CIE IGCSE Biology: 复习笔记：8.1.5 Investigating Temperature & Wind Speed

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 in tube
• Set up the apparatus as shown in the diagram and make sure it is airtight, using vaseline to seal any gaps
• Dry the leaves of the shoot (wet leaves will affect the results)
• Remove the capillary tube from the beaker of water to allow a single air bubble to form and place the tube back into the water
• Set up the environmental factor you are investigating
• Allow the plant to adapt to the new environment for 5 minutes
• Record the starting location of the air bubble
• Leave for a set period of time
• Record the end location of air bubble
• Change the wind speed or temperature (only one - whichever factor is being investigated)
• Reset the bubble by opening the tap below the reservoir
• Repeat the experiment
• The further the bubble travels in the same time period, the faster transpiration is occurring and vice versa

An experimental setup for testing the effect of light intensity on transpiration rates. The apparatus can be modified to test the effects of temperature and wind speed.

• Environmental factors can be investigated in the following ways:
  • Temperature : Temperature of room (cold room and warm room)
    • As temperature increases the rate of transpiration also increases
  • Wind speed : Use an electric fan to mimic different wind speeds
    • As wind speed increases the rate of transpiration also increases