The table shows the relative rate of nitrate ion uptake by root hair cells. Temperature and nitrate concentration in the soil are kept constant.
Table
| Condition | Relative rate of nitrate uptake |
|---|---|
| Normal oxygen supply | 100 |
| Very low oxygen supply | 28 |
| Normal oxygen supply restored | 94 |
The nitrate concentration is higher inside the cells than in the soil throughout.
Which explanation best accounts for the results?
Less photosynthesis reduces the concentration gradient needed for diffusion.
Less aerobic respiration reduces the energy available for active transport.
Less photosynthesis reduces the energy available for active transport.
Less aerobic respiration reduces the concentration gradient needed for diffusion.
43 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.