1- you are an environmental toxicologist, and want to test whether a high concentration of copper in water causes cancer in fish.
A) write the null hypothesis for this question
B) write an alternative hypothesis for this question
C) what is the dependent variable in this case ? What is the independent variable?
2) You decide to survey natural areas with high amounts of copper and low amounts of copper in the water, and look at the fish there to see whether one area has fish with higher cancer rates. Would this be an observational or an experimental study ? What might be some challenges with making inferences about causation in your study?
3) Now you set up tanks in your lab and stock them with fish. Describe how you could use these tanks to test your hypothesis above. Define your experimental control.
4) define experimental replicate. Why are they important? How would you include them in the study above ?

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