Concept introduction: Osmosis
Teacher in-charge: Ms. Rupal Srivastava
Osmosis is a special kind of diffusion by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one that tends to equalize the concentrations of solute on the two sides of the membrane. Osmosis helps in stabilizing the internal environment of the organism by balancing the levels of water and intracellular fluids.
Students of Grade IX were introduced to the concepts of osmosis, hypotonicity, isotonicity and hypertonicity; endosmosis and exosmosis. The concept was further extended to osmosis in plant and animal cells. Plant cell gets turgid and plasmolyzed in hypertonic and hypotonic solutions respectively. Animal cell gets lysed and shriveled in hypertonic and hypotonic solutions respectively.
The process of osmosis was made understood by three simple activities. The first activity involved observing osmosis in deshelled eggs. Students performed simple experiments of osmosis in potato using salt and sugar (green food colour was added to make the rise in water level more evident). Concepts of endosmosis and exosmosis were further clarified with experiment with resins.