For each situation, name the limitation of the ecological pyramids that it shows…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
For each situation, name the limitation of the ecological pyramids that it shows.
- A pyramid is drawn for a lake as one straight chain, but the lake has many linked chains.
- Fungi and bacteria are not drawn in the pyramid of a forest, although they break down much of the dead matter.
- A crow eats seeds and also eats frogs, but the pyramid puts it in one level.
- The pyramid of a lake cannot show that the heron eats both fish and tadpoles.
Need a reminder? The key ideaShow
The pyramids of number, biomass and energy have the producers at the base. The pyramid of number of a tree and the pyramid of biomass of the sea can be inverted. The pyramid of energy is always upright. Production in a year is the biomass times the turnover.
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. (a) The pyramid assumes a simple food chain, which is never found in nature.
Step 2. (b) Saprophytes are not given a place in a pyramid, although they play a vital role.
Step 3. (c) The pyramid does not take into account a species that belongs to more than one trophic level.
Step 4. (d) The pyramid cannot accommodate a food web.
Answer: (a) a simple chain is assumed; (b) no place for saprophytes; (c) a species at more than one level; (d) no food web.
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