Osmosis

• What is osmosis?

  The movement of water across a membrane
• What is the role of cholesterol in the cell membrane?

  It provides stability and regulates fluidity
• Define simple diffusion.

  Passive movement from high to low concentration
• What types of molecules can diffuse through the phospholipid bilayer?

  Small, non-polar molecules like oxygen
• What is facilitated diffusion?

  Passive transport via protein channels or carriers
• What is the water potential of pure water under standard conditions?

  Zero
• What does water potential refer to?

  The pressure exerted by water molecules
• How does adding solutes affect water potential?

  It lowers the water potential
• How does water move by osmosis?

  From higher to lower water potential
• If a plant cell has a water potential of -20 kPa, where will water move if placed in -30 kPa solution?

  Water will move out of the plant cell
• What happens to a plant cell in pure water?

  It becomes turgid due to water intake
• What is plasmolysis?

  Process where plant cells lose water
• What happens to red blood cells in pure water?

  They swell and burst (haemolysis)
• Why do animal cells exist in solutions with the same water potential as their cytoplasm?

  To prevent bursting from water intake
• What occurs when animal cells are in a solution with lower water potential?

  Water leaves the cell, causing it to shrink
• What is the significance of dynamic equilibrium in osmosis?

  No net water movement occurs at equilibrium
• What is the symbol for water potential?

  Psi (Ψ)
• In what units is water potential measured?

  KiloPascals (kPa)
• What happens to water potential values when solute concentration increases?

  Water potential becomes more negative
• How do you determine the water potential of cells or tissues?

  By placing them in solutions with varying potentials
• What is the highest water potential value?

  Zero
• What is the relationship between diffusion and osmosis?

  Osmosis is the movement of water only
• What are the effects of osmosis on animal and plant cells?

  • Animal cells in pure water: swell and burst (haemolysis)
  • Plant cells in pure water: become turgid
  • Plant cells in hypertonic solution: undergo plasmolysis
  • Animal cells in hypertonic solution: shrink and shrivel
• What factors affect water potential?

  • Solute concentration: more solutes lower water potential
  • Pressure: affects the overall water potential
  • Temperature: influences kinetic energy of water molecules
• What is the process of osmosis in terms of water movement?

  • Water moves from higher (less negative) to lower (more negative) water potential
  • Dynamic equilibrium occurs when water potentials equalize