Which of the following best explains why ecosystems need a continual influx of new energy?
Which of the following is true about the efficiency of energy transfer in an ecosystem?
Which of the following statements about C3 carbon fixation is true?
Which of the following organisms is located only in the 3rd trophic level of the soil food web?
Which of the following is required for photosynthesis to take place?
Which of the following statements about energy and trophic levels is not true?
Moving through trophic levels _______.
Which of the following is a product of photosynthesis?
Bacteria in soil feed on _______.
What percentage of a lower trophic level’s energy flows to the next higher trophic level?
Increases in entropy lead to _______.
Explain why energy in most ecosystems must flow from the sun, then to autotrophs and finally to heterotrophs, in that order.
Most of the energy in ecosystems enters as sunlight, so it is the principal source of energy for the biosphere. Autotrophs are organisms that can convert sunlight, solar radiation, into chemical energy that they and other organisms can use. Heterotrophs cannot utilize sunlight directly to make their food, so energy can only flow to them after passing through autotrophs.
Explain why photosynthesis is vital for life.
Photosynthesis is vital for plant life, because it provides plants with a means to produce energy. Photosynthesis indirectly provides organisms that feed on plants with energy as well. Organisms that feed on plants derive their energy from the plants, which obtained their energy from sunlight through the process of photosynthesis. Photosynthesis also helps maintain atmospheric levels of carbon dioxide and oxygen. Carbon dioxide is taken in by plants during photosynthesis, and oxygen is released.
Relate the concept of gross and net production to the concept of energy conversion.
Gross production is the total energy captured by producers. Net production is gross production minus energy lost to respiration. The difference between gross and net production determines the efficiency of energy conversion to the next trophic level (~10%).
Put the following organisms in an aquatic food chain in the order in which energy flows through them, explaining the reason for their placement.small fish, mammal, phytoplankton, zooplankton
phytoplankton → zooplankton → small fish → mammal. Energy flows from producers (phytoplankton) to primary consumers (zooplankton) to secondary consumers (small fish) to tertiary consumers (mammal).
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