Most gastrointestinal tract diseases are ultimately self-limiting and nonfatal, so long as fluids are replaced. How do these two general observations help explain why such diseases so commonly affect humans all over the world? Why do these disease characteristics help explain why so many different pathogens cause this disease?

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.

characterization of nanoparticles is a critical step in nanomaterial production as it provides information of dimension, morphology, surface charge, distribution and degree of surface functionalization.

it cools slower in the earth meaning the crystals have more time to form than lava on the surface