Transpiration Practical

• Investigating the Rate of Transpiration

  1. Cut a shoot underwater

  2. Place the shoot in the tube

  3. Set up the apparatus

  4. Dry the leaves of the shoot

  5. Remove the capillary tube from the beaker of water to allow a single air bubble to form

  6. Set up the environmental factor you are investigating

  7. Allow the plant to adapt to the new environment for 5 minutes

  8. Record the starting location of the air bubble

  9. Leave for a set period of time

  10. Record the end location of the air bubble

  11. Change the light intensity or wind speed or level of humidity or temperature (only one- whichever factor is being investigated)

  12. Reset the bubble by opening the tap below the reservoir

  13. Repeat the experiment
• Potometer


  • Can be used to investigate the effect of environmental factors on the rate of transpiration
• Apparatus


  • Plant shoot
  • Cutting board
  • Scalpels/scissors
  • Paper Towels
  • Potometer
  • Volume scale
  • Beaker
  • Capillary tube
  • Stopwatch
  • Vaseline
• Environmental factors affecting transpiration rate

  • Air movement
  • Humidity
  • Temperature
  • Light intensity
• Environmental factors are high


  Transpiration rate is more
• Environmental factors are low


  Transpiration rate is less
• Investigating environmental factors


  • Airflow: Set up a fan or hairdryer
  • Humidity: Spray water in a plastic bag and wrap around the plant
  • Light intensity: Change the distance of a light source from the plant
  • Temperature: Temperature of room (cold room or warm room)
• The further the bubble travels in the same time period, the faster transpiration is occurring and vice versa