CHAPTER 1
The Nature of Science and the
Characteristics of Life
This Class is about You…
• This class is about us and how we connect
with other living beings and our surroundings
• Many controversies facing society today
require an understanding of science to make
informed decisions
– What are some examples of these controversies?
What is Biology?
• Biology is the scientific study of life
– What does Bio mean?
– What does –ology mean?
The Language of Science
• Challenging vocabulary: heck no!
• Most scientific vocabulary are “little words”,
or roots, that are linked together
• If you learn the meanings of these roots, you'll
find scientific vocabulary much easier to
understand!
The Language of Science
these words will not be on the test
What is hydrology?
What is a cytoskeleton?
What is hyperthyroid?
What is abiotic?
What is hypodermic?
Learning roots will help in EVERY part of
your college career! Take this time in BI101
to familiarize yourself with roots!
The Nature of Science
• Humans have a natural spirit of inquiry,
driving science
– We start this as babies, this is how we learned
many things!
– Both types of inquiry are important! Discover
through both experience and study.
The Nature of Science
• Scientific thinking is objective and values
evidence
– W2L: What does it mean to be objective?
– W2L: What kinds of things can be judged
objectively? What about subjectively?
The Nature of Science
• Science:
• is a body of knowledge
• is an evidence-based
process for acquiring
knowledge
• deals with the natural
world
• is based on evidence that
can be demonstrated
through observation
and/or experiments
The Nature of Science
• The process that
generates scientific
knowledge is called
the scientific
method
• The scientific
method is used in
all areas of science
An Example of
the Scientific
Method
You have observed that
some fish swim slower
than others.
The Nature of Science: Observations
• The process of science
begins with an observation
of the natural world
• An observation is a
description, measurement,
or record of any object or
phenomenon
• An observation must be
reproducible
An Example of
the Scientific
Method
You develop a hypothesis
that states: the faster a
fish swims, the larger gill
area is relative to body
size.
--Does this hypothesis make sense?
The Nature of Science: Hypotheses
• A scientific
hypothesis is an
informed, logical,
and plausible
explanation about
the natural world
• Must be testable!
An Example of
the Scientific
Method
You predict that: If a fish
swims faster than another
fish then the faster fish will
have a larger gill area
relative to its body size
when compared to the
slower fish.
The Nature of Science: Predictions
• Using the hypothesis make a prediction in an “ifthen” statement
• Does not have to be an “if-then” statement but it is
easier to write this way.
An Example of
the Scientific
Method
You test your hypothesis
by measuring the following
on many types of fish:
• Gill area
• Body size
 W2L: Why test many types of
fish?
The Nature of Science: Test
Using Good Experimental Design
• An experiment is a repeatable manipulation of
one or more aspect of the natural world by
experimenters
• In a well designed experiment:
– only one independent variable is manipulated at a
time
– The experiment is controlled
The Nature of Science: Independent vs.
Dependent Variable
• The dependent variable
is effected by the
independent variable.
• Remember only one
independent variable is
manipulated at a time
• What would happen if
we tested two?
The Nature of Science: Independent vs.
Dependent Variable
• In this experiment which
is the independent and
dependent variable?
Hint: “I” determine the
independent variable
as the researcher.
• In an experiment, only one
independent variable is
manipulated at a time. Why?
The Nature of Science: Independent vs.
Dependent Variable
• W2L: Let’s graph this!
– Which variable is on the xaxis?
– Which variable is on the yaxis?
The Nature of Science: Controlled Experiment
• A controlled experiment:
– Comparable in all respects
except one or more
group(s) are exposed to
systemic change and one
is not
• Control group:
– No change in
independent variable
• Treatment group:
– Independent variable is
manipulated by the
researcher
An Example of
the Scientific
Method
What were your results?
Is your hypothesis
supported or not?
An Example of
the Scientific
Method
Now you have another
observation that you can
base another hypothesis
on.
An Example of
the Scientific
Method
1*
9*
18
30*
50*
What if the data doesn’t
support the hypothesis?
• This is when science
gets even more fun!!
Sometimes
*this data has been changed and does not reflect what actually occurs in nature
The Nature of Science: Scientific Theory
• A scientific theory is a body of knowledge that
has stood the test of time
• A hypothesis becomes a scientific theory:
– After it has been repeatedly confirmed through
diverse methods of testing
– When it is accepted by experts as the best
explanation of the truth about the phenomenon
• A scientific fact is a direct and repeatable
observation about the natural world
Just a theory?
• When we use the word "theory" in everyday
life, we usually mean an idea or a guess, but
the word has a much different meaning in
science…
• Some theories in Biology:
– Cell Theory
– Theory of Natural Selection
– Germ Theory
Characteristics of Living Organisms
• All living organisms share a set of common
characteristics
• Living organisms:
– Are composed of one or more cells
– Reproduce using deoxyribonucleic acid (DNA)
– Obtain energy from their environment to support
metabolism
– Sense and respond to their environment
– Maintain homeostasis
– Are capable of evolving as a group
Characteristics of Living Organisms: Cells
• Cells:
– Basic unit of life
– Cells enclosed by a water-repellent
layer called the plasma membrane
Characteristics of Living Organisms: Reproduce
via DNA
• DNA:
– DNA is genetic
material that
contains all the
instructions for
building new
organisms
– Passes
information from
parent to
offspring
Characteristics of Living Organisms:
Energy from the Environment
• All organisms need energy
to live, they get this energy
from their environment.
• Plants are producers:
– convert energy from
the sun into chemical
energy
• Consumers use energy
from other consumers or
directly from producers
– Ex: cat eats mouse and gets
some of the energy that the
mouse contained
Characteristics of Living Organisms:
Homeostasis
• Keeping the balance
• Organisms sense and
respond to their
environment in order to
maintain constant
internal conditions
through a process called
homeostasis
Characteristics of Living Organisms:
Groups Evolving
• Evolution allows an organism to survive and
reproduce better than competing organisms
In biology there is
a hierarchy in
order from less to
more complex.