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Ice Mummies -- Frozen in Heaven
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Classroom Activities
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Objective
To investigate the rate of microbial growth at different
temperatures.
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copy of "This Is Rotten" student handout (HTML)
- 3 small Petri dishes
- 1 small packet unflavored gelatin
- small saucepan
- 1/2 cup water
- 2 teaspoons sugar
- tape
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one food sample (such as tofu/bean curd, strawberries, or bread)
- knife for slicing
- refrigerator and freezer
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Organize students into groups and distribute materials and
student handouts. With students, determine what food they would
like to use in the experiment, and assign each group one sample
to study (samples might include tofu/ bean curd, strawberries or
bread). Also discuss how students will quantify and measure
microbial growth rates.
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Have students predict what will happen to their sample at
various temperatures. Then have them prepare the medium that
will contain their samples. Important: Discuss with
students that their medium may not be completely sterile and
that what grows in it might not be directly related to their
samples. (As an extension, you may have students repeat the
experiment using sterile techniques and compare the results with
the first experiment.)
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The containers should be left in a dark place at room
temperature. Once microorganisms have begun to grow, have
students record the temperature for the refrigerator, freezer,
and cupboard or drawer, and then place one of their samples in
each environment.
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Have students check their samples every few days for two weeks
and record their observations.
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To conclude, ask students to describe the differences in the
rate of microbial growth among the samples in the different
environments, and possible reasons for those differences. Then
discuss with students what might be responsible for promoting or
inhibiting growth in each specimen.
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As an extension, students could examine their final products
unaided, with a hand-held magnifying glass, and then with a 10x
(or stronger) microscope and describe what they see.
Microbial growth will continue to flourish at room temperature, will
be slower in the refrigerator, and will be slowed to the extent that
growth may not be visible within the given time in the freezer. The
microorganisms that have grown in each sample will probably include
bacteria, which are single-celled organisms that feed on waste
materials and dead organisms. Mold may also be evident.
Books
Lauber, Patricia. Painters of the Cave. Washington, D.C.:
National Geographic Society, 1998.
Provides an introduction to Ice Age people. Text and images depict
artifacts and cave paintings left behind by ancestors of modern
humans.
Moseley, Michael Edward.
The Incas and Their Ancestors: The Archaeology of Peru. New
York, NY: Thames and Hudson, 1992.
Provides the prehistory of the Andean region, including a thorough
summary of Inca civilization.
Articles
Reinhard, Johan. "Research Update: New Inca Mummies."
National Geographic (July 1998): 128-135.
Describes the December 1997 return of Reinhard and his crew of
archeologists to the summit of Pichu Pichu in the Peruvian Andes to
discover more human ritual remains, gold figurines and other
evidence of the Inca heritage.
Web Sites
NOVA Online—Ice Mummies
http://www.pbs.org/nova/icemummies/
This Web site, originally a NOVA/PBS Online Adventure launched in
Fall 1996, will provide
Updated information about the archeological expeditions that
discovered three different ice mummies.
Mummies 101
http://www.pbs.org/nova/chinamum/mummies101.html
Contains information about mummification, specifically the practices
of the Aleut. Note: This site contains some graphic photos.
Preview first to determine its appropriateness for your students.
Ice Treasures of the Inca
http://www.nationalgeographic.com/features/96/mummy/index.html
Contains extensive information on the Inca ice mummies.
Archaeology
http://www.archaeology.org/
Archaeology is an online and print publication of the
Archaeological Institute of America. The site includes articles
about current archeological topics and a news brief about the
Iceman's return to Italy.
The "This is Rotten" activity aligns with the following National
Science Education Standards:
Grades 5-8
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Science Standard C: Life Science
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Populations and ecosystems: The number of organisms an
ecosystem can support depends on the resources available and abiotic
factors, such as quantity of light and water, range of temperatures
and soil composition. Given adequate biotic and abiotic resources
and no disease or predators, populations (including humans) increase
at rapid rates. Lack of resources and other factors, such as
predation and climate, limit the growth of populations in specific
niches in the ecosystem.
Grades 9-12
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Science Standard C: Life Science
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Matter, energy and organization in living systems:The
distribution and abundance of organisms and populations in
ecosystems are limited by the availability of matter and energy and
the ability of the ecosystem to recycle materials.
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