What is the majior organ of the respiratory system where gas is exchanged

Which part of the cell is affected by the movement of molecules through diffusion, osmosis and active transport?

Can ground tissue do photosynthesis

On a spring day, a middle-latitude city (about 40? north latitude) has a surface (sea-level) temperature of 10 ? c. if vertical soundings reveal a nearly constant environmental lapse rate of 6.5 ? c per kilometer and a temperature at the tropopause of –55 ? c, what is the height of the tropopause?