miércoles, 24 de abril de 2013
lunes, 1 de abril de 2013
Pasteur Swan Neck Flask Experiment
In
his famous experiment, Louis Pasteur used a special flask whose neck was
shaped like an S or the neck of a swan, hence the name "Swan Neck
Flask." He put a nutrient rich broth in the flask, which he called the
"infusion." He then boiled the infusion killing any microorganisms
which were already present. Then he allowed the infusion
to sit.
Because
of the shape of the flask, the infusion was exposed to air. However, dust
particles and other things in the air never made it into the infusion.
Because they were trapped in the curve of the Swan Neck Flask. No matter how
long he allowed the flask to sit, microorganisms never appeared in the
infusion. However, if he tipped the flask and allowed the things trapped in
the neck to get into the infusion then microorgranisms began to appear in the
infusion and multiply rapidly. This demonstrates that microorganisms do not
appear as a result of Spontaneous Generation. Instead, they are introduced
into food through dust particles and other things that happen to land on the
food.
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Authors: Philip Durkin and Susanne Coleman
Grade Level: 5
For additional free online lessons integrating media literacy and critical thinking into the curriculum, go towww.projectlooksharp.org.
Summary:
Students will view the first scene from the “The Lion King” during which baby Simba is introduced. They will analyze the interactions or relationships they observe between the living things in each environment and infer which relationships are realistic and which are fictional and explain their reasoning.
Key terms: ecology, biotic factors, abiotic factors, population, community, ecosystem, symbiosis, mutualism, commensalism, parasitism, predator-prey
Objectives: