Sub-topic 1
2024 · National Preliminary
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Nitrogen fixation and the nitrogen cycle
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Sub-topic 2
2025 · National Preliminary
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Nitrogen fixation and the nitrogen cycle
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Sub-topic 3
2025 · National Preliminary
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The carbon cycle: photosynthesis and respiration
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Sub-topic 4
2025 · National Preliminary
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The carbon cycle: photosynthesis and respiration
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Sub-topic 5
2026 · National One-Eighth
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Nitrogen cycle: the enzyme nitrogenase
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Sub-topic 6
2018 · National Preliminary
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Nitrogen cycle: ploughing legumes into soil (green manuring)
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Sub-topic 7
2025 · National Preliminary
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Distinguishing ammonification from nitrogen fixation and nitrate assimilation (true/false)
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Sub-topic 8
2016 · National One-Eighth
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Problem of the day: labelling components of the water cycle diagram
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Sub-topic 9
2019 · National Preliminary
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Ammonia as the product of ammonification
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Sub-topic 10
2020 · National One-Eighth
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Riddle: evapotranspiration, the combined water loss from land/ocean to atmosphere
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Sub-topic 11
2021 · National Semifinal
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Cyanobacteria improve crop yields via biological nitrogen fixation
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Sub-topic 12
2022 · National Preliminary
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Leghemoglobin protects the nitrogen-fixing enzyme nitrogenase in legume root nodules
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Sub-topic 13
2023 · National Preliminary
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True or false: removing microorganisms from a forest ecosystem would impair nitrogen fixation and decomposition
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