Label the diagram above to complete the processes and flows in the nitrogen cycle.

Distinguish between a transfer and a transformation in the nitrogen cycle.

Describe two ways in which humans may impact the nitrogen cycle.

Must include: clear arrows with processes attached
Award [1 mark] for 2 arrows correctly labelled.

Only credit arrow labelled with process (not storages).
Allow any other reasonable arrow with process.

[3 max]

transfer is the movement/change in location of nitrogen in the cycle;
whereas transformation is chemical conversion/change of state of nitrogen in the cycle;
[1 max] if there is no reference made to the nitrogen cycle but student distinguishes between transfer and transformation process.
Accept examples of each process such as examples given below

Transfer [1 max]:
nitrates from soil to roots of plants;
movement of nitrogen in plants to nitrogen in animals;

Transformations [1 max]:
bacteria convert one form of nitrogen to another;
ammonium to nitrite;
nitrite to nitrate;
denitrification from ammonium/nitrate to N₂;

[2 max]

use of Haber process to produce fertilizers / addition of nitrogen fertilizers/manure to soil;
addition/removal of nitrogen fixing plants in agriculture monocultures;
removal of crops without addition of fertilizers (loss of nitrogen in cycle for a particular area) / removal of plants/crops resulting in reduction of nitrogen in the soil;
addition of nitrogen compounds to the atmosphere by combustion of fossil fuels;

[2 max]

Responses were wide ranging achieving form 0 to 3 marks. A significant number of responses were left blank or only had drawn arrows without any labels.

Although a number of candidates confused the two processes, many were able to clearly distinguish between the two and provide appropriate examples.

A number of responses were too vague and ‘stated’ factors rather than ‘describing’ how they impacted on the nitrogen cycle.