Biology · Continuity and change

D4.2 — Stability and change

Biology · SL / HL · syllabus-mapped notes

1. D4.2.1

   Stability as a property of natural ecosystems

   Define stability, resistance and resilience, with examples of long-persisting ecosystems.

2. D4.2.2

   Requirements for stability in ecosystems

   State the three requirements for ecosystem stability, and what disrupts them.

3. D4.2.3

   Deforestation of Amazon rainforest as an example of a possible tipping point in ecosystem stability

   Explain the Amazon as a possible tipping point, and calculate percentage change in forest area.

4. D4.2.4

   Use of a model to investigate the effect of variables on ecosystem stability

   Use mesocosms to model ecosystems, and evaluate their limitations.

5. D4.2.5

   Role of keystone species in the stability of ecosystems

   Explain keystone species using Paine's sea star experiment.

6. D4.2.6

   Assessing sustainability of resource harvesting from natural ecosystems

   Use the sigmoid growth curve to judge whether harvesting is sustainable.

7. D4.2.7

   Factors affecting the sustainability of agriculture

   Explain feed conversion ratios and greenhouse gas emissions in food production.

8. D4.2.8

   Eutrophication of aquatic and marine ecosystems due to leaching

   Explain how leaching causes eutrophication and raises biochemical oxygen demand.

9. D4.2.9

   Biomagnification of pollutants in natural ecosystems

   Explain biomagnification, and why it differs between aquatic and terrestrial food webs.

10. D4.2.10

    Effects of microplastic and macroplastic pollution of the oceans

    Explain the effects of macroplastic and microplastic pollution of the oceans.

11. D4.2.11

    Restoration of natural processes in ecosystems by rewilding

    Explain rewilding as restoration of natural processes.

12. D4.2.12

    Ecological succession and its causes

    Explain ecological succession and its cause in reciprocal interactions.

13. D4.2.13

    Changes occurring during primary succession

    Describe primary succession at Glacier Bay and the soil changes that accompany it.

14. D4.2.14

    Cyclical succession in ecosystems

    Explain cyclical succession as a repeating sequence of stages.

15. D4.2.15

    Climax communities and arrested succession

    Explain climax communities and how succession can be arrested.