C6e 54 - lecture Notes PDF

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Ch. 54 Ecosystems Questions for Chapter 54 1) A cow's herbivorous diet indicates that it is a(n) A) primary consumer. B) secondary consumer. C) decomposer. D) autotroph. E) producer. Answer: A 2) Which of the following organisms fix nitrogen in aquatic ecosystems? A) c yanobacteria B) chemoautotrophs C) phytoplankton D) legumes E) fungi Answer: A 3) Which of the following statements is (are) true? A) An ecosystem's trophic structure determines the rate at which energy cycles within the system. B) At any point in time, it is impossible for consumers to outnumber producers in an ecosystem. C) Chemoautotrophic prokar yotes near deep-sea vents are primary producers. D) There has been a well-documented increase in atmospheric carbon dioxide over the past several decades. E) Both C and D are true. Answer: E 4) Production, consumption, and decomposition are important ecos ystem processes. Organisms in which of the following taxa perform decomposition? A) bacteria

B) vertebrates

C) invertebrates

D) A and C

E) A, B, and C

Answer: E 5) Organisms in which of the following taxa are responsible for most of the conversion of organic materials into inorganic compounds that can be utilized in primary production? A) autotrophs

B) bacteria

C) fungi

D) B and C

E) A, B, and C

Answer: D Use Figure 54.1 to answer the following q uestions. Examine this food web for a particular terrestrial ecosystem. Each letter is a species. The arrows represent energy flow.

Figure 54.1 6) Which species is autotrophic? Answer: A

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7) Which species is most likely the decomposer? Answer: E 8) A toxic pollutant would probably reach its highest concentration in which species? Answer: D 9) Species C makes its predators sick. Which species is most likely to benefit from being a mimic of C? Answer: B 10) Excluding the decomposer, biomass would probably be smallest for which species? Answer: D 11) The main decomposers in an ecosystem are A) fungi.

B) plants.

C) insects.

D) prokaryotes.

E) A and B.

Answer: E 12) The fundamental difference between materials and energy is that A) materials are c ycled through ecosystems; energy is not. B) energy is cycled through ecosystems; materials are not. C) energy can be converted into materials; materials cannot be converted into energy. D) materials can be converted into energy; energy cannot be converted into materials. E) ecosystems are much more efficient in their transfer of energy than in their transfer of materials. Answer: A 13) The concept that energ y cannot c ycle through an ecosystem is best explained by A) the law of conservation of energy. B) the second law of thermodynamics. C) the competitive exclusion principle. D) the Green World h ypothesis. E) the principle of biomagnification. Answer: B 14) Subtraction of which of the following will convert gross primar y productivit y into net primary productivity? A) the energy contained in the standing crop B) the energy used by heterotrophs in respiration C) the energy used by autotrophs in respiration D) the energy fixed by photosynthesis E) all solar energy Answer: C 15) The difference between net and gross primary productivity would likely be greatest for A) phytoplankton in the ocean. B) corn plants in a farmer's field. C) prairie grasses. D) an oak tree in a forest. E) sphagnum moss in a bog. Answer: D

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16) Which of these ecosystems accounts for the largest amount of Earth's primary productivity? A) tundra B) savanna C) salt marsh D) open ocean E) tropical rain forest Answer: D 17) The producers in ecosystems include which of the following? I. prokaryotes II. algae III. plants A) I only

B) II only

C) III only

D) I and III only

E) I, II, and III

Answer: E 18) Which of these ecosystems has the highest primary productivity per square meter? A) savanna B) open ocean C) boreal forest D) tropical rain forest E) temperate forest Answer: D 19) The total biomass of photosynthetic autotrophs present in an ecosystem is known as the A) gross primary productivity. B) standing crop. C) net primary productivit y. D) secondary productivity. E) trophic efficiency. Answer: B 20) Aquatic primary productivit y is often limited by which of the following? I. light II. nutrients III. pressure A) II only

B) III only

C) I and II only

D) II and III only

E) I, II, and III

Answer: C 21) The highest primary productivity occurs in the open ocean rather than other ecosystems. Why? A) It contains greater concentrations of nutrients. B) It receives a greater amount of solar energy per unit area. C) It has the greatest total area. D) It contains more species of organisms E) Its producers are generally much smaller than its consumers. Answer: C 22) Compared with the open ocean, marine life is especially abundant and diverse near the shore because A) the open ocean is too salty. B) the water is calmer near the shore. C) the water is warmer near the shore. D) there is less competition for light near the shore. E) inorganic nutrients are more plentiful near the shore. Answer: E Page 643

23) The amount of chemical energy in consumers' food that is converted to their own new biomass is called the A) biomass. B) standing crop. C) biomagnification. D) primary production. E) secondary production. Answer: E 24) Organisms in which of the following groups can be primary producers? A) c yanobacteria B) zooplankton C) flowering plants D) A and C E) A, B, and C Answer: D 25) Aquatic ecosystems are unlikely to be limited by insufficient A) nitrogen. B) carbon. C) phosphorus. D) iron. E) More than one of the above is correct. Answer: B 26) Trophic efficiency is A) the ratio of net secondary production to assimilation of primary production. B) the percentage of production transferred from one trophic level to the next. C) the ratio of net production at one trophic level to the net production at the level below, expressed as a percent. D) usually greater than production efficiencies. E) both B and C. Answer: E 27) If you had a large quantity of excess grain and wanted to convert it into the greatest amount of animal biomass, to what would you feed it? A) chickens B) mice C) cattle D) carp (a type of fish) E) mealworms (larval insects) Answer: E 28) Which of the following is primarily responsible for limiting the number of trophic levels in most ecosystems? A) Many primary and higher-order consumers are opportunistic feeders. B) Most predators require large home ranges. C) Nutrient c ycles involve both abiotic and biotic components of ecosystems. D) Nutrient c ycling rates tend to be limited by decomposition. E) Each energy transfer is less than 100% efficient. Answer: E

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29) In general, the total biomass in a terrestrial ecosystem will be greatest for which trophic level? A) producers B) herbivores C) primar y consumers D) tertiary consumers E) secondary consumers Answer: A 30) Some aquatic ecosystems can have inverted biomass pyramids because A) phytoplankton are much larger than zooplankton. B) phytoplankton have a relatively short turnover time. C) consumption of phytoplankton by zooplankton is so rapid that the standing crop of ph ytoplankton remains relatively low. D) both B and C are true. E) A, B, and C are true. Answer: D 31) Which of the following terms actually encompasses all of the others? A) heterotrophs B) herbivores C) carnivores D) primary consumers E) secondary consumers Answer: A Ref er to Figure 54.2, a diagram of a f ood web, for the following questions. (Arrows represent energy flow and letters represent species.)

Figure 54.2 32) If this were a terrestrial food web, the combined biomass of C + D would probably be A) greater than the biomass of A. B) less than the biomass of H. C) greater than the biomass of B. D) less than the biomass of A + B. E) less than the biomass of E. Answer: D 33) If this were a marine food web, the smallest organism might be A) A.

B) F.

C) C.

D) I.

E) E.

D) D

E) E

Answer: A 34) Which species might be described as an omnivore? A) F

B) B

C) I

Answer: E

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35) For most terrestrial ecosystems, pyramids of numbers, biomass, and energy are essentially the same: They have a broad base and a narrow top. The primary reason for this pattern is that A) secondary consumers and top carnivores require less energy than producers. B) at each step, energy is lost from the system as a result of keeping the organisms alive. C) as materials pass through ecosystems, some of them are lost to the environment. D) biomagnification of toxic materials limits the secondary consumers and top carnivores. E) top carnivores and secondary consumers have a more general diet than primary producers. Answer: B 36) Which of the following pyramids cannot possibly be inverted? A) production

B) biomass

C) numbers

D) both A and B

E) A, B, and C

Answer: A 37) Which of the following situations is consistent with the Green World hypothesis? A) Milkweed plants are eaten by monarch caterpillars. B) Some gyps y moths cannot feed and die because others have defoliated the trees in the area. C) Webworms cooperate with each other to build a protective silken structure around themselves. D) A mild winter improves the survival rate of overwintering cutworms. E) Grasshoppers in a corn field are killed by a viral infection. Answer: E The following questions refer to the organisms in a grassland ecosystem listed below. Each term may be used once, more than once, or not at all. A. B. C. D. E.

hawks snakes shrews grasshoppers grass

38) an autotroph Answer: E 39) an herbivore Answer: D 40) smallest biomass Answer: A 41) tertiary consumer Answer: B 42) probably the highest internal concentration of toxic pollutants Answer: A 43) All of the following statements about energy flow are correct except: A) Secondary productivity declines with each trophic level. B) Only net primary productivit y is available to consumers. C) About 90% of the energy at one trophic level does not appear at the next. D) Eating meat is probably the most efficient way of acquiring the energy of photosynthetic productivit y. E) Only about one-thousandth of the chemical energy fixed by photosynthesis actually reaches a tertiary-level consumer. Answer: D

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44) Many homeowners mow their lawns during the summer and collect the clippings, which are then hauled to the local landfill. Which of the following would comprise an alternative that would cause the least disturbance to local ecosystems? A) Don't mow the lawnπhave a sheep graze on it and put the sheep's feces into the landfill. B) Collect the clippings and burn them. C) Either collect the clippings and add them to a compost pile, or don't collect the clippings and let them decompose in the lawn. D) Collect the clippings and wash them into the nearest storm sewer that feeds into the local lake. E) Dig up the lawn and cover the yard with asphalt. Answer: C 45) To recy cle nutrients, the minimum an ecosy stem must have is A) producers. B) producers and decomposers. C) producers, primary consumers, and decomposers. D) producers, primary consumers, secondary consumers, and decomposers. E) producers, primary consumers, secondary consumers, top carnivores, and decomposers. Answer: B 46) Nitrogen is available to plants only in the form of A) ammonium.

B) nitrite.

C) nitrate.

D) A and C.

E) A, B, and C.

D) Plantae.

E) Animalia.

Answer: D 47) All organisms capable of fixing nitrogen belong to the group A) Protista.

B) Archaea.

C) Fungi.

Answer: B 48) In the nitrogen cycle, the bacteria that replenish the atmosphere with N 2 are A) Rhizobium bacteria. B) nitrifying bacteria. C) denitrif ying bacteria. D) methanogenic protozoans. E) nitrogen-fixing bacteria. Answer: C 49) How does phosphorus normally enter the atmosphere? A) respiration B) photosynthesis C) rock weathering D) geological uplifting (subduction and vulcanism) E) It does not enter the atmosphere in biologically significant amounts. Answer: E 50) Which of the following statements is correct about biogeochemical cycling? A) The phosphorus cycle involves the rapid recycling of atmospheric phosphorus. B) The phosphorus cycle is a sedimentary cycle that involves the weathering of rocks. C) The carbon cy cle is a localized cycle that primarily reflects the burning of fossil fuels. D) The carbon cy cle has maintained a constant atmospheric concentration of CO2 for the past million years. E) The nitrogen cycle involves movement of nitrogen in which very little of it is chemically altered by either the biotic or abiotic components of the ecosystem. Answer: B

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51) Long-term ecological research at the Hubbard Brook Experimental Forest indicates that A) intensive logging can dramatically increase levels of nitrate and calcium ions retained in the soil. B) the amount of nutrients leaving an intact forest ecosystem is controlled by the plants themselves. C) selective logging can actually increase species richness in deciduous forests. D) two of the above are true. E) all of the above are true. Answer: B 52) Human-induced modifications of the nitrogen cycle can result in A) eutrophication of freshwater ecos ystems. B) increased availability of fixed nitrogen to primary producers. C) accumulation of toxic levels of nitrates in groundwater. D) depletion of atmospheric ozone. E) all of the above. Answer: E 53) The high levels of pesticides found in birds of prey is an example of A) eutrophication. B) predation. C) biological magnification. D) the Green World hypothesis. E) chemical c ycling through an ecosystem. Answer: C 54) If the flow of energy in an Arctic ecosystem goes through a simple food chain from seaweeds to fish to seals to polar bears, then which of the following is true ? A) Polar bears can provide more food for Eskimos than seals can. B) The total energy content of the seaweeds is lower than that of the seals. C) Polar bear meat probably contains the highest concentrations of fat-soluble toxins. D) Seals are more numerous than fish. E) The carnivores can provide more food for the Eskimos than the herbivores can. Answer: C 55) When levels of CO2 are experimentally increased, C3 plants generally respond with a greater increase in productivity than C 4 plants. This is because A) C3 plants are more efficient in their use of CO2. B) C3 plants are able to obtain the same amount of CO2 by keeping their stomata open for shorter periods of time. C) C4 plants don't use CO2 as their source of carbon. D) the rate of photosynthesis is limited more by CO2 in C3 plants than in C4 plants. E) both B and D are correct. Answer: D The following questions refer to the terms below. Each term may be used once, more than once, or not at all. A. B. C. D. E.

Green World hypothesis turnover biological magnification greenhouse effect cultural eutrophication

56) increased concentrations of CO2 in the atmosphere Answer: D

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57) caused by excessive nutrient input into lakes Answer: E 58) caused excessive levels of DDT in fish-eating birds Answer: C 59) occurs at a high rate for nutrients in tropical rain forests Answer: B 60) All of the following are likely results of land-clearing operations such as deforestation and agricultural activity except A) destruction of plant and animal habitats. B) erosion of soil due to increased water runoff. C) leaching of minerals from the soil. D) rapid eutrophication of streams and lakes. E) decreased carbon dioxide in the atmosphere. Answer: E

Media Activity Questions 1) Which of these terms applies to organisms that produce the organic molecules needed by all living things? A) producers B) primary consumers C) secondary consumers D) tertiary consumers E) detritivores Answer: A 2) On Earth, most organic molecules are produced by A) photorespiration. B) photosynthesis. C) glycolysis. D) hydrol ysis. E) cellular respiration. Answer: B 3) Which of these processes removes carbon dioxide from the atmosphere? A) death B) decomposition C) burning D) cellular respiration E) photosynthesis Answer: E 4) Denitrifying bacteria convert __________ to __________. A) ammonium ... nitrogen gas B) nitrates ... nitrogen gas C) nitrogen gas ... nitrates D) nitrogen gas ... ammonium E) nitrogen gas ... nitrites Answer: B

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5) Proteins are converted into ammonia b y A) decomposers. B) tertiary consumers. C) secondary consumers. D) producers. E) primary consumers. Answer: A

Self-Quiz Questions 1) Which of the following organisms is incorrectly paired with its trophic level? A) c yanobacteriaπprimary producer B) grasshopperπprimary consumer C) zooplanktonπsecondar y consumer D) eagleπtertiary consumer E) fungiπdetritivore Answer: C 2) One of the lessons from a pyramid of production is that A) only one-half of the energy in one trophic level is passed on to the next level. B) most of the energy from one trophic level is incorporated into the biomass of the next level. C) the energy lost as heat or lost in cellular respiration is 10% of the available energy of each trophic level. D) production efficiency is highest for primary consumers. E) eating grain-fed beef is an inefficient means of obtaining the energy trapped by photosynthesis. Answer: E 3) The role of decomposers in the nitrogen cycle is to A) fix N2 into ammonia. B) release ammonia from organic compounds, thus returning it to the soil. C) denitrif y ammonia, thus returning N 2 to the atmosphere. D) convert ammonia to nitrate, which can then be absorbed by plants. E) incorporate nitrogen into amino acids and organic compounds. Answer: B 4) The Hubbard Brook Experimental Forest study demonstrated all of the following except that A) most minerals were recycled within a forest ecosystem. B) mineral inflow and outflow within a natural watershed were nearly balanced. C) deforestation resulted in an increase in water runoff. D) the nitrate concentration in waters draining the deforested area became dangerously high. E) deforestation caused a large increase in the density of soil bacteria. Answer: E 5) The recent increase in atmospheric CO2 concentration is mainly a result of an increase in A) primary production. B) the biosphere's biomass. C) the absorption of infrared radiation escaping from Earth. D) the burning of fossil fuels and wood. E) cellular respiration by the exploding human population. Answer: D

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6) Which of the following is a result of biological magnification? A) Top-level predators ma y be most harmed by toxic environmental chemicals. B) DDT has spread throughout every ecosystem and is found in almost every organism. C) The greenhouse effect will be most significant at the poles. D) Energy is lost at each trophic level of a food chain. E) Many nutrients are being removed from agricultural lands and shunted into aquatic ecosystems. Answer: A 7) Which of these ecosystems has the lowest primary production per square meter? A) a salt marsh B) an open ocean C) a coral reef D) a grassland E) a tropical rain forest Answer: B 8) Quantities of mineral nutrients in soils of tropical rain forests are relatively low because A) the standing crop is small. B) microorganisms that recycle chemicals are not very abundant in tropical soils. C) the decomposition of organic refuse and reassimilation of chemicals by plants occur rapidly. D) nutrient cycles occur at a relatively slow rate in tropical soils. E) the high temperatures destroy the nutrients. Answer: C 9) Coastal water polluted with phosphate and nitrogenous compounds from duck farms showed detectable levels of phosphates but not nitrogen. In experiments, algae were grown in water...