IB Biology HL 4.2.5 Keystone Species
Practise analysing HL community data to explain keystone effects, trophic change and conservation consequences.
- Syllabus
- First assessment 2025
- Course
- Biology HL
- Level
- HL
Exam points
- Use food-web evidence to explain how keystone-species removal changes community structure.
- Evaluate repeated community evidence for a keystone species and its conservation importance.
D4.2.5—Keystone species question 1
The gut of a healthy human contains more than 1000 species of bacteria. Some of these species are shown in the cladogram.
Scientists have found that B. fragilis and B. stercosis are keystone species in the human gut ecosystem.
Define keystone species.
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