The nutrients in an ecosystem are:

1.  continuously lost from an ecosystem
2.  needed as a continuous supply from the outside
3.  recycled time and again indefinitely
4.  continuously synthesized by physical forces

 80%
Level 1: 80%+
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The earth is regarded as “open” system with respect to:

1.  organisms 2.  chemicals
3.  energy 4.  water
Subtopic:  Energy Flow |
 73%
Level 2: 60%+
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If decomposers go extinct on Earth:

1. Detritivores will replace them
2. Primary production will increase
3. Nutrients will accumulate in dead plants and animals
4. There will be no effect on carnivores
Subtopic:  Decomposition |
 85%
Level 1: 80%+
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A chemical that enters living organisms primarily from the atmosphere is:

1.  phosphorus 2.  sulfur
3.  sodium 4.  carbon
 81%
Level 1: 80%+
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What is the best description of trophic efficiency?

1.  the ratio of net secondary production to the assimilation of primary production.
2.  the percentage of production transferred from one trophic level to the next.
3.  a measure of how nutrients are cycled from one trophic level to the next.
4.  usually greater than production efficiencies.

Subtopic:  Ecosystem Productivity |
 62%
Level 2: 60%+
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What percent of the energy fixed by primary producers in a typical field ecosystem is received by a secondary consumer?
1. 0.1%
2. 1%
3. 10%
4. 20%

Subtopic:  Energy Flow |
Level 4: Below 35%
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The residual, after autotrophic respiration is subtracted from GPP, is:

1.secondary productivity2.net primary productivity
3.standing crop biomass4.chemosynthesis

Subtopic:  Ecosystem Productivity |
 90%
Level 1: 80%+
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Energy and nutrients enter an ecosystem and hence in a community through:
1. Producers
2. Consumers
3. Detritivores
4. Apex predators

Subtopic:  Energy Flow |
 68%
Level 2: 60%+
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The prime driving force for the water cycle is:

1.  evapotranspiration from plants
2.  rainfall
3.  snowmelt
4.  percolation of water through the soil
 54%
Level 3: 35%-60%
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The producers in aquatic ecosystems include all except:

1. cyanobacteria 2. algae
3. plants 4. zooplankton
Subtopic:  Energy Flow |
 67%
Level 2: 60%+
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