What is osmosis?

Osmosis is specifically defined as the movement of water molecules across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. This process is vital for maintaining the proper balance of fluids in biological systems, allowing cells to regulate their internal environment in response to external conditions.

The key aspect of osmosis is that it specifically concerns water movement, distinguishing it from processes such as diffusion, which involves the movement of solute molecules. Semipermeable membranes are crucial to osmosis because they allow water to pass through while preventing certain solute molecules from doing so, facilitating the selective transfer of water in response to osmotic pressure differences.

In contrast to osmosis, active transport involves the movement of ions or molecules against their concentration gradient, which requires energy expenditure by the cell. This is different from osmosis, as osmosis does not require energy—the water moves passively along its concentration gradient. Additionally, cell division and replication pertain to entirely different biological processes and are unrelated to osmotic movement. Therefore, the correct definition of osmosis is centered on water movement across semipermeable membranes, directly capturing its essence within biological contexts.