A crop is grown with its roots in a nutrient solution. The magnesium ion concentration is 0.40 mmol dm−30.40\,\mathrm{mmol\,dm^{-3}}0.40mmoldm−3 in the nutrient solution and 1.60 mmol dm−31.60\,\mathrm{mmol\,dm^{-3}}1.60mmoldm−3 inside the root hair cells.
A grower changes the dissolved oxygen concentration around the roots. All other conditions are kept the same.
| Dissolved oxygen concentration (mg dm−3\mathrm{mg\,dm^{-3}}mgdm−3) | Mean magnesium ion uptake rate (μmol g−1 h−1\mathrm{\mu mol\,g^{-1}\,h^{-1}}μmolg−1h−1) |
|---|---|
| 1.0 | 0.7 |
| 3.0 | 1.8 |
| 5.0 | 2.9 |
Explain the pattern in the results.
Suggest how increasing the dissolved oxygen concentration could affect chlorophyll production in 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.