Ch.25 - Ecosystem Dynamics Final Test Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. ____ 1. NASA originally hired James Lovelock to consult on a project for identifying life on Mars because Lovelock ________. a. had expertise in designing instruments to detect traces of chemicals b. had produced a credible description of an extraterrestrial sighting c. was a renowned physical chemist with a specialization in thermodynamics d. was a noted ecologist with experience in computer simulations of living systems e. had a spiritual approach to space exploration that NASA felt would add a positive dimention to their work ____ 2. James Lovelock suggested that the best way to identify extraterrestrial forms of life would be to survey a planet for ______. a. entities that move b. high molecular-weight carbon compounds c. localized regions of low entropy d. photosynthetic pigments e. an atmosphere with oxygen ____ 3. Ecology is the study of _______. a. mathematical computations of the changing distribution of allele frequencies b. evolution, both before and after the appearance of living organisms c. the process by which organisms regulate their internal environment d. how humans have changed the biology and climate of the earth e. the interactions of organisms with one another and with their physical environment ____ 4. Which of the following is NOT an abiotic component of the ecosystem? a. wind b. humidity c. salinity d. temperature e. All of these are abiotic components. ____ 5. Ecosystems differ from living organisms in that ecosystems do NOT _____. a. reproduce themselves b. respond to environmental changes c. obtain and use energy d. a and b only e. b and c only ____ 6. Ecosystems maintain local order by ______. a. using free energy to increase entropy b. using free energy to decrease entropy c. transferring matter out of the system d. isolating themselves from other ecosystems e. avoiding contact with humans ____ 7. Most of the energy that enters the biosphere comes from ______ and is captured by ______ organisms. a. organic chemicals; photosynthetic b. organic chemicals; fermenting c. the sun; photosynthetic d. the sun; chemoautotrophic e. inorganic chemicals; chemoautotrophic ____ 8. Organisms that produce their own food are ____. a. primary producers b. autotrophs c. herbivores d. a and b only e. a, b, and c ____ 9. Organisms that obtain food from the decomposition of dead organisms are _______. a. consumers b. heterotrophs c. saprophytes d. b and c only e. a, b, and c ____ 10. The final breakdown of dead plants and animals is performed by ________. a. saprophytes b. scavengers c. plants d. carnivores e. herbivores ____ 11. Consider the organisms occupying various trophic levels of a food web. The first level would be likely to have _______. a. saprophytes b. scavengers c. plants d. carnivores e. herbivores ____ 12. Consider the organisms occupying various trophic levels of a food web. If an organism occupied the third trophic level, it could NOT be a(n) _______. a. parasite b. herbivore c. scavenger d. saprophyte e. carnivore ____ 13. The least variation in light on a seasonal basis is found in _____ regions a. arctic b. Antarctic c. temperate d. equatorial e. a and b ____ 14. Generally about _____ of the energy in any one trophic level will be passed on to the next. a. 1% b. 10% c. 20% d. 30% e. 50% ____ 15. Which of the following ecosystems has the highest rate of productivity? a. marshes b. wheat fields c. temperate forests d. rain forests e. deserts ____ 16. Which of the following ecosystems is likely to have the highest biomass per acre? a. wheat fields b. temperate forests c. rain forests d. deserts e. marshes ____ 17. The biomass of an ecosystem would not include _______. a. plant cell walls b. animal bones c. bacterial DNA d. water e. The biomass would include all of these. ____ 18. Which of the following is true for any ecosystem? a. The biomass of the plants is greater than the biomass of the herbivores. b. The energy picked up by the plants is greater than the energy picked up by the herbivores. c. The average size of the individual plants is less than the average size of a typical herbivore. d. The carnivores are larger than the animals they eat. e. All of the above are true. ____ 19. Top carnivores tend to _______. a. range widely in search of food b. specialize in particular types of herbivores c. be relatively numerous in most habitats d. have very large litters of offspring e. a and d ____ 20. Human currently use, for either food, shelter, or recreation, about ________ percent of the world's primary productivity. a. 1 b. 10 c. 20 d. 40 e. 80 ____ 21. Which of the following tends to escape from the biosphere? a. water b. energy c. nitrogen d. carbon e. phosphorus ____ 22. Most of the water entering a plant ______. a. is split by photosynthesis b. remains in the plant as part of the tissues c. leaves through the stomata of the leaves d. is pumped into the fruit during ripening e. exits from the stems through the cuticle ____ 23. Most of the water on earth is found ______. a. in the soil b. in plants c. in animals d. as vapor in the air e. in the oceans ____ 24. The greatest impact on CO2 concentrations in the air have been brought about by human activity that involves ______. a. releasing the carbon stored in sedimentary rocks b. releasing the carbon stored as fossil fuels c. removing the carbon dioxide from the air through agriculture d. incorporating carbon into the increased biomass of human bodies e. releasing carbon dioxide into the air by burning rain forests ____ 25. Which of the following has been suggested as a technologically possible and economically practical way of removing CO2 from the atmosphere? a. fertilizing oceans to promote algal growth b. pumping CO2 directly underground c. using CO2 to construct an atmosphere on the moon d. a and b only e. a and c only ____ 26. When animals and other organisms break down proteins during respiration, they first convert the amino groups to _______. a. ammonia b. nitrogen c. pyruvate d. nitrate e. nitrite ____ 27. Why do most living organisms find useable nitrogen in short supply? a. N2 does not dissolve well in water, and enzymes act primarily on reactants in solution. b. N2 is a highly oxidized form of nitrogen in an atmosphere this is currently highly oxidizing as well. c. N2 is held together by a triple bond that is highly stable and difficult to break. d. N2 makes up less than 1% or the earth's atmosphere. e. The biosphere relies on lightning for reaction of N2 to useable nitrogen, and there are currently fewer and less violent storms than there were 3.6 billion years ago. ____ 28. Most of the N2 in the air enters the biosphere as useable nitrogen as a result of ______, a. photosynthesis by green plants b. bacterial action c. emission from volcanoes d. conversion by lightning e. fixation by soil fungi ____ 29. One way that sizeable amounts of nitrogen enter the biosphere without the intervention of living organisms is _______. a. emission from volcanoes b. rock weathering c. sea shore erosion d. conversion by lightning e. action of ultraviolet light on the atmosphere ____ 30. Plants can use ______ to synthesize amino acids. a. ammonia b. N2 c. nitrate d. a and b only e. a and c only ____ 31. The process of fixing nitrogen involves converting atmospheric nitrogen from a(n)_________. a. maximally oxidized state to a more reduced form b. maximally reduced state to a more oxidized form c. inorganic to an organic form d. organic to an inorganic form e. gas to an organic compound ____ 32. Currently the major source of nitrogen used by grain crops is _______. a. symbiotic bacteria b. soil bacteria c. industrially manufactured fertilizers d. lightning e. mycorrhizae ____ 33. Which of the following, when dissolved in water, can produce acid rain? a. nitric acid b. ammonia c. N2 d. O2 e. All of these can produce acid rain. ____ 34. Which of the following is NOT a way that excess nitrate in the soil can lower its fertility? a. acidifying the soil b. making nitrogen unavailable to plants c. promoting leaching of minerals d. promoting aluminum build-up in soil water, which poisons roots e. discouraging fungal growth ____ 35. Replacing natural vegetation with crop plants has increased the availability of soil nitrogen because _________. a. grains can directly fix nitrogen with chloroplast enzymes b. grains harbor nitrogen-fixing bacteria c. peas and other legumes can directly fix nitrogen with chloroplast enzymes d. peas and other legumes harbor nitrogen-fixing bacteria e. commercial crops deplete soil nitrogen, and the soil bacteria over-react ____ 36. A coastal marine "dead zone" most directly results from _______. a. poisoning by excess nitrogen b. poisoning by algal toxins c. suffocation by fecal pellets d. suffocation from oxygen depletion e. ion imbalances caused by the influx of fresh water Matching Match the organism to its role in the nitrogen cycle. a. convert nitrate in N2 b. make nitrogen available to animals by incorporating it into organic compounds c. remove N2 from the atmosphere, converting it to nitrate and ammonia d. gain energy from urea, releasing ammonia e. oxidize organic compounds, excreting urea ____ 37. plants ____ 38. nitrifying bacteria ____ 39. ammonifying bacteria ____ 40. mammalian herbivores ____ 41. denitrifying bacteria Essay – Attempt to answer the following questions with no more than one paragraph response. You may use symbols, words and or brief diagrams to incorporate into your responses. 42. What arguments could be used to support the tenet of the Gaia hypothesis that the biosphere is a connected ecosystem? 43. Define the word "ecosystem" and describe your favorite ecosystem and its components, both biotic and abiotic. 44. If the boundaries of an ecosystem are hard to define, how might a scientist studying a population of migrating caribou view the boundaries of an arctic ecosystem differently from a scientist studying gene flow in population of mosses used by the caribou for food? 45. Trace the energy from the sun through the trophic levels of a hypothetical food chain, including the five types of producers and consumers discussed in your text. 46. Explain how the burning of fossil fuels could result in a rise in global temperatures.