Unit 2: Ecosystems and Ecology
Topic 2.3: Habitat, Niche and Interactions Questions
Practice 20 exam-style questions for IB ESS Topic 2.3. Review the question stems below, then unlock the full Question Bank to access markschemes, model answers, and AI grading.
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Define the term nitrogen fixation.
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State the end product of nitrification that is most readily taken up by plants.
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• Aimnova PP-practice — 2.3.2
State the name of the process by which soil bacteria convert nitrates back into atmospheric nitrogen gas.
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• Aimnova PP-practice — 2.3.3
Describe one benefit and one drawback of the Southern Ocean acting as a major carbon sink for the global atmosphere.
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State two major carbon stores in a forest ecosystem.
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Distinguish between infiltration and surface runoff.
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State one reason why carbon stored in timber products may be released more slowly than carbon released by burning.
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State the largest store of water in the hydrological cycle.
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Define the term carbon source.
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• Aimnova PP-practice — 2.3.3
Outline four processes or events that RAISE atmospheric CO₂ concentration, and two that LOWER it. For each, state where the carbon comes from and where it goes.
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Define the term hydrological cycle.
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State what is meant by evapotranspiration.
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State the largest store of nitrogen in the nitrogen cycle.
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Define the term carbon sink.
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Outline one way that nitrogen fixation can occur naturally.
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Suggest one impact of dam construction on the hydrological cycle within a river system.
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Outline the difference between the hydrological cycle as a closed system globally and an open system locally.
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Figure 3(b) compares seagrass meadows with and without green sea turtles.
Suggest how the conservation of green sea turtles could contribute to reducing atmospheric carbon dioxide levels. [2 marks]
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Outline one way that deforestation can alter flows in the hydrological cycle.
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Outline how photosynthesis transfers carbon from the atmosphere into a forest ecosystem.
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