Ecology — Life and Its Environment

Ecology studies the interactions among organisms and between organisms and their physical environment. It operates at every scale, from a single population to the entire biosphere.

Levels of Organisation

• Organism → Population → Community → Ecosystem → Biosphere.

Key Concepts

• Energy flow and trophic levels.
• Nutrient cycles — carbon, nitrogen, phosphorus, water.
• Carrying capacity and limiting factors.
• Biodiversity, extinction and conservation biology.