Which of the following is NOT a component of the insect exoskeleton?

The insect exoskeleton is primarily composed of several key components, one of which is chitin. Chitin is a long-chain polymer that provides structural support and strength to the exoskeleton. Another critical component is sclerotin, which is a tough protein that contributes to the hardening and rigidity of certain parts of the exoskeleton, allowing insects to protect themselves from physical damage and desiccation. Additionally, the epidermis is the living layer of cells that secretes the materials that form the exoskeleton.

Collagen, on the other hand, is a fibrous protein commonly found in the connective tissues of vertebrates, like skin and cartilage, rather than in the exoskeleton of insects. While it plays an essential role in the structure and strength of many organisms, collagen does not form part of the insect exoskeleton. Thus, identifying collagen as not being a component of the insect exoskeleton aligns with understanding the unique biological materials and structural elements that define insect anatomy.