducing sugars.

Polysaccharides, such as starch, cellulose, and glycogen, yield numerous monosaccharide units upon hydrolysis. They are non-sweet in taste and often referred to as non-sugars, playing essential roles in structural and storage functions.

Oligosaccharides are carbohydrates yielding two to ten monosaccharide units upon hydrolysis. Disaccharides, a common type, produce two monosaccharide units, which may be the same or different. For instance, sucrose hydrolysis yields glucose and fructose, while maltose provides two glucose molecules.

A monosaccharide is a carbohydrate that cannot be further hydrolyzed and represents a polyhydroxy aldehyde or ketone unit. Examples include glucose, fructose, and ribose.

Chemically, carbohydrates are defined as optically active polyhydroxy aldehydes or ketones, or compounds that produce such units on hydrolysis. Sugars like sucrose and lactose, common carbohydrates, are also referred to as saccharides, deriving from the Greek word “sakcharon,” meaning sugar.

Acetic acid fits the general formula C₂(H₂O)₂ but is not a carbohydrate because carbohydrates are defined as optically active polyhydroxy aldehydes or ketones, and acetic acid lacks these specific functional groups.

The general formula for carbohydrates is Cₓ(H₂O)ᵧ. The term “carbohydrate” originates from the idea that these compounds are hydrates of carbon, as seen in the molecular formula of glucose (C₆H₁₂O₆).