Form 5 · Paper 2 essay guide

Environmental Sustainability, Paper 2 essay guide

How Environmental Sustainability appears in Paper 2 essays: themes, a planning grid, a model answer structure and the keyword list.

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Essay themes this chapter supports

Explaining threats to the environment and their specific causes and effects: Name a specific human activity and link it to a specific pollutant. → Explain the greenhouse effect and distinguish natural warming from global warming. → Describe the stages of eutrophication from nutrient runoff to fish death. → Explain how CFCs cause ozone layer depletion and its effect on humans. → Use BOD data to compare the pollution level of two water samples.
Distinguishing preservation, conservation and restoration with named examples: Define each of the three terms precisely. → Give one named example of each, such as a strict reserve, a fishing quota and a replanting project. → Explain how a single protected area can contain more than one of these approaches in different zones. → Avoid describing an area only as 'protected' without naming the specific approach used.
Discussing sustainable development and sustainable practices: Explain the three pillars sustainable development balances: economic, social and environmental. → Name a sustainable practice in forestry, fishing or agriculture and explain its mechanism. → Explain the 3R principle and how it reduces resource extraction and waste. → Link a named practice to the specific resource it protects.
Evaluating green technology and Environmental Impact Assessments: Name a specific green technology and explain how it reduces environmental harm. → Compare a named renewable energy source with a fossil fuel alternative, including its limitations. → Explain the purpose of an EIA and why it is carried out before project approval. → State that no technology, including renewable energy, is entirely free of environmental impact.

How to structure your essay

Open with one or two sentences that define the topic and set the scope.
Devote one paragraph to each key concept, in a logical order.
Use precise biological terms and, where relevant, a labelled diagram.
Give an example or state where the process happens in the body or plant.
Close by linking the ideas back to the question.

Planning grid

Question	Answer
Introduction	State what the question asks and define the key term it uses, such as 'sustainable development', 'green technology' or 'BOD', in one sentence.
Point 1	Name the specific activity, pollutant, technology or practice involved, and state what it is.
Point 2	Explain the mechanism or process the question asks about, such as how a pollutant causes its effect or how a technology reduces harm.
Point 3	Support the answer with a named, concrete example, such as a specific renewable energy source or protected area.
Conclusion	Link the explanation back to the wider goal, such as reduced pollution, protected biodiversity, or sustainable development.

Key terms to include

air pollution
greenhouse effect
global warming
biochemical oxygen demand
eutrophication
ozone layer depletion
preservation
conservation
restoration
sustainable development
green technology
renewable energy
Environmental Impact Assessment
3R principle
acid rain

A model essay outline

Threats to the environment, Human activities such as burning fossil fuels, deforestation and improper waste disposal cause air, water and land pollution, alongside a rise in greenhouse gases that drives global warming. Each threat has a distinct cause, so an exam answer should name a specific activity and its specific effect rather than describing pollution in general terms. Open burning and vehicle exhaust, for example, are two separate sources of air pollution with different pollutants and different control measures.
Greenhouse effect and global warming, Greenhouse gases such as carbon dioxide and methane trap heat in the atmosphere that would otherwise escape into space, a natural effect that keeps Earth warm enough for life. Human activities release extra greenhouse gases, trapping more heat and raising the average global temperature, which is global warming.
Biochemical oxygen demand (BOD), BOD measures how much oxygen microorganisms use to break down the organic matter in a water sample over a set time. A high BOD value means the water contains a lot of organic pollution, since more oxygen is used up, leaving less available for fish and other aquatic organisms. Comparing BOD values upstream and downstream of a discharge point is a common way to judge how much a specific source has polluted a river.
Preservation, conservation and restoration, Preservation protects an area of nature and keeps it untouched by human use, such as a strict nature reserve. Conservation manages the wise, sustainable use of a resource so it is not exhausted, such as controlled fishing. Restoration actively repairs an ecosystem that has already been damaged, such as replanting a cleared forest.
Green technology, Green technology reduces environmental harm compared with older methods, including renewable energy, recycling processes and cleaner production methods that release less pollution. Choosing a green technology usually involves weighing its environmental benefit against its cost and how practical it is to adopt widely. An electric vehicle, for example, produces no exhaust emissions itself, though the source of the electricity used to charge it also matters.

Frequently asked questions

What is the difference between preservation and conservation?

Preservation means protecting a natural area and keeping it untouched by human use, for example a strict nature reserve. Conservation means using and managing natural resources carefully and sustainably so they are not used up, for example controlled fishing or selective logging. Preservation avoids use; conservation allows wise use.

What does biochemical oxygen demand (BOD) tell us?

Biochemical oxygen demand is the amount of oxygen that microorganisms use to break down the organic matter in a sample of water over a set time. A high BOD means there is a lot of organic pollution, because the microorganisms use a lot of oxygen, which can leave too little for fish and other aquatic life. Cleaner water has a low BOD.

How does the greenhouse effect cause global warming?

Greenhouse gases such as carbon dioxide and methane in the atmosphere trap some of the heat that would otherwise escape to space, keeping the Earth warm enough for life. When human activities release extra greenhouse gases, more heat is trapped, and the average global temperature rises. This is global warming, which changes climates and sea levels.