In arthropods, the primary material of the exoskeleton is:

In arthropods, the primary material of the exoskeleton is:

• A. Chitin
• B. Collagen
• C. Silk
• D. Keratin

Answer: (A)

Arthropod exoskeletons are built mainly from chitin, a tough, nitrogen-containing polysaccharide. This chitin forms a layered, lightweight protective layer, which is often strengthened by proteins and sometimes reinforced with minerals in certain groups. The hardening process, called sclerotization, makes the shell rigid enough to protect organs and provide muscle attachment sites while still allowing growth through periodic molting. Silk is used by some arthropods for webs or cocoons, not as the external skeleton. Collagen and keratin are key structural materials in other organisms—collagen in many connective tissues and keratin in skin and derivatives—but they do not compose the primary exoskeleton of arthropods.

Arthropod exoskeletons are built mainly from chitin, a tough, nitrogen-containing polysaccharide. This chitin forms a layered, lightweight protective layer, which is often strengthened by proteins and sometimes reinforced with minerals in certain groups. The hardening process, called sclerotization, makes the shell rigid enough to protect organs and provide muscle attachment sites while still allowing growth through periodic molting. Silk is used by some arthropods for webs or cocoons, not as the external skeleton. Collagen and keratin are key structural materials in other organisms—collagen in many connective tissues and keratin in skin and derivatives—but they do not compose the primary exoskeleton of arthropods.