IB Biology HL D4.2.2 Requirements for Stability Questions
Analyse how energy input, decomposers, nutrient cycling, population regulation and biodiversity sustain ecosystems.
- Syllabus
- First assessment 2025
- Course
- Biology HL
- Level
- HL
Exam points
- Explain how producers and light provide energy input while decomposers recycle nutrients and prevent waste accumulation in a sealed mesocosm.
- Relate nutrient cycling, energy flow, population regulation and biodiversity to sustainable ecosystem function.
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IB Biology HL D4.2.2 Requirements for Stability Questions question 1
[Maximum number: 4]
Outline the features of ecosystems that make them sustainable.
a. recycling of nutrients/elements/components/materials
b. carbon/nitrogen/another example of recycled nutrient/element
c. decomposers/saprotrophs break down organic matter/release «inorganic» nutrients
d. energy supplied by the sun
OR
energy cannot be recycled «so ongoing supply is needed»
OR
energy is lost from ecosystems as heat
e. energy flow along food chains/through food web/through trophic levels
f. photosynthesis/autotrophs make foods/trap energy
OR
autotrophs supply the food that supports primary consumers
g. oxygen «for aerobic respiration» released by autotrophs/photosynthesis/plants
h. carbon dioxide «for photosynthesis» released by respiration
i. populations limited by food supply/predator-prey/interactions/competition OR
populations regulated by negative feedback
OR
fewer/less of each successive trophic level «along the food chain»/OWTTE
j. supplies of water from rainfall/precipitation/rivers/water cycle
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