Practice 2.2 Energy and biomass 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]
Describe two ecosystem services provided by healthy ecosystems.
Question 2
SLPaper 2
Figure 1 represents a system of aquaculture with four groups of harvestable species.
Figure 1: Integrated aquaculture
1.[1]
Identify one producer in the system illustrated in Figure 1.
2.[1]
Outline one reason why aquaculture production has increased globally.
3.[2]
Describe two negative environmental impacts that may arise from integrated aquaculture.
4.[4]
Explain why this system may cause fewer environmental impacts than systems that farm only fish.
Question 3
SLPaper 2
1.[4]
Explain the processes involved in the formation of fertile soils from bare rock.
2.[7]
Discuss how negative and positive feedback mechanisms may influence the growth of decomposer populations in the soil.
3.[9]
To what extent are natural limiting factors more likely than population policies to limit global human population growth in the future?
Question 4
SL & HLPaper 2
1.[4]
Explain how energy flows through an ecosystem, from sunlight to top predators.
Question 5
SLPaper 1
Figure 1: Fact file on the round goby (Neogobius melanostomus)
- An invasive species from Asia.
- First discovered in the St Lawrence River in 1990.
- Females lay eggs three times a year; up to 5000 eggs at a time.
- Young fish mature quickly.
- Can eat up to 4000 eggs of other fish in 15 minutes.
- Eat invasive zebra mussels.
- Eaten by native fish, such as lake trout and yellow perch.
- Aggressively defend the best egg-laying sites, out-competing the native mottled sculpin (Cottus bairdii).
Figure 2:The round goby and mottled sculpin
1.[1]
Using Figure 1 and 2, identify one feature of the round goby that shows it is an r-selected species.
2.[3]
With reference to Figure 1, outline how the round goby both positively and negatively affects the St Lawrence River ecosystem.
3.[3]
With reference to Figure 1, explain why the realized niche of the mottled sculpin has changed in recent years.
Question 6
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 7
SL & HLPaper 2
1.[4]
Explain how climate change can affect ecosystem structure and function.
Question 8
SL & HLPaper 2
1.[4]
Describe the process of succession in an ecosystem, distinguishing between primary and secondary succession.
Question 9
SLPaper 1
Figure 1: Example of a Tundra food web
1.[2]
Outline the impact that a reduction in the polar bear population may have on other populations in the food web shown in Figure 1.
2.[2]
Outline why a reduction in the polar bear population may increase its probability of extinction.
Question 10
SLPaper 2
1.[4]
Explain how soil can be viewed as an ecosystem.
2.[7]
Compare and contrast the impact of humans on the carbon and nitrogen cycles.
3.[9]
Examine the role of humans in the destabilization of ecological systems.