I believe it affects the amount of runoff because soil in plants tries to absorb water which would take some of that runoff water
Other molecules such as proteins, starch and sugar are simply too large to diffuse across the membrane. Sometimes, some of these large molecules are transported across the cell membranes by carrier proteins; this does not require energy and as a result is a form of passive transpor
It is possible that there are side effects to a garden. One possible side effect is the excessive amount of moisture which could loosen up the soil. Also a bunch of bugs will begin to appear that could just eventually kill the garden in the long run if not treated properly