1. The Study of Biology Chapter 1

2. Science as a Process Scientific method—organized approach to determine how the natural world works Two assumptions: – Events in the natural world have natural causes – Uniformity; laws of nature operate the same way in all places and at all times

3. Steps of the Scientific Method 1. Observation/asking questions 2. Hypothesis/make prediction 3. Experiment 4. Analyze data 5. Communicate data to peers Robert Hooke – In 1665, he was the first to observe cells in cork

4. Forming Hypothesis Good hypotheses answer a question and are testable. Make a prediction that logically follows from the hypothesis – Rene Dutrochet – In 1824, proposed that cells are the basic units of life

5. Designing an Experiment Experiment: a procedure that tests a hypothesis by the process of collecting information under controlled conditions – Control Group: the group in which all the conditions are kept the same – Independent Variable: the only condition in an experiment that is changed X-axis on a graph – Dependent Variable: the condition that any changes that happen to it depend on changes made to the independent variable Y-axis of a graph

6. Parts of a Graph Dependent Variable Independent Variable

7. Collecting and Analyzing Data Data: information obtained from experiments – Can support or disprove a hypothesis – Also called experimental results Can be expressed in many ways – Words – Numbers – Ratios

8. Drawing Conclusions A hypothesis that was rejected or a new theory may prompt scientists to ask new questions or form additional hypotheses In 1833, after the theory that cells are fundamental to life, Robert Brown hypothesized that the nucleus is an important control center of the cell Revision of theories occur when new information relating to the original theory is gathered The cell theory gave biologists a start for exploring the basic structure of all life

9. Constructing a Theory Theory: an explanation of a natural phenomenon or hypothesis that is supported by a large body of scientific evidence obtained from many different investigations and observations By 1839, many scientific observations supported the hypothesis that cells are fundamental to life – This hypothesis became theory

10. Communicating Ideas Scientists often work together in research teams to publish their results in scientific journals or to present their findings at scientific meetings You, as biology students, will publish your results in lab reports Four sections in research paper: introduction, materials and methods, results, discussion; followed by peer review

11. Honesty and Bias A good reputation for solid science is key! Avoid potential conflicts of interest—might lead to scandal.

12. Observation– owls capture prey on dark nights Question– how do owls detect prey on dark nights? Hypotheses: – a. Owls hunt by vision; – b. owls hunt by hearing; – c. owls hunt by sensing body heat Experiment: Test predictions of three hypotheses. Control—in the light; Experimental: In the dark Data Collection/Analysis: measure and compare the distance from the owl’s strike to the mouse and to the leaf in light and dark Conclusion: Data supported the hearing hypothesis: Owls hunt in the dark by hearing