Paper 6 structured question: Transpiration
Method
Method to Investigate Transpiration Rate
1. Cut a leafy shoot and immediately place it in water. 2. Set up a potometer to measure water uptake by the shoot. 3. Place the potometer in a controlled environment. 4. Measure the volume of water taken up over 10 minutes at different temperatures (15°C, 25°C, 35°C). 5. Repeat the measurements with a fan blowing at different wind speeds (0 m/s, 2 m/s, 4 m/s) at a constant temperature. 6. Record all data carefully and repeat each measurement three times for accuracy.
| Temperature (°C) | Wind Speed (m/s) | Water Uptake (cm³/10 min) |
|---|---|---|
| 15 | 0 | 2.0 |
| 25 | 0 | 3.5 |
| 35 | 0 | 5.0 |
| 25 | 0 | 3.5 |
| 25 | 2 | 4.5 |
| 25 | 4 | 6.0 |
- a[1]
Identify the independent variable in this investigation.
Aim for approximately 1 distinct marking point.
- b[2]
Describe how the rate of transpiration changes with temperature based on the data.
Aim for approximately 2 distinct marking points.
- c[3]
Explain why increasing wind speed increases the rate of transpiration.
Aim for approximately 3 distinct marking points.