Interdependence within ecosystems

Biology · Ecosystems

What is in an ecosystem?

Sort each part of this ecosystem: is it biotic (living) or abiotic (non-living)?

9 of 9 still to sort.

An ecosystem can be very large or very small. A bottle garden counts.

What you need to know

• An ecosystem is all the living organisms in a place, interacting with each other and with their non-living surroundings.
• The living (biotic) parts form communities of interacting populations. Non-living (abiotic) parts include soil, rocks, water, air and light.
• Have a goIs the air in a wood part of its community? Answer yes or no, then name the word for non-living parts.

  No. Air is abiotic (non-living); a community is only the living organisms.

  A community is all the interacting populations of different organisms in an area, so air, like soil, rocks, water and light, belongs to the abiotic part of the ecosystem.

• Ecosystems come in all sizes, from very large to very small, like a bottle garden.
• Organisms in an ecosystem are interdependent: they depend on each other for what they need to survive, and food is one example.
• A producer makes its own food from water and carbon dioxide, using light, in a process called photosynthesis.
• Have a goYour friend says: 'Grass is a consumer, because it is always getting eaten.' Politely fix the mistake.

  Grass is a producer: it makes its own food from water and carbon dioxide, using light.

  Being eaten does not make something a consumer. Producers make their own food by photosynthesis; consumers get theirs by eating.

• Food chains begin with a producer. Consumers eat producers or other consumers, so every organism in the chain relies on the producer.
• Organisms use food and oxygen in respiration, which makes water and carbon dioxide and provides energy for life processes.
• Producers release oxygen and take in the carbon dioxide and water that organisms release, forming a cycle of materials.
• Dead organisms and waste are food for others: scavengers, like vultures, eat dead animals, then decomposers break down what is left.
• Have a goA vulture feeds on a dead animal. Is it a scavenger or a decomposer, and who deals with what is left?

  A scavenger. Decomposers break down what is left.

  Scavengers are animals that feed on dead animals. They do not finish the job: what they leave is eaten and broken down by decomposers.

• Decomposers, such as fungi and bacteria, return essential chemicals like nitrates to the soil for producers to use to grow healthily.

The big picture

Organisms in an ecosystem depend on each other: producers make food, consumers eat it, and decomposers break down dead material and waste and return chemicals that producers need.

⚠ Watch out

Thinking a food chain stops at the top consumer and decomposers are just clean-up. A decomposer feeding on a dead consumer is itself a consumer, and decomposers return essential chemicals to the soil that producers need to grow.

Memory hook

A loop, not a ladder: food goes up the chain, and the dead and the waste come back round.

Check yourself

Cover the screen and tell the loop in your own words, starting at the producers and going all the way back round to the producers. Which stage was hardest to remember?