1. Biology and the Scientific Method

3. The Scientific Method Observation
State the Problem (worded as a question)
Gather information
Form a Hypothesis (if…then…)
Experiment to test the hypothesis
(the experimental group will have ONE variable that differs from the control group)

4. Independent Variable – being tested
Dependent variable- being measured
Record and analyze data (charts, tables, graphs)
Draw Conclusions
Repeat to check for accuracy
Publish

5. Hypothesis
Educated guess or prediction that can be tested
Theory
Thoroughly tested explanation of why experiments give certain results
Proven fact

6. Scientists who helped develop the Scientific Method

7. 1668-Francesco Redi
Observed flies land on meat that later develops maggots.
Hypothesis: Maggots come from flies
Experiment
control - jars with meat covered
experimental – jars with meat open
Results: open jar had flies and maggots
Conclusion: maggots come from flies

8. Critics said there were no maggots in the closed jar because there was no air! Redi redesigned his experiment and covered the jar with netting. Result: Flies and maggots were on the netting, not in the jar. His hypothesis was correct! First scientist to use a control group

9. 1668 -Redi

11. 1700’s - Spallanzani
Hypothesis: microbes do not come from broth Experiment: Flask with boiled gravy left open – microbes grew Flask with boiled gravy sealed – no growth Critics said “no air “– no redesign

12. Critics said “bad broth” Persevered and proved his point!
Pasteur
Redesigned Spallanzani’s experiment using a swan-necked flask
Flask was left open - no growth
Critics said “bad broth”
Pasteur broke off the neck and growth began
Persevered and proved his point!

13. Pasteur’s swan-necked flask: