B6: Measuring water uptake and water lossPractical B6: Washing line method

Use the washing line method to investigate the factors affecting the rate of water loss from leaves.

Procedure

1. Remove a number of leaves from a plant.
2. Smear petroleum jelly over the cut stalks to make them waterproof.
3. Measure the mass of each leaf.
4. Using paperclips hang the leaves on a line of string (held up by 2 retort stands).
5. If investigating the effect of temperature on water loss by a leaf, hang half of the leaves at a high temperature and the other half at a low temperature.
6. After a period of time, find the new mass of each leaf.
7. Calculate the average loss of mass at each temperature.