Chapter 3

Ecosystems: What Are They and How Do They Work




See bulleted list of questions on p. 51 of text.



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


2.      Distinguish among lithosphere, hydrosphere, atmosphere, and biosphere. 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.      Define soil horizon. Briefly describe four soil layers. Using Figure 3-24 on p. 69 in the text, compare soil profiles of five important soil types.


5.      Describe a fertile soil. In doing so, be sure to refer to soil texture, porosity, loam, and acidity.


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


7.      Define abiotic component of an ecosystem. List three important physical factors and three important chemical factors that have large effects on ecosystems.


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


9.      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.


10.    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.


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


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


13.    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. 56)

aerobic respiration (p. 60)

anaerobic respiration (p. 60)

aquatic life zones (p. 56)

atmosphere (p. 54)

biomass (p. 63)

biomes (p. 56)

biosphere (p. 53)

biotic (p. 56)

carbon cycle (p. 73)

carnivores (p. 60)

chemosynthesis (p. 60)

community (p. 53)

consumer (p. 60)

decomposers (p. 60)

detritivores (p. 60)

dissolved oxygen (DO) content (p. 58)

distribution (p. 53)

ecological efficiency (p. 64)

ecosystem (p. 53)

food chain (p. 63)

food web (p. 63)

fossil fuels (p. 73)

freshwater life zones (p. 56)

genetic diversity (p. 53)

gross primary productivity (GPP) (p. 66)

habitat (p. 53)

herbivore (p. 60)

humus (p. 68)

hydrologic (water) cycles (p. 70)

hydrosphere (p. 54)

infiltration (p. 69)

leaching (p. 69)

limiting factor (p. 57)

limiting factor principle (p. 57)

lithosphere (p. 54)

natural greenhouse effect (p. 56)

net primary productivity (NPP) (p. 66)

nitrogen cycle (p. 74)

nitrogen fixation (p. 74)

nutrient (p. 70)

omnivores (p. 60)

organism (p. 52)

phosphorous cycle (p. 76)

photosynthesis (p. 58)

population (p. 53)

primary consumers (p. 60)

producers (p. 58)

pyramid of energy flow (p. 64)

range of tolerance (p. 57)

salinity (p. 58)

secondary consumers (p. 60)

soil (p. 67)

soil horizons (p. 68)

soil profile (p. 68)

soil texture (p. 70)

species (p. 52)

stratosphere (p. 54)

sulfur cycle (p. 77)

tertiary (higher level) consumers (p. 60)

trophic level (p. 63)

troposphere (p. 54)

weathering (p. 67)