Two students use potometers to investigate how temperature affects water uptake by leafy shoots.
Investigation A uses the same shoot at each temperature. The students keep light intensity, air movement and measurement time constant, and calculate a mean rate from three trials at each temperature.
Investigation B uses a different shoot at each temperature. The leaf area increases with temperature, and the students record one rate for each shoot.
| Temperature / °C | Mean rate in investigation A / mm min⁻¹ | Rate in investigation B / mm min⁻¹ |
|---|---|---|
| 15 | 2.6 | 3.0 |
| 20 | 3.8 | 4.1 |
| 25 | 5.2 | 5.8 |
Compare the evidence from the two investigations and justify which investigation gives stronger evidence that increasing temperature increases water uptake.
80 exam-style questions on Edexcel GCSE Biology 6.2 Transport in plants, covering 6.2.1 Root hair cell adaptations, 6.2.2 Structure of xylem and phloem, 6.2.3 Transpiration and stomata, 6.2.4 Translocation of sucrose, 6.2.5 Leaf structure for photosynthesis, 6.2.6 Environmental factors on water uptake, 6.2.7 Rate calculations for transpiration, and 6.2.8 Plant adaptations to extreme environments. Each one has a worked solution and a mark scheme showing where the marks go.