Which of the following is not correct about ecosystem?

The correct answer is C. An ecosystem is an open system, not a closed one. Energy enters from the sun and leaves as heat, and water, nutrients and organisms move across its boundary. Energy flows one way, while matter cycles within the system. A closed system would exchange neither matter nor energy with its surroundings, and no real ecosystem does that.

Why the other options are acceptable:

• A: An ecosystem has abiotic components (soil, water, air, temperature, sunlight) and biotic components (producers, consumers, decomposers). Tansley's 1935 concept rests on this interaction.
• B: Ecosystems have their own productivity, primary by autotrophs and secondary by heterotrophs, measured as energy or biomass per unit area per unit time.
• D: The wording is poor, but ecosystems and their services are commonly treated as natural resources in the environment chapter, so this is not the intended wrong statement.

Core concept: ecosystem structure and function, covering energy flow, nutrient cycling and productivity. For Mains, this connects to ecosystem services valuation and the carrying capacity debate.

Trap: Candidates confuse "self-sustaining" with "closed." An ecosystem recycles matter internally but still exchanges energy and matter with its surroundings.