What does osmosis and active transport have in common?

Answer 1

Osmosis is the movement of water (solvent) over a semipermeable membrane - as long as there is a difference in concentrations of osmotically active substances (proteins for instance) on the two sides of the membrane, the water keeps moving to the side where concentration is higher, until there's no longer a difference. Water hence moves freely, passively, from a lower water concentration to a higher one. Active transport usually happens against an electrochemical gradient, i.e. energy (ATP) is used to pump a substance (solute) over a non-permeable membrane from lower to higher concentration. In this case it is the specific substance, not water, that moves over the membrane. The way of movement is different and the transported molecule is different in the two scenarios, but in both cases the molecule moves from a lower to a higher concentration with a membrane separating the two solutions.