Title: Scientific Method/ Background
1Scientific Method/ Background
2- 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.
3Scientific 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
4Cont. 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
5Cont. 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
6- 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)
7Cont. 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
8Limitations 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.
9Cont. 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
10Cont. 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.
11Cont. 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
12Microscopes Used in Biology
- Light Microscope ? tissues, whole cells
- 2. Transmission Electron Microscope (TEM)? slices
of cells - 3. Scanning Electron Microscope (SEM)? surfaces
of cells
13SCOPE 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)
14Light Microscope
Staph aureus (100x)
Onion Cells
15Transmission Electron Microscope
E. coli
Striated muscle
16Scanning 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)
17Guess What?!?
18The 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.
19Redis 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.
20Spallanzanis 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.