Passive transport is a movement of ions and other atomic or molecular substances across cell membranes without need of energy input. Unlike active transport, it does not require an input of cellular energy because it is instead driven by the tendency of the system to grow in entropy.
Active transport the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.
Osmosis a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one.
diffusion is a movement of gaseous atoms or molecules from high concentrated ( or higher pressure) region to low concentration ( or lower pressure) region, no external source of energy is used
respiratory surface, also known as the respiratory membrane, in which gases molecules are exchanged