Nutrients are recycled within natural ecosystems, exemplified by the nitrogen cycle and the phosphorus cycle
Unlike energy, nutrients such as nitrogen and phosphorus are not lost from ecosystems. Living organisms, dead matter, and the environment continuously pass these elements between each other in repeating cycles.
Real World
The Haber process, developed by Fritz Haber in 1909, now fixes roughly 150 million tonnes of atmospheric nitrogen into fertiliser annually — effectively doubling the natural rate of nitrogen entering ecosystems and feeding nearly half the world's population.
Exam Focus
Name specific bacteria (e.g. Rhizobium for nitrogen fixation, Nitrosomonas for nitrification) — generic 'bacteria' often scores zero.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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