- Only a fraction of the energy that leaves the sun hits the earth; plants intercept only a fraction of that energy. It is estimated that about 1% of the energy in sunlight is available for primary producers. From this small amount, plants produce 170 billion tons of biomass. - The illustration on the left shows the flow of energy through trophic levels. The relative amount of energy obtained by each trophic level is reflected in the graphic.

- green plants and other organisms that can bind energy from inorganic sources into the chemical bonds of organic compounds. Plants convert solar energy into chemical energy in the form of carbohydrates. Plants produce a relatively large amount of chemical energy. Overall, the transfer of energy from trophic level to trophic level is 10% on average. Energy that is consumed on respiration, growth, and waste matter at any previous trophic level is no longer available to the subsequent trophic levels.

- consume the energy available from all of the other trophic levels after organisms in those levels die. Because plants are the primary producers in many communities, it is of great interest to measure the amount of chemical energy they produce and how much of that is available to higher trophic levels.

gross primary productivity

- a measure of the energy that is bound (and organic matter created) per unit area by the photosynthesis of green plants. As discussed earlier, not all of the energy obtained by the plants is available for the other trophic levels. The plants use some of the energy for respiration

net primary productivity

- gross primary productivity minus plant respiration. The more efficient a plant is at conserving energy, the greater its net primary productivity

Which of the following statements best explains why there are so few top-level predators?

- Only a small fraction of the energy is transferred from one trophic level to the next.

14.9.2 Ecosystems: Productivity and Energy Flow Flashcards by Irina Soloshenko

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14.9.2 Ecosystems: Productivity and Energy Flow Flashcards

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