3: effects of osmosis on plant tissue

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

  Investigate the effect of osmosis on plant tissue
• What is osmosis?

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

  Water moves into the cell, causing expansion
• What occurs when plant cells are placed in a concentrated solution?

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

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

  The skin can affect osmosis
• What tool is used to produce potato cylinders?

  Cork board
• Why do we trim the potato cylinders to the same length?

  To ensure consistent measurement of osmosis
• What is a good length for the potato cylinders?

  About three centimeters
• What do we measure before placing the potato cylinders in the solution?

  The length and mass of each cylinder
• How much of the sugar solution is added to the first test tube?

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

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

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

  To avoid forcing water out of the cells
• What do we measure again after removing the potato cylinders?

  The length and mass of the cylinders
• How do we calculate percentage change?

  Change in value divided by original value
• What is the percentage change formula?

  Percentage change = (change/original) * 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 show?

  Mass gain in water, loss in concentrated solution
• What does it mean when the graph crosses the x-axis?

  No change in mass occurs
• What does the concentration at the x-axis crossing indicate?

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

  1. Peel the potato.
  2. Use a cork board to create cylinders.
  3. Trim cylinders to the same length.
  4. Measure length and mass of cylinders.
  5. Place cylinders in different sugar solutions.
  6. Leave overnight for osmosis.
  7. Roll on paper towel to remove moisture.
  8. Measure length and mass again.
  9. Calculate percentage change.
• What are the key points for calculating percentage change?

  • Formula: Percentage change = (change/original) * 100
  • Change is the difference in mass or length.
  • Original is the initial mass or length.
  • Important for analyzing osmosis results.
• What are the effects of osmosis on potato cylinders in different solutions?

  • In distilled water: Gains mass (water enters).
  • In concentrated sugar solution: Loses mass (water exits).
  • No change at isotonic concentration (equal inside and outside).