In short
An ecosystem is a community of living things together with the non-living environment they interact with, such as soil, water, air and sunlight.
The biotic parts are the living organisms, and the abiotic parts are the non-living ones. Energy flows through an ecosystem in one direction, from the Sun to producers to consumers, while nutrients such as carbon and nitrogen are recycled. Examples are a pond, a forest, a grassland and a coral reef. A change in one part, such as removing a predator, can affect all the others.
In a pond, the abiotic parts are water, light and dissolved oxygen. The biotic parts include algae, water plants, insects, fish and bacteria.
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