Question

Which of the following best defines an ecosystem?

• A. A collection of all plant species in an area
• B. A whole community of organisms and its environment as one unit
• C. Only the physical surroundings of living beings
• D. A group of organisms of the same species living together

Answer 1

Answer:

B. A whole community of organisms and its environment as one unit

Understanding Ecosystems for Competitive Exams

• An Ecosystem is a fundamental ecological unit comprising a community of living organisms (biotic components) interacting with their non-living physical environment (abiotic components) as a single, interdependent system.

• Key Components of an Ecosystem:

  • Biotic Components: These are the living parts of the ecosystem and include:
    • Producers (Autotrophs): Organisms like plants and algae that produce their own food through photosynthesis (e.g., green plants, phytoplankton).
    • Consumers (Heterotrophs): Organisms that obtain energy by consuming other organisms. They are further categorized as primary (herbivores), secondary (carnivores eating herbivores), and tertiary consumers (carnivores eating other carnivores).
    • Decomposers (Detritivores): Organisms like bacteria and fungi that break down dead organic matter, recycling nutrients back into the ecosystem.
  • Abiotic Components: These are the non-living physical and chemical factors that influence the organisms in an ecosystem. Examples include:
    • Sunlight
    • Water
    • Temperature
    • Soil
    • Atmospheric gases (oxygen, carbon dioxide)
    • Nutrients (nitrogen, phosphorus)
    • pH levels

• Key Processes within an Ecosystem:

  • Energy Flow: Energy primarily originates from the sun and flows unidirectionally through the ecosystem from producers to consumers and decomposers. This is often represented by food chains and food webs.
  • Nutrient Cycling (Biogeochemical Cycles): Essential nutrients like carbon, nitrogen, phosphorus, and water are continuously cycled through the biotic and abiotic components of the ecosystem (e.g., Carbon Cycle, Nitrogen Cycle).

• Historical Context and Terminology:

  • The term 'Ecosystem' was first coined by the British botanist Sir Arthur George Tansley in 1935.
  • The study of the interactions between organisms and their environment is known as Ecology.
  • A Biome is a large naturally occurring community of flora and fauna occupying a major habitat, e.g., forest or tundra. It is a much larger scale than an ecosystem.
  • An Ecotone is a transition area between two different biomes or ecosystems, often exhibiting characteristics of both and having high biodiversity.

• Examples of Ecosystems:

  • Terrestrial Ecosystems: Forests, deserts, grasslands, tundras.
  • Aquatic Ecosystems: Ponds, lakes, rivers, oceans, estuaries, coral reefs.
• Ecosystems can vary greatly in size, from a small puddle to an entire ocean or a vast forest, but they all share the fundamental characteristic of interdependent biotic and abiotic components.