Answer:
It's Gills because there not human and use gills to breathe in water
Materials move within the cell 's cytosol by diffusion, and certain materials move through the plasma membrane by diffusion. ... Diffusion: Diffusion through a permeable membrane moves a substance from an area of high concentration (extracellular fluid, in this case) down its concentration gradient (into the cytoplasm). Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion (or a type of diffusion known as osmosis ). Diffusion is one principle method of movement of substances within cells, as well as the method for essential small molecules to cross the cell membrane.The cell membrane controls what goes in and out by having protein channels that act like funnels in some cases and pumps in other cases. ... Active transport requires energy, because protein machines actively grab molecules on one side of the membrane and push them through to the other side
