Chapter 13 · Biology

Our Environment

Only about a tenth of the energy at one trophic level reaches the next. The module builds any food chain you like and computes the actual energy left at every level from the ten percent law.

Ecology Lab — Food Chains, Energy Flow & Pollution

Build a food chain, watch the 10% energy law shrink the pyramid, and see pollutants biomagnify up the chain.

Food chain (grassland)

Energy pyramid (10% law)

Sort: biodegradable vs non-biodegradable

Banana peel

Plastic bag

DDT/pesticide

Paper

Cotton cloth

Glass bottle

Aluminium can

Wood

Vegetable waste

Styrofoam

Chain length4

Producer energy10000 kcal

Producer (Grass): 10000.0 kcal · pollutant ×1
Primary consumer (Grasshopper): 1000.0 kcal · pollutant ×4
Secondary consumer (Frog): 100.0 kcal · pollutant ×16
Tertiary consumer (Snake): 10.0 kcal · pollutant ×64

Formula sheet

Ten percent law

Energy at next level = 10 % of the previous level

Lindeman's law; 90 % is lost as heat and in life processes.

Energy after n levels

Eₙ = E₀ × (0.1)ⁿ

Explains why food chains rarely exceed 4–5 levels.

Ozone formation

O₂ →(UV) O + O ; O + O₂ → O₃

Ozone in the stratosphere absorbs harmful UV.

Trophic levels

Producer → Herbivore → Carnivore → Top carnivore

Each step is one trophic level.