PROFESSIONAL LEARNING COMMUNITY MODEL FOR ENTRY INTO TEACHING SCIENCE
A professional learning community of STEM educators, scientists, and engineers
http://plcmets.pbworks.com/
PLCMETS Inquiry Resources Collection:
Food Chains and Food Webs
Current TEKS:
7.12 A: identify components of an ecosystem
7.12 B: observe and describe how organisms including producers, consumers, and decomposers
live together in an environment and use existing resources
7.12 C: describe how different environments support different varieties of organisms
7.12 D: observe and describe the role of ecological succession in ecosystems
Future TEKS:
8.11 A: describe producer/consumer, predator/prey, and parasite/host relationships
8.11 B: investigate how organisms and populationsin an ecosystem depend on and may compete
for biotic and abiotic factors
Scope & Sequence:
Aldine: Grade 7, 5th six weeks
Cy-Fair: Grade 7, 5th 6 weeks
Big Ideas:
A food chain is the concept that food energy transfers from its source in plants and other
photosynthetic organisms (primary producers) through herbivores (primary consumers)
through carnivores (secondary and tertiary consumers) and eventually to decomposers,
which is to say energy moves up through each trophic level. A trophic level refers to the
different energy levels in a food chain that is to say each link in the food chain is a separate trophic
level. A food web expands upon a food chain, showing a more interconnected rather than linear
pathway of energy transfer. A food web better captures the essence of how energy is transferred in
Nature.
A Food Chain
A Food Web
http://www.absc.usgs.gov/research/seabird_foragefish/marinehabitat/images/Food_Web3.gif
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PROFESSIONAL LEARNING COMMUNITY MODEL FOR ENTRY INTO TEACHING SCIENCE
A professional learning community of STEM educators, scientists, and engineers
http://plcmets.pbworks.com/
For more information on ecosystem dynamics, see Community and Ecosystem Dynamics from Estrella
Mountain C.C.
Case Study:
The Reintroduction of Gray Wolves into Yellowstone National Park. Once commonly thought of
as a nuisance, the gray wolf (Canis lupis) was systematically hunted and destroyed in the 1930's
from the area around Yellowstone National Park. There were no wolves in Yellowstone in 1994.
The wolves that were reintroduced in 1995 and 1996 thrived and there are now over 300 of their
descendents living in the Greater Yellowstone Area. Wolves were captured in Canada and
transported to the United States. In mid-January 1995, 14 wolves from many separate packs were
captured in Canada and then transported into Yellowstone Park and placed into one-acre
acclimation pens. The biologists had reasons for not capturing an entire pack, or packs. For
starters, it is very difficult if not impossible to round up an entire pack. When a pack hears a
helicopter approaching they generally run for cover i.e. the timber. Biologists were lucky to
capture one or two individual wolves out of each pack. Capturing individuals out of different packs
also cut down on the chances of inbreeding later on and increased our DNA pool right from the
start.
The Gray Wolf (Canis lupis)
http://www.ypf.org/projects/wildlife/wolfproject.asp
Three pens were constructed at three different locations in the Northern range of Yellowstone; one
at Crystal Creek, one at Rose Creek, and the third at Soda Butte creek. Biologists placed a
dominant male wolf with a dominant female wolf along with several young subordinate wolves
into each 1 acre acclimation pen, and within about 24 hours or so the wolves in each of three pens
had the entire pack structure figured out, and in all but one case, the newly formed alphas mated
and gave birth, which lead to a larger pack more complete pack to be released.
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PROFESSIONAL LEARNING COMMUNITY MODEL FOR ENTRY INTO TEACHING SCIENCE
A professional learning community of STEM educators, scientists, and engineers
http://plcmets.pbworks.com/
Capture Map
http://www.yellowstone-bearman.com/wolves.html
Scientists hypothesized that by taking the appropriate steps to reintroduce wolves like acclimating
them to their surroundings and building pack dynamics with individuals originally from multiple
separate populations in Canada then the wolves could establish thriving breeding populations that
could be sustainable without further human intervention. In order to test this, scientists have taken
detailed observations about pack dynamics and population numbers.
For more information about wolves in Yellowstone, see Yellowstone National Park - Wolves of
Yellowstone USNPS.
Good Questions for Research
What is the role of gray wolves in their ecosystem?
What does the Yellowstone food web look like?
How might the Yellowstone food web respond to a lack of gray wolves after they were removed in
the 1930's?
What biotic factors may play role in the successful re-introduction of gray wolves into
Yellowstone?
What abiotic factors may play role in the successful re-introduction of gray wolves into
Yellowstone?
How did the different wolf packs' ranges change over their initial release?
Not So Good Questions for Research
Is it a good thing to reintroduce wolves back into Yellowstone?
Simulated Research Activities:
Simulation: Food Chain Interactions - Illustrates changes in populations over time of three
ecosystem members graphically in terms of biomass and population and well as a visual display of
the numbers of plants, rabbits, and foxes.
Dataset: Comparing 2 years of Gray Wolf population data after their reintroduction into
Yellowstone National Park with graphic representations of their ranges Yellowstone Wolf.xls
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