How Ecosystems Work: Energy Flow and Nutrient Cycles Bubble in your ID and the answer to the 25 questions. You can look up the answers to these question on line. 1. The flow of solar energy through an ecosystem is marked by a) plants converting light energy to chemical energy via photosynthesis b) herbivores eating plants to obtain energy and carnivores eating herbivores. c) scavengers obtaining energy from the remains left by predators. 2. The solar energy in an ecosystem is a) severely limited. b) used up as goes from trophic level to trophic level. c) retained in full as it flows from one organism to the next. d) not replenished by the sun. 3. Which statement about nutrients and energy is most accurate? a) Energy cycles through ecosystems, while nutrients flow through them. b) Carbon, nitrogen, phosphorous, and water are examples of the energy that powers life. c) Solar energy is necessary to build nutrients. d) Energy flows through ecosystems, while nutrients cycle through them. 4. How much solar energy that reaches the Earth is captured by plants and other producers?
a) 1% b) less than 3% c) less than 0.03% d) 10% 5. Photosynthetic organisms a) rely on the high-energy molecules made by autotrophs. b) produce food not only for themselves but for nearly all other life as well. c) are called heterotrophs. 6. Which is true about net primary productivity? a) It can be measured in units of energy (calories). b) It can be measured as the dry weight of organic material per unit area per year. c) It is the total energy that photosynthetic organisms make available to other members of the community. d) All of the above. 7. Which statement about trophic levels is correct? a) Organisms at higher trophic levels are less abundant than those at lower levels. b) Carnivores that feed primarily on herbivores form the fourth trophic level. c) Photosynthetic organisms are primary consumers, and form the second trophic level. d) Herbivores that feed exclusively on producers are considered secondary consumers. 8. The feeding relationships in an ecosystem are a) very easy to describe as most organisms eat only one organism. b) difficult to describe as most organism eat a variety of other organisms. c) of little use to ecologists in trying to understand an ecosystem. d) marked by the transfer of energy from consumers to producers. 9. Examples of detritivores include a) fungi b) bacteria c) both of the above d) none of the above 10. What is true about detritivores and decomposers? a) They are among the least important organisms in an ecosystem. b) They are usually among the largest organisms in an ecosystem. c) Their excretory products serve as food for herbivores. d) They form a vital link in the nutrient cycle by returning nutrients to the environment. 11. As energy is transferred from one trophic level to the next
a) some of the energy is lost to the environment as heat. b) some of the energy is lost to metabolic processes. c) some of the energy is lost to power the motion and other biological processes of organisms. 12. The 10% Law refers to the fact that a) there is only a 10% inefficiency in the transfer of energy between trophic levels. b) the energy transfer between trophic levels is roughly 10% efficient. c) 10% of the organisms in an ecosystem produce a 100% of the energy. d) 10% of the initial energy in an ecosystem comes from predators. 13. Which of the following is true? a) The lower the trophic level utilized, the more food energy available to human populations. b) Far more people can be fed on grain than on the meat produced by grain fed cattle. c) Both of the above. d) Neither of the above. 14. Which statement regarding nutrients is most accurate? a) Nutrients are replenished from a source outside of our atmosphere. b) The major source of nutrients is generally in the living environment. c) The atmosphere is the major source for the nutrient phosporous. d) The same pool of nutrients has been supporting life for over 3 billion years. 15. CO2 makes up what percentage of the gas in the atmosphere? a) 0.33% b) 0.033% c) 33% d) 3.30% 16. Carbon is captured from the atmosphere a) by producers during photosynthesis. b) and some of it is returned to the atmosphere through cellular respiration. c) and some of it is passed on to herbivores that eat producers. e) none of the above. 17. CaCO3, calcium carbonate, is formed as a) ancient plant and animal remains are transmuted by pressure and vast expanses of time. b) mollusks extract carbon dioxide dissolved in water and combine it with calcium. c) the shells of dead mollusks collect into limestone formations. d) none of the above. 18. Human are effecting the carbon cycle by a) cutting down forests that absorb CO2 from the atmosphere.
b) burning fossil fuels that contain the carbon stored in the bodies of organsims buried during the Carboniferous period. c) neither of the above. d) both of the above. 19. Plants obtain nitrogen from a) amino acids. b) ammonia and nitrates. c) nitrous oxide. d) nitrogen gas. 20. Which statement is most accurate regarding the nitrogen cycle? a) Plants capture nitrogen directly from the atmosphere. b) Plants capture nitrogen directly from the soil. c) Certain bacteria obtain nitrogen from the roots of plants d) Nitrates may be produced by electric storms. 21. Accelerated eutrophication is marked by a) increased levels of nutrients such as phosphates in a body of water. b) huge algae blooms increase the demand for dissolved oxygen in a body of water. c) the development of anaerobic conditions in an body of water that result in the massive die off of animal life. 22. Which statement is not true about the hydrologic cycle? a) It would continue in the absence of life on Earth. b) It is driven by solar energy and gravity. c) The distribution of life does not depend on patterns of precipitation and evaporation. d) The Earth's oceans cover 65% of the planet. 23. What is the Greenhouse Effect? a) CO2 acting like the glass in a greenhouse, allowing light energy in and holding that energy once it has been converted to heat. b) CO2 acting like the glass in a greenhouse, reflecting light energy out and not allowing that energy to be converted to heat. c) The releasing of heat into the atmosphere by heterotrophs. d) Changes in temperature that result from changes in elevation. 24. The CO2 content of the atmosphere has a) always been stable because of the nature of the carbon cycle. b) increased by 300% in the past 25 years. c) increased due to the burning of fossil fuels and the destruction of forests. d) been proven to be the major cause of global warming.
25. Human activities can create changes in the a) cycling of energy that may have a dramatic impact on an ecosystem. b) cycling of nutrients that may have a dramatic impact on an ecosystem. c) flow of energy that may have a dramatic impact on an ecosystem. d) flow of nutrients that may have a dramatic impact on an ecosystem.