Biology • Year 11 • Module 4 • Lesson 3
Food Chains and Food Webs
Lock in the vocabulary, arrow-direction rule, trophic level labels and the food-chain-vs-food-web distinction before moving to analysis.
1. Term–definition match
Each definition below matches one term from the lesson's Key Terms panel. Write the matching term in the right-hand column. Terms: food chain, food web, trophic level, apex predator, omnivore, resilience, producer, primary consumer, decomposer, detritivore. 10 marks
| # | Definition | Matching term |
|---|---|---|
| 1.1 | A linear sequence showing the transfer of energy and matter from one organism to the next through feeding. | |
| 1.2 | A network of interconnected food chains showing multiple feeding relationships in an ecosystem. | |
| 1.3 | The feeding position of an organism in a food chain (e.g. T1 = producer, T2 = primary consumer). | |
| 1.4 | A predator at the top of a food chain with no natural predators of its own. | |
| 1.5 | An organism that eats both producers and consumers, occupying multiple trophic levels. | |
| 1.6 | The ability of a food web to resist disruption when one species is removed or reduced. | |
| 1.7 | An autotroph that captures energy from the sun or inorganic chemicals; occupies trophic level 1. | |
| 1.8 | A herbivore that feeds directly on producers; occupies trophic level 2. | |
| 1.9 | An organism (e.g. fungus, bacterium) that breaks down dead organic matter by secreting enzymes and absorbing nutrients. | |
| 1.10 | An organism (e.g. earthworm, woodlouse) that physically ingests and fragments dead organic matter. |
2. Arrow direction — correct or incorrect?
Each food chain below either follows the correct arrow convention or contains the single most common error. For each chain, write Correct or Incorrect. If incorrect, rewrite the chain with arrows pointing in the right direction. 8 marks (1 per chain: 0.5 for verdict, 0.5 for correction where needed)
2.1 grass → grasshopper → frog → snake → hawk
Verdict: _______________
2.2 hawk → snake → frog → grasshopper → grass
Verdict: _______________
2.3 phytoplankton → zooplankton → small fish → barramundi → saltwater crocodile
Verdict: _______________
2.4 saltwater crocodile → barramundi → small fish → zooplankton → phytoplankton
Verdict: _______________
2.5 aquatic plants → water snails → great egret
Verdict: _______________
2.6 great egret → water snails → aquatic plants
Verdict: _______________
2.7 eucalyptus leaves → koala → dingo
Verdict: _______________
2.8 dingo → koala → eucalyptus leaves
Verdict: _______________
3. Label the trophic levels
For each organism in the food chain below, write its trophic level (T1, T2, T3, T4 or T5) and its role name (producer, primary consumer, secondary consumer, tertiary consumer, apex predator). 10 marks — 1 per correct organism row
grasses → kangaroo → dingo → wedge-tailed eagle
| Organism | Trophic level (T1–T5) | Role name |
|---|---|---|
| Grasses | ||
| Kangaroo | ||
| Dingo | ||
| Wedge-tailed eagle |
Now add a decomposer and a detritivore to the table below, and state the trophic level(s) they feed on. 2 bonus marks
| Type | Named example | Trophic level(s) they feed on |
|---|---|---|
| Decomposer | ||
| Detritivore |
4. Food chain vs food web — comparison table
Complete the comparison table. Each cell needs one clear, correct point. 8 marks — 1 per cell
| Feature | Food chain | Food web |
|---|---|---|
| Number of pathways shown | ||
| Accuracy as a model of real ecosystems | ||
| Ability to show omnivores | ||
| Usefulness for predicting consequences of species removal |
5. True or false — with correction
For each statement, circle T or F. If false, write the correction. 8 marks — 1 per T/F verdict, 1 for each correction where needed
5.1 Arrows in a food chain point from the predator to the prey, showing the direction the predator moves when hunting. T / F
5.2 A species at trophic level 1 is an autotroph that captures energy from the sun or inorganic chemicals. T / F
5.3 A food web is simply a collection of food chains placed side-by-side without any interactions between them. T / F
5.4 An omnivore can occupy multiple trophic levels because it eats both producers and consumers. T / F
Q1 — Term–definition matches
1.1 food chain • 1.2 food web • 1.3 trophic level • 1.4 apex predator • 1.5 omnivore • 1.6 resilience • 1.7 producer • 1.8 primary consumer • 1.9 decomposer • 1.10 detritivore.
Q2 — Arrow direction verdicts
2.1 Correct. Arrows point from eaten to eater throughout.
2.2 Incorrect. Correction: grass → grasshopper → frog → snake → hawk.
2.3 Correct. Each arrow points from prey to predator (energy flow direction).
2.4 Incorrect. Correction: phytoplankton → zooplankton → small fish → barramundi → saltwater crocodile.
2.5 Correct.
2.6 Incorrect. Correction: aquatic plants → water snails → great egret.
2.7 Correct.
2.8 Incorrect. Correction: eucalyptus leaves → koala → dingo.
Q3 — Trophic level labelling
Grasses: T1, producer. • Kangaroo: T2, primary consumer. • Dingo: T3, secondary consumer. • Wedge-tailed eagle: T4, tertiary consumer (or apex predator if no predators eat it).
Decomposer example: Soil fungus / bacterium; feeds on dead organisms from all trophic levels (T1–T4).
Detritivore example: Earthworm / dung beetle; feeds on detritus/faeces from all trophic levels.
Marking note: Award 1 mark per correct organism row (both level and name needed). Bonus marks for any biologically valid example with correct trophic level statement.
Q4 — Comparison table
Number of pathways: Food chain — one linear pathway. Food web — multiple interconnected pathways.
Accuracy as a model: Food chain — oversimplified; no real ecosystem is a single chain. Food web — far more accurate; reflects the true complexity of feeding relationships.
Omnivores: Food chain — cannot represent omnivores without assigning them one level only, losing information. Food web — can show omnivores occupying multiple levels by connecting them to prey at different trophic positions.
Predicting species removal: Food chain — can only predict direct impacts; predicts collapse if any species is lost. Food web — can identify alternative pathways that buffer the loss, giving a more realistic prediction.
Marking note: Any biologically correct contrast that matches the feature column earns the mark.
Q5 — True or false with correction
5.1 False. Correction: arrows point from the organism that is eaten TO the organism that eats it — they show the direction of energy flow, not predator movement.
5.2 True.
5.3 False. Correction: a food web is constructed by connecting all food chains in an ecosystem into an integrated network; species at any level can interact with species from multiple other chains.
5.4 True.