Key Concepts: Osmosis

Key Concepts: Osmosis

  • Osmosis refers to the movement of water molecules from an area of high water concentration to an area of low water concentration across a partially permeable membrane.

  • A partially permeable or semi-permeable membrane is a type of biological or synthetic, or a mixture of both, membrane that will enable certain molecules or ions to pass through it by means of diffusion and sometimes active transport too.

  • This process is critical to maintaining water balance and optimal functionality of cell structure.

  • In terms of plant cells: osmosis can cause cells to become turgid when water enters them. This is integral for maintaining plant structure. If water leaves a plant cell, it becomes flaccid, and further loss of water can result in a condition known as plasmolysis.

  • Particularly in animal cells: losing or gaining too much water can be harmful. A cell that swells too much could burst, while a cell that contains very little water can shrivel.

  • Osmosis enables cells to absorb minerals and eliminate waste efficiently.

  • The direction and flow of water in osmosis can be altered by the presence of solutes, temperature, and pressure.

  • Hypotonic, hypertonic and isotonic solutions can influence the rate of osmosis. A hypotonic solution contains fewer solute particles than the cell, hence more water enters. A hypertonic solution contains more solute particles, so water leaves the cell. In an isotonic solution, water movement in and out of the cell is balanced.

  • Osmotic pressure relates to the force required to prevent water moving by osmosis across a membrane.

  • Understanding osmosis contributes to insights in several fields including health sciences, food preservation, and water treatment.

  • Remember osmosis in real life situations: Over-watering plants can cause their cells to burst, while plants in very dry soil can lose water and wilt. Similarly, soaking salty ham in water will cause it to ‘swell’ as water moves into the cells.