Answer:
The answer is Diffusion .
Explanation:
Diffusion is a net movement of molecules from a region of high concentration to a region of low concentration down a concentration gradient.
The systems are:
Nervous system: this is because the brain sends out commands to the body or it signals other parts which makes your body move like walk or to pick something up.
Muscular system: the muscular system such as your bones and muscles is what keeps the bones together so you could move/walk.
Hope this helped :)
Have a great day
Animals cells are found inside the animals body. We have no exact place where it is found ;)