Moss osmosis: cell plan view (2D)

Water crosses a plant cell membrane toward the side with the higher solute concentration. The osmotic pressure follows van 't Hoff, Pi = R T c, and the elastic cell wall pushes back with turgor pressure that rises once the protoplast fills the wall. Volume changes at a rate proportional to the net drive Pi - P_turgor until the two balance. In a hypertonic bath the protoplast shrinks away from the wall (plasmolysis); in distilled water the cell swells until turgor equals the internal osmotic pressure.

What this 2D view adds

• A plan view of 30 cells: protoplast size, wall and plasmolysis at a glance.
• The Hofler diagram (osmotic, turgor and net drive against volume) and the bath and cell osmolarity over time.

Honest simplifications

Perfect semipermeable membrane, no active solute transport, a linear wall elasticity and a well-mixed bath. Teaching model; the physics module is shared with the 3D page.