Osmosis

• What is the plant tissue used in the osmosis experiment?

  Potato
• Why is it important to cut potato cylinders of the same diameter?

  To compare results more easily
• How many potato cylinders are prepared for the experiment?

  Three
• What is the purpose of removing the potato skin?

  It is impermeable to water
• What length should each potato cylinder be measured to?

  Three centimeters
• Why is it necessary to use a ruler for measuring potato cylinders?

  To ensure they are approximately the same length
• What is the mass of the potato cylinder before the experiment?

  2.92 grams
• What type of water is used in the first boiling tube?

  Distilled water
• How much distilled water is added to the boiling tube?

  10 milliliters
• Why is a bun added to the boiling tube?

  To prevent evaporation of liquid
• What are the concentrations of the sucrose solutions used?

  0.25 molar and 0.5 molar
• What happens to the potato cylinders after being left overnight?


  They absorb water and may increase in mass
• What is the mass of the potato cylinder after being in distilled water?

  3.12 grams
• What does an increase in mass indicate in the distilled water sample?

  Water moved into the potato cells
• What is the mass of the potato cylinder in the 0.25 molar sucrose solution?

  3.06 grams
• What does a small increase in mass in the 0.25 molar sucrose solution suggest?

  Minimal water movement into the cells
• What is the mass of the potato cylinder in the 0.5 molar sucrose solution?

  2.62 grams
• What does a decrease in mass in the 0.5 molar sucrose solution indicate?

  Water moved out of the potato cells
• What calculation is used to compare results in the experiment?

  Percentage change
• How is percentage change calculated?

  Change in mass divided by initial mass
• What trend is observed as sucrose concentration increases?

  Mass gain decreases and may turn negative
• What are the steps of the osmosis experiment with potato tissue?

  1. Prepare potato cylinders of equal diameter.
  2. Remove potato skin to allow water movement.
  3. Measure length and mass of each cylinder.
  4. Place cylinders in different sucrose solutions.
  5. Leave for 24 hours.
  6. Measure length and mass again.
  7. Calculate changes in length and mass.
  8. Determine percentage change for comparison.
• What are the expected results of the osmosis experiment?

  • Distilled water: Increase in mass and length.
  • 0.25 molar sucrose: Small increase in mass.
  • 0.5 molar sucrose: Decrease in mass.
• What is osmosis?

  • Movement of water across a semi-permeable membrane.
  • Water moves from low solute concentration to high solute concentration.