C4.2.11—Energy pyramids
Energy pyramids explains how energy flow, matter cycling, trophic transfer or carbon movement is represented, measured or limited within ecosystems.
- Syllabus
- First assessment 2025
- Objective
- C4.2.11
- Level
- SL
Exam analysis
Chance of appearing16%of analysed past papers
Latest appearanceNovember 2024
Most common paperPaper1
Typical marks1–4
Common command terms
- Identify
- Label
- Explain
- Describe
- Outline
- State
- Draw
- Discuss
- Sketch
Scoring notes
- Common mistake
- Reversing food-web arrows instead of showing energy transfer direction.
Recent exam appearances
November 2024Paper2 ["SL"] · TZ23(b)[ 2 ]C4.2.11—Energy pyramids
November 2023Paper1 ["SL"] · TZ219[ 1 ]C4.2.11—Energy pyramids
May 2023Paper3 ["SL"] · TZ114(c)[ 1 ]C4.2.11—Energy pyramids
May 2021Paper1 ["SL"] · TZ218[ 1 ]C4.2.11—Energy pyramids
November 2020Paper3 ["SL"] · TZ015[ 4 ]C4.2.11—Energy pyramids
Practice this objective
Coverage 2010–2024 · Updated 16 Jul 2026
Energy pyramids show usable energy decreases upward
An energy pyramid uses measured research data to show energy available at successive trophic levels per unit area per unit time.
Choose one specific ecosystem dataset; verify that all values use compatible energy, area and time units; order producer to higher consumers; draw bars with widths proportional to the reported values; label every value and unit.
For each transfer, calculate loss as energy at lower level minus energy at next level, and transfer efficiency as (next-level energy ÷ lower-level energy) × 100%. Use the dataset's real values rather than assuming a fixed percentage.
A correctly constructed pyramid lets the reader compare the measured producer energy with each consumer level and see both absolute loss and proportional transfer between adjacent levels.
An energy pyramid is not a pyramid of numbers or standing biomass. Do not invent missing values or mix units or measurement intervals from different ecosystems.
Energy pyramids
Assessment in practice
1–3 marksHow it is assessed
This objective is assessed through structured response, commonly using Identify / Label / Explain.
Command terms
Identify / Label / Explain / Describe / Outline / State / Draw / Discuss / Sketch
What earns marks
Build the answer around this relationship: Energy pyramids must be linked to the correct source, store, transfer or loss process.
Watch for
Reversing food-web arrows instead of showing energy transfer direction.
Representative question
Question 1
Ecologists sometimes display data from an ecosystem using a diagram called a pyramid of energy. Describe what is shown in pyramids of energy.
Energy and Matter
- Ecosystems are open systems: energy flows through them and leaves as heat, while matter is recycled and may enter or leave.
- Photoautotrophs capture light; chemoautotrophs oxidize inorganic substances. Both build biomass from inorganic carbon. Heterotrophs obtain organic carbon from other organisms.
- Food-web arrows show energy and biomass transfer. Energy decreases between trophic levels through respiration, heat, egestion, excretion and uneaten material, limiting chain length.
- Gross primary production minus producer respiration gives net primary production; secondary production is heterotroph biomass gain.
- Decomposers obtain energy from detritus and return inorganic nutrients to producers.
- Carbon-cycle diagrams distinguish stores and fluxes. Photosynthesis removes CO2; respiration, decomposition and combustion release it.
- A sink absorbs more carbon than it releases; a source does the reverse. The Keeling Curve shows a long-term atmospheric CO2 rise with seasonal oscillation.
Concept essentials
- Energy pyramids must be linked to the correct source, store, transfer or loss process.
- The evidence for energy pyramids depends on distinguishing energy flow from matter cycling.
- Energy pyramids is clearer when arrows, units and trophic positions match the biological process.
- Data or diagrams for energy pyramids need interpretation as ecosystem transfer evidence.