CAIE IGCSE Biology 20.2.3 Human Impacts Through Food Webs
Practise tracing how human removal or introduction of organisms disrupts food chains and damages habitats.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Exam points
- explain how killing producers or non-target species disrupts food chains and reduces biodiversity
- evaluate pesticide damage using toxicity, persistence, application method and resistance risk
20.2.3—Through altering food webs and food question 1
Some crop farmers use herbicides on their fields.
Fig. 4.1 shows a farmer spraying a rice crop with herbicides.
Fig. 4.1
Fields of crop plants were sprayed with two herbicides. A farmer measured the concentration of the two herbicides, A and B, in a lake near the fields.
The water in the lake was sampled at intervals for two weeks.
Fig. 4.2 shows the results.
concentration of herbicides in the lake water samples / mg per kg
Fig. 4.2
Suggest how herbicides damage ecosystems in a lake.
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