Population Pyramids

Page 27 of the CGP A2-Level Biology revision guide.

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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.
    • 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.


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