Year 7 Science · Unit 1 · Lesson 13
Challenge Worksheet
Learning Goals
Find the mistake
A student wrote this answer
"Decomposers are the least important part of an ecosystem because they only eat dead things. Producers and consumers are more important because they are alive and part of the food chain. If decomposers disappeared, we would just have more dead matter on the forest floor, but the ecosystem would recover quickly because producers make their own food anyway."
1. Identify at least two scientific mistakes in the student's answer. List each one clearly.
2. Rewrite the student's answer so that it is scientifically correct. Your rewritten version must explain why decomposers are essential, not just state that they are.
3. Explain why this type of misunderstanding about decomposers is so common among students. What makes it easy to underestimate their importance?
1. A scientist studying Daintree Rainforest in Queensland measures nutrient levels in soil samples taken before and after a flood that washed away most of the topsoil — the layer richest in decomposers. Using your knowledge of nutrient cycling, explain what you would expect to happen to the plant community in that area over the following months, and why.
2. Producers make their own food, so why do they still depend on decomposers to survive? Construct an argument in 3–4 sentences that links nutrient cycling, soil fertility and producer growth. Use at least three scientific terms from this lesson.
Wrap Up
In one sentence, what was the main idea of this lesson?