AQA GCSE (9-1) Biology: Biodiversity and Human Impact on Ecosystems

Key Takeaways for Biodiversity and Human Impact on Ecosystems

1. Biodiversity

• Definition: The variety of species in a specific area (e.g., animals, plants, fungi).
• Examples:
  • High biodiversity: Tropical rainforests (e.g., Borneo), coral reefs.
  • Low biodiversity: Deserts, polar regions.
• Importance: Ensures ecosystem stability by reducing dependency on single species.
• Threats:
  • Deforestation: Cutting down trees for farming/urbanisation (e.g., rainforests halved in 75 years).
  • Habitat destruction: Mining, quarrying (e.g., Bingham Canyon Mine).

Key Terms: Biodiversity, deforestation, sustainable.
Tip: Use the acronym C-BED to remember deforestation impacts: Carbon sink loss, Biodiversity loss, Erosion, Desertification.

2. Waste Management and Pollution

• Types of Pollution:
  • Water pollution: Pathogens (e.g., Salmonella), chemicals (e.g., mercury in Minamata disease).
  • Eutrophication: Excess fertilisers → algal blooms → oxygen depletion.
    Fertilisers→Algae growth→Light blocked→Plant death→Decomposition→Oxygen depletionFertilisers→Algae growth→Light blocked→Plant death→Decomposition→Oxygen depletion
  • Oil spills: Exxon Valdez (1989) killed 250,000+ seabirds; bioaccumulation harms food chains.
  • Plastic pollution: North Pacific Garbage Patch harms marine life (e.g., sea turtles).

Key Terms: Bioaccumulation, eutrophication, zooplankton.
Tip: For eutrophication, memorise the sequence FALDO (Fertilisers → Algae → Light loss → Death → Oxygen depletion).

3. Air and Land Pollution

• Air Pollutants:
  • Greenhouse gases: CO₂ (fossil fuels), methane (landfills), CFCs (ozone depletion).
  • Acid rain: Sulfur dioxide + water → sulfuric acid (pH <5.6). Damages forests, statues.
• Land Pollution:
  • Landfills: Release methane and leachate.
  • Three R’s: Reduce, Reuse, Recycle (e.g., recycling paper saves 17 trees per tonne).

Key Terms: Smog, acid rain, chlorofluorocarbons (CFCs).
Tip: Link greenhouse gases to their sources: CO₂ (combustion), methane (cows/landfills), CFCs (old aerosols).

4. Land Use and Deforestation

• Impacts of Land Use:
  • Urbanisation reduces habitats (e.g., Beijing covers 16,000 km²).
  • Peat bogs: Carbon sinks; destroyed for fuel/compost → releases CO₂.
• Deforestation:
  • Causes: Farming, logging, biodiesel crops.
  • Effects: Loss of 100+ species/day, disrupted water cycle, soil erosion.

Key Terms: Arabic farming, peat bog, carbon sink.
Tip: Peat bogs form in cool, wet, acidic conditions. Remember: CWA (Cool, Wet, Acidic).

5. Global Warming

• Causes: Increased greenhouse gases (CO₂ from fossil fuels, methane).
• Effects:
  • Melting ice → rising sea levels (e.g., Venice at risk).
  • Species migration (e.g., tropical mosquitoes spreading to the UK).
• Data Interpretation:
  • Keeling Curve: Shows CO₂ rising from 315 ppm (1960) to 400+ ppm.
  • Correlation ≠ causation (e.g., CO₂ and temperature rise are linked, but deniers argue natural cycles).

Key Terms: Greenhouse effect, food security.
Tip: Use the Keeling Curve as evidence for human-driven CO₂ increase.

6. Maintaining Biodiversity

• Conservation Methods:
  • Breeding programs: Zoos preserve genetic diversity (e.g., giant pandas).
  • National parks: Protect habitats (e.g., Great Barrier Reef, Serengeti).
  • Hedgerows: Boost biodiversity; removal reduces species (e.g., UK farmland).
• Individual Actions:
  • Compost food, avoid pesticides, buy organic.

Key Terms: Conservation, breeding program.
Tip: Hedgerow age ≈ 110 years × number of plant species in 30 yards.

7. Data and Calculations

• Ecological Footprint:
  Total footprint (ha)=Total score×0.01Total footprint (ha)=Total score×0.01
  • E.g., score 350 = 3.5 ha (UK average = 5.3 ha).
• Percentage Calculations:
  • E.g., 30% of 6,285 amphibians:
    0.3×6285=1885.5≈1886 species0.3×6285=1885.5≈1886 species

Tip: For scatter graphs (e.g., CO₂ vs. temperature), label axes and highlight positive/negative correlations.

Exam Tips:

• Use specific examples (e.g., Borneo, Exxon Valdez).
• Link processes to key terms (e.g., bioaccumulation → Minamata disease).
• Practise calculations (percentages, ecological footprints).
• Correlation vs. causation: Always question if a third variable exists (e.g., population size affecting churches and pubs).

50 GCSE Biology Questions on Biodiversity & Human Impact

Section 1: Biodiversity

1. Define biodiversity.
2. Name two areas with high biodiversity and two with low biodiversity.
3. Explain why tropical rainforests like Borneo are biodiverse.
4. How does deforestation reduce biodiversity?
5. What is the significance of hedgerows in maintaining biodiversity?

Section 2: Pollution & Waste Management

6. Describe the process of eutrophication.
7. What caused Minamata disease, and how did mercury enter the food chain?
8. Explain why oil spills harm top predators like dolphins.
9. Why is plastic pollution in oceans problematic?
10. Calculate 30% of 6,285 amphibians. Show working.
11. What is bioaccumulation? Give an example.
12. How do pesticides affect aquatic ecosystems?
13. Name two consequences of acid rain.
14. Why are CFCs harmful to the ozone layer?
15. What are the three R’s of waste management?

Section 3: Land Use & Deforestation

16. Define “arable farming”.
17. How does peat bog destruction contribute to global warming?
18. Why are peat bogs considered carbon sinks?
19. What environmental conditions favour peat bog formation?
20. Calculate the ecological footprint for a student with a total score of 350.
21. Why is Beijing’s urban expansion ecologically damaging?
22. List three impacts of deforestation.
23. How does deforestation disrupt the water cycle?
24. What proportion of rainforests has been lost in the last 75 years?
25. Why is biodiesel production linked to deforestation?

Section 4: Global Warming

26. Name three greenhouse gases and their sources.
27. Explain the greenhouse effect using the Keeling Curve.
28. How does melting Arctic ice affect polar bears?
29. Why might malaria spread to the UK due to global warming?
30. What is food security, and how is it threatened by climate change?
31. Which country emits the most CO₂ per capita?
32. Describe two long-term effects of global warming.
33. Why do some people dispute human-driven global warming?
34. How do scientists estimate historical CO₂ levels?
35. Interpret Figure 20.21: What correlation exists between CO₂ and temperature?

Section 5: Conservation & Data

36. What is a breeding program, and why is genetic diversity important?
37. Give two examples of national parks and their conservation roles.
38. Why is the Sumatran tiger debate complex for local communities?
39. How can composting reduce landfill waste?
40. Name three actions individuals can take to boost biodiversity.
41. Explain the term “sustainable” with an example.
42. Why is reusing better than recycling?
43. What is the average global ecological footprint, and how does the UK compare?
44. Describe how to calculate hedgerow age.
45. Plot a scatter graph for Table 20.1. What trend is shown?
46. Why is correlation not the same as causation? Use churches/pubs as an example.
47. What is a spurious correlation?
48. Define “food security”.
49. How does smog form?
50. Why is recycling batteries critical?

Detailed Answers

1. Biodiversity: The variety of species in a specific ecosystem (e.g., Borneo has 15,000 plant species).
2. High: Tropical rainforests, coral reefs. Low: Deserts, polar regions.
3. Borneo’s biodiversity: Diverse habitats (rainforests, mangroves) allow niche species evolution.
4. Deforestation: Destroys habitats → species extinction (e.g., 100+ species lost daily in rainforests).
5. Hedgerows: Provide habitats; removal reduces biodiversity (e.g., UK farmland species decline).
6. Eutrophication:
   Fertilisers→Algal bloom→Light blocked→Plant death→Decomposition→Oxygen depletionFertilisers→Algal bloom→Light blocked→Plant death→Decomposition→Oxygen depletion
7. Minamata disease: Mercury from factory waste → zooplankton → fish → humans (neurological damage).
8. Oil spills: Toxins bioaccumulate in food chains (e.g., shrimp mutations → dolphin deaths).
9. Plastic: Breaks into microplastics → ingested by marine life (e.g., sea turtles).
10. Calculation:
    0.3×6285=1885.5≈1886 amphibians0.3×6285=1885.5≈1886 amphibians
11. Bioaccumulation: Toxins increase up food chains (e.g., mercury in top predators).
12. Pesticides: Kill non-target species (e.g., bees) and contaminate water.
13. Acid rain: Lowers pH → forest death, statue erosion.
14. CFCs: Break ozone → UV radiation increase → skin cancer.
15. Three R’s: Reduce, Reuse, Recycle.
16. Arable farming: Growing crops (e.g., wheat fields).
17. Peat burning: Releases stored CO₂ → global warming.
18. Carbon sink: Stores carbon long-term (e.g., peat bogs).
19. Peat conditions: Cool, wet, acidic (CWA).
20. Footprint:
    350×0.01=3.5 hectares350×0.01=3.5 hectares
21. Beijing: Urban sprawl destroys habitats (16,000 km²).
22. Deforestation: Biodiversity loss, soil erosion, CO₂ release.
23. Water cycle: Less transpiration → drier climates → desertification.
24. Rainforest loss: 50% in 75 years.
25. Biodiesel: Requires large crop areas (e.g., palm oil plantations).
26. Greenhouse gases: CO₂ (fossil fuels), methane (landfills), CFCs (aerosols).
27. Keeling Curve: CO₂ rose from 315 ppm (1960) to 400+ ppm → traps heat.
28. Polar bears: Less sea ice → harder to hunt seals.
29. Malaria: Warmer UK climates allow mosquito survival.
30. Food security: Crop failures from droughts/floods threaten supply.
31. CO₂ per capita: Qatar (44 tonnes/person).
32. Global warming: Rising seas, species migration.
33. Skeptics: Argue natural climate cycles, not human activity.
34. CO₂ estimates: Ice core samples from ancient glaciers.
35. Figure 20.21: Strong positive correlation (CO₂ ↑, temperature ↑).
36. Breeding programs: Prevent inbreeding (e.g., giant pandas in zoos).
37. Parks: Great Barrier Reef (protects coral), Serengeti (safeguards migration routes).
38. Sumatran tiger: Farmers vs. conservationists (livestock vs. tourism).
39. Composting: Reduces methane from landfills.
40. Actions: Avoid pesticides, compost, buy organic.
41. Sustainable: Activities that don’t harm the environment (e.g., organic farming).
42. Reuse vs. recycle: Reuse requires no energy (e.g., jam jars).
43. Footprint: Global average = 1.7 ha; UK = 5.3 ha.
44. Hedgerow age: Number of species in 30 yards × 110 years.
45. Scatter graph: Positive correlation (population ↑, extinctions ↑).
46. Correlation ≠ causation: Churches/pubs linked via population, not each other.
47. Spurious correlation: False link (e.g., ice cream sales and drowning).
48. Food security: Reliable access to affordable, nutritious food.
49. Smog: Pollutants (e.g., NOₓ) + sunlight → haze.
50. Batteries: Heavy metals (e.g., lead) leak into soil/water.