Generally the term is "anatomy," the same as for humans.
Centrioles
centriols
that the animal once had a use for that structure depending on where it lived. or that it decended from an animal that had that structure and used it.
An insect is a type of animal. Any structure on an insect is, by definition, a structure on an animal.
The nucleus
An animal cell's structure is flexiable while a plants cell's structure is rigid
It is the part that controls both animal and plant cells
Gland
Cell membranes are found surrounding both plant and animal cells
If by structure you mean organelles, then ribosomes.
Gland
no