Zusammenfassung der Ressource
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
- Four leafy shoots are used.
- A: one left untreated
- B: top surface
covered in vaseline
- C: lower surface covered in vaseline
- D: Leaves removed from shoot
- 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
- and weigh them
again after 48hrs
- RESULTS
- Tube A lost the most mass
- No stomata were covered so there
was nothing to prevent water loss
so the water loss was greatest
- Tube D lost the least
mass (not including E)
- There were no stomata for the water to
evaporate out of so water loss was minimised
and the plant did not lose much mass
- The difference between tubes B and C...
- 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.
- Why was oil put over the surface of the water in the flasks?
- To prevent any water
evaporating from the
flask, not the stomata
- What is the function of tube E?
- Control - to prove that it was the
varying leaves affecting their mass
- What must be kept constant?
- Volume of water, temperature
of water, species of leaf, light
intensity, humidity