3: effects of osmosis on plant tissue

• What should you be able to describe by the end of the video?

  How to investigate osmosis on plant tissue
• What is osmosis?

  Diffusion of water through a membrane
• What happens to plant cells in water?

  Water moves in, causing cells to expand
• What occurs when plant cells are placed in a concentrated solution?

  Water moves out, causing cells to shrink
• What vegetable is commonly used to investigate osmosis?

  Potato
• Why do we peel the potato before the experiment?

  To prevent the skin from affecting osmosis
• What tool is used to produce potato cylinders?

  Cork borer
• What length should the potato cylinders be trimmed to?

  Approximately three centimeters
• Why is it important to measure the length and mass of each cylinder?

  To assess the effect of osmosis accurately
• How much of a 0.5 molar sugar solution is added to the first test tube?

  10 centimeters cubed
• Why do we use distilled water instead of tap water?

  Distilled water has no dissolved substances
• What should you do after leaving the potato cylinders overnight?

  Gently roll them on paper towel
• Why is it important not to press on the cylinders when drying them?

  To avoid forcing water out of the cells
• What do you need to calculate after measuring the length and mass again?

  Percentage change in length and mass
• What is the formula for calculating percentage change?

  Percentage change = (change in value / original value) × 100
• If a potato cylinder has a starting mass of 1.56 grams and increases by 0.25 grams, what is the percentage change?

  +16.03 percent
• If a potato cylinder has a starting mass of 1.32 grams and decreases by 0.19 grams, what is the percentage change?

  -14.39 percent
• What does the graph of percentage changes in mass or length against sugar concentration show?

  Mass changes with varying sugar concentrations
• What does it mean when the graph crosses the x-axis?

  No change in mass occurs at that concentration
• What does the concentration where the graph crosses the x-axis indicate?

  Approximate concentration inside the cell
• What are the steps to investigate the effect of osmosis on plant tissue?

  1. Peel the potato to prevent skin effects.
  2. Use a cork borer to create uniform cylinders.
  3. Trim cylinders to approximately three centimeters.
  4. Measure length and mass of each cylinder.
  5. Place cylinders in different sugar solutions.
  6. Leave overnight for osmosis to occur.
  7. Roll cylinders on paper towel to remove surface moisture.
  8. Measure length and mass again.
  9. Calculate percentage change in length and mass.
• What are the key points about osmosis in plant cells?

  • Water moves into cells in dilute solutions.
  • Cells expand when water enters.
  • Water moves out in concentrated solutions.
  • Cells shrink when water exits.
• What are the reasons for using distilled water in osmosis experiments?

  • Contains no dissolved substances.
  • Prevents interference with osmosis results.
• What are the implications of the graph showing osmosis results?

  • Indicates mass changes with sugar concentration.
  • Shows no mass change at equilibrium concentration.
  • Helps determine the concentration inside plant cells.