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IB ESS SL 2 Ecology Questions

Interpret ecology data, trace energy and matter, explain population and ecosystem change, and evaluate human impacts using evidence.

Syllabus
First assessment 2026
Course
ESS SL
Level
SL

Exam points

  • identify and explain how species, populations and communities are defined and linked, using habitat, niche, interactions, limiting factors, carrying capacity and ecosystem structure
  • design and interpret ecological sampling and fieldwork methods, including quadrats, transects, capture-mark-release-recapture, climate or biomass figures and repeated measurements, while judging reliability and units
  • trace energy and matter through food webs and biogeochemical pathways, identifying trophic levels, stores, flows, productivity, respiration, decomposition, nutrient cycling and pollutant transfer
  • calculate or interpret ecological quantities such as population abundance, productivity, biomass, storage change, concentration and diversity, then explain what the data show about ecosystem structure or function
  • explain how abiotic conditions, species interactions, feedbacks, climate circulation, ocean heat, biome conditions and succession alter distribution, productivity, diversity, stability and resilience

Covered syllabus points

2.1 Individuals, populations, communities, and ecosystems2.2 Energy and biomass in ecosystems2.3 Biogeochemical cycles2.4 Climate and biomes2.5 Zonation, succession and change

Learn this topic

Study Topic 2: Ecology conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

Question 1

[Maximum number: 5]
Figure: Example of a lake ecosystem

Figure:Example of a lake ecosystem

Figure: Example of a lake ecosystem below shows an example of a lake ecosystem.

Rooting flowering plants: producers

Question (a)

(a)

State the source of energy for this ecosystem.
(a) (i) State the source of energy for this ecosystem.

[ 1 ]

Question (b)

(b)

Identify one way in which energy may leave this ecosystem.

Birds: secondary and tertiary consumer eg kingfisher

Floating plants: producers eg lilies, water fern

Frog: secondary consumer

[ 1 ]

Question (c)

(c)

Draw a food chain from the ecosystem in Figure: Example of a lake ecosystem consisting of four trophic levels.

[ 1 ]

Question (d)

(d)

Identify two possible effects of removing trout on this ecosystem.

[ 2 ]

Question 2

[Maximum number: 11]

Question (a)

(a)

Identify four characteristic features of the tropical rainforest biome.

[ 4 ]

Question (b)

(b)

Explain how a community of decomposers contributes to the stability of the whole ecosystem.

[ 7 ]

Question 3

[Maximum number: 3]

Question (a)

(a)
Fact file on Hokkaido

Figures:Fact file on Hokkaido and Climate graph for Sapporo, Hokkaido

Using the climate graph for Sapporo, state the annual temperature range for Sapporo.

[ 1 ]

Question (b)

(b)
World map showing location of Japan

Figure:World map showing location of Japan

Fact file on Hokkaido

Figures:Fact file on Hokkaido and Climate graph for Sapporo, Hokkaido

Elevation map of Hokkaido

Figure:Elevation map of Hokkaido

Using Figures: World map showing location of Japan, Climate graph for Sapporo, Hokkaido and Elevation map of Hokkaido, identify one terrestrial biome found on Hokkaido.

[ 1 ]

Question (c)

(c)
Hokkaido's national parks and airports

Figure:Hokkaido's national parks and airports

Using Figures: Elevation map of Hokkaido and Hokkaido's national parks and airports, outline one relationship between the location of Hokkaido's national parks and their elevation.

[ 1 ]

Question 4

[Maximum number: 1]
Salinity variation in the Large Ocean Management Area

Figure:Salinity variation in the Large Ocean Management Area

Water-surface temperature variation across the LOMA

Figure:Water-surface temperature variation across the LOMA

temperature scale

Figure:temperature scale

Suggest one reason for the zonation seen in Figure: Water-surface temperature variation across the LOMA.

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