S3.2.4 For the adult
Energy through a food chain
There is plenty of grass but only a few foxes. Why?
What this chapter teaches
Energy from sunlight enters a food chain through plants. At each step most of it is used for living or lost as heat, so about a tenth passes on. This is why food chains are short and why top hunters are few.
Three questions to ask
There is no one right wording. Listen for the idea.
- Where does the rest of the energy go when a rabbit eats grass?
- Why is there so little energy at the top of a chain?
- Can you draw a pyramid of numbers for a chain you know?
After the chapter, the learner can
- Explain why food chains rarely have more than five links
- Draw a pyramid of numbers for a food chain
What they copy into their notebook
Energy goes up a food chain, but only about a tenth passes on at each step. The rest is used for living or lost as heat. A pyramid of energy always narrows going up. A pyramid of numbers need not.