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KS4 Humans Impact On The Environment
Learning Objectives

7.2.2. How materials are cycled (NB: Students are not expected to study the nitrogen cycle.)

Students should:

• Be able to recall that many different materials cycle through the abiotic and biotic components of an ecosystem
• Be able to explain the importance of the carbon and water cycles to living organisms.
• Know that all materials in the living world are recycled to provide the building blocks for future organisms.
• Know that the carbon cycle returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis.
• Know that the water cycle provides fresh water for plants and animals on land before draining into the seas, where water is continuously evaporated and precipitated.
• Be able to explain the role of microorganisms in cycling materials through an ecosystem by returning carbon to the atmosphere as carbon dioxide and mineral ions to the soil.
• Be able to interpret and explain the processes in diagrams of the carbon cycle and the water cycle.

7.2.3 Decomposition

Students should:

• Be able to explain how temperature, water and availability of oxygen affect the rate of decay of biological material.
• Know that gardeners and farmers try to provide optimum conditions for rapid decay of waste organic matter and that the compost produced is used as a natural fertiliser for growing garden plants or crops.
• Know that anaerobic decay produces methane gas.
• Know that Biogas generators can be used to produce methane gas as a fuel.
• Be able to calculate rate changes in the decay of organic matter; and translate information between numerical and graphical form and plot and draw appropriate graphs selecting appropriate scales for the axes.

7.2.4 Impact of environmental change

 Students should:

• Be able to evaluate the impact of environmental changes on the distribution of species in an ecosystem given appropriate information.
• Know that environmental changes such as availability of water, temperature and atmospheric gases affect the distribution of species in an ecosystem and that these changes may be seasonal, geographic or caused by human interaction.

7.3.1 Biodiversity

Students should:

• Know that Biodiversity is the variety of all the different species of organisms on earth, or within an ecosystem.
• Know that a great biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment.
• Know that the future of the human species on Earth relies on us maintaining a good level of biodiversity.
• Know that many human activities are reducing biodiversity and only recently have measures been taken to try to stop this reduction.
• Be able to explain how waste, deforestation and global warming have an impact on biodiversity.

7.3.2 Waste management

Students should:

• Know that a rapid growth in the human population and an increase in the standard of living mean that increasingly more resources are used and more waste is produced.
• Know that unless waste and chemical materials are properly handled, more pollution will be caused.
• Know that pollution can occur:

• in water, from sewage, fertiliser or toxic chemicals
• in air, from smoke and gases such as sulphur dioxide, which contributes to acid rain
• on land, from landfill and from toxic chemicals such as pesticides and herbicides, which may be washed from land into water.

• Know that pollution kills plants and animals which can reduce biodiversity.

7.3.3 Land use

Students should:

• Know that humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste.
• Know that the destruction of peat bogs, and other areas of peat to produce garden compost, reduces the area of this habitat and thus the variety of different plant, animal and microorganism species that live there (biodiversity).
• Know that the decay or burning of the peat releases carbon dioxide into the atmosphere.
• Recognise the conflict between the need for cheap available compost to increase food production and the need to conserve peat bogs and peatlands as habitats for biodiversity and to reduce carbon dioxide emissions.

7.3.4 Deforestation

Students should:

• Know that large-scale deforestation in tropical areas has occurred to:
  - provide land for cattle and rice fields to provide more food
  - grow crops from which biofuels, based on ethanol, can be produced
• Know that destruction of large areas of trees has:
  - increased the release of carbon dioxide into the atmosphere (because of burning and the activities of microorganisms)
  - reduced the rate at which carbon dioxide is removed from the atmosphere by photosynthesis and ‘locked up’ in wood for hundreds of years
  - led to reduction in biodiversity of both plant species and the animals that live there.
• Evaluate the environmental implications of deforestation.

7.3.5 Global warming

Students should:

• Know that levels of carbon dioxide and methane in the atmosphere are increasing, and contribute to ‘global warming’.
• Know that biological consequences of global warming include:
  - loss of habitat when low-lying areas are flooded by rising sea levels
  - changes in the distribution of species in areas where temperature or rainfall has changed
  - changes to the migration patterns of animals

7.3.6 Maintaining biodiversity

Students should:

• know that scientists and concerned citizens have put in place programmes to reduce these negative effects on ecosystems and biodiversity, including:
  - breeding programmes for endangered species
  - protection and regeneration of rare habitats such as coral reefs, mangroves, and heathland
  - reintroduction of field margins and hedgerows in agricultural areas where farmers grow only one type of crop
  - reduction of deforestation and carbon dioxide emissions by some governments
  - recycling resources rather than dumping waste in landfill.
• Be able to evaluate given information about methods that can be used to tackle problems caused by human impacts on the environment.
• Be able to explain and evaluate the conflicting pressures on maintaining biodiversity given appropriate information.

Required practical 10: investigate the effect of temperature on the rate of decay of fresh milk by measuring pH change.

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