Ecosystem and its components
An ecosystem is all the living organisms of an area together with the non-living parts of their environment. Producers, consumers and decomposers keep it working.
What is an ecosystem?
All the living organisms in an area, together with the non-living parts of their environment, form an ecosystem. The living parts are the biotic components: plants, animals and microorganisms. The non-living parts are the abiotic components: temperature, rainfall, wind, soil, water and minerals. The two interact all the time. Plants need sunlight, water and minerals, and animals depend on plants and on one another. A forest, pond or lake is a natural ecosystem. A garden, crop field or aquarium is a human-made (artificial) ecosystem.
Biotic components: how each group gets food
| Group | What they do | Examples |
|---|---|---|
| Producers | Make their own food from simple substances by photosynthesis, using sunlight | Green plants such as grass and paddy; blue-green algae |
| Herbivores (consumers) | Eat plants | Cow, goat, deer, grasshopper, rabbit |
| Carnivores (consumers) | Eat other animals | Tiger, snake, frog, eagle |
| Omnivores (consumers) | Eat both plants and animals | Human beings, crow, bear |
| Parasites (consumers) | Live on or inside another organism and feed on it | Lice, ticks, tapeworm |
| Decomposers | Break down dead plants, dead animals and waste into simple substances | Bacteria and fungi |
Why decomposers matter
Decomposers, mainly bacteria and fungi, break down the dead remains and waste of plants and animals into simple substances. These substances go back into the soil and are used again by plants. Without decomposers, dead matter would pile up and the soil would run short of nutrients. This is also why a pond stays clean on its own, while a home aquarium must be cleaned by hand. The pond has a full community, including decomposers, that recycles its waste.
A paddy field or a terrace kitchen garden is a human-made ecosystem: people choose the plants, but earthworms, bacteria and fungi still recycle the waste. A compost pit works only because of decomposers.
2 marks: “What are decomposers? What would happen if they disappeared from an ecosystem?” Bacteria and fungi that break down dead remains into simple substances. Without them, dead matter would pile up and the soil would not get its nutrients back.
2 marks: “A village pond never needs cleaning, but a home aquarium does. Explain why.” The pond is a complete natural ecosystem with decomposers that recycle waste. An aquarium is a human-made ecosystem without enough decomposers, so waste builds up.
3 marks: “What are the biotic and abiotic components of an ecosystem? Give two examples of each, and one example each of a natural and a human-made ecosystem.” Biotic: living, such as plants and bacteria. Abiotic: non-living, such as temperature and soil. Natural: forest; human-made: crop field.
Bio = life, a-bio = no life. Producers Prepare food, Consumers Consume it, Decomposers Dismantle what is left.