Rolly-Polly (Pill Bug, Isopod)
Chi Square Lab
Name _____________________________________________________ Period _______
Orientation of Isopods in Response to Moisture
Procedure: Behavior chambers (choice chambers) will be set up so that they simulate two
different environments, one moist and one dry. Five isopods will be placed on each side
of the chamber (total of 10).

Count and record the number of animals on each side of the chamber every 30
seconds for 10 minutes.
Null Hypothesis (Ho):
________________________________________________________________________
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Hypothesis (Halt):
________________________________________________________________________
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
After the Pillbugs have been in the choice chamber for 10 minutes, you might
observe one of the situations shown below. Keeping in mind that Pillbugs are
crustaceans, and they respire through gills, which situation would you predict to
occur — A, B, or C?

Write a concise hypothesis above.
.

How many variables may be tested in an experiment?

What is the variable being tested in this experiment?
Data Table 1:
Time (min)
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
Caption:
# Pillbugs in Wet Chamber
# Pillbugs in Dry Chamber
Graph
Complete a graph by hand using two different colors for the two sets of data (wet
chamber and dry chamber) and include a key to define the colors used. Your graph
should be a line graph showing the changing number of pillbugs in each side of the
chamber over time. Follow the criteria for making the graph. Attach your graph to the
lab.
Statistical Analysis
Complete a chi-square analysis on a separate sheet of paper and construct a table showing
the steps of the χ2 test.
Note: Class data or data from multiple trials should be analyzed. Construct a data table to collect
the class data for analysis.
χ2 = _________
df = number of possible outcomes – 1 = ________
Critical Value at p = 0.05 ____________
Conclusion statement: (should include the terms: reject or fail to reject the null
hypothesis, critical value, probability level, significant or not significant)
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________________________________________________________________________
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Conclusion and Inferences

Conclusion - Did the Pillbugs demonstrate a chemotaxis in relation to the substance
you tested?

Inference – What related information about the natural habitat of Pillbugs is most
likely is true based on the data and conclusions obtained in this experiment.
Questions Based on Background Information
What sensory organs do Pillbugs have to detect stimuli in the environment?
Define the terms taxis and kinesis?
Analysis Questions
Based on the data collected in the virtual simulation, do Pillbugs exhibit taxis or kinesis
in regard to moist environments? Explain your answer.
If the experiment was modified so that both of the chambers in the experiment were
moist but one was illuminated and the other was in the dark, would it be considered
kinesis or taxis if all the Pillbugs moved to the dark chamber, stayed there, and did not
venture back into the illuminated chamber? Explain your answer.
Design an Experiment
Thinking about the anatomy and physiology of Pillbugs, how could the experiment be
modified to test another environmental condition? Choose a different environmental
condition to test and describe the control and experimental set-ups that should be used to
test this variable. As well, make a hypothesis in regard to what you think will occur. This
should be completed, in detailed writing, on separate paper and attached.