Osmosis

• Osmosis

  The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
• Water concentration

  The amount of water as compared to the other molecules like sugars or salts that are dissolved in that water
• Dissolving molecules

  • Solutes
• Beakers with different water concentrations

  • Beaker with 1 solute particle
  • Beaker with 3 solute particles
• The beaker with more solute particles has a lower water concentration
• The key point is that it's not the volume of water but the proportion of water compared to solutes that determines the concentration
• Osmosis in cells

  Water particles diffuse from the outside of the cell (higher water concentration) down the concentration gradient into the cell (lower water concentration)
• The difference in water concentration between the outside and inside of the cell drives the process of osmosis