Key Idea: Most marks in topic 3.2 come from threats to biodiversity and the IUCN Red List. Learn those first, then invasive species and your three named species.
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. Invasive alien species
- Invasive species compete for resources, eat native species or spread disease.
- They spread fast with no natural predators or competitors.
- Know a local example and how it was managed, such as coypu removed from East Anglia.
- The tragedy of the commons: a shared resource with no limits is overused.
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 threat | a threat that kills or removes the organisms, such as poaching |
| Indirect threat | a threat that changes their environment, such as habitat loss |
| Invasive alien species | a species brought to a new area that spreads and harms natives |
| IUCN Red List | the global list of species' conservation status |
| Habitat fragmentation | a habitat split into small, separate patches |
| Tragedy of the commons | a shared resource overused because no one limits its use |
Last-minute check: answer, then tap to see.
Is habitat loss a direct or indirect threat? Indirect: it changes the environment.
Name two IUCN criteria. Population size and rate of decline (also range, breeding, threats).
Why do invasive species spread so fast? No natural predators or competitors in the new area.
Why does a status help conservation? It publicizes the risk so money and action go where needed.
What happens to a shared resource with no limits? It is overused: the tragedy of the commons.
The vaquita, a small porpoise found only in the northern Gulf of California, is listed as Critically Endangered. Fewer than 20 are thought to survive. Explain why the vaquita is so close to extinction.
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.
- Learn your three named species with one fact each: cause, status, what was done.