Practice IB Environmental systems and societies (ESS) - Old Topic 2.2 Energy and Biomass in Ecosystems with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for 2.2 Energy and Biomass in Ecosystems and mirrors Paper 1, 2 style where relevant.
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Describe two ecosystem services provided by healthy ecosystems.
Table 1 displays various ecological characteristics measured at three different stages (A, B, and C) of a primary succession on a newly formed volcanic island.
Table 1: Ecological characteristics of three stages in a primary succession
| Characteristic | Stage A | Stage B | Stage C |
|---|---|---|---|
| Species Diversity | Low | High | Medium-High |
| Total Biomass | Low | Intermediate | High |
| Mineral Cycling | Open | Improving | Largely closed |
| Net Productivity | High | Decreasing | Low |
Identify which stage in Table 1 represents a pioneer community.
State one human activity that could arrest an ecological succession, preventing it from reaching Stage C.
Outline two reasons why species diversity typically increases as a site progresses from Stage A to Stage B.
Explain how the relationship between Gross Primary Productivity () and total community Respiration () changes as an ecosystem reaches the climax stage (Stage C).
Explain how energy flows through an ecosystem, from sunlight to top predators.
Figure 1: Fact file on North American beavers
Source: adapted from www.sbaa.ca, www.ecology.info, www.tobyhemenway.com and http://acs7.cortland.edu
Figure 2: Algonquin wolf pack territories and protected areas
With reference to Figure 1, outline one reason why there are more beaver remains in wolf faeces during summer.
The number of wolves in Algonquin Provincial Park is estimated to be between 250 and 1000. Outline two reasons why it is so difficult to estimate the number of wolves accurately.
With reference to Figure 2, explain the threats to the future existence of a small and sustainable population of wolves as a result of their protection in limited area.
Explain how climate change can affect ecosystem structure and function.