Lesson Notes By Weeks and Term v5 - Grade 12
Human impact on the environment (Grade 12 focus) and examination preparation – Week 7 focus
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Human impact on the environment (Grade 12 focus) and examination preparation – Week 7 focus
Download the Lessonotes Mobile South Africa app for faster lesson access on Android and iPhone.
Subject: Life Sciences
Class: Grade 12
Term: Term 4
Week: 7
Theme: General lesson support
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This week we delve into the profound and often devastating impact that human activities have on our environment. Understanding this impact is crucial, not just for doing well in your exams, but also for becoming informed and responsible citizens who can contribute to a sustainable future, especially within the South African context. South Africa, with its rich biodiversity and unique ecosystems, is particularly vulnerable to environmental degradation. Issues like water scarcity, air pollution from mining and industrial activities, and the impact of climate change on our agriculture are very real challenges we face daily.
2. 1. Pollution Pollution refers to the contamination of the environment by harmful substances.
It manifests in various forms: Water Pollution: This occurs when harmful substances contaminate water bodies such as rivers, lakes, and oceans.
Causes: Industrial discharge (e.g., toxic chemicals from factories), agricultural runoff (e.g., fertilizers and pesticides), sewage disposal, oil spills, and mining activities (acid mine drainage).
Consequences: Eutrophication (excessive nutrient enrichment leading to algal blooms and oxygen depletion, harming aquatic life), contamination of drinking water sources, spread of waterborne diseases, and destruction of aquatic ecosystems. South African
Example: Acid mine drainage from abandoned gold mines in the Witwatersrand region pollutes rivers and groundwater, impacting water availability and quality for communities downstream.
Air Pollution: This involves the release of harmful substances into the atmosphere.
Causes: Burning of fossil fuels (coal, oil, and gas) in power plants and vehicles, industrial emissions, mining activities (dust particles), and burning of waste.
Consequences: Respiratory problems (asthma, bronchitis), acid rain (damaging ecosystems and infrastructure), climate change (greenhouse gas emissions), and reduced visibility. South African
Example: High levels of particulate matter (PM2.5 and PM10) in industrial areas like Secunda, Mpumalanga, due to coal-fired power plants, leading to respiratory illnesses in local communities.
Land Pollution: This refers to the contamination of soil and land resources.
Causes: Improper waste disposal (landfills), agricultural practices (pesticide and fertilizer use), industrial waste, mining activities (toxic waste), and deforestation.
Consequences: Soil degradation (loss of fertility), contamination of groundwater, accumulation of toxic substances in the food chain, and habitat destruction. South African
Example: Illegal dumping of waste in informal settlements and along roadsides, leading to soil contamination and health risks for residents. 2.
2. Deforestation Deforestation is the clearing of forests for other land uses, such as agriculture, urbanization, and mining.
Causes: Agricultural expansion (cattle ranching, crop cultivation), logging (timber production), mining activities, infrastructure development, and fuelwood collection.
Consequences: Loss of biodiversity (habitat destruction), soil erosion, climate change (reduced carbon sequestration), disruption of water cycles, and increased flooding. South African
Example: Deforestation in KwaZulu-Natal for sugarcane farming and timber plantations, leading to soil erosion and loss of indigenous forest ecosystems. 2.
3. Loss of Biodiversity Biodiversity refers to the variety of life on Earth, including genetic diversity, species diversity, and ecosystem diversity. Loss of biodiversity is the decline in the number and variety of species and ecosystems.
Causes: Habitat destruction (deforestation, urbanization), pollution, climate change, overexploitation of resources (overfishing, hunting), and invasive species.
Consequences: Disruption of ecosystem services (pollination, water purification), increased vulnerability to diseases, reduced resilience to environmental changes, and loss of potential resources (medicines, food). South African
Example: Poaching of rhinos for their horns, driven by international demand, is a major threat to rhino populations in South Africa. The expansion of agriculture and urban areas further reduces available habitat. 2.
4. Climate Change Climate change refers to long-term changes in temperature and weather patterns, primarily caused by human activities that release greenhouse gases into the atmosphere.
Greenhouse Effect: Greenhouse gases (carbon dioxide, methane, nitrous oxide) trap heat in the Earth's atmosphere, warming the planet. Increased concentrations of these gases due to human activities enhance the greenhouse effect, leading to global warming.
Causes: Burning of fossil fuels (coal, oil, and gas) for energy production, deforestation (reduced carbon sequestration), industrial processes, and agriculture (methane emissions from livestock).
Consequences: Rising global temperatures, melting glaciers and ice sheets, rising sea levels, changes in precipitation patterns (droughts and floods), more frequent and intense extreme weather events (heat waves, storms), and disruptions to ecosystems and agriculture. South African
Example: Increased frequency and severity of droughts in the Western Cape, impacting agriculture and water availability for urban areas like Cape Town. Rising sea levels threaten coastal communities and ecosystems. 2.
5. Examination Preparation: Analysis and Evaluation Questions The Grade 12 Life Sciences exam often includes questions that require you to analyze data, evaluate scenarios, and propose solutions related to human impact on the environment.