IB ESS SL 2.2.17 Ecological Pyramids Question Bank
Interpret pyramids of numbers, biomass and energy and identify their limitations.
- Syllabus
- First assessment 2026
- Course
- ESS SL
- Level
- SL
Exam points
- identify the ecological process or energy relationship
- apply the correct thermodynamic, productivity or trophic concept
- justify the conclusion from evidence and system boundary
2.2.17—Ecological pyramids question 1
[Maximum number: 7]
Explain why pyramids of numbers, biomass and productivity may vary in shape for different food chains.
a. pyramids of productivity tend to get smaller at higher levels;
b. this is because energy is lost between trophic levels;
c. seasonal productivity at lower levels could temporarily be smaller;
d. ...but annual productivity should always decrease at higher levels;
e. pyramids of numbers tend to get smaller at higher levels due to losses;
f. ...but may get larger if individuals at lower trophic levels are larger (e.g. trees);
g. pyramids of biomass tend to get smaller at higher levels due to losses;
h. ...but as they reflect standing stock (and not rate of flow) they can be inverted;
i. pyramids may become larger at higher levels if they represent a single food chain in a larger food web;
j. ...because more biomass may be fed in from other food chains;
k. food chain with more trophic levels will have longer shape;
I. pyramids of productivity tend to be pyramid shaped because they show flow of energy over time;
m. ...and because the second law of thermodynamics means energy is lost in the flow;
Note: Alternative valid points describing/explaining why pyramid shape may vary can be credited.
Do not credit vague statements claiming shape will be "different" without explaining in what way it will differ.
All question bank results loaded