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IB ESS SL 4.1.5 Human Activity Impacts Questions

Evaluate how extraction, land use and pollution alter water stores and flows.

Syllabus
First assessment 2026
Course
ESS SL
Level
SL

Exam points

  • explain how urbanization, deforestation, agriculture, industry and water extraction alter hydrological stores, flows and freshwater quality
  • analyse cause-and-effect links between human activity and runoff, infiltration, evapotranspiration, groundwater recharge, pollution, river flow and marine ecosystems
  • evaluate the relative impacts and management trade-offs of human activities on freshwater availability, water quality, ecosystem health and downstream communities

IB ESS SL 4.1.5 Human Activity Impacts Questions question 1

[Maximum number: 4]
MangroveSeagrassCoral reef
Provides nursery and habitat for fish and shellfishProvides nursery and habitat for variety of speciesProvides nursery and habitat which supports high biodiversity
Intercepts freshwater flow, traps sediments and absorbs nutrientsTraps sediments and absorbs nutrients from the waterFilters particulate matter from the water, increasing water clarity
Absorbs carbon dioxide and emits oxygenAbsorbs carbon dioxide and emits oxygen
Provides a source of fish and shellfishProvides a source of fish and shellfishProvides a source of fish and shellfish
Reduces coastal erosionProvides coastal protection by buffering incoming waves and currents
Provides a source of woodProvides a tourist and recreation attraction

Figure:Ecosystem goods and services in coastal marine habitats

Figure 7: Threats to biodiversity and ecosystems within the Coral Triangle
• Coral reefs and mangroves in the Coral Triangle have declined by over 40 % since the 1970s.
• Over 85 % of coral reefs are under threat from population growth and human activity.
• Mangroves have commonly been removed to make way for agriculture, aquaculture or urban development.
• Increase in unsustainable fishing practices, because of the demand for marine resources, has led to the decline of many species, such as bigeye tuna (Thunnus obesus) and yellowfin tuna (Thunnus albacares).
• Destructive fishing methods that impact marine habitats have been used throughout the region, such as use of dynamite and cyanide.
• Demand for wildlife goods such as turtle products and shark fins (used to make shark-fin soup) has caused a reduction in population numbers of some species.
• Land-based pollution from agriculture, logging, mining and urban development has damaged habitats within the Coral Triangle.

Large-scale tourism development also threatens the Coral Triangle through:
• pollution produced by tourists, such as sewage effluent, plastic waste materials
• coral trampling by snorkelers and divers
• physical damage caused by boat anchors ripping up corals and seagrass
• stress to marine wildlife caused by tourists following them too closely
• collection of wildlife souvenirs, such as corals, shellfish or turtle shells.

Climate change is a major threat to the Coral Triangle. The World Wide Fund for Nature (WWF) estimates that at current rates of global temperature increase, most coral reefs could be destroyed by 2050.

Explain how the following land-based activities could have a damaging effect on marine ecosystems within the Coral Triangle:

Question (a)

(a)

deforestation

[ 2 ]

Question (b)

(b)

agricultural activity.

[ 2 ]
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