Is this accurate? what should I change?

Which could be a pathway of food through an ecosystem

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.

The starting materials in a nuclear change have a total mass of 2.3465 x 10-27 kg. after the change, the resulting materials have a mass of 2.3148 x 10-27 kg. how much energy was released during the change? 2.85 x 10-12 2.08 * 10-10 j 0 211 * 10-10 j 8.56 * 10-43