yourBioPortal.comGo to ANIMATED TUTORIAL 1.1Using Scientific Methodology1. Make observations.2. Speculate, ask a question.4. Make a prediction: What else would be true if your hypothesis is correct?5. Design and conduct an experiment that uses quantifiable data to test your prediction.Reexamine theexperiment foruncontrolledvariables.Ask newquestions.Use statistical tests to evaluatethe significance of your results.Significant resultssupport hypothesis.Experiment repeated and results verified by other researchers.Results do notsupport hypothesis.3. Form a hypothesis toanswer the question.Revise yourhypothesis.FIGURE 1.8 Scientific Methodology The process of observation, speculation, hypothesis, prediction, and experimentation is a cornerstone of modern science, although scientists may initiate their research at several different points. Answers gleaned through experimentation lead to new questions, more hypotheses, further experiments, and expanding knowledge.
12Chapter 1 |Principles of LifeIn the Hayes laboratory, an atrazine concentration as low as 0.1 ppb had a dramatic effect on tadpole develop-ment: it feminized the males. In some of the adult males that developed from these larvae, the vocal structures used in mating calls were smaller than normal, female sex or-gans developed, and eggs were found growing in the tes-tes. In other studies, normal adult male frogs exposed to 25 ppb had a tenfold reduction in testosterone levels and did not produce sperm. You can imagine the disastrous effects these developmental and hormonal changes could have on the capacity of frogs to breed and reproduce.But Hayes’s experiments were performed in the labora-tory, with a species of frog bred for laboratory use. Would his results be the same in nature? To find out, he and his students traveled across the middle of North America, sampling water and collecting frogs. They analyzed the water for atrazine and examined the frogs. In the only site where atrazine was undetectable in the water, the frogs were normal; in all the other sites, male frogs had abnor-malities of the sex organs.Like other biologists, Hayes made observations. He then made predictions based on those observations, and de-signed and carried out experiments to test his predictions. Some of the conclusions from his experiments, described below, could have profound implications not only for am-phibians but also for other animals, including humans. Good experiments have the potential to falsify hypothesesOnce predictions are made from a hypothesis, experiments can be designed to test those predictions. The most infor-mative experiments are those that have the ability to show that the prediction is wrong. If the prediction is wrong, the hypothesis must be questioned, modified, or rejected.