Final answer:
The plates of an exoskeleton are called sclerites, and the exoskeleton, primarily constructed of chitin, is segmented into three parts for the head, thorax, and abdomen. It provides support, protection, and sites for muscle attachment in insects and related arthropods.
Step-by-step explanation:
The plates of an exoskeleton in insects and other arthropods are called sclerites. The exoskeleton is an external hard covering that provides support, protection, and sites for muscle attachment. It is primarily made up of chitin, a polysaccharide that gives the exoskeleton its strength and flexibility. The cuticle, which is the outer layer of the exoskeleton, has two sublayers: the thin, waxy, and water-resistant exocuticle and the much thicker endocuticle. The exocuticle is notably thin in soft-bodied insects, like caterpillars. Arthropods have segmented bodies, organized into three distinct parts: the head, the thorax, and the abdomen, each protected by the exoskeleton's sclerites that allow for movement and flexibility, similar to a suit of armor.