Scientific Method/ Background

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Scientific Method/ Background
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• OBJECTIVES
• List and describe/ explain the 5 steps in the
  scientific method in the correct sequence.
• Apply/ use steps in the scientific method in a
  given problem.
• Analyze a scientific problem and be able to
  identify specific examples of a hypothesis,
  experiment, data, etc.
• Contrast a hypothesis and a theory.
• List the 2 functions of a good theory.
• Discuss the limitations of science.
• Contrast science vs non-science.
• Differentiate a control group from an
  experimental group and an independent variable
  from a dependent variable.
• Explain the work of Aristotle, Redi, Spallanzani,
  Needham, and Pasteur concerning the origin of new
  living organisms--- relate their work to the
  scientific method.
• Compare and contrast 3 kinds of microscopes used
  in biology--- gives some advantages and
  disadvantages for each.
• Identify and sequence the various levels of
  organization for the study of life.
• Describe common metric units used in science for
  length, mass, volume, and temperature.

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Scientific Method

• 1. Observation
• Must be repeatable
• Correct observation is most difficult- due to
  unsuspected bias
• People see what they want to see difficult to
  explain unconscious prejudice
• Several scientists repeating it independently
  give observation more validity
•  
• 2. Statement of Problem
• To be valuable scientifically, a question must be
  relevant as well as testable and specific
• Proper testing techniques must be available
• In general, science does best with how or
  what questions
• Why questions are more difficult/ Ex Why
  does the universe exist? ? untestable

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Cont. Scientific Method

• 3. Formulation of Hypothesis
• Not a random guess
• Hypothesis? a tentative answer or postulation
  based on numerous observations
• Scientist does not know if his guess was
  correct or incorrect until he has completed
  experimentation
• 4. Experimentation
• Provides enough evidence to explain hypothesis
• Most difficult step? must be a controlled
  experiment
• Requires at least 2 parallel sets of tests,
  identical in all respects except one
• Control Series provides a standard or reference
  for assessing results of the Experimental Series

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Cont. Experimentation

• Ex In drug experiments on people, up to 100,000
  to 200,000 test, 2 of them controls and 2
  experimental groups

Control Series Experimental Group
a. All conditions same as Experimental group a. All conditions same as Control group
b. No drug taken b. Drug taken-specific dose
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• Cont. Experimentation
• e) Large samples () of organisms must be used
• f) Even after careful execution, etc. results
  may not be clear
• g) Results of any experiment represents EVIDENCE?
  the original guess about the answer is confirmed
  as correct or incorrect (invalid)
• h) If invalid, a new hypothesis and new
  experiments must be designed
• - Process must be repeated until a hypothesis is
  found that can be supported with experimental
  evidence
• i) Results of experiments cannot be called
  proof or fact, merely evidence for a
  hypothesis (some hypothesis have more evidence
  than others)

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Cont. Scientific Method

• 5. Formulation of Conclusion Theory
• Based on evidence produce by experimentation
• Theory? a hypothesis that has withstood repeated
  testing by many scientists doing independent work
• Good theory has predictive value? forecasts
  certain results based on substantial evidence
• - Scientific forecast does not guarantee
  something will happen-- indicates that it is
  likely to happen with a stated degree of
  probability
• d) Natural Laws? theories that have proved so
  universally valid to a high degree of probability
  
• - Ex Apple falls from tree? no exception even
  observed Law of Gravity
• e) Most theories are valid for a time, but with
  time, exceptions are found
• f) Science is a steady progression, not
  revolution
• - Ex Isolation and synthesis of a gene took 5
  years

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Limitations of Science

• Science is confined to use of the Scientific
  Method-- this is the beginning and end of
  science.
• 2. Anything to which the scientific method can
  be applied now or in the future. Anything to
  which this method cannot be applied is NOT
  science.

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Cont. Limitations of Science

• Does the idea of God lend itself to scientific
  study? 
• a) Test hypothesis God is universal and exists
  everywhere and in
• everything
• b) An experiment about God would require 2
  situations one w/ God,
• one without, but otherwise identical
• c) If hypothesis is correct God would exist
  everywhere-- be present in
• every test and could never devise a
  situation in which God is NOT
• present
• d) If hypothesis is wrong God would not
  exist-- would be absent from
• any test and could never devise a
  situation in which God is present
• e) Hypothesis is untestable-- cannot run
  controlled experiment
• f) Concept of God falls out of scientific
  domain
• g) Are scientists godless? Science does not
  prove nor disprove God- leaves anyone free
  to believe in any God or in none/ many
  first- rate scientists are priests, many are
  agnostics

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Cont. Limitations of Science

• 4. The aim and purpose of science is to make and
  use theories. Science finds evidence for
  theories-- does not deal with truth or proof.
• 5. Science does not make value judgments or moral
  decisions. Scientific results do not contain
  built-in values.
• 6. Science cannot determine whether or not one
  should have moral standards or which set one
  should live by.

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Cont. Limitations of Science

• 7. Forms of Science
• a) Basic Research (Pure Science)
• Done to further understand nature
• Practical applications are disregarded
• Publish papers, experiments, research
• b) Applied Science (Practical Science)
• Applies the results of pure science to practical
  uses
• Doctors, engineers, criminologists, physical
  therapists, etc.
• Technology

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Microscopes Used in Biology

• Light Microscope ? tissues, whole cells
• 2. Transmission Electron Microscope (TEM)? slices
  of cells
• 3. Scanning Electron Microscope (SEM)? surfaces
  of cells

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SCOPE ADVANTAGES DISADVANTAGES
LIGHT Living cells Color Movement Processes Low magnification No fine detail
TEM Very high magnification Extremely fine details No living cells No color No movement No processes Special technique ( fix, slice, stain, freeze, vacuum)
SEM Surface details 3D image Same as TEM (no slicing)
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Light Microscope
Staph aureus (100x)
Onion Cells
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Transmission Electron Microscope
E. coli
Striated muscle
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Scanning Electron Microscope
Mascara brush covered w/ dried mascara flakes
of skin
Cat flea flattened from side to side along with
the spines on its head (have either simple eyes
or no eyes at all)
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Guess What?!?
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The dentist drill is covered with tiny diamond
chips. Diamonds are the hardest substance known
and will easily wear away tooth particles as the
drill spins at high speeds.
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Redis Experiment on Spontaneous Generation
REDIS EXPERIMENT ON SPONTANEOUS GENERATION
Section 1-2
OBSERVATIONS Flies land on meat that is left
uncovered. Later, maggots appear on the meat.
HYPOTHESIS Flies produce maggots.
PROCEDURE
Uncovered jars
Covered jars
Controlled Variables jars, type of
meat, location, temperature, time
Several days pass
Manipulated Variables gauze covering that keeps
flies away from meat
Responding Variable whether maggots appear
Maggots appear
No maggots appear
CONCLUSION Maggots form only when flies come in
contact with meat. Spontaneous generation of
maggots did not occur.
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Spallanzanis Experiment

Section 1-2
Gravy is boiled.
Flask is open.
Gravy is teeming with microorganisms.
Flask is sealed.
Gravy is free of microorganisms.
Gravy is boiled.