SNC1D
Ecology: Food Chains, Webs & Energy Flow through Ecosystems
Why Study Ecology?
Sustainability:
• _______________________________________________________________
Ecology:
 The study of the __________________ of _____________________ with each
other and with _______________ factors in their environment.
Abiotic Factors:
e.g.
Biotic Factors:
e.g.
Ecology can begin at the level of a single organism… But organisms do not live in ________________
Ecological Ladder
Biosphere*
________________
________________
________________
________________
________________
Organism*
• Ecosystems rarely have sharp ______________________
• Organisms can _____________ from one ecosystem to another
Ecotone: ___________________________________________ __________________________________
• Contains members of the community of both ecosystems
Biodiversity: ____________________________________________________________________________
• Ecotones have ________ biodiversity.
• High biodiversity usually indicates a ____________________________ ecosystem.
Energy Flow in Ecosystems
The Sun:
• The source of all energy
• ______________
• ______________
• __________________ (for precipitation)
• ________________________
• ___% of the total energy is reflected by clouds or Earth’s
surface
• ___% heats atmosphere, surfaces,
• _____% heats and evaporates water
• _____ % wind
• _______% for photosynthesis
SNC1DE: Ecology
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Biotic Factors
Producer
Consumer
Alternate Name
Energy Source
•
•
Example
Make (produce) their own food
From sunlight and basic nutrients
(abiotic factors)
Herbivores
Omnivores
Carnivores
Trophic Levels
Categorize living things (biotic factors) according to _______________________________________________
First Trophic Level
• Contains organisms that are able to _____________________________ food from ____________
factors (e.g.______________________________________________________)
• Organisms in the 1st trophic level are called ________________ or ______________________
• E.g. ____________________________________________________________________
Second Trophic Level
• Contains organisms that feed on producers
• Rely DIRECTLY on _________________ for their source of energy.
• Organisms in the 2nd trophic level are called ______________ / _________________ /
_______________
• E.g. ___________________________________________________________________________
Third Trophic Level
• Contains organisms that rely on __________________ consumers as their main energy source
• But, indirectly, are still dependent on ___________________
• Organisms in the 3rd trophic level are called ____________________________
• E.g. _________________________________________________________________________
Decomposers
• Organisms that feed on __________________
Detritus: __________________________________________________________________________
• Return _________________ (abiotic factors) to the ecosystem
• E.g. ______________________________________________________________________________
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Food Chains:
•
•
•
•
Step-by-step sequence linking organisms that _______ on each other
Arrows show the ______________________________ (“is eaten by”)
Do not exist in nature (more complex)
Show ____________ feeding relationships
Food Webs:
•
•
In reality, each organism has a _______________ of
food sources and is therefore involved in
_________________ food chains
These food chains interlock to form a complex
_____________________
Food Web: Representation
_______________________________________
_______________________________________
Energy Flow Through Ecosystems:
•
Organisms use about _____ % of the energy they
take in to _____________ and ________________,
leaving just ______% of the energy they receive to
_______________________ to the next trophic
level.
→
→
→
→
Ecological Pyramids
•
Type
Are used to organize the information of these transfers, and the most common are:
Pyramid of ________________ Pyramid of _______________
Pyramid of _____________
Based on…
Drawing
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Homework:
 Terms to define: (add to glossary)
o organism, species, biome, sustainable Ecosystem, Natural and Artificial Ecosystems, albedo, pest,
niche
 Complete Food Web assignment sheet

Answer Questions:
1. Why are producer organisms called autotrophs?
2. How does a heterotroph differ from an autotroph?
3. What type of food would be consumed by a secondary consumer? Explain your answer.
4. In your own words, explain what is meant by the term “top carnivore” Give 3 examples of a top
carnivore, including the ecosystem in which you would find each one.
5. Distinguish between a food chain and a food web using examples for each.
6. Explain why an Arctic ecosystem would be more fragile than a southern forest ecosystem.
7. Why are there only a small number of tertiary consumers found in an ecosystem?
SNC1DE: Ecology
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