Materials cycle, energy flows
Materials cycle, energy flows

Atoms of carbon, water and mineral ions are repeatedly transferred between organisms and their surroundings. They are recycled because the atoms remain available after organisms respire, excrete waste or die.
Step-by-step lessons on AQA GCSE Biology 7.2.2 How materials are cycled. Each one builds up to exam-style questions. Start with the foundational topics and build up to the higher-tier material.