The diagram below shows a simplified representation of the nitrogen cycle in an agricultural ecosystem.
Complete the table below by matching each biological process to the correct letter (AAA, BBB, CCC, DDD, EEE, or FFF) from the diagram.
| Process | Letter |
|---|---|
| Assimilation | |
| Decomposition (Ammonification) | |
| Denitrification | |
| Nitrification | |
| Nitrogen fixation (by mutualistic root bacteria) |
The uptake of inorganic ions, such as nitrate ions, from the soil solution into root hair cells occurs primarily via active transport.
Describe the biochemical mechanism of active transport across a cell-surface membrane.
Waterlogged soils are severely depleted of oxygen gas. Explain why this condition drastically decreases the rate of active transport in root hair cells.
A sustainable agriculture initiative recommends growing alfalfa (a legume) during a fallow period and then mechanical tilling (ploughing) the crop directly into the soil as 'green manure'. Explain how this agricultural strategy enhances soil nitrogen levels and improves the yield of a subsequent non-legume crop without using synthetic chemical fertilizers.
