are substances found in foods that are not in a form directly usable by the body, but that can be converted into an active form once they are absorbed; however vitamins found in foods that are already in the active form, called vitamins, do not undergo conversion.

I Think part of the answer is provitamins and the second answer is  preformed

Explanation:

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.

answer: that would be cheating

explanation: