A normal sunflower and a mutant sunflower are grown in the same moist soil. The mutant's root hair cells have much shorter projections and contain fewer mitochondria than those of the normal plant. Its xylem vessels develop normally.
The soil solution is more dilute than the cell sap. The table shows nitrate ion concentrations around the mutant's roots.
| location | nitrate ion concentration / mmol dm−3\mathrm{mmol\,dm^{-3}}mmoldm−3 |
|---|---|
| soil solution | 0.50 |
| root hair cell sap | 3.0 |
While the stomata are open, nitrate ions reach the mutant's leaves more slowly than they reach the normal plant's leaves. Water continues to reach the mutant's leaves.
Explain why nitrate ions reach the mutant's leaves more slowly, but water continues to move from the soil to its 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.