Chitin is chemically

Chittin is chemically a polymer of or The chitinous exoskeleton of arthropods is formed by the polymerisation of

Chitin is a

Chitin is a

Keratin and chitin are chemically

Keratin and chitin are chemically

Keratin and chitin are chemically

Keratin and chitin are chemically

Chitin is a/an

Chitin is a/an