ATP as the immediate energy currency
ATP as the immediate energy currency

Energy enters most ecosystems as sunlight and is eventually stored in biomass. Inside cells, the immediate energy carrier that powers reactions is ATP, so cells do not usually use glucose directly in each reaction.
Step-by-step lessons on Edexcel A A Level Biology ATP, productivity and energy transfer. Each one builds up to exam-style questions. Build a strong foundation in cell biology and biochemistry early on, since later topics on genetics, ecology and physiology all draw on these core concepts.