Biology Investigation and Experimental
Design Name: __________________________
Roly Poly Taxis
Date:
__________________ Per: _____
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State Objectives |
Competency
Goal 1: The learner will develop abilities necessary to do and understand
scientific inquiry. |
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Time Required |
two 50 minute class periods. |
Purpose:
∙ to
study the responses of the common pill or sow bug to a variety of solutions
∙ to
analyze the various parts of an experiment
∙ to
develop a testable hypothesis
Initial Observations:
Land isopods live in dark,
moist places beneath undisturbed objects lying on the ground such as rotting
logs, boards, bricks, or rocks.
Sometimes isopods can be found alongside buildings where there is
moisture and food (decaying matter, fungi).
Living organisms, in general, avoid some chemicals and are attracted to
others. This is referred to as chemotaxis.
Positive chemotaxis is when an animal moves
towards a chemical. Negative chemotaxis describes an animal’s movement away from a
chemical.
Materials:
4 isopods
Petri dish
filter paper cut to fit Petri dish
droppers
water
1% salt solution
1% glucose (sugar) solution
1% acetic acid (vinegar) solution
Hypothesis: Read the
procedure of this experiment. State one
hypothesis that this experiment tests.
Your hypothesis might answer the question of which chemicals will
attract or repel the isopods.
My hypothesis is that....
Procedure:
1. Cut the filter paper into
quarters. Trim a bit off each edge so as
to leave about 0.5 cm between the pieces of paper when they lay flat in the
Petri dish.
2. Label the four sections A,
B, C, and D in pencil.
3. Place drops of solution
on the sections of filter paper according to the following table. Be sure that the paper is totally wet BUT that
no solutions run together. The paper
pieces should lie flat on the Petri dish.
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A = Water |
C = Glucose |
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B = Salt |
D = Acetic acid |
4. Place 4 isopods in the
middle and begin recording where they are every 15 seconds for a total of 5
minutes.
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TIME |
A Water |
B Salt |
C Glucose |
D Acetic
Acid |
In Between |
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15 sec |
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30 sec |
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45 sec |
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1 minute |
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15 sec |
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30 sec |
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45 sec |
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2 minutes |
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15 sec |
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30 sec |
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45 sec |
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3 minutes |
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15 sec |
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30 sec |
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45 sec |
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4 minutes |
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15 sec |
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30 sec |
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45 sec |
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5 minutes |
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Class average |
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Conclusions: Use complete
sentences.
1. What is the control?
2. What are the variables?
3. Was your hypothesis
supported? Use the data to explain your answer.
4. Did the isopods
demonstrate positive chemotaxis? What about negative chemotaxis? Explain.
5. What are the survival
advantages for the behavior you observed?
6. How could the experiment
be improved?
Plan your own experiment:
Design your own experiment to
test to response of isopods to some other environmental condition such as light
versus dark, dry versus moist, different concentrations of the same solutions,
different solutions, or something else you are curious about. Be sure to include all the parts of a good
experimental design.
a. Describe what you will be investigating. Give the control and the variables (5
points).
b. State your hypothesis (3 points).
c. List your materials (1 point).
d. Give the steps of your procedure to test the
hypothesis (5 points).
e. Set up a table to collect the data (3 points).
f. Conduct the experiment and state whether you support
the hypothesis (3 points).