1. BI143: Fundamentals of Life Science
THE PROCESS of SCIENCE
CHAPTER 1

2. SCIENCE:
The Body of Knowledge Accumulated Using the SCIENTIFIC METHOD

3. The Scientific Method Observations: Plants grow better in sunny areas.
Question: Do plants need sunlight to grow?
Hypothesis: Plants need sunlight to grow.
Prediction: If plants need sunlight to grow, then plants not in sunlight will die.

4. The Scientific Method cont.
Controlled Experiment:
Control Group: Plants in sunlight
Experimental Group: Plants without sunlight
Independent Variable: Exposure to sunlight
Dependent Variable: Growth of plants
Data/Results: Plants with no sunlight die.
Conclusion: Hypothesis is correct.
Theory: ???

5. There is a difference between a theory and a hypothesis
A hypothesis is a proposed explanation for a set of observations
A theory is supported by a large and usually growing body of evidence

6. The History of a THEORY:
SPONTANEOUS GENERATION
ARISTOTLE’S THEORY
4th Century B.C.

7. REDI’S EXPERIMENT
1668
Tries to disprove Spontaneous Generation of small organisms (flies)
Meat Sealed in jar: Produces no maggots
Meat in Unsealed jar: Produces maggots
Conclusion: Flies are needed to produce flies
Problem with the experiment???

9. SPALLANZANI’S EXPERIMENT
1767
Tries to disprove Spontaneous Generation of Microorganisms
Sterilizes broth by boiling it for 1 hour
Broth in sealed flask produces no microorganisms
Broth in open flask produces microorganisms
Problems with the experiment???

10. PASTEUR’S EXPERIMENT
1860
Similar to Spallanzani’s experiment, but uses a swan-neck flask instead of a sealed flask (let’s “LIFE FORCE” from air into both flasks
Flask with swan-neck produces no microorganisms
Material from the bend in the swan-neck flask produces microorganisms

12. Mistakes Can Lead to Discovery
Fleming discovers Penicillin (1929)
Fleming was investigating the bacterium, staphylococci
Fleming returned to his laboratory after a vacation and noticed that one culture was contaminated with a fungus
The part of the culture near the fungus was killed
Fleming identified the mold as being from the Penicillium genus
The substance (first antibiotic) that was produced by the mold was named penicillin