Question

differentiate between tergum and sternum

Answer 1

The body of an arthropods like cockroach is covered by exoskeleton called sclerites. The exoskeleton (sclerites) on the dorsal surface is known as Tergum plural Terga and the exoskeleton rings present on the ventral side is called Sternum plural sterna.

Answer 2

in cockroaches the vental portion of the body is called as sternum
and the dorsal portion of the body is called as tergum (or) notum
and the lateral portions are called as pleura