What does each part of the brunch of grapes model representation in relation to breathing system?

The main stem of this branch of grapes is the trachea. They then branch into smaller ducts called bronchi.

These bronchi/stems branch into even smaller branches/stems called bronchioles.

The bundle of grapes are the alveolar sacs that stem from alveolar ducts/bronchioles.

Each grape represents an alveolus. This is where the gas exchange occurs.

This is the path that air travels when you inhale.

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.