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What is Biology?
Bio. 100
Tri-County Tec. College
Pendleton, S. C.
Biology
The Science of Life
Best defined as the “scientific study of
life
Two critical important questions that
divide our society: (1) When does life
begin, and (2) When does life end?
Characteristics of Life
Living things can and do:
Metabolize
Maintain homeostasis
Respond to stimuli (irritability)
Grow and reproduce
Adapt and evolve
Cell Theory
The cell is the structural and functional
unit of life
All living things are composed of one or
more cells
Cells can only come from preexisting
cells
Types of Cells
Prokaryotic cells do not have a nucleus
or membrane-bound organelles
Not as complex, sophisticated, nor as
large as eukaryotic cells
Eukaryotic cells have a nucleus and
membrane-bound organelles
Subdivided by membranes into
compartments
The Three Domains
It has been proposed to divide all living
things into one of three domains:
Archaea

More closely related to Eukarya
Bacteria
Eukarya

Contains all the eukaryotes
Five Kingdom Scheme
Monera (Prokaryotae)

Contains all the prokaryotes
Protista

Estes defines as the “swing’ kingdom
Fungi
Plantae
Animalia
The Unifying Theme of
Biology
Evolution is the unifying theme of
biology

“change through time”
Descent with modification

Descent (life’s unity) and modification
(diversity)
Mechanism is natural selection

Environment selects most suited traits
What is Science?
A process that involves testing possible
solutions to a problem or understanding
an event in nature.
The process that science uses is known
as the scientific method
What is the scientific method?
The Scientific Method
a way of getting information
an organized way of questioning
involves rigorous testing of a proposed
solution
One aspect of the scientific method is
observation.
Observations
the use of our senses to record an
event
examples of observation


the leaves on that tree are different from
the others of the same kind of tree
I urinate a lot when I drink coffee.
Observations are followed by forming a
hypothesis and testing it.
Hypotheses
A hypothesis is a statement that
provides a possible answer to a
question or an explanation for an
observation.
Example-
Chemical A will kill weeds.
To test this hypothesis, we set up
experiments and controls.
Experiments and Controls
Experiment


recreation of an event in a way that enables a
scientist to support or reject a hypothesis.
experimental group and a control group
Experimental group

all members receive the experimental treatment
Control group

do not receive the experimental treatment
Definitions, continued
Placebo is typically an nonmedicated
substance given to the control group

NCTR studies time
Blind study: The participants do NOT know if
they are in the control or experimental group
Double-blind study: Participants and
researcher(s) do NOT know which group is
experimental and which is control
Testing our Hypothesis
Hypothesis: chemical A will kill weeds
Select two plots of soil with
miscellaneous weeds growing on them.
Treat one plot with chemical A

Experimental Plot
Treat another plot with water

Control Plot
Plot A treated with
Plot B treated with
Chemical A is the
water becomes the
experimental plot.
control plot.
Testing, ctd.
Allow two weeks to elapse.
Count the number of living weed plants
on Plot A and Plot B.
Keep careful records of the appearance
of the plots such as when signs of dying
begin to develop.
What do you expect to see?
Plot A
Plot B
Conclusions
Chemical A will kill weeds under
conditions of this study.
Our hypothesis is supported by the
experiment.
One experiment is usually not enough
to support a hypothesis.
Medicine and the Sci. Method
When you go to a physician, he or she
collects data through the process of physical
examination, lab. tests, and other means.
The physician then formulates two
hypotheses-

a diagnosis of your ailment
a course of treatment to help you get better
Medicine, ctd.
You, the patient, then carries out the
experiment by following whatever
treatment protocol is prescribed
If you get well the hypothesis is
supported.
If you don’t get well the hypothesis is
not supported and the physician
formulates another hypothesis.
Theories and Laws
Theory


a hypothesis that has been supported by years of
repeated experimentation and evidence gathering.
“Germ Theory of Disease”
Law



a widely accepted theory
a constant fact of nature
Law of Biogenesis
Two Mindsets of Science
Inductive reasoning is generalization that
summarizes many concurrent observations
Specific to the general
Hypothesis driven (Deductive) asks questions
and seeks explanations
General to specific
Takes form of prediction(s)
“if…then” logic
Believe it or Not
Peppered moths data
Spider mimic experiments
DDT; antibiotics; HIV
Time for an Estesism