Year 8 Science · Unit 1 · Lesson 19
Apply Worksheet
Learning Goals
Match each word to its meaning
Write the matching letter in the middle column. Each letter is used once.
| Word | Letter | Meaning |
|---|---|---|
| Ecosystem | A. A non-living part of an area, such as temperature, wind or rainfall. | |
| Biotic factor | B. Breaks down dead plants and animals and returns nutrients to the soil. | |
| Abiotic factor | C. Makes its own food, usually using energy from sunlight. | |
| Producer | D. Cannot make its own food, so it eats other organisms. | |
| Consumer | E. All the living and non-living things in an area, interacting as one system. | |
| Decomposer | F. Any living part of an area, including tiny ones such as bacteria and plankton. |
Odd one out
In each row, circle the one that does not belong. Give a reason.
| Row | Group | Odd one out and reason |
|---|---|---|
| 1 | sunlight · rainfall · mushroom · soil pH | |
| 2 | kangaroo · algae · grass · gum tree | |
| 3 | fungus rotting a log · lizard eating a beetle · bacteria breaking down dead leaves · mould on a dead mouse |
Name the role and give the evidence
When the tide goes out on a rocky NSW shore, pools of sea water are left behind. For each organism found in one rock pool, write its role and the clue that told you.
| Organism | Producer, consumer or decomposer? | Clue that told you |
|---|---|---|
| An octopus catching and eating a crab | ||
| Neptune’s necklace, a brown seaweed that grows using sunlight | ||
| Bacteria breaking down a dead fish | ||
| A periwinkle snail scraping algae off the rocks |
Scenario: a farm dam in a drought
A farmer recorded the rainfall and the depth of water in her dam each month. At dusk on the first day of each month, she stood by the dam for 5 minutes and counted the frogs she heard calling.
| Month | Rainfall (mm) | Water depth (cm) | Frogs heard calling in 5 minutes |
|---|---|---|---|
| September | 42 | 150 | 24 |
| October | 18 | 128 | 20 |
| November | 9 | 95 | 13 |
| December | 4 | 60 | 6 |
| January | 2 | 30 | 2 |
Source: sample farm records.
1. Which columns of Table 1 record abiotic factors, and which records a biotic factor? By how many centimetres did the water depth fall from September to January?
2. Describe the link between water depth and the number of frogs calling. Suggest one reason for it.
3. A student says: “The drought only affects the water, because water is non-living.” Use Table 1 and the idea of consumers to explain why the student is wrong. Include one animal that eats frogs.
4. A student says: “Decomposers are the least important role in an ecosystem, because they only eat things that are already dead.” Do you agree or disagree? Justify your answer.
Match each word to its meaning
Ecosystem → E; Biotic factor → F; Abiotic factor → A; Producer → C; Consumer → D; Decomposer → B.
Odd one out
Row 1: mushroom (living, a biotic factor; the others are abiotic). Row 2: kangaroo (a consumer; the others are producers). Row 3: lizard eating a beetle (a consumer; the others are decomposers).
Name the role and give the evidence
Octopus: consumer; it eats another organism (the crab). Neptune’s necklace: producer; it makes its own food using sunlight. Bacteria: decomposer; they break down dead matter (the dead fish). Periwinkle: consumer; it eats algae.
Go Deeper
1. Abiotic: rainfall and water depth. Biotic: frogs heard calling. 150 − 30 = 120 cm. [2 marks: 1 classification, 1 calculation]
2. As the water depth fell, fewer frogs called (24 at 150 cm down to 2 at 30 cm). Reason, any one: frogs need water to breed and to keep their skin moist; with less water there is less habitat and less food. [2 marks: 1 link, 1 reason]
3. Frogs are living consumers, and the observed calling activity fell as the water depth fell (24 calls at 150 cm to 2 calls at 30 cm), so the abiotic change affected a biotic activity. Snakes or herons are consumers that eat frogs. The table measures calls, not population size, so it cannot show whether frog abundance or predators’ food supply changed. [3 marks: 1 frog-call data, 1 predator named, 1 limit of the evidence]
Show What You Know
4. Marking guide (points expected): 1 disagree; 1 decomposers (bacteria and fungi) break down dead plants and animals; 1 they return nutrients to the soil; 1 producers need these nutrients to grow, and consumers depend on producers; 1 without decomposers dead matter would pile up, nutrients would stay locked away and the ecosystem would run down. [5 marks]
Common error to watch for: treating decomposers as “clean-up” only. Their key job is recycling nutrients that producers need.