Required Practical

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

  How to investigate the effect of osmosis on plant tissue
• What is osmosis?

  The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
• What happens to plant cells when they are placed in water?

  Water moves into the cell by osmosis, causing the cell to expand
• What occurs when a plant cell is placed in a concentrated solution?

  Water moves out of the plant cell by osmosis, causing the cell to shrink
• What is the typical plant tissue used to investigate osmosis?

  • Potato
  • Other vegetables: beetroot, parsnip
• Why do we peel the potato before the experiment?

  Because the potato skin can affect osmosis
• How do we ensure all potato cylinders are the same diameter?

  By using a cork borer
• What is the recommended length for the potato cylinders?

  Approximately 3 centimeters
• Why is it important to measure the length and mass of each potato 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 in the experiment?

  Because distilled water contains no dissolved substances that could affect osmosis
• What should you do after leaving the potato cylinders in the solutions overnight?

  Gently roll them on a paper towel to remove surface moisture
• What is the formula to calculate 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%
• 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%
• What does the graph of percentage changes in mass or length against the concentration of sugar solution show?

  • In water, potato cylinders gain mass (water moves in)
  • In concentrated sugar solution, cylinders lose mass (water moves out)
  • The x-axis crossing indicates no change in mass (equal concentration inside and outside)
• What is the significance of the concentration where the graph crosses the x-axis?

  It indicates the concentration inside the cell
• What are the key steps in investigating the effect of osmosis on plant tissue?

  1. Peel the potato
  2. Cut cylinders using a cork borer
  3. Trim to the same length
  4. Measure length and mass
  5. Place in different sugar solutions
  6. Leave overnight
  7. Remove and measure again
  8. Calculate percentage change