Year 7 Science · Unit 1 · Lesson 13

Producers, Consumers, Decomposers

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Learning Goals

Describe the steps of the nutrient cycle through decomposition in the correct order.
Trace the effects of losing decomposers through a cause-and-effect chain.
Use scientific vocabulary to explain how decomposers support ecosystem function.

Warm Up

Order the steps

Number the events from 1 to 6 to show the correct order of nutrient cycling through decomposition. Event 1 = what happens first.

Order	Event
	Plant roots absorb the simple nutrients from the surrounding soil.
	Fungi and bacteria colonise the surface of the dead leaf and begin to grow.
	The absorbed nutrients are incorporated into new plant tissue (leaves, stems, roots).
	A leaf falls from a gum tree onto the forest floor.
	Enzymes produced by the decomposers break complex molecules in the leaf into simple nutrients.
	Simple nutrients (nitrogen, phosphorus, potassium) are released into the surrounding soil.

Your Turn

Because… chain

Fill in the missing effects. Each cause leads to the next step in the chain. Use scientific vocabulary from this lesson.

A fungal disease kills all the decomposers in a patch of Australian bush.

→

Dead leaves, fallen branches and animal bodies pile up on the forest floor without breaking down.

→

Plants (producers) can no longer absorb enough nutrients from the soil and begin to weaken and die.

→

Herbivores lose their food source and consumer populations across the ecosystem collapse.

Overall outcome:

Show What You Know

1. A scientist finds that a patch of forest soil contains far fewer bacteria and fungi than a healthy forest nearby. Predict what effect this would have on plant growth in that patch. Explain your reasoning using the idea of nutrient cycling.

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2. A magpie eats both insects and berries. A crow eats the carcass of a dead kangaroo. Using the correct scientific terms, classify each animal (e.g. herbivore, carnivore, omnivore, detritivore, decomposer) and explain why neither is a decomposer.

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Wrap Up

In one sentence, what was the main idea of this lesson?