• An ecosystem is a community of organisms along with their physical and chemical environment.
  
  
• Living components contribute to an ecosystem in their own way. Some are autotrophic and produce organic nutrients. Others are heterotrophic and consume organic nutrients.
  
  
• Communities are characterized by a flow of energy and chemical cycling.

1. What are levels of organization from organism to biosphere? What is ecology?
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2. What is the niche and habitat of an organism?
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3. Why are autotrophs called producers and heterotrophs called consumers? What are the different types of consumers in a community?
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4. What two processes characterize communities? Explain.
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Essential Study Partner

• Introduction

Bioethical Focus

• Ecosystem Preservation

• Energy flow begins when autotrophs use solar energy to produce organic nutrients for themselves and all living things. Eventually these nutrients are broken down and solar energy returns to the atmosphere as heat.
  
  
• The loss of energy in an ecosystem can be illustrated using food chains, food webs, and ecological pyramids.

1. What type of diagram represents the various paths of energy flow in a community?
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2. What type of diagram represents a single path of energy flow in a community?
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3. What is the difference between a grazing food web (chain) and a detrital food web (chain)?
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4. What type of diagram illustrates that energy is lost in ecosystems?
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Essential Study Partner

• Energy Flow

Art Quiz

• Path of Energy Through Food Webs

• Chemical cycling begins when autotrophs take in inorganic nutrients and use them to make organic nutrients. With death and decay, the inorganic nutrients return to autotrophs once more.
  
  
• Biogeochemical cycles are gaseous (carbon cycle and nitrogen cycle) or sedimentary (phosphorus cycle).
  
  
• Water, carbon, nitrogen, and phosphorus are examples of substances that cycle in an ecosystem. Human activities can alter these cycles impacting the environment.

1. Chemical cycling in the biosphere may involve what three components?
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2. What are two examples of gaseous biogeochemical cycles? What is an example of a sedimentary biogeochemical cycle?
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3. How do water, carbon, nitrogen, and phosphorus cycle in the biosphere?
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Essential Study Partner

• Nutrient Cycles

Animation Activity

• Carbon Cycle
• Nitrogen Cycle
• Global Warming

Art Quiz

• The Water Cycle
• The Carbon Cycle
• The Nitrogen Cycle

Case Study

• Radioactive Wastes From Medical Facilities: Where Do They Go?

• Starting on bare rock or disturbed land, complex communities arise by a series of successive stages.
  
  
• Aquatic communities are either saltwater or freshwater. Oceans cover three quarters of the Earth.
  
  
• There are seven major biomes; temperature and rainfall in general determine the locations of these biomes.
  
  
• The major communities of the world differ in productivity and therefore in the variety of species they contain.

1. Aquatic communities are divided into what two general types? What are some examples of each type?
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2. What is ecological succession?
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3. What are the major terrestrial biomes of the world?
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4. How does primary productivity differ among aquatic and terrestrial communities?
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Essential Study Partner

• Succession
• Land Biomes
• Aquatic Systems

Art Quiz

• Food Web in Cayuga Lake