Energy Flow & the 10% Rule (College Board AP® Environmental Science): Flashcards
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Define 10% rule.
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Cards in this collection (15)
Define 10% rule.
The 10% rule states that approximately 10% of the energy from one trophic level is passed to the next level.
What happens to the energy that is not passed on to the next trophic level?
The rest of the energy is lost as heat, used in metabolism, or remains in undigested parts of organisms.
Transfer between trophic levels is never 100% because, of the food that is consumed, not all is .
Transfer between trophic levels is never 100% because, of the food that is consumed, not all is absorbed.
Define first law of thermodynamics.
The first law of thermodynamics states that energy cannot be created or destroyed; it can only be transformed from one form to another.
In what form does all energy ultimately leave a food chain?
All energy ultimately leaves a food chain, food web, or ecosystem as heat energy.
Define second law of thermodynamics.
The second law of thermodynamics states that energy transfers in systems are inefficient, so transfers in any ecosystem are never 100% efficient.
True or False?
Producers absorb and transfer the Sun's light energy with almost no losses.
False.
Energy absorption by producers is inefficient because of reflection, transmission (light passing through leaves), and inefficient energy transfer during photosynthesis.
Which process causes the biggest energy losses in ecosystems?
The biggest energy losses in ecosystems occur during cellular respiration.
Why are food chains usually short?
Food chains are usually short because energy transfers are inefficient, so they rarely contain more than five trophic levels.
What does the width of each box in a pyramid of numbers show?
The width of each box shows the number of organisms at that trophic level.
When does a pyramid of numbers become inverted?
A pyramid of numbers becomes inverted when individuals at lower trophic levels are relatively large, such as a single oak tree supporting large numbers of insects.
A pyramid of biomass shows the mass of the organisms at each trophic level, excluding the water they contain.
A pyramid of biomass shows the dry mass of the organisms at each trophic level, excluding the water they contain.
True or False?
Pyramids of biomass are always pyramid-shaped.
False.
They are usually pyramid-shaped but can be inverted, for example in some marine ecosystems where phytoplankton reproduce very quickly and are constantly eaten by zooplankton, giving a lower standing crop.
What does a pyramid of energy (productivity) show?
A pyramid of energy shows the flow of energy through trophic levels, per unit area per unit time.
True or False?
A pyramid of energy can be inverted.
False.
Pyramids of energy are always widest at the base and narrow upward, following the second law of thermodynamics.
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