2. 3-1 What is Ecology?
Interactions and Interdependence
Ecology - _______________________________________________________________
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biosphere - ______________________________________________________________
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Levels of Organization
• To understand relationships within the biosphere ecologists ask questions about
events and organisms that range in complexity from single individuals to the entire
biosphere
• Studies can focus on…
Species - ________________________________________________________________
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Populations - ____________________________________________________________
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Communities - ___________________________________________________________
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Ecosystem - _____________________________________________________________
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4. Ecological Methods
• Regardless of the tools they use, scientists conduct modern ecological research using
3 basic approaches:
1.
2.
3.
Name ____________________________________ Date _________________ Per _____
3-1 Section Review
1. List the six different levels of organization that ecologists study, in order from smallest
to largest.
2. Describe the three basic methods of ecological research.
3. Identify two ways in which you interact with each of the three parts of the biosphere—
land, water, and air—every day.
5. 4. Suppose you wanted to know if the water in a certain stream is safe to drink. Which
ecological method(s) would you choose, and why?
3 – 2 Energy Flow
• The flow of energy through an ecosystem is one of the most important factors that
determines the systems capacity to sustain life
Producers
• _______________________ is the main energy source for life on Earth
• Some types of organisms rely on the energy stored in organic chemical compounds
Producers (autotrophs) - ____________________________________________________
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ex.)
Energy From the Sun
Photosynthesis - __________________________________________________________
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6. Life Without Light
• Some autotrophs rely on energy within the chemical bonds of inorganic molecules
such as hydrogen sulfide
Chemosynthesis - _________________________________________________________
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7. Consumers
• Many organisms cannot harness energy directly from their environment like
autotrophs do
Consumers (heterotrophs) - _________________________________________________
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• There are many kinds of heterotrophs
Herbivores - _____________________________________________________________
Carnivores - _____________________________________________________________
Detritivores - ____________________________________________________________
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Decomposers - ___________________________________________________________
Feeding Relationships
• Energy flows through an ecosystem in one direction, from the sun or inorganic
compounds to autotrophs (producers) and then to various heterotrophs (consumers)
Food Chains
Food chain - _____________________________________________________________
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8. • In most ecosystems, feeding relationships are more complex than they can be shown
in a food chain
Food Webs - _____________________________________________________________
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9.
10. Trophic Levels - __________________________________________________________
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1st - ____________________________________________________
2nd – 3rd or higher - ________________________________________
• Each consumer depends on the trophic level below it for energy
Ecological Pyramids
Ecological Pyramid – a diagram that shows the relative amounts of energy or matter
contained within each trophic level in a food chain or food web
• There are 3 types of ecological pyramids
1. Energy Pyramid - _______________________________________________________
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• Only about ________ of the energy available within one trophic level is transferred to
organisms at the next trophic level
2. Biomass Pyramid - ______________________________________________________
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12. Name ______________________________ Date _____________________ Per _______
3 – 2 Section Review
1. What are the two main forms of energy that power living systems?
2. Briefly describe the flow of energy among organisms in an ecosystem.
3. What proportion of energy is transferred from one trophic level to the next in an
ecosystem?
4. Show the following as a food chain: omnivore, autotroph, herbivore.
5. Draw an energy pyramid for a five-step food chain. If 100 percent of the energy is
available at the first trophic level, what percentage of the total energy is available at the
highest trophic level?
13. 3 – 3 Cycles of Matter
• Energy is crucial to an Ecosystem, but organisms need more than that to survive
• They also need
o
o
o
o
o
o
Recycling in the Biosphere
• unlike the one way flow of energy, matter is recycled within and between ecosystems
The Water Cycle
Evaporation - ____________________________________________________________
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transpiration - ____________________________________________________________
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15. Nutrient Cycles
Nutrients - ______________________________________________________________
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• Every living organism needs nutrients to grow and carry out essential life functions.
Like water; nutrients are passed between organisms and the environment through
cycles
The Carbon Cycle
• There are four different kinds of processes involved in the carbon cycle:
1. biological processes, such as photosynthesis, respiration, and decomposition of
plants and animals;
2. geochemical processes, such as the release of carbon dioxide (CO2) gas to the
atmosphere by volcanoes;
3. mixed biogeochemical processes, such as the burial of carbon rich remains of
organisms and their conversion into coal and petroleum (fossil fuels) by the
pressure of the overlying earth; and
4. human activity, including mining, the burning of fossil fuels, and the cutting and
burning of forests.
16. The Nitrogen Cycle
• All organisms require nitrogen to make amino acids, which in turn are used to build
_________________________
• Many different forms of nitrogen occur naturally in the biosphere
• Although nitrogen gas is the most abundant form of nitrogen on Earth, only certain
types of bacteria can use this form directly
Nitrogen fixation - ________________________________________________________
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17. The Phosphorus Cycle
• Phosphorus is essential to living organisms because it forms part of important life
sustaining molecules such as ________________________
• Unlike Carbon, oxygen and nitrogen, phosphorus does not enter the atmosphere
• Phosphorus remains mostly on land in rock and soil minerals, and in ocean sediments
• As the rocks and sediments gradually wear down, phosphate is released
• Plants absorb phosphate then move to the rest of the ecosystem
18. Nutrient Limitation
• Ecologists are often interested in the primary productivity
Primary productivity - _____________________________________________________
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• If a nutrient is in short supply, it will limit an organisms growth
Limiting nutrient - ________________________________________________________
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