1-2 how scientists work
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1-2: How Scientists workTRANSCRIPT
UNIT 1: THE NATURE OF LIFE
CHAPTER 1: THE SCIENCE OF BIOLOGY
Ms. PetrucciBiology
Chapter 1: The Science of Biology
Vocabulary
Section 1-2: How Scientists Work
• Spontaneous generation• Controlled experiment• Manipulated (Independent) Variable• Responding (Dependant) Variable• Theory
1-2 How Scientists Work• Systematically
Designing an Experiment
1. Make Observations/Ask a Question
2. Research/Form a Hypothesis
3. Set up a Controlled Experiment
4. Record and Analyze Results
5. Draw a conclusion• Communicate Results• Repeat
Set up a Controlled Experiment
• Use only one variable• Control (keep unchanged) all others• Manipulated variable is changed• Responding variable is observed
• Francesco Redi (1668)• Needham (1748)• Lazzaro Spallanzini (1765)• Louis Pasteur (1800's)
Variables• Dependent Variable
• Independent Variable
Redi’s Experiment• Spontaneous Generation
Needham’s Experiment• Spontaneous generation can occur under the right
conditions. Was Redi wrong!?
• 1765
• Nonliving Gravy does not produce living things.
• New organisms are produced only by existing organisms
• 1861
• Fixed the “no air” claim of Needham.
• Some flasks still sterile today.
Disproved Spontaneous Generation!
Life can only come from other life.
Three Experiments
Practice the Scientific Method
• Think about how you would test how the amount of a certain fertilizer determines if the fertilizer would grow taller plants.
Brainstorm• Decide how you would go about conducting an
experiment or investigation to study this.
• Identify the Dependant Variable and the Independent Variable
• I will provide you results
Data
Does more fertilizer = better growth?
Analyze these results.
What if you Cannot Experiment?• When might an experiment not be possible?• How can we answer scientific questions without
experimentation?Human Studies
Field Studies
Obs
erva
tiona
l Stu
dies
Models
What is a Theory??