The Science of Biology
• The concepts, principles, and theories that
allow people to understand the natural
environment form the core of biology, the
study of life.
• The word biology comes from the Greek
word bios meaning “life” and logos meaning
“study”. Biology is the study of life.
The Science of Biology
• Life on Earth includes
not only the common
organisms you notice
every day, but also
distinctive life forms that
have unusual behaviors.
The Science of Biology
• When studying the different types of living
things, you’ll ask what, why, and how
questions about life.
• The answers to such questions lead to the
development of general biological principles
and rules.
Biologists study the interactions of life
• One of the most general principles in biology
is that living things do not exist in isolation;
they are all functioning parts in the delicate
balance of nature.
Biologists study the interactions of life
• Living things
interact with their
environment and
depend upon other
living and
nonliving things to
aid their survival.
Biologists study the Diversity of Life
• Through your study
of biology, you will
come to appreciate
the great diversity of
life on Earth and the
way all living
organisms fit into
the dynamic pattern
of life on our planet.
Biologists study the interactions of
the environment
• Because no living things, including
humans, exist in isolation, the study of
biology must include the investigation
of living interactions.
• The study of one living thing always
involves the study of the others with
which it interacts.
Biologists study problems and
propose solutions
• The study of biology will teach you how
humans function and how we fit in with
the rest of the natural world.
• It will also equip you with the knowledge
you need to help sustain this planet’s web
of life.
Characteristics of Living Things
• Biologists have formulated a list of
characteristics by which we can
recognize living things.
• Only when something has all of them
can it then be considered living.
Characteristics of Living Things
• Anything that possesses all of the
characteristics of life is known as an
organism.
Characteristics of Living Things
All living things:
• have an orderly structure
• produce offspring
• grow and develop
• adjust to changes in the environment
Living things are organized
• When biologists search for signs of life, one
of the first things they look for is structure.
That’s because they know that all living
things show an orderly structure, or
organization.
• Whether an organism is made up of one cell
or billions of cells, all of its parts function
together in an orderly, living system.
Living things make more living things
• One of the most
obvious of all the
characteristics of
life is reproduction,
the production of
offspring.
Living things make more living things
• Reproduction is not essential for the
survival of an individual organism, but it
is essential for the continuation of the
organism’s species.
• A species is a group of organisms that
can interbreed and produce fertile
offspring in nature.
Living things change during their lives
• Growth results in an increase in the amount
of living material and the formation of new
structures.
• All organisms grow, with different parts of
the organism growing at different rates.
• All of the changes that take place during
the life of an organism are known as its
development.
Living things adjust to their surroundings
• Organisms live in a constant interface with
their surroundings, or environment, which
includes the air, water, weather, temperature,
any other organisms in the area, and many
other factors.
Living things adjust to their surroundings
• Anything in an organism’s external or
internal environment that causes the
organism to react is a stimulus.
• A reaction to a
stimulus is a
response.
Living things adjust to their surroundings
• Living things reproduce themselves, grow
and develop, respond to external stimuli, and
maintain homeostasis by using energy.
• Regulation of an organism’s internal
environment to maintain conditions suitable
for its survival is called homeostasis.
• Energy is the ability to cause change.
Living things adapt and evolve
• Any structure, behavior, or internal process
that enables an organism to respond to
environmental factors and live to produce
offspring is called an adaptation.
• Adaptations are inherited from previous
generations.
• The gradual change in a species through
adaptations over time is evolution.
Question 1
How does society benefit from the
study of biology?
Benefits include advances in
medical treatments and disease
prevention, learning more about
how the human body functions,
increasing knowledge of human
relationships and better
understanding of how to sustain
the web of life on Earth.
Question 2
What is the origin of the term "biology"?
"Biology" comes from
two Greek words, "bios"
meaning life, and "logos"
meaning study. Biology is
the study of life.
Question 3
What are some characteristics of
living things?
All living things have an orderly structure,
produce offspring, grow and develop, and adjust
to changes in the environment. Sometimes
nonliving things have one or more of these
characteristics, but unless something has all of
them it is not considered to be a living thing.
These plants are called Lithops from
the Greek lithos, meaning “stone.”
Although they don’t appear to be so,
Lithops are just as alive as elephants.
Both species possess all of the
characteristics of life.
Question 4
A group of organisms that can interbreed
and produce fertile offspring is a(n)
__________.
A. organization
B. species
C. environment
D. niche
The answer is B, species.
Question 5
What is the importance of homeostasis?
Homeostasis is the regulation
of an organism's internal
environment to maintain
conditions suitable for
survival. An example is the
adjustment an organism
makes in the amount of water
in its cells; without the ability
to make such adjustments,
organisms die.
Question 6
Which of the following is an example
of an adaptation?
A. the gradual change in a species over time
B. changing only one condition at a
time during an experiment
C. possessing large eyes for efficient night vision
D. all the changes that take place during
the lifetime of an organism
The answer is C. A structure,
behavior or internal process
that enables an organism to
respond to environmental
factors and live to reproduce
is an adaptation. Evolution is
the gradual change of a
species over time and occurs
through adaptations.
Section Objectives:
• Compare different scientific methods.
• Differentiate among hypothesis, theory,
and principle.
Observing and Hypothesizing
• When scientists answer one question, other
questions are sometimes answered but also
new questions are created.
The methods biologists use
• The common steps that biologists and other
scientists use to gather information and
answer questions are collectively known as
scientific methods.
• Scientific methods usually begin with
scientists identifying a problem to solve
by observing the world around them.
The methods biologists use
• A hypothesis is an explanation for a question
or a problem that can be formally tested.
• A hypothesis is not a random guess.
Experimenting
•An experiment is an
investigation that
tests a hypothesis by
the process of
collecting
information under
controlled conditions.
What is a controlled experiment?
•Experiments involve two or more groups
•control group - group in which all
conditions are kept the same.
•experimental group(s) - the test group, in
which all conditions are kept the
same except for the single
condition being tested.
Designing an experiment
• In a controlled experiment, only one condition
is changed at a time.
• The condition in an experiment that is
changed is the independent variable, because
it is the only variable that affects the outcome
of the experiment.
Designing an experiment
• While changing the independent variable, the
scientist observes or measures a second
condition that results from the change.
• This condition is the dependent variable,
because any changes in it depend on changes
made to the independent variable.
Data gathering
• Information
obtained from
investigations is
called data.
• Often, data are in
numerical form.
Conveying Data
• Most quantitative
• Line Graph
data can be displayed
in one of the
• Circle Graph
following graphs:
• Bar Graph
Line Graphs
Absences vs. Average
100
80
Average
• Show a change over
time, graphs the
dependent variable
(y-axis) and
independent variable
(x-axis).
60
40
20
0
0
2
4
6
8
Number of Absences
10
12
14
Circle Graphs
• Used to show how a
fixed quantity is
broken down into
parts.
Bar Graphs
• Compares different
information gathered
by counting.
Data gathering
• Numerical data may be
measurements of time,
temperature, length,
mass, area, volume, or
other factors.
Numerical data
may also be counts.
• Sometimes data are expressed in verbal
form, using words to describe observations
made during an investigation.
Thinking about what happened
After review of the data, the scientist must
come to a conclusion:
• Was the hypothesis supported or rejected by
the data?
• Are more data needed?
Verifying results
• After results of an investigation have been
published, other scientists can try to verify
the results by repeating the procedure.
• When a hypothesis is supported by data
from additional investigations, it is
considered valid and is generally accepted
by the scientific community.
Theories and laws
• In science, a hypothesis that is supported
by many separate observations and
investigations, usually over a long period
of time, becomes a theory.
• A theory is an explanation of a natural
phenomenon that is supported by a large body
of scientific evidence obtained from many
different investigations and observations.
Reporting results
• Results and conclusions of investigations are
reported in scientific journals, where they are
available for examination by other scientists.
•Why is this important?
Theories and laws
• In addition to theories, scientists also
recognize certain facts of nature, called
laws or principles, that are generally
known to be true.
Question 1
What is the difference between a
hypothesis and an observation?
A hypothesis is an explanation for a
question or problem and can be formally
tested. An observation is something that
has been noticed, often generating
questions that lead to the formation of a
hypothesis.
Question 2
A scientist conducts an experiment to test the
effect of light on plant growth. In each
experiment, three plants of the same variety
are each given 10 mL of water. One plant is
exposed to full sunlight for 8 hours, one is
exposed to full sunlight for 4 hours, and one
plant is kept in a dark room. Plant height is
measured after two weeks. What is the
independent variable in this experiment?
Question 2
What is the independent variable in this
experiment?
A. soil volume
B. amount of sunlight
C. plant height
D. amount of water
The answer is B. The independent variable is
the condition that is changed. In this case, the
amount of sunlight is changed for each plant.
Plant heights are measured results of the
experiment, so plant height is the dependent
variable.
Question 3
Which of the following is the group in an
experiment in which all conditions are kept
the same?
A. standard
B. independent variable
C. experimental
D. control
The answer is D. Conditions are kept the
same in the control group. The experimental
group is the test group.
Question 4
Compare the terms "theory" and
"principle".
A theory is an explanation of a natural
phenomenon that is supported by a large body
of scientific evidence. A principle is a fact of
nature, generally known to be true, such as the
law of gravity.
Question 5
Why is the hypothesis that black cats
cause bad luck not science?
A theory is an explanation of a natural
phenomenon that is supported by a large body
of scientific evidence. A principle is a fact of
nature, generally known to be true, such as the
law of gravity.
Section Objectives:
• Compare and contrast quantitative and
qualitative information.
• Explain why science and technology
cannot solve all problems.
Types of information
Quantitative information
• Biologists sometimes conduct controlled
experiments that result in counts or
measurements—that is, numerical data.
• When you think of quatitative think of
quantity.
Quantitative information
Number of paramecia surviving
Paramecium Survival Rates
Temperature
• Quantitative
data may be
graphed
or put in a
table.
Quantitative information
Number of paramecia surviving
Paramecium Survival Rates
Temperature
• Graphs and
tables
communicate
large amounts
of data in a
form that is
easy to
understand.
Measuring in the International System
• Scientists always report measurements in a form
of the metric system called the International
System of Measurement, commonly known as SI.
SI Base Units
Measurement
Unit
Length
meter
Mass
kilogram
Time
second
ampere
Electric current
Temperature
kelvin
Amount of substance mole
Intensity of light
candela
Symbol
m
kg
s
A
K
mol
cd
Measuring in the International System
In biology, the metric units you will encounter
most often are:
• meter (length),
• gram (mass),
• liter (volume),
• second (time), and
• Celsius degree (temperature).
Types of Information
Qualitative information
• Observational data—that is, written
descriptions of observational data—are often
just as important in the solution of a
scientific problem as numerical data.
• When biologists use purely observational
data, they are using qualitative information.
Science and Society
• Ethics refers to the moral principles and
values held by humans. Determines what
is right or wrong.
• Society as a whole must take responsibility
for the ethical use of scientific discoveries.
Can technology solve all problems?
• Scientific study that is carried out mainly for
the sake of knowledge—with no immediate
interest in applying the results to daily
living—is called pure science.
Can technology solve all problems?
• Other scientists work in research that has
obvious and immediate applications.
• Technology is the
application of
scientific research to
society’s needs and
problems.
Can technology solve all problems?
• Science and
technology will
never answer all of
the questions we
ask, nor will they
solve all of our
problems.
Question 1
Explain the difference between
quantitative and qualitative information.
Quantitative information can be
expressed numerically, and may
also be used to generate graphs
or tables in order to
communicate data clearly.
Qualitative information is not
expressed numerically.
Observational data and written
descriptions of what scientists
observe, are qualitative
information.
U.S. Students Enrolled
in Physical Education
Male
Female
Question 2
Why is the SI system important to
scientists?
SI is the International System of Measurement.
The use of SI enables scientists anywhere in the
world to understand data reported by other
scientists, and makes peer review of results
easier.
SI Base Units
Measurement
Length
Mass
Time
Electric current
Temperature
Amount of substance
Intensity of light
Unit
meter
kilogram
second
ampere
kelvin
mole
candela
Symbol
m
kg
s
A
K
mol
cd
Question 3
Which of the following is an SI unit?
A. foot
B. pound
C. second
D. yard
The answer is C. Second is the SI unit of time.
SI Base Units
Measurement
Unit
Length
meter
Mass
kilogram
Time
second
ampere
Electric current
Temperature
kelvin
Amount of substance mole
Intensity of light
candela
Symbol
m
kg
s
A
K
mol
cd
Question 4
Explain how ethics are part of scientific
discoveries.
Ethics are a system of moral values or
principles of right conduct. The knowledge
gained through scientific research is not good
or bad, but some applications of scientific
knowledge may be considered unacceptable to
some people. It is the responsibility of society
as a whole to determine the ethical use of
scientific discoveries.
Question 5
How does technology benefit a society?
Technology is the application of scientific
research to society's needs and problems. It can
result in improvements in such areas as food
production, waste and pollution reduction, and
medical care. While technology has provided
numerous benefits, sometimes problems result
as well.
What is biology?
• Biology is the organized study of living things
and their interactions with their natural and
physical environments.
• All living things have four characteristics in
common: organization, reproduction, growth
and development, and the ability to adjust to
the environment.
The Methods of Biology
• Biologists use controlled experiments to
obtain data that either do or do not support a
hypothesis. By publishing the results and
conclusions of an experiment, a scientist
allows others to try to verify the results.
Repeated verification over time leads to the
development of a theory.
The Methods of Biology
• Scientific methods are used by scientists
to answer questions or solve problems.
Scientific methods include observing,
making a hypothesis, collecting data,
publishing results, forming a theory,
developing new hypotheses, and revising
the theory.
The Nature of Biology
• Biologists do their work in laboratories and
in the field. They collect both quantitative
and qualitative data from their experiments
and investigations.
• Scientists conduct investigations to increase
knowledge about the natural world.
Scientific results may help solve some
problems, but not all.