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Unformatted text preview: Biology 1103 Lecture #2
August 18, 2011 What is science?
Science is a way of knowing What is science? Everything that is properly called
Everything science has been based on
experiments designed in
accordance with scientific
methods. Science relies on
observation and experiments.
observation and experiments Observation Something that cannot be
Something observed cannot be investigated
by Ask a question? Define a problem by asking a
Define question about the
Then, propose what the answer to
the question might be. This is a
To have scientific value,
hypotheses must be a logical and
testable explanation. Experiment
Do results support the
hypothesis? If not, a new hypothesis and
experiment must be
designed. The Use of Controls
Question – Do herbicides affect the
development of chicken embryos?
Hypothesis – Herbicides cause developmental
abnormalities in chicken embryos.
abnormalities Uncontrolled experiment
Pierce egg. Test herbicide added in alcohol solution. Seal hole with wax and incubate.
Potential sources of error
1. Does piercing affect development?
2. Does adding alcohol affect development?
3. Could the results be due to chance?
4. Could there be something wrong with the
incubator? Controlled experiment
Group 1 Experiment:
herbicide in alcohol solution added to a number of
Group 2 Control:
alcohol solution added to a number of eggs.
Group 3 Control:
a number of eggs pierced but nothing added.
Group 4 Control:
a number of eggs untreated but handled in identical
ways. Pasteur and “spontaneous generation” Pasteur’s experiments The use of
science Nothing in science is ever finally proven!
Nothing Every assertion in science is subject to change
based on evidence.
based Any scientific hypothesis must be falsifiable –
open to negation through scientific inquiry.
open Supernatural explanations lie outside the realm
of science and –thus- cannot be examined
through the scientific process
through What is the difference between a
hypothesis and a theory?
hypothesis What about scientific creationism?
Scientific creationism should not be labeled
science for two reasons;
1) It is not supported by any scientific
2) It does not infer its principles from
observation, as does all science.
observation, Nearly ALL scientists agree on the following:
1) The earth has a history of approximately 4.5
2) Organisms have inhabited it for a greater part
of that time.
3) All living things – including human beings –
have arisen from earlier, simpler living things.
have Science is a process: Experimentation Controlled experiments use experimental groups
and control groups to test a hypothesis.
control Science is a process: Experimentation The experimental group is the group in an
experiment that experiences the
experimental intervention or manipulation.
experimental The control group is the group in an
experiment that experiences no
experimental intervention or manipulation.
experimental Science is a process: Experimentation The independent variable is the variable, or factor,
being deliberately changed in the experimental
group. Science is a process: Experimentation The control group receives a placebo – a fake treatment
given to control groups to mimic the experience of the
– – The placebo effect is the effect observed when
members of a control group display a measurable
response to a placebo because they
think they are receiving a “real” treatment. In
order to rule this out, the participants in the
experiment do not know whether they are
receiving a placebo or the experimental treatment.
receiving Science is a process: Experimentation The dependent variable is the measured result of an
experiment. It is analyzed in both the experimental
and control groups.
and In a controlled experiment, the control
group and experimental group differ only
in the independent variable, so the results
of the experiment provide evidence-based
conclusions. Drawing conclusions Confidence in scientific findings is increased
Confidence by repetition of an experiment by other
scientists. Drawing conclusions The sample size of the experiment can
strengthen our confidence in the results of
the study. The sample size is the number of
experimental subjects or the number of
times an experiment is repeated.
times In human studies, the sample size is the
number of subjects.
number The larger the sample size, the more likely the results will have statistical
significance. Statistical significance is a measure of confidence that the
results obtained are “real,” rather than due to random chance.
results Science is a process: Drawing conclusions The more experiments that support a
hypothesis, the more confident we can be
that it is true.
that A hypothesis that continues to hold up after
many years of rigorous testing may
eventually be considered a scientific
theory Science is a process:
science, a theory
is a hypothesis
that has never
even after many
years of rigorous
The smallest particle of an element
Oxygen Subatomic particles
protons, neutrons, electrons – make
up an atom Periodic Table Atomic number Number of protons. The number of
protons equals the number of electrons. Atomic mass Mass of protons, neutrons and electrons
(mainly protons and neutrons) electron shells:
2+8+8 Argon Stable 2
2, 8 2, 8, 8 ...
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