Two cucumber seedlings, P and Q, were grown in the same moist soil under identical conditions.
In both seedlings, the soil solution was more dilute than the root hair cell sap, and the nitrate ion concentration was lower in the soil than in the root hair cells.
| Seedling | Total root-hair surface area (cm²) | Water uptake (cm³ per hour) | Nitrate ion uptake (mg per hour) |
|---|---|---|---|
| P | 84 | 6.3 | 0.21 |
| Q | 42 | 3.2 | 0.11 |
Explain the relationship shown between total root-hair surface area and the uptake of both substances, and how this is likely to affect their delivery to the leaves.
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.