Protein channels are required for a  "facilitated" form of this to occur.
One form of this process is regulated by aquaporins. This process causes gas exchange in   alveoli, and it distributes nutrients in flatworms. Protein channels are required for a  "facilitated" form of this to occur. Oxygen (*) enters the cell via this process, and osmosis is a  type of this process involving water. For 10 points, name this movement of particles from regions of  higher concentration to regions of lower concentration.
One form of this process is regulated by aquaporins. This process causes gas exchange in   alveoli, and it distributes nutrients in flatworms.
diffusion (accept passive transport; accept osmosis before "gas exchange")