Aquaponics is an intensive food production method that integrates aquaculture (raising aquatic animals) with hydroponics (cultivating plants in water) in a symbiotic closed-loop system.
Which of the following correctly pairs the primary biological process required to make nitrogen from fish waste bioavailable to the crops, with a major disadvantage of this farming method?
Process: Nitrification (NH4+→NO2−→NO3−NH_4^+ \rightarrow NO_2^- \rightarrow NO_3^-NH4+→NO2−→NO3−)
Disadvantage: High electrical energy dependency and high vulnerability to catastrophic system collapse if circulation pumps or aerators fail.
Process: Denitrification (NO3−→N2NO_3^- \rightarrow N_2NO3−→N2)
Disadvantage: Extremely high water consumption compared to traditional open-field crop cultivation due to constant system evaporation.
Process: Nitrification (NH4+→NO2−→NO3−NH_4^+ \rightarrow NO_2^- \rightarrow NO_3^-NH4+→NO2−→NO3−)
Disadvantage: Significantly slower crop growth rates than traditional soil-based farming because of the lack of organic soil microbes.
Process: Nitrogen fixation (N2→NH4+N_2 \rightarrow NH_4^+N2→NH4+)
Disadvantage: Accumulation of toxic nitrogenous compounds in edible plant tissues, making crops unsafe for human consumption.
25 exam-style questions on OCR GCSE Biology 6.2 Feeding the human race, covering 6.2.1 Biological factors affecting food security, 6.2.2 Agricultural solutions to growing demand, 6.2.3 Selective breeding, 6.2.4 Genetic engineering, 6.2.5 Steps in genetic engineering, 6.2.6 Benefits and risks of gene technology in agriculture, and 6.2.7 Biotechnological solutions to growing demand. Each one has a worked solution and a mark scheme showing where the marks go.