osmosis

• Osmosis in plants

  • Water moves via osmosis from dilute concentration of solution in soil to high concentration in root hair cells
• Osmosis:

  • Diffusion of water from a dilute solution to a more concentrated solution through a partially permeable membrane.
  • No energy is required for osmosis, passive process.
• percentage change mass=final mass -original mass /original x 100
• REQUIRED OSMOSIS PRACTICAL:

  1. Set up test tubes containing 10 cm3 of different sucrose solutions. Concentrations ranging from pure water (control) to very concentrated solution (1 mol/dm3)(1 mol/dm3).
  2. Prepare the potato, cut it into cylinders of equal size using a cork borer. Measure and record their masses in grams using a balance
  3. Place a potato cylinderin each beaker and leave them for 24 hours.
  4. Take the cylinders out of the solutions, dry them with a paper towel and measure and record their masses again.
• Could repeat experiment at each sucrose concentration with different potato cylinders to identify anomalous results and make the results more reliable by calculating mean values.

  1. The independent variable is the concentration of sucrose solutions.
  2. The control variables include the volume of sucrose solution, time, temperature and type of sugar used.
• Analyse osmosis PRAC:

  • If mass increased, water moved into potato cells via osmosis
  • If mass decreased, water moved out of potato via osmosis
• rate of change (grams/hr)= change in mass​/24(hr)