Oxygen comes from alveoli to blood by-: (A) Diffusion, (B) Receptor mediated, (C) Active transport, (D) Osmosis
Answer is A. Ans. (a) Diffusion(Ref: Ganong, 25th ed/p.640)Diffusion means movement of molecules from area of high concentration to area of low concentrationGas exchange in lungs happens in the form of diffusion in lungs