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## 'Food Chains' printed from http://nrich.maths.org/

Here is a food chain:

A wildcat will eat 3 birds every day. These three birds will eat 10 caterpillars each, every day, totaling 30 caterpillars. The 30 caterpillars will eat one small bush together every day.

**a.** The area that these animals live in currently has 500 small bushes: calculate the number of the other animals.

**b.** As you go up the food chain, the amount of energy available to the following predator decreases. For this food chain, the amount of energy available decreases by 25% for every level in the chain. Calculate how much more energy the wildcat could obtain from becoming a
vegetarian and eating the bush rather than from eating birds.

**c.** One year, a bacteria kills 5000 caterpillars. What effect will this have on the food chain?

**d.** What would happen to the cat, bird and caterpillar populations if the cats decided to become vegetarians and eat bushes to keep alive instead of starving?