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Lesson · Grade 8 · Science

Microbes as Decomposers: Recycling Nutrients

  • Grade 8
  • Science
  • 1 min 33 s
  • British Columbia
  • BC8-SC-10

A fallen log on the forest floor is broken down in a time-lapse by bacteria and fungi, the main decomposers, which release nutrients such as nitrogen and phosphorus into the soil and water, where roots take them up so the same nutrients are recycled again and again. The same diagram then shows that without decomposers dead matter would pile up and its nutrients would stay locked away, so rot is not only harmful: it gives nutrients back to the soil.

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In one sentence

The question this lesson answers

A fallen log on the forest floor slowly disappears over the years. Where does it go?

The log and the fallen leaves are dead matter, the remains of living things.

Transcript

What the lesson says

A fallen log on the forest floor slowly disappears over the years. Where does it go?

The log and the fallen leaves are dead matter, the remains of living things.

Microbes, also called micro-organisms, live on the log. Most are too small to see without a microscope.

Bacteria and fungi are the main decomposers: living things that break down dead matter to get their food.

Over months and years, they digest the log and the leaves and break them down into simpler substances.

This releases nutrients, substances that plants need to grow, such as nitrogen and phosphorus, into the soil and water.

Plant roots take up these nutrients, and the plant uses them to grow.

When the plant dies, it is broken down too, and its nutrients are taken up again. The nutrients are recycled.

Without decomposers, dead matter would pile up, and its nutrients would stay locked away inside it.

The soil would run short of nutrients, and plants could not grow well.

So rot is not only harmful. Rotting is decomposition, and it gives nutrients back to the soil.

Decomposers, mainly bacteria and fungi, break down dead matter and recycle its nutrients for living things to use again.

Curriculum

Where this fits

British Columbia, Grade 8

Science, Biology: the relationship of micro-organisms with living thingsBC8-SC-10

Previous: Photosynthesis and Respiration: Two Halves of One CycleNext: Helpful and Harmful Microbes

The outcomes and strands follow the British Columbia curriculum.

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