To improve crop yield, a farmer ploughs and drains a clay-heavy, waterlogged field, significantly increasing the oxygen concentration within the soil. Which of the following biological processes in the nitrogen cycle is directly promoted by this aeration, and which chemical transition does it perform?
Denitrification, which reduces nitrate ions (NO3−NO_3^-NO3−) into nitrogen gas (N2N_2N2)
Nitrification, which oxidises ammonium ions (NH4+NH_4^+NH4+) into nitrate ions (NO3−NO_3^-NO3−)
Nitrogen fixation, which oxidises nitrogen gas (N2N_2N2) into ammonium ions (NH4+NH_4^+NH4+)
Ammonification, which converts ammonium ions (NH4+NH_4^+NH4+) into organic compounds like proteins
37 exam-style questions on OCR A A Level Biology Ecosystems. Each one has a worked solution and a mark scheme showing where the marks go.