Level 1 — RecognitionEcology & Ecosystems

Ecology & Ecosystems

⏱ 20 minutes30 marksprintable — key stays hidden on paper

Level 1: Recognition

Time limit: 20 minutes Total marks: 30

Section A — Multiple Choice (1 mark each) [10 marks]

Choose the single best answer.

Q1. The study of interactions between organisms and their environment is called: A) Physiology B) Ecology C) Taxonomy D) Genetics

Q2. Which of the following is an abiotic factor? A) Fungi B) Predators C) Soil pH D) Bacteria

Q3. The role or "profession" of an organism within its ecosystem is its: A) Habitat B) Population C) Niche D) Biome

Q4. In the 10% rule, if producers store 8000 kJ, the energy available to primary consumers is approximately: A) 8000 kJ B) 800 kJ C) 80 kJ D) 0.8 kJ

Q5. Organisms that convert atmospheric nitrogen ( $N_2$ ) into ammonia are called: A) Decomposers B) Nitrogen-fixing bacteria C) Producers D) Denitrifiers

Q6. Which trophic level always occupies the base of an energy pyramid? A) Producers B) Herbivores C) Carnivores D) Decomposers

Q7. Primary succession begins on: A) An abandoned farm field B) Bare rock or newly exposed land C) A forest after fire D) A pond with existing soil

Q8. A biome characterised by permafrost, low temperatures, and short growing seasons is the: A) Tropical rainforest B) Desert C) Tundra D) Grassland

Q9. The process by which carbon returns to the atmosphere as $CO_2$ from living organisms is: A) Photosynthesis B) Respiration C) Nitrification D) Transpiration

Q10. The correct sequence of ecological organisation from smallest to largest is: A) Population → Organism → Community → Ecosystem B) Organism → Population → Community → Ecosystem C) Ecosystem → Community → Population → Organism D) Community → Population → Ecosystem → Organism

Section B — Matching (1 mark each) [6 marks]

Match each term in Column X with its correct description in Column Y.

#	Column X		Column Y
Q11	Producer	A	Feeds on dead organic matter, recycling nutrients
Q12	Herbivore	B	Autotroph that makes food by photosynthesis
Q13	Decomposer	C	Physical place where an organism lives
Q14	Habitat	D	Primary consumer that eats plants
Q15	Evaporation	E	Water changing from liquid to vapour (water cycle)
Q16	Denitrification	F	Conversion of nitrates back to $N_2$ gas

Section C — True/False WITH Justification (2 marks each) [14 marks]

State True or False (1 mark) and give a one-line justification (1 mark).

Q17. A food web is more stable than a single food chain.

Q18. In a pyramid of numbers, the base is always larger than the top.

Q19. Secondary succession occurs faster than primary succession.

Q20. All the energy from one trophic level is passed to the next trophic level.

Q21. Fungi and bacteria are examples of biotic factors.

Q22. Legume root nodules contain nitrogen-fixing bacteria.

Q23. A community includes both the living organisms and the non-living components of an area.

Answer keyMark scheme & solutions

Section A — MCQ (1 mark each)

Q1. B) Ecology — By definition, ecology studies organism–environment interactions. (1)

Q2. C) Soil pH — Abiotic = non-living chemical/physical factor; the others are living organisms. (1)

Q3. C) Niche — The niche is the functional role; habitat is merely the place. (1)

Q4. B) 800 kJ — 10% of 8000 kJ = $0.10 \times 8000 = 800$ kJ transferred to next level. (1)

Q5. B) Nitrogen-fixing bacteria — They reduce $N_2 \rightarrow NH_3$ ; denitrifiers do the reverse. (1)

Q6. A) Producers — Producers capture the most energy and form the pyramid base. (1)

Q7. B) Bare rock or newly exposed land — Primary succession starts where no soil exists. (1)

Q8. C) Tundra — Permafrost and short growing seasons are defining tundra features. (1)

Q9. B) Respiration — Respiration releases $CO_2$ ; photosynthesis removes it. (1)

Q10. B) Organism → Population → Community → Ecosystem — Correct increasing hierarchy. (1)

Section B — Matching (1 mark each)

Q11 → B (Producer = autotroph, photosynthesis) Q12 → D (Herbivore = plant-eating primary consumer) Q13 → A (Decomposer = breaks down dead matter) Q14 → C (Habitat = physical place) Q15 → E (Evaporation = liquid → vapour) Q16 → F (Denitrification = nitrate → $N_2$ ) (1 mark each, total 6)

Section C — True/False + Justification (2 marks each)

Q17. True (1) — Multiple feeding pathways mean if one species declines, others provide alternatives, so the ecosystem resists collapse. (1)

Q18. False (1) — Not always: e.g. one large tree (few producers) supports many insects, giving an inverted-base pyramid of numbers. (1)

Q19. True (1) — Soil, nutrients, and seeds already exist, so recolonisation is much faster than primary succession starting from bare rock. (1)

Q20. False (1) — Only ~10% is transferred; the rest is lost as heat, respiration, and undigested matter. (1)

Q21. True (1) — Fungi and bacteria are living organisms, hence biotic factors. (1)

Q22. True (1) — Rhizobium in legume nodules fixes atmospheric nitrogen into usable form. (1)

Q23. False (1) — A community is only the living organisms; adding non-living components makes it an ecosystem. (1)

[
  {"claim":"Q4: 10% of 8000 kJ equals 800 kJ","code":"result = (0.10*8000 == 800)"},
  {"claim":"10% rule over two transfers from 8000 kJ gives 80 kJ to secondary consumers","code":"result = (0.10*(0.10*8000) == 80)"},
  {"claim":"Q20: energy transferred (10%) is not 100% of the previous level","code":"result = (0.10*8000 != 8000)"},
  {"claim":"Energy lost at first transfer is 90% of 8000 kJ = 7200 kJ","code":"result = (8000 - 0.10*8000 == 7200)"}
]