Temperature & Wind Speed | Biology for GCSE/IGCSE - Year 11 PDF Download

Investigating the Effect of Temperature & Wind Speed on Transpiration Rate

Investigating the role of environmental factors in determining the rate of transpiration from a leafy shoot:

• Cut a shoot underwater to prevent air entering the xylem and place it in a tube.
• Assemble the apparatus according to the diagram, ensuring it is airtight by using vaseline to seal any gaps.
• Ensure the leaves of the shoot are dry, as wet leaves could affect the results.
• Remove the capillary tube from the water beaker to allow a single air bubble to form, then place the tube back into the water.
• Set up the environmental factor being investigated.
• Allow the plant to acclimatize to the new conditions for 5 minutes.
• Record the initial position of the air bubble.
• Let the setup sit for a specific duration.
• Record the final position of the air bubble.
• Adjust either the wind speed or temperature (only one variable at a time, depending on the investigation).
• Reset the bubble by opening the tap under the reservoir.
• Repeat the experiment.
• The greater the distance the bubble travels in the same time frame, the higher the rate of transpiration; conversely, a shorter distance indicates slower transpiration.

• Environmental factors can be investigated in the following ways:
  • Temperature: Room Temperature (Cold and Warm Settings)
    • Higher temperatures lead to increased transpiration rates.
  • Wind Speed: Utilize an electric fan to simulate varying wind speeds.
    • Higher wind speeds correspond to increased rates of transpiration.