Year 9 Science · Unit 2 · Lesson 19
Challenge Worksheet
Learning Goals
1. Explain why an apex predator is the organism most at risk from a pollutant that biomagnifies.
Someone claims…
“Microplastics aren’t a serious problem for Australia. The Great Pacific Garbage Patch is in the North Pacific, far away from us. Anyway, UV light breaks plastic down until it disappears. And microplastics only end up in fish guts, which we throw away, so they never get into people.”
2. The claim makes three errors. For each one, explain what the evidence actually shows. You may use Table 1 below.
Read the data
| Measurement | Result |
|---|---|
| Great Pacific Garbage Patch (North Pacific Ocean) | |
| Area of the patch | 1.6 million km² |
| Mass of floating plastic | about 79 000 tonnes |
| Number of pieces | about 1.8 trillion |
| Share that are microplastics (under 5 mm) | 94% of the pieces, but 8% of the mass |
| Share of the mass that is fishing nets | at least 46% |
| Cocos (Keeling) Islands (Australian territory, Indian Ocean) | |
| Pieces of plastic on the beaches | about 414 million, weighing 238 tonnes |
| Share buried up to 10 cm below the surface | 93% |
| Items found | about 977 000 shoes and 373 000 toothbrushes |
Sources: Lebreton, L. and others (2018), Scientific Reports 8, article 4666; Lavers, J. L. and others (2019), Scientific Reports 9, article 7102. Area of New South Wales: about 800 000 km² (Geoscience Australia).
3. Use Table 1 to calculate: (a) how many times larger the patch is than New South Wales; (b) the mass of microplastics in the patch, in tonnes; (c) the number of pieces on Cocos beaches that are buried.
4. A news headline reads: “Giant island of plastic in the Pacific is now twice the size of NSW.” Use your answers to Question 3 and Table 1 to explain what is accurate and what is misleading about this headline.
Scenario: do the particles biomagnify?
A research group sampled three animals from one food chain. They counted plastic particles in each animal’s tissue and also measured a chemical pollutant, X, that the particles carry.
| Animal | Microplastic particles per g of tissue | Pollutant X (ng per g of tissue) |
|---|---|---|
| Zooplankton | 0.8 | 5 |
| Small fish | 0.3 | 40 |
| Tuna | 0.05 | 300 |
Sample data, made up for this question.
5. A student concludes: “Table 2 proves that microplastic particles biomagnify.” Evaluate this conclusion using both columns. Suggest why the two columns show different patterns.
6. Evaluate the claim: “Beach clean-ups, like those on the Cocos (Keeling) Islands, can solve Australia’s plastic pollution problem.” Use Table 1 and what you know about photodegradation and food chains.