The mouth, pharynx, esophagus, stomach, both intestines, and the anus make up the GI tract. Accessory organs are the salivary glands, liver, pancreas, and gallbladder. I hope this helps.
Fungi is a decomposer, therefore feeding off of dead matter
The process by which unspecialized cells become specialized into one of many different types of cells, such as neurons or epithelial cells.
All of the above, you need all of those to survive. Especially a community with a big population