Question

Chemical nature of chitin is
a. Carbohydrates
b. Protein
c. Fat
d. Nucleic acid

Answer 1

It is the major constituent of the exoskeleton in arthropods, and is also found in the cell wall of fungi. It is also found in the radula of mollusks, cephalopod breaks, and scales of fishes. It is a tough, semi-transparent natural polymer.

Complete answer:
Chitin is a long polymer of N-acetylglucosamine which is a glucose derivative. The units of N-acetyl-D-glucosamine (2-(acetylamino-2- deoxy-D-glucose)) are synthesized to form chitin. It is a modified polysaccharide that contains nitrogen and beta- $1 \to 4$ linkages with covalent bonding. Therefore, it can be said that chitin is a nitrogen-containing polysaccharide. It is the second most abundant polysaccharide to cellulose and it is biodegradable. This distinctive feature makes it an important industrial candidate for a variety of applications in the market.

Since it is a polysaccharide therefore it belongs to the family of carbohydrates.
Hence, the correct answer is option (A).

Additional information:
Chitin is an important source of carbon and nitrogen for marine organisms. It is one of the most abundantly renewable polymers in nature.
Chitin can only be degraded by the chitinolytic bacteria. This is the key step of recycling nutrients back to the oceans. Instead of a hydroxyl group, there is an amyl group attached to the glucose molecule.

Note: Chitin is one of the most important biopolymers in nature. It supports the cuticles of the epidermis and the trachea as well as the peritrophic matrices lining the gut epithelium. Chitin is harder and more stable than cellulose. This is because the hydroxyl group in chitin is replaced with the acetyl amine group, which forms a stronger hydrogen bond between the bordering polymers. The enzyme chitinase attacks the beta $1 \to 4$ glycosidic bond in chitin.