The CNS involves the brain and spinal cord and the PNS involves the body nerves.
Large organisms include...
Mammals (Mammalia)
Stem-mammals (Synapsida)
Reptiles (Reptilia)
Dinosaurs (Dinosauria)
Studying cells helps us to construct better medicines and vaccines, which is beneficial to understanding life.
Mutualism. e.g. oxpecker and zebra
commensalism. e.g. remora fish and sharks
parasitism. e.g. tapeworms and cow
