Biological Principles 2 -- HW#59

1.      How does the production efficiency of ectotherms and endotherms compare? Usually higher in ecotherms than in endotherms.

2.      Describe the various environmental influences and limitations on primary production.

·         Different factors in terrestrial and aquatic ecosystems limit primary production. The limiting factor is the feature needed for growth that is in the shortest supply.

·         In terrestrial ecosystems, the major limiting factors are water, temperature, and nutrient availability. In aquatic ecosystems, the major limiting factors are primarily light and secondary nutrient availability.

·         In the study shown in Figure 59.11 on primary production of a salt marsh sedge, it was determined that the limiting factor for growth was nitrogen. Once the factor was added, the new limiting factor was phosphorous.

·         The availability of producer biomass is limited by secondary production. The production efficiency of invertebrates is higher than that of vertebrates, because invertebrates transfer moe plant biomass into their own biomass than do vertebrates.

3.      Primary production is generally highest in wetlands.

4.      What two types of organisms are responsible for decomposition? Fungi and bacteria

5.      When an organism is decomposed, where do the released nutrients go? To support the life of the decomposers.

6.      What do yellow slime molds feed on? Decomposers

7.      Which of the following would NOT be a consequence of the loss of all decomposers? Food webs would be unchanged.

8.      Which of the following statements about decomposers is TRUE? Decomposers return CO2 to the atmosphere via aerobic respiration.

9.      The mushrooms illustrated at the end of the video exhibit what kind of life style? They are heterotrophs, but they are not parasites.

10.  The amount of CO2 in the atmosphere is stable over a period of one year. False

11.  In food webs, chain lengths tend to be short.

12.  Animal biomass exceeds plant biomass in most ecosystems. False

13.  Label the figure with the appropriate processes or stages of the carbon cycle.

·         Decomposition and respiration: moves carbon into the atmosphere

·         Photosynthesis: incorporates carbon into the tissues of plants

·         Deforestation: releases carbon into the atmosphere

·         Burning of fossil fuels: human caused release of carbon

·         Sedimentation forms fossil fuels: aquatic systems

·         Deposits of fossil fuels: carbon becomes compressed on land

14.  Food chains represent oversimplifications of producer-consumer relationships. Indicate if the following statements about interactions among trophic levels are true or false in explaining the complexity of these interactions.

·         Plants may be consumed by many different species, which in turn are the potential prey of many other different species. True

·         Energy flows both from producers to consumers and from consumers to producers, which makes it difficult to depict relationships in a linear food chain. False

·         Species can be in more than one trophic level (e.g., might be both a primary and secondary consumer). True

·         While consumers get most of their energy by eating other organisms, most are also capable of producing their own food, blurring the line between producers and consumers. False

·         Decomposers might feed on plant leaves or branches that have fallen to the ground, making them primary consumers, but they might also feed on animal carcasses, making them secondary consumers. True

·         Decomposers are thought to be at the base of complex food webs, whereas producers are depicted as the base of most food chains. False

15.  How do primary producers provide energy for the food chain? They make their own organic molecules via photo- or chemosynthesis.

16.  The process by which elevated nutrient levels lead to an overgrowth of algae and the subsequent depletion of water oxygen levels is known as eutrophication.

17.  In subarctic saltmarshes, scientists have found that the addition of calcium has no effect on productivity, but additional iron does increase productivity. In this example, iron is a limiting factor.

18.  Classify each concept as the appropriate type of ecological pyramid.

·         Pyramid of numbers

¨      Inverted versions are relatively common

¨      Requires counting individuals at each trophic level

·         Pyramid of energy

¨      Inverted versions do not occur

¨      Requires measuring production rate of individuals at each trophic level

·         Pyramid of biomass

¨      Inverted versions are relatively rare

¨      Requires weighing individuals at each trophic level

19.  What is production efficiency? The percentage of energy assimilated by an organism that becomes new biomass.

20.  Most of the Earth's phosphorus is trapped in sedimentary rocks. True

21.  What biogeochemical cycles have been heavily affected by human activities?

§  The water cycle; The phosphorus cycle

§  The nitrogen cycle; The carbon cycle

22.  Biomagnification results in an increased concentration of bioaccumulated chemicals as one moves from upper to lower trophic levels. False

23.  The giant interconnected global ecosystem is called the biosphere.

24.  The movement of chemicals through ecosystems is known as biogeochemical cycling.

25.  What percentage of the earth's atmosphere consists of nitrogen (N2) gas? 78%

26.  Plants, algae, and cyanobacteria are primary producers upon which entire ecosystems are dependent. During photosynthesis, primary producers convert the carbon from inorganic carbon dioxide into organic compounds (glucose and other organic compounds). The amount of carbon that is processed during photosynthesis is referred to as gross primary production. Net primary production, however, is always less than gross primary production. Which of the following statements help to explain this difference?

§  Only some of the carbon converted by the plant is used to create new biomass.

§  Plants utilize some of the incoming energy derived from photosynthesis for self-maintenance.

§  Plants and algae carry out cellular respiration, which requires biochemical energy produced during photosynthesis

27.  Match the following descriptions with the appropriate trophic level.

§  Primary producers => Photosynthesizers; Make their own food; Oak trees

§  Primary consumers => Consume producers; Herbivores; Deer

§  Secondary consumers => Primary carnivores; Small snake species

§  Tertiary consumers => Secondary carnivores; Bald eagle

28.  A positive feedback loop is one that tends to amplify a process. Why would the effect of deforestation on the water cycle be considered a positive feedback loop? Because deforestation leads to a decrease in precipitation, which results in further loss of vegetation.

29.  Trophic-level transfer efficiency averages about 10%

30.  Lead is known to undergo biomagnification and accumulates in the bones. What do you think is the fate of lead taken up by a tiger that has dies of natural causes? Assume the tiger occupies the highest trophic level of its ecosystem. The lead will re-enter the food chain via decomposers breaking down the tiger's bone tissue.

31.  The process by which soil bacteria convert NH3 or NH4 to nitrate (NO3-) is called nitrification.

32.  What are the most important transformers of energy in ecosystems? Plants and algae.

33.  Place each concept or scenario into the appropriate method of measuring efficiency of consumers.

§  Production efficiency

·         Using this measure, a beetle would be more efficient than a shark

·         Used to measure efficiency of a single taxon

·         Helps explain why ecosystems with low primary production may have few mammals

§  Trophic level transfer efficiency

·         Used to report the proportion of energy that flows between levels of a food web

·         Helps to explain the limit on the number of levels in a food web.

·         Using this measure, primary consumers have more energy available to them than secondary consumers.

34.  Deforestation in areas like Madagascar can significantly affect the water cycle. Why is this? Less moisture is transpired into the atmosphere after deforestation.

35.  In the figure, each letter represents a species within a community and the arrows represent energy flow though the ecosystem. Which species is most likely a primary producer? A

36.  What is gross primary production?     The carbon fixed during photosynthesis.

37.  A single oak tree can support hundreds of beetles, caterpillars and other primary consumers. Such a phenomenon is an example of an inverted pyramid of numbers.

38.  Zooplankton are heterotrophs. True

39.  Which of these is a heterotroph? A fish.

40.  What is the role of the dung beetle? They disperse the dung to other areas.

41.  What nutrient in the dung fertilizes the grasslands? Nitrogen

42.  What organism is the primary producer in this food web? Grass

43.  If the feces were experimentally removed from the grasslands, which geochemical cycle would be disrupted over time? The nitrogen cycle

44.  What would be a consequence to the grasslands if the dung beetles were removed from the grassland ecosystem? The nitrogen contained in the dung would not be distributed over greater area and therefore nitrogen would not be available to as many individual grasses.

45.  If primary production increases in an ecosystem, it would be reasonable to expect that the biomass of herbivores would increase.

46.  Where are the largest reserves of carbon on the planet? Rocks and fossil fuels.

47.  Ecosystem ecology is primarily concerned with movement of energy and materials through organisms and their communities.

48.  Based on data from the figure above, grasslands tend to have a higher herbivore biomass than deserts. True

49.  All living organisms require phosphorus for ATP. True

50.  In aquatic ecosystems, zooplankton are consumed by phytoplankton.

51.  What does net primary production represent? The amount of energy in plants that is available to primary consumers.