Pre Quiz: Get out a pencil and answer the questions.
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If you start with 1000kg of biomass of primary producers, how much biomass would you have of…
What is biomass?
Primary Consumers?
Secondary Consumers?
Tertiary Consumers
Why does a biomass diagram form a pyramid?

Where does the Energy come from?
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All the energy in an ecosystem comes from the sun.
1 - 2 % of the sun ’ s energy that strikes the earth is absorbed by plants
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The rest is absorbed by abiotic objects or deflected to space
Plants use that energy through photosynthesis to produce sugar (glucose) which can then be converted to the biomass of the plant.

 Biomass – This is the mass of all matter at any level in a food chain
 The amount of biomass in a in each trophic level of a a food chain creates a pyramid (diagram) when shown graphically.

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How much of the mass is transferred to the next level?
*Approximately 10% of biomass at one level becomes biomass at the next level.
What happens to the other 90 %
*The other 90% is uneaten, undigested (this energy is available to decomposers) or given off as heat from the activities of the organism.

What Causes a
Decrease in Biomass?
 Biomass decreases with each additional step upward in a food chain.
 Energy is lost as heat
(and cannot be reused) in each step of the food chain
(diagram on next slide) or as waste.

Which diagram in more accurate?

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The amount of biomass created by an ecosystem at the producer level. The rate at which solar energy is converted to usable energy in the ecosystem.

 This is a pyramid showing that a large number of organisms (see primary productivity) is required at the base of the food chain (there are exceptions) to support a small number of organisms at the top.

 The number of organisms at the highest level in a food chain is directly related to the number of levels in the chain. How can more organisms be supported in an ecosystem?
 What is the difference between a pyramid of biomass and a pyramid of numbers?

 http://www.youtube.com/watch?v=NJplkrliUEg