Required Practical- Measuring the Uptake of Water- BIOLOGY

• How can you measure water uptake?

  Using a potometer
• What does the rate of water uptake give a measure of?

  Transpiration
• What is the method for measuring water uptake?


  Fill the potometer with water, cut a shoot from plant and put the end under water to make sure the xylem remains water-filled and prevents air locks, shoot is inserted into rubber tubing at the end of the potometer, the potometer is raised so a bubble of air is taken up and lowered into the water, the distance travelled by the air bubble is recorded over a period of time
• What is the independent variable in this?

  Time
• What is the dependent variable in this?

  The distance moved by the bubble along the capillary tube
• What are the control variables in this?

  Temperature, air flow or droughts, adequate supply of water
• What are the risks/solutions?

  Care must be taken when inserting the plant shoot into the rubber tubing attached to the capillary tube and with the scissors used to cut the plant shoot