Transcript 1-3 The study of Biology

1-3 The study of Biology
Objectives
• Outline the steps of the scientific method
• Summarize how observations are used to form
hypothesis
• List the elements of a controlled experiment
• Describe how scientists use data to draw
conclusions
• Compare a hypothesis and theory
• State how communication & peer review prevent
dishonesty
Scientific Method
• Organized approach
– Natural causes
• Not supernatural
• Have to be able to disprove something
– Uniformity: The laws of nature are the same
everywhere
Steps of method
1.
2.
3.
4.
5.
6.
Observation
Hypothesis
Prediction
Exeperiment
Analyze data
Communicate findings
Experimental design
• Control Groups: provide a normal standard
• Experimental Group: Different from control
by 1 factor  the independent variable
• Dependant variable: what is affected by
independent variable
• Quantitative vs. Qualitative
Analyzing Data
• Is the data reliable?
• Does it support your hypothesis or not?
Conclusions
• Can’t prove much
• Theories: when hypothesis is confirmed
many times and it explains a lot
• Law: Theories that have been confirmed
many many times
• Beyond a doubt
Scientific Method
• Bacon (1561-1626) and Descartes (1596-1650)
– were not scientists but did invent new habits of scientific
thought
• scientific method as habits of disciplined creativity,
careful observations, logical thinking & analysis of
observations
• way of seeking trends & drawing generalizations
• Convinced governments of England & France to form
academies of science that still exist today
• Scientific way of thinking based on assumptions & methods
that are reliable, objective & testable
Making observations until
capable of drawing
generalizations and making
predictions
– anatomy is a product of
inductive method
• Proof in science can not go
past “proved beyond
reasonable doubt”
– reliable methods of
observation
– tested and confirmed
repeatedly
– not falsified by any
credible observation
• In science, all truth is
tentative
Inductive
Method
Hypothetico-Deductive Method
• Physiological knowledge
gained by this method
• Ask a question and
formulate a hypothesis -an educated possible
answer
• Good hypothesis
– consistent with what is
already known
– capable of being tested
and falsified with certain
evidence
• If nothing could prove it
wrong, it is not a scientific
belief
• Hypotheses are written
as If-Then predictions
Experimental Design
• Sufficient sample size to prevent chance event
• Control group and treatment group receive the
same treatment except for the variable being
tested
• Prevention of psychosomatic effects
– use of placebo in control group
• Experimenter bias
– prevented with double-blind study
• Statistical testing to be sure the difference
between groups was not random, but was due
to variable being tested
Peer Review
• Critical evaluation
by other experts in
the field
– prior to funding
– verification and
repeatability of
results
• Ensures honesty,
objectivity & quality
in science
Health Minister Manto Tshabalala-Msimang of South Africa, known for
putting vegetable remedies ahead of anti-retrovirals, endorses Dr
Matthias Rath's vitamin treatments.
Dr. Rath and his cure for AIDS:
Mega Doses of Vitamin C
• A doctor who worked
with Nobel Prize
winner Linus Pauling
• has taken the advocacy
of vitamins into all-out
war on the
pharmaceutical
companies
• Buys ad space in the NY
Times, and fills them with
editorials masked as facts
• Without getting
confirmation of his
studies is taking his cure
to the people of Africa
• Problems: Too much
Facts, Laws and Theories
• Scientific fact is information that can be independently
verified by any trained person
– iron deficiency leads to anemia
• Law of nature is a description of the way matter and
energy behave
– resulting from inductive reasoning & repeated
observations
– written as verbal statements or mathematical formulae
• Theory is a summary of conclusions drawn from
observable facts
– it provides explanations and predictions
– sliding filament theory of muscle contraction
Logic is the anatomy of thought
-John Locke
• Conditional arguments: the
basis of hypothesis forming.
Two parts
• Part 1: If p then q
– P = antecedent
– Q = Consequent
• Part 2 allows us to draw
conclusions
– If P happens then Q
happens (Modus Ponens
– If Q did not happen, P did
not happen (Modus
Tollens)
There is a claim that lycopene, the reddish substance in
tomatoes and peppers, is of value in protecting people from
Alzheimer Disease. How would you, as a scientist, go
about substantiating or refuting this suggestion?