Key Idea: Most marks in topic 3.2 come from threats to biodiversity and the IUCN Red List. At HL, also learn hotspots, KBAs, indigenous management and environmental justice.
1. Threats (most marks)
- Direct threats: overharvesting, poaching, the illegal pet trade.
- Indirect threats: habitat loss, climate change, pollution, invasive species.
- Most ecosystems face several impacts at once, and together they do more harm.
- Small, fragmented populations lose genetic diversity and are more likely to die out.
2. The IUCN Red List
- Status is set from population size, rate of change, breeding potential, geographic range and threats.
- The ranks run from Least Concern to Extinct.
- A status publicizes a species' risk, so governments, NGOs and citizens can set priorities.
- Learn three named species: one extinct, one critically endangered, one that recovered.
3. Invasives and HL ideas
- Invasive species compete for resources, eat native species or spread disease.
- They spread fast with no natural predators or competitors.
- At HL: hotspots, Key Biodiversity Areas, indigenous land management and environmental justice.
- The biosphere integrity boundary has already been crossed.
How it is examined:
| Question | How to score |
|---|---|
| [1] State an IUCN criterion from data | Name the criterion: population size, decline, range, breeding, threats. |
| [1] to [2] Identify the most threatened group from a chart | Read the right bar; quote the figure. |
| [2] to [3] Explain why a named species is threatened | One threat per point, linked to the species. |
| [3] Evaluate a conservation programme | Strengths, limitations, and a judgement. |
| [7] to [9] Human population growth and biodiversity loss | Direct and indirect threats, named examples, both sides. |
Key terms, one line each:
| Term | In one line |
|---|---|
| Direct / indirect threat | kills the organisms / changes their environment |
| Invasive alien species | a species brought to a new area that spreads and harms natives |
| Biodiversity hotspot | a region with many endemic species that has lost most of its habitat |
| Key Biodiversity Area | a site identified as a global priority for conservation |
| Environmental justice | fair treatment of the people affected by conservation |
| Biosphere integrity | the planetary boundary for species loss, already crossed |
Last-minute check: answer, then tap to see.
What makes a biodiversity hotspot? Many endemic species and most of its habitat already lost.
Why can indigenous land management be more sustainable? Long local knowledge and low-impact use, such as cool burns.
Name one community moved out for conservation. The Maasai from the Serengeti, or the Batwa from Bwindi.
Has the biosphere integrity boundary been crossed? Yes: extinction rates are far above the safe level.
Why do combined impacts do more harm? One impact lowers resilience, so the next hits harder.
In the 1950s and 1960s, the Maasai were moved out of the Serengeti when it became a national park. Discuss whether conservation that removes local people is justified.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Exam tips
- Say whether a threat is direct or indirect, and name the species it affects.
- For an IUCN question, use the exact criterion words: population size, decline, range.
- In an evaluate, give strengths and limitations, then a judgement.
- For environmental justice, name the community and what they lost.