Organisation & Trophic Levels - Pyramids of Biomass (GCSE Biology)

Pyramids of Biomass

Biomass

Pyramids of Biomass

Biomass is tissue that is living or recently dead.

You can use pyramids of biomass to map out the trophic levels in a food chain. The biomass should decrease as you go up trophic levels. When you construct these graphs, there are a few rules:

  1. The producer is at the bottom of the pyramid, at trophic level 1.
  2. You must construct the pyramid to scale. Therefore, if the mass of a producer is 100kg, the second trophic level 70kg, the third trophic level 50kg and the final trophic level 10kg, the bars must have a length of 10, 7, 5 and 1 units respectively.
  3. The bars must be equally spaced from the midpoint.
  4. The bars must be touching.
Pyramids of Biomass
Pyramids of Biomass
GCSE Biology Online Course
Covering every topic in the GCSE syllabus
Buy Now£29

Pyramids of Numbers

Pyramids of numbers show the number of organisms at each stage of the food chain instead of showing the energy transferred. For example, 2,000 chickweeds would be followed by 40 chickens which would be followed by 1 fox which would be followed by 400 flees. When using pyramids of numbers, the number of organisms might increase at the next trophic level e.g. 1 fox to 400 fleas. So when drawing it out, the bar for the fleas would be longer than the bar for the fox. However, in reality, the amount of energy transferred decreases.

Pyramids of Biomass
Pyramids of Biomass

Using a pyramid of biomass would be better to represent the transfer of energy. Even though there are more fleas than foxes, their biomass in total is still significantly lower and energy is lost at each trophic level. Hence, the transfer of biomass can be represented in a nice pyramid.

Pyramids of Biomass
Pyramids of Biomass
Get Access to 20 Free GCSE Tutorials

    Still got a question? Leave a comment

    Leave a comment

    Post as “Anonymous”