Osmosis

• 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 borer
• 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 is the purpose of measuring the length and mass of each cylinder?

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

  10 cm³
• Why do we use distilled water instead of tap water?

  Distilled water contains no dissolved substances
• What should be done 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 we 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%
• 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 sugar solution concentration show?

  • In water, potato gains mass (osmosis in)
  • In concentrated sugar solution, potato loses mass (osmosis out)
  • X-axis crossing indicates no mass change (equal concentrations)
• What does it mean when the graph crosses the x-axis?

  No change in mass occurs at that concentration
• What is the importance of this required practical on osmosis?

  • Helps understand osmosis in plant cells
  • Essential for exam preparation
  • Provides practical experience in scientific investigation