• 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.
• Ecosystems 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 difference between the niche and the 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 an ecosystem?
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4. What two processes characterize an ecosystem? Explain.
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Essential Study Partner

• Introduction

• 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 flow 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 an ecosystem?
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2. What is the difference between a grazing food web and a detrital food web?
   
3. What type of diagram represents a single path of energy flow in an ecosystem?
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4. What type of diagram illustrates that usable energy is lost in ecosystems?
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Essential Study Partner

• Energy Flow

Art Quiz

• Path of Energy Through Food Webs (from 24.2 in 7 th edition)

• 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, phosphorus, nitrogen, and carbon cycle in the biosphere?
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4. What ecological problems are associated with each of the cycles? Explain.
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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

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

1. Aquatic ecosystems 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 ecosystems of the world?
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4. How does primary productivity differ among aquatic and terrestrial ecosystems?
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Essential Study Partner

• Succession
• Land Biomes
• Aquatic Systems

Art Quiz

• Food Web in Cayuga Lake