A researcher has hypothesized that the chemical tributyltin (an additive in boat paint) seeps into the water causing reproductive defects in developing marine snails. In an experiment testing the effects of tributyltin on developing snails, which condition should be used as a control?
A) Developing snails are kept in a tank of water and exposed to below-expected levels of tributyltin.
B) Developing snails are kept in a tank of water and exposed to boat paint without tributyltin.
C) Developing snails are kept in a dry tank to avoid exposure to contaminated water.
D) Developing snails are kept in a tank of water that has been cleaned with chlorine bleach.

Question

Quizplus · Accepted Answer

The control group in this experiment should consist of developing snails kept in the same conditions as the experimental group (i.e. exposed to boat paint), but without the addition of tributyltin. This allows the researcher to evaluate the effects of tributyltin specifically, by comparing the reproductive defects of the experimental group to the control group. Option A exposes the developing snails to below-expected levels of tributyltin, which is not a true control group. Option C avoids exposure to tributyltin altogether, which is not useful for testing the hypothesis. Option D is irrelevant to the investigation of the effects of tributyltin.

A Researcher Has Hypothesized That the Chemical Tributyltin (An Additive