Year 12 / Functioning ecosystems and succession

Energy moves through the web.

Producers capture energy and build biomass. Consumers obtain chemical energy by feeding. At each transfer, much energy is used in respiration, lost as heat, or remains in material not eaten or digested.

Energy flow is directional, unlike nutrient cycling. Ecological pyramids show why higher trophic levels usually support less biomass. Transfer efficiency can be calculated from energy received divided by energy available at the previous level.

INTERACTIVE MODEL

Trophic energy transfer

10% transfer · 10.0 kJ reaches secondary consumersTransfer efficiency10%5%30%

Explore: Adjust transfer efficiency and follow the amount remaining at each trophic level.

\text{efficiency}=\frac{E_{\mathrm{next}}}{E_{\mathrm{previous}}}\times100\%

WORKED EXAMPLE

Producers contain 1000 kJ; primary consumers receive 100 kJ.

Divide 100 by 1000.
The transfer efficiency is 10%.

Assumed knowledge

Percentages.

Learning checkpoints & source

YOUR LEARNING CHECKPOINT

Trace energy between trophic levels.
Explain why food chains have limited length.

QCAA Biology · Unit 3 · Functioning ecosystems and succession ↗

READY TO TRY IT?

Energy moves through the web.

Trophic energy transfer

Producers contain 1000 kJ; primary consumers receive 100 kJ.

Put the idea to work.