Answer: cell membrane
such as water, micro-organism
physical process
simple diffusion, osmosis and filtration
such as potasssium permaganate in water,urea a liver waste diffuses from the body and the kidney help in filtering it out
physiological processs
active transport, phagocytosis and pinocytosis
such as soduim-potassium pump, exocytosis
Explanation: transportation in and out of cell is done in different ways listed above but a barrier to this movement is the cell membrane which is an outer covering of the cell. it protect the cell and only some materials can penetrate the cell membrane e.g micro-organism, water e.t.c. the various physical and physiological processes are the various ways substance cna be liquid, solid or gas are transported within or outside the cell e.g food
