Firstly, the Rule of 10 is not a rule! It is really more of a trend that scientists noticed. The trend is that the available energy to a tropic level is usually about 10% of the total energy available to the tropic level before it. Why? Well, all organisms have to use some of the energy that is available to maintain life. Plants use energy to grow and reproduce, as do animals. In addition, animals use energy to move and maintain body functions. As they use the energy they consumed to do useful things, they also produce heat. Heat is not a usable form of energy for living organisms, so it is lost to the surroundings. The important thing to remember is that this 'rule' applies ONLY to energy. Mass does not demonstrate the same 'rule'. We know this because there is no such thing as an inverted energy pyramid but it is possible to have an inverted biomass pyramid. Although it is possible to calculate the mass that an organism would gain due to consumption of a specified mass of food, it is a much more complicated calculation than you have been taught. You will only be required to use the basic calculation as shown here.
Lastly, remember that 10% is a generalization. Each energy relationship has its own percentage of energy transfer that can be calculated, it is just around 10%. However, some questions will ask you to calculate the energy available at the next tropic level if the energy transfer is 13%. So now you need to calculate 13% of the original energy rather than 10. Do the math! Comments are closed.
|
Archives
December 2017
Categories
All
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. |