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S3 Science: Ecosystems and Energy Flow (Paper 1: basics)
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S3 Science: Ecosystems and Energy Flow (Paper 1: basics)
The first paper starts from the basic definitions: producers, consumers, food chain arrows and the ten per cent rule of an energy pyramid.
Direct answers Six of the ten questions simply apply the ten per cent rule with tidy numbers, so the habit settles first.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: S3 Science: Ecosystems and Energy Flow |
| Level | S3 Science |
02 Questions (10 items)
- FoundationWhich kind of organism always takes the first place in a food chain?
- FoundationGrass to rabbit to fox: which level of consumer is the rabbit?
- FoundationWhat does an arrow in a food chain stand for?
- IntermediateHow much energy is roughly left at each step up an energy pyramid?
- IntermediateGrass holds 10 000 kJ. How much reaches the primary consumer at ten per cent transfer?
- IntermediateA primary consumer holds 1 000 kJ. How much reaches the secondary consumer at ten per cent transfer?
- ChallengeProducers fix 50 000 kJ. How much reaches the third trophic level?
- ChallengeProducers fix 8 000 kJ. How much reaches the primary consumer?
- ChallengeWhat do decomposers do in the carbon cycle?
- Error redoA student claims the top of an energy pyramid holds the most energy. What is the correct statement?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | A producer | A producer makes its own food and is the only entry point of energy into a food chain. |
| 2 | A primary consumer | The rabbit feeds directly on the producer grass, which makes it a primary consumer. |
| 3 | The direction of energy flow | The arrow runs from the eaten to the eater and shows the direction in which energy passes on. |
| 4 | About one tenth (roughly 10 per cent) | The other nine tenths leave through respiration, movement and waste, so only about one tenth is left. |
| 5 | 1 000 kJ | Ten per cent of 10 000 kJ is 1 000 kJ. |
| 6 | 100 kJ | Ten per cent of 1 000 kJ is 100 kJ, and every further step cuts it by ten again. |
| 7 | 500 kJ | Two steps are needed: 50 000 falls to 5 000 and then to 500 kJ. |
| 8 | 800 kJ | Ten per cent of 8 000 kJ is 800 kJ. |
| 9 | They break down dead bodies and waste and release carbon back to the air as carbon dioxide | Decomposers turn organic carbon back into carbon dioxide, which producers can use again. |
| 10 | The top level holds the least energy | Energy is lost at every step, so the top has the least energy available and supports the fewest large predators. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
Three basics: the first box of a food chain is always a producer, the arrow points at the eater and shows the direction of energy flow, and each step up an energy pyramid keeps only about one tenth.Tutor Registration →
Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.