upon close inspection of movement in annelids and nematodes, you would notice an obvious difference. nematodes tend to wriggle back and forth, while annelids tend to contract along their length as their girth swells and then thin out as they stretch. what anatomical feature explains this type of movement?

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.