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A Level H1 Biology Ecology Quiz
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Questions
A-Level Biology H1 Quiz - Ecology
Name: _____________________________
Class: ______ Date: _____________
Score: ______ / 40
Duration: 45 minutes
Total Marks: 40
Instructions:
- Answer all questions in the spaces provided.
- Write your answers clearly and concisely.
- Marks for each question are shown in brackets.
- Where diagrams are referred to, use the information provided in the descriptions.
Section A: Short Answer and Terminology
Answer all questions (1–5).
1. Define the term “ecological niche” and give an example. [2]
2. (a) List two abiotic factors that affect the distribution of organisms. [2]
(b) Using one of the factors named in (a), explain how it limits the population size of a species. [2]
3. Explain why energy flow in an ecosystem is described as unidirectional. [2]
4. State the term for the total mass of living organisms in a given area. [1]
5. Name one greenhouse gas and state its effect on global temperatures. [1]
Section B: Structured Questions
Answer all questions (6–10).
[Figure 1: Freshwater pond food web]
Algae → Water flea → Small fish → Large fish
Water flea → Frog (eaten by large fish)
6. With reference to Figure 1:
(a) Identify the producer. [1]
___________________________________________
(b) Name one primary consumer. [1]
___________________________________________
[Figure 2: Simplified nitrogen cycle]
Atmospheric nitrogen (N₂) --(Process P)--> Ammonium compounds (NH₄⁺) --(Process Q)--> Nitrites (NO₂⁻) --(Process Q)--> Nitrates (NO₃⁻)
Nitrates are taken up by plants. Denitrification returns N₂ to the atmosphere.
7. With reference to Figure 2:
(a) Name process P and process Q. [2]
P: ___________________________________________
Q: ___________________________________________
(b) Explain how nitrogen fixation occurs. [1]
___________________________________________
___________________________________________
(c) State the role of nitrifying bacteria. [1]
___________________________________________
8. Describe two ways deforestation can disrupt the carbon cycle. [2]
9. What is the term for the maximum population size that an environment can sustain? [1]
10. State one advantage of using biological control over chemical pesticides in agriculture. [1]
Section C: Data Interpretation
Answer all questions (11–15).
[Graph description: Population growth of rabbits over 10 years. Population rises steeply for 4 years, then levels off at approximately 200 individuals.]
11. (a) Identify the carrying capacity from the graph. [1]
___________________________________________
(b) Suggest two factors that prevented further population growth. [2]
1. ___________________________________________
2. ___________________________________________
[Table 1: Atmospheric CO₂ concentration (ppm) from 1960 to 2020]
| Year | CO₂ (ppm) |
|---|---|
| 1960 | 317 |
| 1970 | 326 |
| 1980 | 339 |
| 1990 | 354 |
| 2000 | 370 |
| 2010 | 390 |
| 2020 | 414 |
12. (a) Describe the trend shown in Table 1. [2]
___________________________________________
___________________________________________
(b) Explain one reason for the increase in atmospheric CO₂ concentration. [2]
___________________________________________
___________________________________________
13. Define “biodiversity”. [1]
14. Name one method used to measure species diversity in a habitat. [1]
15. State one benefit of conserving biodiversity for humans. [1]
Section D: Extended Responses
Answer all questions (16–20).
16. Discuss the impacts of climate change on coral reef ecosystems. [4]
17. Explain how the greenhouse effect contributes to global warming. [3]
18. Define the term “trophic level”. [1]
19. Explain why food chains rarely exceed five trophic levels. [1]
20. Suggest one way individuals can reduce their carbon footprint. [1]
--- End of Quiz ---
Answers
A-Level Biology H1 Quiz - Ecology – Answer Key
Total marks: 40
Section A
1. Definition: The role and position an organism has in its environment, including its interactions with other organisms and its use of resources. [1]
Example: (any valid, e.g.) A barn owl occupies the niche of a nocturnal predator of small mammals. [1]
(Accept other suitable definitions and examples.)
2. (a) Any two abiotic factors: temperature, light intensity, water availability, pH, salinity, wind, etc. [1 mark each, 2 total]
(b) Explanation linking the chosen factor to population limits. Example: Low temperature can slow enzyme activity in poikilotherms, reducing metabolic rate and reproductive success, thus limiting population growth. [2]
(Award 1 mark for stating the limiting mechanism, 1 mark for linking it to population size.)
3. Energy passes through the ecosystem from producers to consumers and is eventually lost as heat; energy cannot be recycled back to the sun or producers. [1] Therefore, the flow is always one-way from the sun/producers upwards. [1]
(Accept: energy enters as sunlight, is transferred along food chains, and is ultimately dissipated as heat.)
4. Biomass [1]
5. Gas: carbon dioxide (or methane, water vapour). [1 for name] Effect: it traps heat/infrared radiation in the atmosphere, leading to warming. [1 for correct effect]
(If only name given, no mark for effect; total 1 mark.)
Section B
6. (a) Algae [1]
(b) Water flea (or any primary consumer from food web) [1]
7. (a) P: Nitrogen fixation [1]
Q: Nitrification [1]
(b) Nitrogen fixation is the conversion of atmospheric nitrogen (N₂) into ammonium compounds (NH₄⁺) by nitrogen-fixing bacteria (e.g., Rhizobium) or by lightning. [1 for any correct description]
(c) Nitrifying bacteria oxidise ammonium compounds to nitrites and then to nitrates, making nitrogen available to plants. [1]
8. Any two of the following (1 mark each):
- Deforestation reduces the number of trees, which absorb CO₂ for photosynthesis, leading to higher atmospheric CO₂.
- Burning of forests releases stored carbon as CO₂.
- Decomposition of dead plant material releases CO₂ back to the atmosphere.
- Destruction of forest soils releases carbon from organic matter.
(Accept other valid points.)
9. Carrying capacity [1]
10. Any one advantage, e.g.: Biological control agents are specific to the pest and do not harm other organisms; pests do not develop resistance as quickly; it does not leave chemical residues. [1]
Section C
11. (a) 200 individuals (or as indicated on graph) [1]
(b) Any two limiting factors: food shortage, predation, disease, competition, limited space/ nesting sites, etc. [2]
12. (a) The CO₂ concentration has steadily increased over the years 1960–2020. [1] The rate of increase appears to be accelerating/ greater in recent decades. [1]
(Accept: overall upward trend with specific data reference.)
(b) Any valid reason: increased burning of fossil fuels, deforestation reducing CO₂ uptake, industrial processes, increased vehicle emissions, etc. [1 for reason, 1 for explanation linking to CO₂ release.]
13. Biodiversity is the variety of living organisms in an ecosystem, including genetic diversity, species diversity, and ecosystem diversity. [1]
14. Any valid method: Simpson’s diversity index, quadrat sampling with species identification, transect line sampling, mark–release–recapture (for animals), etc. [1]
15. Any benefit: provides resources (food, medicine), ecosystem services (pollination, water purification), cultural/aesthetic value, stability of ecosystems, etc. [1]
Section D
16. Discuss impacts; 4 marks. Award for:
- Increased sea temperature causes coral bleaching (loss of symbiotic zooxanthellae), leading to coral death and reef degradation.
- Ocean acidification (due to more CO₂ dissolving) reduces calcification, weakening coral skeletons.
- Rising sea levels may alter light availability for photosynthesis.
- Changes in storm intensity can physically damage reefs.
- Loss of coral reefs reduces biodiversity, fish habitats, and coastal protection.
(Award 1 mark for each distinct, well-explained impact up to 4.)
17. Greenhouse gases (e.g., CO₂, methane) absorb and re-emit infrared radiation emitted by the Earth’s surface. [1] This traps heat in the atmosphere, reducing heat loss to space. [1] The enhanced greenhouse effect (due to increased gas concentrations from human activities) leads to greater warming, i.e., global warming. [1]
18. A trophic level is the position an organism occupies in a food chain, determined by its feeding relationship. [1]
19. Energy is lost at each trophic level (e.g., through respiration, heat, undigested material), so only a small percentage (about 10%) is transferred to the next level. [1] After a few transfers, insufficient energy remains to support another level, limiting the length to about 4–5.
20. Any realistic action: reduce energy use, use public transport, recycle, adopt a plant-based diet, reduce meat consumption, use energy-efficient appliances, plant trees, etc. [1]
(Total: 40 marks)