Answer – Osmosis is a form of passive transport.
Explanation:
Molecules move in and out of cells across membranes through one of two modes: active transport and passive transport.
Active transport involves the movement of molecules/ions against a concentration gradient (from lower to higher concentration of the solvent) and hence requires energy to be expended. Passive transport, on the other hand, is simply the movement of molecules/ions in line with the concentration gradient (from higher to lower concentration of the solvent); this requires no external energy and occurs as a result of the entropy of the system.
Osmosis is the movement of water molecules across a semipermeable membrane from a region of higher water concentration to that of lower water concentration. The membrane restricts solute movement but freely allows water to make its way through. The process is shown in the image below.
The beaker on the left has the same volume of water but varying solute concentrations on either side of the semipermeable membrane. The water molecules slowly start moving across the membrane in the absence of external energy. They continue to do so till the solution has the same solute concentration throughout (as shown in the second beaker).
Since the process occurs along the concentration gradient of water without any external energy being expended, osmosis is a type of passive transport.
