Practical B6

Use a potometer (bubble and weight potometer) to investigate the factors affecting the rate of water uptake by a plant.

Bubble potometer procedure

  1. Set up a bubble potometer (under water and using petroleum jelly).
  2. Note the position of the bubble.
  3. Leave for a period of time.
  4. Note the new position of the bubble.
  5. Calculate the rate of bubble movement over this period of time.
  6. Reset the apparatus.
  7. Repeat steps 2-6 under the same conditions to increase the reliability of the experiment.
  8. Adjust the environmental conditions.
  9. Repeat steps 2-7 for the new environmental condition.
  10. Record results in a table.

Weight potometer procedure

  1. Set up a weight potometer.
  2. Measure the mass of the container and plant.
  3. Leave for a period of time.
  4. Measure the new mass of the container and shoot.
  5. Calculate the rate of change of mass over this period of time.
  6. Repeat steps 1-5 under the same conditions to increase the reliability of the experiment.
  7. Adjust the environmental conditions.
  8. Repeat steps 1-6 for the new environmental condition.
  9. Record results in a table.