In an Amazon catchment, vapour fluxes were measured before and after clearing under similar temperature and wind speed. Which conclusion is supported?
| Condition | Canopy cover / % | Incoming vapour flux / arbitrary units | Outgoing vapour flux / arbitrary units | Downwind rainfall / mm day⁻¹ |
|---|---|---|---|---|
| Before clearing | 92 | 10 | 16 | 5 |
| After clearing | 31 | 13 | 15 | 2 |
Net moisture recycling = outgoing vapour flux − incoming vapour flux.
After nutrient enrichment, equal algal biomass was transferred to vessels for 24 hours. Which process best explains the results?
Which agricultural scenario would be most unsustainable in the long term?
What is a reliable indicator that a resource is being harvested sustainably?
Why might deforestation of the Amazon reach an ecological tipping point?
Practice IB Biology Topic D4.2 Sustainability and Change with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for D4.2 Sustainability and Change and mirrors Paper 1A, 1B, 2 style where relevant.
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| Vessel | Algae | Decomposers | Conditions | Change in dissolved oxygen / arbitrary units |
|---|
| P | living | absent | light | +4 |
| Q | dead | present | dark | −7 |
| R | dead | absent | dark | 0 |
