Biologists, like other scientists, ask questions about the natural world. Their questions are either why questions or how questions, such as the following:

As they attempt to answer such questions, biologists first offer a tentative explanation, or hypothesis, for something they have observed. They perform an experiment to test their hypothesis. If the results from the experiment match the original predictions, then they consider the hypothesis supported, but not proved, since biologists cannot account for all conditions. Other biologists will continue to formulate new hypotheses and offer new findings.