12 marks
Briefly describe natural ultraviolet (UV) radiation.
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Syllabus Edition
First teaching 2024
First exams 2026
Stratospheric Ozone (DP IB Environmental Systems & Societies (ESS): HL): Exam Questions
1 hour25 questions
23 marks
Briefly outline what happens when UV radiation interacts with a molecule of ozone.
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32 marks
State two effects of ultraviolet (UV) radiation on humans.
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41 mark
State one source of ozone depleting substances.
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51 mark
The Montreal Protocol on Substances that Deplete the Ozone Layer is an international treaty established in 1987 to address the depletion of the Earth's ozone layer.
It aims to phase out the production and consumption of ozone-depleting substances (ODS).
The protocol has been highly successful in reducing ODS, leading to the gradual recovery of the ozone layer and mitigating the harmful effects of ultraviolet (UV) radiation on the environment and human health.
Suggest one reason why an illegal market for ozone-depleting substances still exists.
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62 marks
Define the term ozone-depleting substance.
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71 mark
State a condition needed for polar stratospheric cloud (PSC) formation.
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81 mark
State one disadvantage of replacing CFCs with HFCs.
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92 marks
Briefly describe the polar vortex
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101 mark
Briefly outline how volcanic eruptions can contribute to ozone depletion in the stratosphere.
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15 marks
Depletion of the ozone layer by CFCs is an example of positive feedback.
Explain how.
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23 marks
Explain how naturally occurring stratospheric ozone destruction and reformation is an example of negative feedback.
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33 marks
Complete the table below to outline three possible strategies for reducing the impacts of ozone-depleting substances (i.e. one strategy for each stage of pollution management).
Stage of Pollution Management | General Description | Strategy for Reducing Impacts of Ozone Depleting Substances (ODSs) |
|---|---|---|
1 | Manage the human activity producing the pollutant(s) | |
2 | Manage the release of the pollutant(s) | |
3 | Manage the long-term impact of the pollutant(s) on the ecosystem |
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44 marks
For years, scientists have been engaging in discussions regarding the "ozone hole" located in the upper atmosphere over the Antarctic region.
The graph below shows the changes in the ozone concentration at Halley Bay in the Antarctic since 1955.
A Dobson unit is a measure of the total amount of ozone in the atmosphere at a particular place.
Describe the trend in ozone levels shown in the graph above.
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54 marks
Outline the potential effects of ozone depletion on living systems.
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64 marks
Outline two methods for reducing the manufacture and release of ozone-depleting substances, as part of pollution management to mitigate ozone depletion.
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73 marks
Outline the alternatives to air conditioning that can reduce heat indoors.
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85 marks
Explain how chlorine from CFCs leads to ozone depletion.
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92 marks
Explain why ozone depletion is more severe during polar spring.
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103 marks
Suggest why the Antarctic ozone hole is larger than the Arctic ozone hole.
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114 marks
Chlorofluorocarbons (CFCs) were widely used as refrigerants and aerosol propellants until their environmental impact became apparent. Following international agreements, many countries replaced CFCs with hydrofluorocarbons (HFCs) as alternatives.
The graph below shows the atmospheric concentrations of CFC-11 and HFC-134a measured at a monitoring station from 1990 to 2020.
Concentrations are measured in parts per trillion (ppt) in the atmosphere.
Awaiting image: Graph showing atmospheric concentrations of CFC-11 and HFC-134a from 1990 to 2020.
Describe the trends in atmospheric concentrations of both compounds shown in the graph above.
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17 marks
Explain the processes that can lead to the depletion of ozone in the upper atmosphere.
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27 marks
Explain how the Montreal Protocol has contributed to the recovery of the ozone layer.
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39 marks
Evaluate the role of national and international organisations in reducing the emissions of ozone-depleting substances.
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47 marks
Explain the environmental and economic impacts of replacing CFCs with HFCs.
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