Required Practical: Effects 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 vegetable used to investigate osmosis in plant tissue?

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

  Because the potato skin can affect osmosis
• What tool is used to produce uniform cylinders of potato?

  A cork borer
• What is the recommended length for the potato cylinders?

  Approximately three centimeters
• Why is it important to measure the length and mass of each potato cylinder?

  To assess the effect of osmosis on the cylinders
• 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 be done to the potato cylinders after leaving them overnight?

  Gently roll them on 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 increase?

  16.03%
• If a potato cylinder has a starting mass of 1.32 grams and decreases by 0.19 grams, what is the percentage decrease?

  • 14.39%
• What does the graph of percentage changes in mass or length against the concentration of the 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 does it mean when the line on the graph crosses the x-axis?

  There is no change in mass, indicating equal concentration inside and outside the cell
• Why is it important to learn the details of this required practical?

  Because it is likely to be tested in exams
• What is the significance of osmosis in plant cells?

  It helps maintain cell turgor and nutrient uptake
• How does a partially permeable membrane function in osmosis?

  It allows water to pass through while blocking solutes
• Why is it important to use a balance for measuring mass in the experiment?

  To ensure accurate measurements for calculating percentage change
• How do different concentrations of sugar solutions affect osmosis in plant cells?

  Higher concentrations cause water to move out, while lower concentrations allow water to move in
• Why is precision important when measuring and cutting potato cylinders?

  To ensure consistent results across all samples
• What impact does surface moisture have on the accuracy of results?

  It can lead to inaccurate mass measurements
• How is this experiment relevant to understanding plant biology?

  It illustrates the principles of osmosis and its effects on plant health