Investigating Osmosis

• What is the purpose of the experiment described in the study material?

  To investigate osmosis using potato cylinders in sucrose solutions
• What is the main variable being changed in the osmosis experiment?

  The concentration of sucrose solutions
• What are the steps to prepare for the osmosis experiment?

  1. Prepare sucrose solutions of varying concentrations (0.0M to 2.0M).
  2. Cut potatoes into cylinders of about 1 cm in diameter.
  3. Measure the mass of groups of three cylinders.
  4. Place each group in different sucrose solutions.
  5. Leave for at least 40 minutes.
  6. Weigh the cylinders again and record results.
  7. Calculate the % change in mass.
  8. Plot a graph of the results.
• What is the diameter of the potato cylinders used in the experiment?

  About 1 cm
• Why is it important to keep all variables constant except for the sucrose concentration?

  To ensure the reliability of the results
• How do you calculate the percentage change in mass?

  Using the formula: $\text{percentage change} =$$\frac{\text{final mass} - \text{initial mass}}{\text{initial mass}} \times 100$
• If a group of potato cylinders weighed 13.5 g at the start and 11.4 g at the end, what is the percentage change in mass?

  $\text{percentage change} =$$\frac{11.4 - 13.5}{13.5} \times 100 =$$-15.6\%\text{ (loss of mass)}$
• What happens to potato cylinders in solutions with higher water potential?

  • They draw in water by osmosis.
  • They become longer and gain mass.
• What happens to potato cylinders in solutions with lower water potential?

  • They lose water by osmosis.
  • They shrink and decrease in mass.
• What occurs when the water potential of the sucrose solution is the same as that of the potato cylinders?

  There will be no net water loss or gain, and the size and mass will remain the same.
• What is the significance of the experiment in relation to making skinny fries?

  • Demonstrates how osmosis affects potato cylinders.
  • Explains why potatoes lose water in concentrated solutions.