Weight potometer experiment

In a weight potometer the mass of water lost is measured by recording the loss in mass over a period of time
1. Four leafy shoots are used.
  1. A: one left untreated
  2. B: top surface covered in vaseline
  3. C: lower surface covered in vaseline
  4. D: Leaves removed from shoot
  5. E: CONTROL/ no shoot
Once the shoots are in the water, put cooking oil carefully onto the surface of the water
Then weigh the tubes
1. and weigh them again after 48hrs
RESULTS
1. Tube A lost the most mass
  1. No stomata were covered so there was nothing to prevent water loss so the water loss was greatest
2. Tube D lost the least mass (not including E)
  1. There were no stomata for the water to evaporate out of so water loss was minimised and the plant did not lose much mass
3. The difference between tubes B and C...
  1. Tube B lost more mass than C because the lower surface of the leaf contains more stomata, so as it is covered in C it will conserve more weight and have a lower change in mass.
4. Why was oil put over the surface of the water in the flasks?
  1. To prevent any water evaporating from the flask, not the stomata
5. What is the function of tube E?
  1. Control - to prove that it was the varying leaves affecting their mass
6. What must be kept constant?
  1. Volume of water, temperature of water, species of leaf, light intensity, humidity

Resource summary

	Created by jeacur over 11 years ago