Biology 110 - Scientific Method Assignment - Due Sept. 14, 2005 (20
points)
The Scientific Method
Scientists attempt to explain their observations by generating possible
explanations, called hypotheses, that could account for the
observed phenomenon. They then devise controlled methods (experiments)
to evaluate the validity of each individual hypothesis. This "process"
of observing, hypothesizing and experimenting is described in your textbook
on pages 19-24. Please read this carefully before proceeding with
this assignment.
Assignment
-
State a biological observation you have made which piques your curiosity.
This observation should be a clear, precise statement of observed fact. No
questions or possible explanations should be included in your observation.
Keep your observation simple and specific and it will be easier to generate hypotheses and to test these hypotheses.
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Generate several (at least 2) possible explanations for your observation.
These are your hypotheses. Each hypothesis should provide a reasonable
explanation for what you have observed. As with your observation,
the more specific your hypotheses are, the easier they will be to test.
-
Select one of your hypotheses and describe how you could test its
validity experimentally. This experiment must be a specific test
for just this one hypothesis. The experiment should 'control' other
variables so that the results will either support or negate the selected
hypothesis.
Here is an example of a completed assignment to help get you started:
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Observation - Dr. Hamilton's son often receives mosquito
bites which are large, red and itchy, however Dr. Hamilton almost
never receives noticeable mosquito bites.
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Hypotheses
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Mosquitoes prefer hairless human skin to hairy human skin.
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Mosquitoes bite Dr. H. and his son equally frequently, however Dr. H.'s
body does not react to the bites (so they are not noticeable) while
his son reacts strongly to the bites.
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Experiment - To test hypothesis #1, both Dr. H. and his son submit
to electrolysis on identical places on their arms, with identical quantities
of skin rendered hairless. They are then exposed to equal environmental
conditions (including mosquitoes) for an equal period of time. The
number of bites in the hairless areas are counted.
Things to Think About
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If in fact it is only the presence or absence of hair which affects
the number of noticeable mosquito bites, then we expect to see nearly equal
numbers of bites in the shaved areas.
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If we do see equal numbers of bites in the shaved areas, are we sure
that it must be the hair that was influencing the mosquitoes? Could
we have altered some other factor by shaving?
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Experiments do not 'prove' something is true, but rather amass evidence
in support of a particular hypothesis.
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If we still see no bites on Dr.H. and many on his son after shaving, what
does this tell us?
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Scientists spend alot of time 'ruling out' hypotheses, which in turn helps
them focus closer and closer to the 'truth'.
110 HOME
D. Sillman dys100@psu.edu
08/17/2005