IB Biology HL 4.2.2 Requirements for stability Question Bank

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

4 max
(Plus up to [1] for quality: The candidate's answers are clear enough to be understood without re-reading. The candidate has answered the question succinctly with little or no repetition or irrelevant material.)