Exam skills
What the paper asks you to do
- Interpret pyramids and population graphs
- Predict food-web consequences
- Evaluate conservation decisions
Continuity & environment
Relationships of organisms with one another and with the environment
Use food webs, nutrient cycles, population data and human impacts to explain ecosystem change.5090 syllabus routeConcept · skill · exam language
What to know
Build the topic around four anchors.
- 01Energy flow and food webs
- 02Carbon and water cycles
- 03Population change
- 04Conservation and human impact
Common mistakes
Where marks disappear
- Showing energy cycling instead of flowing
- Confusing a habitat with an ecosystem
- Claiming one correlation proves a cause
Structured practice
Answer these without looking back.
For each prompt, write the biological chain clearly enough that every mark-worthy link is visible.
- 01Predict the effect of removing one consumer.
- 02Explain why energy decreases along a food chain.
- 03Evaluate a conservation strategy from supplied data.
Continue learning
Read the connected explanation.
Separate historical explanations from modern evolutionary reasoning and follow how heritable variation changes populations.
This independent teaching resource follows the Cambridge O Level Biology 5090 syllabus direction and is not endorsed by Cambridge International Education.