Chapter 1 Methods and Concepts in Biology
I. Introduction
A. What is life?
1. The answer changes during our path to maturity.
2. The degree of insight changes with experience and education.
3. This book is biology revisited. It will provide:
a. Deeper understanding.
b. A more organized level of understanding.
B. To biologists, life reflects its ancient molecular origins and its degree of
organization. Life is:
1. A way of capturing and using energy and materials.
2. A commitment to a program of growth and development.
3. A capacity for reproduction.
4. An adjustment to changing conditions.
C. Life cannot be understood in isolation from its history and adaptive potential.

II. Shared Characteristics of Life
A. DNA and Biological Organization
1. Living and nonliving matter are composed of the same particles,
operating according to laws governing energy.
2. Deoxyribonucleic acid, or DNA, is the special molecule that sets the
living world apart from the nonliving by carrying the hereditary
instructions for assembly of new organisms.
3. The cell, composed of “biological molecules,” is the basic unit of life.
4. Multicelled organisms have increasingly complex levels of organization
that result in tissues >> organs >> organ systems >> organisms >>
populations >> communities >> ecosystems >> biosphere.
B. Metabolism
1. Metabolism is the cell’s capacity to:
a. extract and transform energy from its surroundings,
b. use energy for maintenance, growth, and reproduction.
2. By photosynthesis, plants acquire energy from sunlight and store it as
chemical energy in carbohydrates and ATP.
3. In aerobic respiration, cells release stored chemical energy.
C. Interdependency Among Organisms
1. Energy flows from the sun.
a. Plants (“producers”) trap this energy by photosynthesis.
b. Animals (“consumers”) feed on the stored energy in plants, using
aerobic respiration.
c. Bacteria and fungi (“decomposers”) break down complex molecules
of other organisms to simple raw materials suitable for recycling.
2. All organisms are part of webs that depend on one another for energy
and raw materials.
D. Homeostasis
1. Homeostatic controls allow organisms to detect environmental changes
via receptors and make controlled responses to:
a. heat and cold,
b. harmful substances,
c. varying food supplies.
2. Homeostasis refers to a state in which the conditions of the “internal
environment” are maintained within a tolerable range.
3. Homeostatic mechanisms control blood sugar levels.
a. Increased sugar causes insulin release, which stimulates cells to take
up sugar.
b. Decreased blood sugar causes another hormone to call on stored
sugar reserves.
E. Reproduction
1. Each organism arises through reproduction&emdash;the production of offspring
by one or more parents.
2. Each organism is part of a reproductive continuum that extends back
through countless generations.
F. Mutation and Adapting to Change
1. Hereditary instructions are encoded in molecules of DNA.
2. Variations in hereditary instructions arise through mutations.
a. Mutations are changes in the kind, structure, sequence, or number of
parts of DNA.
b. Most mutations are harmful.
c. Some may be harmless or even beneficial.
3. The environment tests the combination of patterns expressed in each
organism and may prove the trait adaptive&emdash;increases survivability
and reproduction.

III. Life’s Diversity
A. Five Kingdoms, Millions of Species
1. Attempts to clarify the diversity of life forms led to classification schemes.
2. All organisms can be identified by a genus and species name; example:
Ursus americanus (black bear).
3. Groupings from least inclusive to most inclusive are: genera >> family >>
order >> class >> division or phylum >> kingdom.
4. Five kingdoms are presently recognized:
a. Monera&emdash;bacteria.
b. Protista&emdash; one-celled organisms.
c. Fungi &emdash;- molds, mushrooms.
d. Plantae&emdash;familiar multicellular plants.
e. Animalia&emdash;multicellular animals from sponges to humans.
B. An Evolutionary View of Diversity
1. Natural selection of adaptive variations has resulted in the great diversity
of living forms.
2. Charles Darwin reasoned that the practice of artificial selection used by
pigeon breeders could serve as a model for his theory of natural
selection.
a. Members vary in form and behavior; much of the variation is heritable.
b. Some varieties of heritable traits will improve survival and
reproductive chances.
c. Those with improved chances will be more likely to reproduce and
pass the adaptive traits on with greater frequency in future
generations (natural selection).
d. Over time the character of a population may change and lead to
different lines of organisms (evolution).

IV. The Nature of Biological Inquiry
A. On Scientific Methods
1. A principle is a way of explaining a major phenomenon of nature.
2. Explanations are sought using the following approach:
a. Ask a question.
b. Make a hypothesis (educated guess) using all known information.
c. Predict what the outcome would be if the hypothesis is valid
(deductive, “if-then” reasoning).
d. Test the hypothesis by experiments, models, and observations.
e. Repeat the tests for consistency.
f. Examine alternative hypotheses in same manner.
g. Report objectively on the tests and conclusions.
B. Testing Alternative Hypotheses
1. The hypothesis should be phrased as an “if-then” statement, which has a
testable “prediction” in it.
2. Each hypothesis and all the alternates should be repeatedly tested to
provide reliability.
C. The Role of Experiments
1. In contrast to observations, in experiments nature is manipulated.
2. The control group is treated in an identical manner as the experimental
group except for the variable under study.
D. About the Word “Theory”
1. A theory is a related set of hypotheses that form a broad-ranging
explanation of many phenomena.
2. Theories are accepted or rejected on the basis of tests and are subject to
revision.
E. Uncertainty in Science
1. Scientists must be content with relative certainty, which becomes
stronger as more repetitions are made.
2. Scientists must be prepared to change their minds in light of new
evidence.
F. The Limits of Science
1. Science is limited to questions that can be tested.
a. Subjective questions cannot be addressed.
b. All of human society must participate in moral, aesthetic, and other
such judgments.
2. Science may be considered controversial when it offers explanations for
an aspect of nature previously considered supernatural.
a. Copernicus correctly stated that the earth circled the sun&emdash;a heresy in
his day.
b. The external world, not internal conviction, must be the testing ground
for science.