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C. elegans, a nematode or "round worm," is a model organism in biology. A group of AP biology students was investigating behavior in C. elegans.

C. elegans feeds on bacteria, a particular strain of E.coli OPI150. Students placed the nematodes on a Petri dish with four choices: $NaCl$, water, a solution of E.coli, or no solution added, as seen in the image below. After ten minutes, students recorded the location of the C. elegans and recorded their data in the data table.

Which of the following is the null hypothesis for this experiment?

Created for Copyright 2016. All rights reserved.

Location Number of C. elegans
$NaCl$ 12
Water 7
Blank 3
E. coli solution 58

There is a difference between observed and experimental results, with more of the C. elegans located in the E. coli section of the Petri dish.


There is no statistically significant difference between observed and expected results, or 20 worms in each area are expected.


More worms will be present in the section of the E. coli dish since they will be attracted to the food source.


If four different choices are provided to a culture of C. elegans, then the C. elegans will be found more often in the section of E. coli solution because this is a food source for the roundworms.

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