Why is the cell theory an important tool for classifying unknown objects?

If a set of instructions that determines all of the charactersitics of an organism is comparedto a book, and a chromosme is compared to chaper in the book, then what might be compared to a paragraph in the book?

The nervous system interacts with the endocrine system by a. using hormones as connections b. sending nerve impulses directly to glands c. using neuroendocrine cells as connections d. sending neurotransmitters directly to neurons

What type of appendages do sponges cnidarians roundworms annelids mollusks arthropods echinoderms and vertebrate have? jointed, not jointed, absent