Chapter 1.4 - The Process of Life
A. Scientific Method
1. Biology is the scientific study of life.
2. The general process of science is said to be characterized by this sequence
of stages.
B. Observation
1. Scientists believe nature is orderly and measurable.
2. Science also considers that natural laws do not change with time.
3. Phenomena can therefore be understood from observations.
4. Actual science research may also involve chance (e.g., Alexander Fleming’s
discovery of penicillin).
*This principle of science is known as NATURAL CAUSALITY, by its nature it excludes supernatural phenomenon*
What are some things that are considered supernatural?
Shows like ghost hunters only “pretend” to be scientific. Why is it impossible to truly study this phenomenon?
C. Hypothesis
1. Inductive reasoning allows a person to combine isolated facts into a cohesive whole.
Examples of inductive reasoning.
2. A hypothesis is a possible explanation for a natural event - must be testable
Examples of hypotheses, check those that are valid and can be tested
_____Bluebirds sing to attract mates.
_____ Bluebird songs are beautiful.
_____ Only male bluebirds sing.
_____ Sparrows will leave territories where they hear bluebird songs.
_____ Bluebirds hate sparrows.Create your own hypothesis:
D. Experiments/Further Observations
1. Testing a hypothesis involves either further observations or conducting
an experiment.
2. Deductive reasoning involves “if, then” logic that predicts
what will happen based on the hypothesis.
Example of deductive reasoning:
What is a syllogism?
Why must all hypotheses by FALSIFIABLE?
Why is it impossible to prove a negative?
E. Data
1. Data are the results of experiments, and are observable and objective.
2. Data are often displayed in a graph or table.
3. Often the data must be inspected for the probability the data could show
a relationship by chance; this
is a measure of “significance.”
Anecdotes are not data!
F. Conclusion
1. Whether the data support or reject the hypothesis is the basis for the
“conclusion.” - avoid the word "prove"
2. Science findings are reported in scientific journals so results are available
to the research community (peer review).
3. The experiments and observations must be repeatable or the research is
suspect.
****In your own words (or with a graphic) explain the difference between deductive and inductive reasoning.****
G. Scientific Theory
1. The ultimate goal is to understand the natural world in scientific theories, conceptual
schemes supported by a broad range of data. What does this mean?
2. The terms “principle” and “law” are also used for generally accepted theories.
Basic theories of biology
are:
a. Cell theory: all organisms are made of cells.
b. Biogenesis theory: life only comes from life.
c. Evolution theory: living things have a common ancestor and are adapted.
d. Gene theory: Organisms contain coded information that determines their form, function, and
behavior.
e. Germ Theory - proposes that microorganisms are the causes of many diseases
f. Heliocentric Theory - the sun is the center of the solar system, planets revolve around the sun
g. Law of Gravity - masses attract each other
What is the difference between a theory and a law?
Why is creationism not considered science?
H. A Controlled Study
1. Some investigations are managed where conditions can be kept constant - the traditional experiment performed in science classrooms and for science projects.
a. A variable is a factor that can cause an observable change.
b. The experimental (independent) variable is the step that is deliberately manipulated (what you changed).
c. A dependent variable is what you measure (the results).
Examples of experimental (independent) and dependent variables
Question: Does colored light affect plant growth?
What is the experimental variable?
What is the dependent variable?
2. Another example of a controlled study. A control group is one that does not receive any experimental treatment
Observation: Babies are born with severe birth defects, mothers of these babies report taking the drug thalidomide during pregnancy for morning sickness.
Question: Does thalidomide cause birth defects?
Hypothesis: Thalidomide causes birth defects.Control group: Mice not given thalidomide during pregnancy
Experimental Group: Mice given thalidomide during pregnancyIn this experiment, mice born from both the control and variable group will not have birth defects. This experiment was performed long before thalidomide was marketed and prescribed to pregnant women.
Does these mean that the hypothesis is not supported?
What is confirmation bias?
How do scientists address this problem?
A Field Study
It's important to realize that not all science occurs in the lab. Scientists also conduct field studies where they observe organisms in their natural environment, and even manipulate that environment.
Example of a field study:
