Scientific Method

The Nature of Science Cures for disease Explains what our world is like Solve environmental problems Use and discover new technology

Biologist reason in 2 ways: 1. Deductively 2. Inductively

Deductive Reasoning Applies general principles to predict specific results. Example: determining the species of a specimen from its characteristics If A then B type of reasoning, used in math and philosophy

Inductive Reasoning: Logic flows from the specific to the general Example: Cats have fur, dogs have fur, and every mammal you observe has fur, then you may infer that all mammals have hair.

How Science Is Done 1. Question or Observation 2. Hypothesis 3. Controlled Experiment 4. Make Predictions 5. Develop Theory Hypotheses are accepted or rejected based on experimental results.

Establishing Controls (variables) Independent Variable: the investigator manipulates (fertilizer on plants) Dependent Variable: the outcome or results (did the plants grow taller, greener or faster than the group without fertilizer)

Using Predictions A hypothesis is most useful when it makes predictions, because predictions provide a way to test the validity of the hypothesis If experimental results are inconsistent with the predictions then the hypothesis must be rejected. If experimental results are consistent with the predictions then the hypothesis must be accepted.

Fig. 1.4 Observation Question Experiment Hypothesis 1 Hypothesis 2 Hypothesis 3 Hypothesis 4 Hypothesis 5 Potential hypotheses Remaining possible hypotheses Last remaining possible hypothesis Reject hypotheses 1 and 4 Reject hypotheses 2 and 3 Experiment Hypothesis 2 Hypothesis 3 Hypothesis 5 Predictions confirmed Experiment 1 Experiment 2Experiment 3 Experiment 4 Fig. 1.4(TE Art) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Basic vs Applied Research Basic research expands the boundaries of what we know and is usually performed at Universities Applied research is conducted by scientists in industry. Example food additives, new drugs, testing environmental quality

Fig. 1.A Read page 7 How Biologists Do Their Work

Homework ific_method/index.cfm ific_method/index.cfm Do this activity on your computer! Click continue to start Enter your name or initials Do the tutorial part first then the cricket experiment This is a lot of fun!