<u>The cell lacks a nucleus.</u> We know this because prokaryotes are single celled organisms that lack a membrane bound nucleus or membrane bound organelles. So, looking under the microscope, you'd notice that the cell has no distinct nucleus, which immediately helps us find the answer we're looking for.
Flatworms has the least complex body plan
Hydro means water. which means the adding of water; it is digestion. it is the opposite process of dehydration synthesis which is removing water. synthesis hear means small to large so opposite processes. :)