MediumBiologyHigh School (9–10)GeneralEcology and Environment › Ecosystems and Food ChainsConceptual
Kiran says a food chain could easily have six or seven levels if the top animals were small…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Kiran says a food chain could easily have six or seven levels if the top animals were small. Use the ten per cent law to explain why real chains seldom have more than four levels.
Need a reminder? The key ideaShow
Energy enters from the Sun; plants capture about 1% of it. About 10% of the energy passes from one trophic level to the next, and the rest is lost, mostly as heat, so energy flows one way and chains are short. Non-biodegradable chemicals build up along a chain (biological magnification), most at the top.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The loss. Each step keeps only about a tenth of the energy.
Step 2. After a few steps. After four steps, only about a ten-thousandth of the producers' energy is left.
Step 3. So. That is too little to support a further level of animals, however small they are.
Answer: so much energy is lost at each step that little is left after three or four levels.
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