Population Pyramids
Page 27 of the CGP A2-Level Biology revision guide.
- Created by: Hannah Kent
- Created on: 24-01-14 11:42
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- Population Pyramids
- Food chains can be shown by drawing population pyramids with each block representing a trophic level.
- Producers are always at the bottom, then primary consumers are above them, followed by secondary consumers and then tertiary consumers.
- The area of the block tells you the size of each trophic level.
- Producers are always at the bottom, then primary consumers are above them, followed by secondary consumers and then tertiary consumers.
- There are three types of pyramid
- Pyramids of number
- Pyramids of numbers show the number of organims in each trophic level.
- They're not always the true pyramid shape, due to large numbers of small organims etc.
- Pyramids of biomass
- Pyrmaids of biomas show the amount of biomass in each trophic level at a single moment in time.
- They nearly always come out pyramd-shaped, an exception is when they're based on plant plankton.
- Pyramids of energy
- Pyramids of energy show the amount of energy available in each trophic level in kilojoules oer square metre per year, the net productivity of each trophic level.
- Pyramids of energy are always the true pyramid shape.
- Pyramids of number
- Food chains can be shown by drawing population pyramids with each block representing a trophic level.
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