CHAPTER 4: ECOSYSTEMS: COMPONENTS, ENERGY FLOW, AND MATTER CYCLING

Objectives

1. Define ecology. List and distinguish among five levels of organization of matter that are the focus of the realm of ecology.

2. List the characteristics of life.

3. Distinguish among lithosphere, hydrosphere, atmosphere, and ecosphere. Briefly describe how the sun, gravity, and nutrient cycles sustain life on Earth. Compare the flow of matter and the flow of energy through the biosphere.

4. Distinguish between an open system and a closed system. Name and describe three types of biogeochemical cycles.

5. Define abioticcomponent of an ecosystem. List three important physical factors and three important chemical factors that have large effects on ecosystems.

6. Summarize the law of tolerance. Compare limiting factors in terrestrial and aquatic ecosystems.

7. Define biotic component of an ecosystem. Distinguish between producers and consumers. List and distinguish four types of consumers. Distinguish among scavengers, detritus feeders and decomposers. Distinguish between photosynthesizers and chemosynthesizers; aerobic respiration and anaerobic respiration.

8. Distinguish between food chains and food webs; grazing food web and detrital food web. Apply the second law of energy to food chains and pyramids of energy, which describe energy flow in ecosystems. Explain how there may be exceptions to pyramids of numbers and biomass, but not energy.

9. Evaluate which ecosystems show the highest average net primary productivity and which contribute most to global net primary productivity.

10. Briefly describe the historical development and distinguishing features of three approaches ecologists use to learn about ecosystems: field research, laboratory research, and systems analysis.

11. Define ecosystem service. List five examples of ecosystem services. Distinguish among three types of biodiversity. Briefly state two principles to sustain ecosystems.

Key Terms (Terms are listed in the same font style as they appear in the text.)

abiotic (p. 71)

acid deposition (p. 87)

atmosphere (p. 68)

autotrophs (p. 74)

biodegradable (p. 74)

biodiversity

biogeochemical cycle (p. 82)

biological diversity (biodiversity) (p. 76)

biomass (p. 77)

biome (p. 70)

biosphere (p. 68)

biotic (p. 71)

carbon cycle (p. 84)

carnivores (p. 74)

climate (p. 70)

community (p. 67)

consumer s (p. 74)

decomposers (p. 74)

detritivores (p. 74)

detritus (p. 74)

dissolved oxygen content (p. 74)

ecological diversity (p. 76)

ecological efficiency (p. 77)

ecosystem (p. 68)

ecosystem services

ecotone (p. 71)

eukaryotic cell(p. 65)

food chain (p. 76)

food web (p. 77)

genetic diversity (p. 76)

gross primary productivity (GPP) (p. 80)

habitat (p. 67)

herbivores (p. 74)

heterotrophs (p. 74)

hydrosphere (p. 68)

law of tolerance (p. 73)

limiting factor (p. 73)

limiting factor principle (p. 74)

lithosphere (p. 68)

natural greenhouse effect (p. 70)

net primary productivity (NPP) (p. 80)

nitrogen cycle (p. 86)

nutrient

omnivores (p. 74)

organism (p. 65)

phosphorous cycle (p. 87)

photosynthesis (p. 69)

phytoplankton (p. 74)

population (p. 67)

primary consumers (p. 74)

producers (p. 74)

prokaryotic cell (p. 65)

pyramid of biomass (p. 79)

pyramid of energy flow (p. 77)

pyramid of numbers (p. 80)

range of tolerance (p. 73)

scavengers (p. 74)

secondary consumers (p. 74)

species (p. 66)

species diversity (p. 76)

stratosphere (p. 68)

sulfur cycle (p. 88)

tertiary (higher-level) consumers (p. 74)

transpiration (p. 82)

trophic level (p. 76)

troposphere (p. 68)

zooplankton

 

* Hydrologic Cycle:

  1. Briefly describe the seven main processes involved in the hydrologic cycle:
  2. Name the two driving forces behind the water cycle:
  3. Relate precipitation and condensation nuclei:
  4. Relate the following terms: groundwater, aquifer, and water table:
  5. Describe three significant anthropogenic interventions in the hydrologic cycle:
  6. Why is the water cycle vital to the biosphere?(Describe three specific functions performed by or made possible by water.)

* Carbon Cycle:

  1. Provide three specific ways in which carbon is essential for biota to function:
  2. Carbon dioxide comprises approximately what percent of tropospheric gases?
  3. How is this relative* amount(%) of CO2 so significant in contributing to the earth’s “natural thermostat”? (*e.g., relative to the amount of water vapor in the troposphere.)
  4. Identify the two processes which have the greatest influence on tropospheric concentrations of carbon dioxide on a monthly or yearly basis. Explain:
  5. Name the two largest sinks(storage areas) for carbon; briefly explain how these areas have become such substantial carbon sinks.
  6. Though you likely commented on this in #56 above, relate “new carbon” stores found in plant and animal tissues to the formation of “old carbon” stores found in fossil fuels.
  7. Discuss how oceans play a major role in regulating CO2 levels in the troposhpere. Include in your discussion the formation of the following ions or compounds CO3 2-, HCO3 -, Ca 2+, CaCO3
  8. Describe the two major human interventions in the carbon cycle:
  9. Discuss three specific ramifications of increased tropospheric temperature as a result of an increase in tropospheric CO2 concentration.
  10. Comment on the type of feedback loop(s) (the relationship) that would likely be involved in a scenario in which tropospheric concentrations of CO2 increase and the amount of snowpack and glacier size/area.

* Nitrogen Cycle:

  1. Why is the nitrogen cycle significant to biota?
  2. Identify the two major ways that nitrogen is “fixed”;
  3. Describe what takes place in each of the following processes or steps of the N-Cycle: (include a description of the events and chemical transformations occurring in each step:)
  1. Nitrogen Fixation:
  2. Nitrification:
  3. Assimilation:
  4. Ammonification:
  5. Denitrification:
  1. Identify the major sinks for nitrogen:
  2. Describe seven anthropogenic interventions in the nitrogen cycle:

* Phosphorus Cycle:

  1. How, specifically, is phosphorus important to biota?
  2. Explain why phosphorus does not circulate in the troposphere to a great extent:
  3. Identify the largest sinks for phosphorus:
  4. Phosphorus is typically found in what ionic form?
  5. Explain why the addition of phosphate compounds to aquatic areas typically has a dramatic effect on biological productivity.
  6. Comment on how human activities have influenced the phosphorus cycle regarding each of the following:
  1. Mining phosphate rock:
  2. Deforestation(especially tropical):
  3. Animal wastes from Livestock Feedlots:
  4. Commercial phosphate Fertilizers in Agricultural areas:
  5. Discharge of Municipal Sewage/Wastewater Treatment Facilities:

* Sulfur Cycle:

  1. How, specifically, is sulfur significant to biota?
  2. Identify the two largest storage areas for sulfur:
  3. Comment on a major natural source of each of the following sulfur compounds: (a) H2S (b) SO2 (c) SO42- (d) CH3SCH3 (dimethyl sulfide, or DMS)
  4. How can fluctuating DMS emissions affect cloud cover in a given region?
  5. Illustrate the chemical transformations(reactions) which occur when SO2 reacts with O2 and H2O in the troposphere to eventually become sulfuric acid:
  6. Identify the three major human activities influencing the sulfur cycle: