A Level Biology H3 Ecology Quiz

<!-- TuitionGoWhere generation metadata: stage=5-1; model=tencent/hy3:free; model_label=Tencent HY3 Free; generated=2026-07-09; Sources: Stage 4-0 LLM templates, syllabus context, and Stage 2 evidence where available. -->

A-Level Biology H3 Quiz - Ecology

Name:
Class:
Date:
Score:

Duration: 60 minutes
Total Marks: 40
Topic: Ecology (syllabus-first practice; not derived from past-year papers)

Instructions:

• Answer all 20 questions.
• Section A: short structured items (1–8). Section B: data and application (9–14). Section C: extended response (15–20).
• Use clear scientific terminology. Show workings where requested.
• This quiz is generated from syllabus context only; no exam-derived template exists for this subject group.

Section A: Knowledge and Direct Application (Questions 1–8)

1. State one defining feature of an ecosystem that distinguishes it from a community. [1]

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2. Define "gross primary productivity" (GPP) in an ecological context. [1]

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3. Name the trophic level occupied by herbivores in a food chain. [1]

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4. Using the Hardy–Weinberg equation, state the term representing the frequency of heterozygous carriers in a population. [1]

---

5. Give one example of a biotic factor that can limit population size. [1]

---

6. State the process by which nitrogen gas is converted into ammonia by soil bacteria. [1]

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7. Explain briefly why a pyramid of biomass can be inverted in an aquatic ecosystem. [1]

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8. Identify one human activity that increases ecological footprint at the national level. [1]

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Section B: Data Handling and Application (Questions 9–14)

9. A pond ecosystem was sampled. The table below shows species counts.

Species	Individuals
A	50
B	30
C	20
Total = 100.

Calculate the Simpson's Index of Diversity $D = 1 - \sum (n/N)^2$. Show working. [3]

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10. The population of a beetle species grew from 200 to 800 in 6 days under constant resources. Calculate the mean daily growth rate as a percentage. [2]

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11. A forest fragment has the following carbon stocks: trees $120\ \text{t C ha}^{-1}$, soil $80\ \text{t C ha}^{-1}$. If climate mitigation requires $250\ \text{t C ha}^{-1}$ to offset local emissions, calculate the deficit per hectare. [2]

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12.

Image pending generation: graph for Q12.

Using the graph, describe the relationship between predator and prey cycles. [2]

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13. Explain how eutrophication from fertilizer runoff reduces dissolved oxygen in a lake. [3]

---

14. A species has $p = 0.7$ allele frequency for a beneficial trait. Use Hardy–Weinberg to find expected frequency of homozygous dominant individuals. [2]

---

Section C: Extended Response (Questions 15–20)

15. Discuss how adaptive radiation can increase regional biodiversity, using one named example. [4]

---

16. Evaluate the role of human microbiota in maintaining ecosystem-like stability within the host. [3]

---

17. Using Core Idea 3 and Extension B, explain how CAM plants respond to climate change stressors. [4]

---

18. A chi-squared test for independence yielded $\chi^2 = 5.99$, df = 2, critical value at p=0.05 is 5.99. State conclusion. [2]

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19. Compare the contribution of C3 and C4 plants to mitigating global warming. [3]

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20. Synthesise how polyploidy and hybridisation may complicate phylogeny reconstruction in disturbed ecosystems. [4]

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</stage5_quiz_answers_md>

A-Level Biology H3 Quiz - Ecology: Answer Key

Total Marks: 40
Syllabus-first content; no past-year template used.

1. [1] An ecosystem includes both biotic (living) community and abiotic (non-living) environment, whereas a community is only the interacting populations.
Teaching note: Ecosystem = community + physical environment.

2. [1] GPP is the total rate of photosynthesis (chemical energy fixed by autotrophs) per unit area/time before respiration losses.
Define: GPP = NPP + respiration.

3. [1] Primary consumers.
Chain: Producer → Primary consumer (herbivore) → Secondary consumer.

4. [1] $2pq$ in $p^2 + 2pq + q^2 = 1$.
Heterozygote frequency = 2pq.

5. [1] Any one: competition, predation, disease, parasitism.
Mark: accept one biotic limiting factor.

6. [1] Nitrogen fixation.
By Azotobacter, Rhizobium etc.

7. [1] Because small phytoplankton have high turnover and support larger zooplankton biomass temporarily.
Inverted biomass pyramid common in oceans.

8. [1] Deforestation / excessive fossil fuel use / urban expansion.
Links to ecological footprint.

9. [3]
$D = 1 - [(50/100)^2 + (30/100)^2 + (20/100)^2]$
$= 1 - [0.25 + 0.09 + 0.04] = 1 - 0.38 = 0.62$.
Marks: 1 for formula, 1 for substitution, 1 for answer.

10. [2]
Growth factor = $800/200 = 4$ over 6 days.
Daily rate $r$: $200(1+r)^6 = 800 \Rightarrow (1+r)^6 = 4 \Rightarrow 1+r = 4^{1/6} \approx 1.26$.
$r \approx 0.26 = 26\%$.
Marks: 1 method, 1 answer.

11. [2]
Stock = $120 + 80 = 200\ \text{t C ha}^{-1}$.
Deficit = $250 - 200 = 50\ \text{t C ha}^{-1}$.
Marks: 1 sum, 1 deficit.

12. [2]
Predator peaks lag prey peaks by ~3 months; cycles oscillate.
Use graph: prey peak month 4, predator peak month 7.
Marks: 1 lag, 1 cycle description.

13. [3]
Fertilizer → nutrient enrichment → algal bloom → death & bacterial decomposition → O₂ consumed → hypoxia.
Marks: 1 enrichment, 1 decomposition, 1 O₂ drop.

14. [2]
$p=0.7, q=0.3$. Homozygous dominant = $p^2 = 0.49$.
Marks: 1 sq, 1 value.

15. [4]
Adaptive radiation: one ancestor diversifies to fill niches. Example: Darwin's finches (Galápagos) – beak forms for seed/insect/flower. Increases species richness and functional diversity.
Marks: 1 def, 1 example, 2 consequence.

16. [3]
Microbiota resist pathogens (competitive exclusion), train immunity, aid metabolism. Stability like ecosystem via redundancy.
Marks: 1 each point.

17. [4]
CAM: nocturnal stomatal opening fixes CO₂ as malate, day photosynthesis with closed stomata → water conservation under heat/drought (Extension B). Links to Core Idea 3 temporal separation.
Marks: 2 mechanism, 2 climate link.

18. [2]
$\chi^2 = 5.99 =$ critical → reject null at p=0.05; significant association.
Marks: 1 compare, 1 conclusion.

19. [3]
C3: dominant, less efficient under heat; C4: high temp adapted, less photorespiration, more carbon gain. Both sequester CO₂; C4 better mitigator in tropics.
Marks: 1 C3, 1 C4, 1 compare.

20. [4]
Polyploidy creates instant reproductive isolation; hybridisation mixes genomes; introgression blurs branches. Disturbed ecosystems show reticulate evolution, not clean tree.
Marks: 1 each concept + synthesis. </stage5_quiz_answers_md>

<stage5_quiz_md>

A-Level Biology H3 Quiz - Ecology

Name:
Class:
Date:
Score:

Duration: 60 minutes
Total Marks: 40
Topic: Ecology (syllabus-first practice; not derived from past-year papers)

Instructions:

• Answer all 20 questions.
• Section A: short structured items (1–8). Section B: data and application (9–14). Section C: extended response (15–20).
• Use clear scientific terminology. Show workings where requested.
• This quiz is generated from syllabus context only; no exam-derived template exists for this subject group.

Section A: Knowledge and Direct Application (Questions 1–8)

1. State one defining feature of an ecosystem that distinguishes it from a community. [1]

---

2. Define "gross primary productivity" (GPP) in an ecological context. [1]

---

3. Name the trophic level occupied by herbivores in a food chain. [1]

---

4. Using the Hardy–Weinberg equation, state the term representing the frequency of heterozygous carriers in a population. [1]

---

5. Give one example of a biotic factor that can limit population size. [1]

---

6. State the process by which nitrogen gas is converted into ammonia by soil bacteria. [1]

---

7. Explain briefly why a pyramid of biomass can be inverted in an aquatic ecosystem. [1]

---

8. Identify one human activity that increases ecological footprint at the national level. [1]

---

Section B: Data Handling and Application (Questions 9–14)

9. A pond ecosystem was sampled. The table below shows species counts.

Species	Individuals
A	50
B	30
C	20
Total = 100.

Calculate the Simpson's Index of Diversity $D = 1 - \sum (n/N)^2$. Show working. [3]

---

10. The population of a beetle species grew from 200 to 800 in 6 days under constant resources. Calculate the mean daily growth rate as a percentage. [2]

---

11. A forest fragment has the following carbon stocks: trees $120\ \text{t C ha}^{-1}$, soil $80\ \text{t C ha}^{-1}$. If climate mitigation requires $250\ \text{t C ha}^{-1}$ to offset local emissions, calculate the deficit per hectare. [2]

---

12.

Image pending generation: graph for Q12.

Using the graph, describe the relationship between predator and prey cycles. [2]

---

13. Explain how eutrophication from fertilizer runoff reduces dissolved oxygen in a lake. [3]

---

14. A species has $p = 0.7$ allele frequency for a beneficial trait. Use Hardy–Weinberg to find expected frequency of homozygous dominant individuals. [2]

---

Section C: Extended Response (Questions 15–20)

15. Discuss how adaptive radiation can increase regional biodiversity, using one named example. [4]

---

16. Evaluate the role of human microbiota in maintaining ecosystem-like stability within the host. [3]

---

17. Using Core Idea 3 and Extension B, explain how CAM plants respond to climate change stressors. [4]

---

18. A chi-squared test for independence yielded $\chi^2 = 5.99$, df = 2, critical value at p=0.05 is 5.99. State conclusion. [2]

---

19. Compare the contribution of C3 and C4 plants to mitigating global warming. [3]

---

20. Synthesise how polyploidy and hybridisation may complicate phylogeny reconstruction in disturbed ecosystems. [4]

---

<!-- TuitionGoWhere generation metadata: stage=5-1; model=tencent/hy3:free; model_label=Tencent HY3 Free; generated=2026-07-09; Sources: Stage 4-0 LLM templates, syllabus context, and Stage 2 evidence where available. -->

A-Level Biology H3 Quiz - Ecology: Answer Key

Total Marks: 40
Syllabus-first content; no past-year template used.

1. [1] An ecosystem includes both biotic (living) community and abiotic (non-living) environment, whereas a community is only the interacting populations.
Teaching note: Ecosystem = community + physical environment.

2. [1] GPP is the total rate of photosynthesis (chemical energy fixed by autotrophs) per unit area/time before respiration losses.
Define: GPP = NPP + respiration.

3. [1] Primary consumers.
Chain: Producer → Primary consumer (herbivore) → Secondary consumer.

4. [1] $2pq$ in $p^2 + 2pq + q^2 = 1$.
Heterozygote frequency = 2pq.

5. [1] Any one: competition, predation, disease, parasitism.
Mark: accept one biotic limiting factor.

6. [1] Nitrogen fixation.
By Azotobacter, Rhizobium etc.

7. [1] Because small phytoplankton have high turnover and support larger zooplankton biomass temporarily.
Inverted biomass pyramid common in oceans.

8. [1] Deforestation / excessive fossil fuel use / urban expansion.
Links to ecological footprint.

9. [3]
$D = 1 - [(50/100)^2 + (30/100)^2 + (20/100)^2]$
$= 1 - [0.25 + 0.09 + 0.04] = 1 - 0.38 = 0.62$.
Marks: 1 for formula, 1 for substitution, 1 for answer.

10. [2]
Growth factor = $800/200 = 4$ over 6 days.
Daily rate $r$: $200(1+r)^6 = 800 \Rightarrow (1+r)^6 = 4 \Rightarrow 1+r = 4^{1/6} \approx 1.26$.
$r \approx 0.26 = 26\%$.
Marks: 1 method, 1 answer.

11. [2]
Stock = $120 + 80 = 200\ \text{t C ha}^{-1}$.
Deficit = $250 - 200 = 50\ \text{t C ha}^{-1}$.
Marks: 1 sum, 1 deficit.

12. [2]
Predator peaks lag prey peaks by ~3 months; cycles oscillate.
Use graph: prey peak month 4, predator peak month 7.
Marks: 1 lag, 1 cycle description.

13. [3]
Fertilizer → nutrient enrichment → algal bloom → death & bacterial decomposition → O₂ consumed → hypoxia.
Marks: 1 enrichment, 1 decomposition, 1 O₂ drop.

14. [2]
$p=0.7, q=0.3$. Homozygous dominant = $p^2 = 0.49$.
Marks: 1 sq, 1 value.

15. [4]
Adaptive radiation: one ancestor diversifies to fill niches. Example: Darwin's finches (Galápagos) – beak forms for seed/insect/flower. Increases species richness and functional diversity.
Marks: 1 def, 1 example, 2 consequence.

16. [3]
Microbiota resist pathogens (competitive exclusion), train immunity, aid metabolism. Stability like ecosystem via redundancy.
Marks: 1 each point.

17. [4]
CAM: nocturnal stomatal opening fixes CO₂ as malate, day photosynthesis with closed stomata → water conservation under heat/drought (Extension B). Links to Core Idea 3 temporal separation.
Marks: 2 mechanism, 2 climate link.

18. [2]
$\chi^2 = 5.99 =$ critical → reject null at p=0.05; significant association.
Marks: 1 compare, 1 conclusion.

19. [3]
C3: dominant, less efficient under heat; C4: high temp adapted, less photorespiration, more carbon gain. Both sequester CO₂; C4 better mitigator in tropics.
Marks: 1 C3, 1 C4, 1 compare.

20. [4]
Polyploidy creates instant reproductive isolation; hybridisation mixes genomes; introgression blurs branches. Disturbed ecosystems show reticulate evolution, not clean tree.
Marks: 1 each concept + synthesis.