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4 Ecology and the Environment

This topic area moves outward from organisms to ecosystems. It connects populations, feeding relationships, material cycles and human environmental impact into one ecological picture.

Core Role

  • Define the main ecological levels of organisation and the factors that affect them.
  • Explain how substances and energy move through food chains and food webs.
  • Connect biodiversity and environmental change to human decisions and conservation choices.

Topic Pages

  • 4a The Organism in the Environment: Ecology begins by naming the levels at which organisms interact with their surroundings. It then moves into ways of measuring populations and biodiversity in real habitats. 3 learning objectives.
  • 4b Feeding Relationships: Feeding relationships show how matter and energy move through ecosystems. The main emphasis is on trophic levels, the meaning of food chains and food webs, and why only a small fraction of energy is transferred onwards. 3 learning objectives.
  • 4c Cycles within Ecosystems: Matter is continually recycled through ecosystems rather than used once and lost. The important cycles here are the carbon cycle and the nitrogen cycle. 2 learning objectives.
  • 4d Human Influences on the Environment: Human activity can alter ecosystems by changing gases, nutrients, water quality and land cover. The topic is mainly about tracing cause and effect from human action to biological consequence. 4 learning objectives.