Answer:
This process would be the one truly responsible for the "evolution" of mitochondria and chloroplasts as we know them from their prokaryotic ancestors. The cell process that would have initiated endosymbiosis is endocytosis; the process of taking things inside the cell
The major differences are that fats are solid at room temperature while oils are liquid, and that oils are usually of plant origin while fats are of animal origin.
Fish are a class of aquatic vertebrates. The combination of gills, fins and the fact that they live only in the water make fish different from all other animals.
