A biological treatment tank contains water with ammonium compounds and nitrate ions. Nitrifying bacteria and denitrifying bacteria are present. An air pump is switched on, increasing the oxygen availability in the water.
What is the most likely result?
More ammonium compounds are changed into nitrates by denitrifying bacteria, so the nitrate concentration increases.
More nitrate ions are changed into ammonium compounds by nitrifying bacteria, so the ammonium concentration increases.
More nitrate ions are changed into nitrogen gas by denitrifying bacteria, so the nitrate concentration decreases.
More ammonium compounds are changed into nitrates by nitrifying bacteria, so the ammonium concentration decreases.
101 exam-style questions on Edexcel GCSE Biology 9.3 Material cycles and decomposition, covering 9.3.1 Cycling of materials through ecosystems, 9.3.2 The carbon cycle, 9.3.3 The water cycle, 9.3.4 The nitrogen cycle, 9.3.5 Indicator species and pollution, 9.3.6 Decomposition in preservation and composting, and 9.3.7 Rate changes in decay of biological material. Each one has a worked solution and a mark scheme showing where the marks go.