Practice 2.5 Zonation, succession and change in ecosystems with authentic IB Environmental systems and societies (ESS) exam questions for both SL and HL students. This question bank mirrors Paper 1, 2 structure, covering key topics like ecosystems, human impact, and sustainability. Get instant solutions, detailed explanations, and build exam confidence with questions in the style of IB examiners.
Paper
Level
Question 1
SL & HLPaper 2
1.[4]
Explain how you would measure the impact of pollution on a freshwater ecosystem.
Question 2
SL & HLPaper 2
Explain how abiotic factors can be measured in an ecosystem investigation.
1.[4]
Choose two factors and describe the measurement method for each.
Question 3
SL & HLPaper 2
1.[4]
Describe two methods for estimating population size in an ecosystem.
Question 4
SL & HLPaper 2
1.[3]
Explain the importance of replication in ecological field studies.
Question 5
SLPaper 1
Figure 1: Fact file on North American beavers
- Typically, one family per square kilometer of river habitat.
- Live in family groups consisting of two adults and up to three kits, born annually between April and June.
- Experience high mortality rates due to harsh weather, limited suitable habitats, and predation.
- North American beaver population:
- Estimated at 250 million before the fur trade.
- Currently around 9 million.
- Primarily feed on tree bark.
- Build lodges using wood and mud, which serve as:
- Safe spaces for eating, sleeping, and raising young.
- Winter shelters where they remain during the colder months.
- Defended structures to keep other beavers out.
- Beavers are being reintroduced in Europe to aid in wetland restoration.
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
1.[1]
With reference to Figure 1, outline one reason why there are more beaver remains in wolf faeces during summer.
2.[2]
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.
3.[3]
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.
Question 6
SLPaper 2
1.[4]
Explain how species diversity and population size influence the resilience of an ecosystem.
2.[7]
Compare and contrast using a biotic index and a diversity index to assess ecosystems.
3.[9]
Using named examples, discuss the significance of diversity in the sustainability of food production systems.
Question 7
SLPaper 2
1.[4]
Identify four ways solar energy reaching vegetation may be lost from an ecosystem before contributing to the biomass of herbivores.
2.[7]
Suggest a series of procedures that could be used to estimate the net productivity of an insect population in .
3.[9]
To what extent are the concepts of net productivity and natural income useful in managing the sustainable harvesting of named resources from natural ecosystems?
Question 8
SLPaper 2
1.[4]
Outline factors contributing to an ecosystem's total biodiversity.
2.[7]
Discuss how ecological techniques can be used to study the impact of human activity on an ecosystem's biodiversity.
3.[9]
To what extent are strategies promoting the conservation of biodiversity successful?
Question 9
SL & HLPaper 2
1.[4]
Describe two methods for measuring primary productivity in an ecosystem.
Question 10
SLPaper 2
A temperate coniferous forest was cleared and left to naturally regenerate. Species numbers were surveyed across three successional stages, and the findings are summarized in Table 1.
Table 1: The number of organisms found in each successional stage for selected species
| Species | Early | Intermediate | Late |
|---|---|---|---|
| Red huckleberry (Vaccinium parvifolium) | 100 | 80 | 70 |
| Western hemlock (Tsuga heterophylla) | 0 | 20 | 60 |
| Douglas fir (Pseudotsuga menziesii) | 50 | 132 | 90 |
| Keen’s mouse (Peromyscus keeni) | 80 | 96 | 90 |
| Douglas squirrel (Tamiasciurus douglasii) | 5 | 30 | 40 |
| American pine marten (Martes americana) | 0 | 2 | 10 |
| Total number of organisms | 235 | 360 | 360 |
| Simpson’s diversity index (D) | 2.94 | 3.80 | --- |
Figure 2: Keen’s mouse was found in all three successional stages
1.[1]
Define species diversity.
2.[2]
Explain why the diversity changes in the different successional stages.
3.[1]
State one method to determine the population size of the Keen’s mouse.