IB ESS HL 2.3.1 Biogeochemical Cycles Purpose Questions
Explain how decomposers recycle nutrients from dead organic matter and help maintain ecosystem stability.
- Syllabus
- First assessment 2026
- Course
- ESS HL
- Level
- HL
Exam points
- explain how decomposers return inorganic nutrients from dead organic matter to living systems, supporting plant growth, food webs and ecosystem stability
Learn this topic
IB ESS HL 2.3.1 Biogeochemical Cycles Purpose Questions question 1
[Maximum number: 7]
Explain how a community of decomposers contributes to the stability of the whole ecosystem.
a. Decomposers will feed on dead organic matter/detritus (like dead leaves, wood, carcasses, feces)...;
b. ... reducing their accumulation / cleaning up Earth;
c. They will break down organic matter into inorganic matter…;
d. ...enhancing soil fertility / increasing nutrient availability;
e. The inorganic minerals (nitrates, phosphates, metals) will then feed plant communities / will be absorbed by plant roots...;
f. ...supporting high vegetation/plant abundance;
g. ...and may support high habitat/niche diversity;
h. Decomposers are responsible for nutrient cycling / e.g. nitrogen cycling (nitrogen fixation/ammonification/nitrification/denitrification/phosphorus cycling/carbon cycle;
i. ...high flow of matter may support complex food webs;
j. Decomposers are the basis of a detritus-based food web / important part of ecosystem flow of energy / may be eaten/pass biomass on to carnivore community...;
k. ...supporting/stabilizing carnivore abundance;
I. As decomposer numbers decrease due to predation, so do carnivores;
m. ... thereby contribute to regulation of the carnivore community / which is an example of negative feedback (leading to stability);
n. Decomposer will release organic matter through their own death/defecation...;
o. ... which would provide food for other decomposers;
p. Decomposers participate in humus formation...;
q. ...increasing water holding capacity of soil (and soil fertility = MPd);
r. Decomposers may compete with one another regulating their populations (another example of negative feedback = MPm);
s. Decomposers, like earthworms, loosen soil / disperse nutrients / create space for air and water circulation...;
t. ...helping root growth / improving soil structure;
u. Fragmentation: larger invertebrates initially fragment larger chunks of organic matter (then bacteria and fungi complete decomposition into nutrients = MPc);
v. After a disturbance, decomposers will increase their metabolic/respiration rate/feeding on detritus...;
w. ...contributing to a faster return to original state (resilience entailing stability);
All question bank results loaded