Question

Which is the second most abundant biomolecule found in biosphere?

• A. Cellulose
• B. Chitin
• C. Glycogen
• D. Starch

Hint:

Chitin differs structurally from cellulose only by the replacement of the hydroxyl group at the C-2 carbon with an acetylated amino group (\(\text{-NH-CO-CH}_3\)).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The biosphere contains vast quantities of organic carbon locked in biopolymers.
These polymers provide structural support, energy storage, and protective barriers for various organisms.

Step 2: Detailed Explanation:
Let us review the abundance of these natural biopolymers:
Cellulose: A linear homopolysaccharide of \(\beta\)-(1\(\rightarrow\)4)-linked D-glucose units. It is synthesized by plants, algae, and some bacteria, forming the primary component of cell walls. It is the most abundant biomolecule on Earth.
Chitin: A linear homopolysaccharide composed of N-acetylglucosamine residues linked by \(\beta\)-(1\(\rightarrow\)4) glycosidic bonds. It is the structural component of the cell walls of fungi and the exoskeletons of arthropods (such as insects, crabs, and shrimp). Because of the biomass of these organisms, chitin is the second most abundant biomolecule in the biosphere.
Starch and Glycogen serve as energy storage molecules in plants and animals respectively, but are synthesized in much smaller net quantities compared to structural polymers like cellulose and chitin.

Step 3: Final Answer:
Chitin is the second most abundant biomolecule found in the biosphere.