Edexcel IGCSE Biology

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4.1 Population, Community, Habitat & Ecosystem

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Key Terms in Ecology

  • There are several key terms that we use when referring to the various different components of an ecosystem and their levels of organisation:
    • A population is defined as a group of organisms of the same species living in the same place at the same time
    • A community includes all of the populations living in the same area at the same time
      • Within a community, each species depends on other species for food, shelter, pollination, seed dispersal etc
      • If one species is removed it can affect the whole community
      • This is called interdependence

    • A habitat is the place where an organism lives
      • E.g. badgers, deer, oak trees and ants are all species that would live in a woodland habitat

    • An ecosystem is defined as all the biotic factors and all the abiotic factors that interact within an area at one time
      • The term 'biotic factors' includes all the living components such as plants and animals
      • The term 'abiotic factors' includes all the non-living components such as light intensity, mineral ions, water availability
      • Ecosystems can vary greatly in size and scale
        • A small ecosystem might be a garden pond
        • A large ecosystem might be the whole of Antarctica

Levels of Organisation in an Ecosystem, IGCSE & GCSE Biology revision notes

Levels of organisation in an ecosystem

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