Which penguins don't migrate?

The small molecule cyclic amp (camp) takes about 0.2 second to diffuse 10 μm, on average, in a cell. suppose that camp is produced near the plasma membrane on one end of the cell; how long will it take for this camp to diffuse through the cytosol and reach the opposite end of a very large cell, on average? assume that the cell is 200 μm in diameter.

All phases of matter may have a fixed mass

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?