How are most animals classified in reference to symmetry? retricemetry bilateral symmetry monolateral symmetry radial symmetry

Most animals are classified in reference to Bilateral Symmetry. This is a basic body plan in which the left and right sides of the organism can be split down the middle and mirror image one another. 

Eukaryotic cells are theorized to have evolved from prokaryotes called the endosymbiotic theory. this explains that the most primitive eukaryotic cell engulfed a prokaryotic cell (by the process of phagocytosis) that is capable of cellular respiration and another prokaryotic cell that is capable of photosynthesis. these prokaryotic cells eventually became organelles and these organelles are the mitochondria and the chloroplast