The building units of oligosaccharides and polysaccharides are

Correct option is A

The correct answer is (A) Monosaccharides

Explanation:
• Carbohydrates are classified based on the number of sugar units they contain. Monosaccharides (simple sugars like Glucose, Fructose, and Galactose) are the fundamental building blocks.
• Oligosaccharides: Consist of 2 to 10 monosaccharide units joined by glycosidic bonds (e.g., Sucrose, Lactose).
• Polysaccharides: Complex carbohydrates consisting of long chains (hundreds or thousands) of monosaccharide units (e.g., Starch, Cellulose, Glycogen).
• Just as amino acids are the building blocks of proteins, monosaccharides are the monomers that polymerize to form larger carbohydrate structures.

Information Booster:
• [Image showing the polymerization of monosaccharides into a polysaccharide chain]
• The bond between two monosaccharides is called a 'glycosidic linkage', formed through a dehydration reaction (loss of a water molecule).
• Polysaccharides serve either as energy storage (Starch in plants) or structural components (Cellulose in plant cell walls).

Additional Knowledge:
• Glyceraldehyde (Option B) and Dihydroxyacetone (Option C): These are specific examples of the simplest monosaccharides (Trioses).
• Trioses (Option D): Monosaccharides containing three carbon atoms; they are building blocks for larger sugars but (A) is the more general and correct term for the category.