Download The Science of Biology - McGraw Hill Higher Education

The Living World
Fifth Edition
George B. Johnson
Jonathan B. Losos
Chapter 1
The Science of Biology
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1.1 The Diversity of Life
• Biology is the study of living things
• Living things are diverse
• There are enough similarities among some living
things that they can be grouped into the same
kingdom
• Members of different kingdoms are usually very
different from each other
The Six Kingdoms of Life Figure 1.1
1.2 Properties of Life
• What qualifies something as “living” versus “nonliving?”
• Consider these points
 complexity
 movement
 response to stimulation
• A life-defining property must be exclusive to
living things
1.2 Basic Properties of Life
• 1. Cellular organization
 all living things are comprised of at least one cell
• 2. Metabolism
 all living things process energy which is used to
power other processes
• 3. Homeostasis
 all living things maintain stable internal environments
to optimize conditions for metabolism and other
processes
1.2 Basic Properties of Life
• 4. Growth and reproduction
 all organisms have the capacity for growth
and reproduction
• 5. Heredity
 all organisms pass genetic information across
generations from parents to offspring
1.3 The Organization of Life
• Living things function and interact with
each other on many levels
• The organization of life is a hierarchy of
levels of increasing complexity
 cellular
 organismal
 populational
Fig. 1.4 Cellular Level
Fig. 1.4 Organismal Level
Fig. 1.4 Population Level
1.3 The Organization of Life
• At higher levels of the living hierarchy, new
properties become apparent that were absent at
the lower levels
• These emergent properties result from the
interaction of diverse but simpler components
• Many higher order processes that are hallmarks
of life are emergent properties
 metabolism
 consciousness
1.4 Biological Themes
• The study of life is organized around
general themes
• 5 biological themes emerge repeatedly at
any hierarchical level of biological study
 refer to Table 1.1
1.4 Biological Themes
• 1. Evolution
 evolution is genetic change in a species over time
 the mechanism for evolution is natural selection
 the diversity of life is explained by evolutionary
processes
1.4 Biological Themes
• 2. The Flow of Energy
 all living things require energy
 energy from the sun flows through the living world
 organisms acquire energy differently
 how much energy is available determines how many
and what kinds of organisms can live together in an
ecosystem
1.4 Biological Themes
• 3. Cooperation
 as energy and other resources are limiting,
many organisms have evolved cooperation as
a means of survival
 symbiosis describes when two species live in
direct contact
1.4 Biological Themes
• 4. Structure Determines Function
 evolution favors structures that function in an
adaptive manner
 many structures are specialized for a particular
function
 the convergence of structure and function occurs at
levels of the organizational hierarchy
1.4 Biological Themes
• 5. Homeostasis
 homeostasis is a physiological condition of “steadystate”
 the internal environment of organisms is remarkably
stable
 organisms act to control their internal environments
so that the complex processes of metabolism function
efficiently
1.5 How Scientists Think
• Science is a process of investigation,
using observation, experimentation, and
reasoning
• There are different philosophical
approaches to reasoning
1.5 How Scientists Think
• Deductive reasoning uses general
principles to explain specific observations
• This form of reasoning is common to many
disciplines, including
 mathematical proofs
 politics
 computing
1.5 How Scientists Think
• Inductive reasoning is the way of discovering
general principles from examination of specific
observations
• Scientists employ inductive reasoning by forming
and testing possible explanations for specific
observations
• These possible explanations are called
hypotheses
Figure 1.5 Deductive and inductive
reasoning
1.6 Science in Action: A Case Study
• Scientist Joseph Farman observed in 1985 that
ozone levels in Anarctica are alarmingly low
• Pollution by chloroflourocarbons (CFCs) was
later found to be the culprit
• CFCs were common components of many
synthetic products, such as
 coolants used in air conditioners
 propellants in aerosols
 foaming agents in Styrofoam
Figure 1.6 How CFCs attack and
destroy ozone
1.6 Science in Action: A Case Study
• Ozone depletion is a serious matter
 ozone acts as a sunscreen against ultraviolet
rays from the sun
 a 1% drop in ozone leads to a 6% increase in
skin cancer
• A world-wide reduction in CFC production
has helped alleviate ozone depletion
1.7 Stages of a Scientific Investigation
• Biology is a dynamic science with new
ideas appearing and replacing old ones
• Scientists systematically conduct
experiments to evaluate hypotheses about
observed phenomena
1.7 Stages of a Scientific Investigation
•
The scientific process has six stages
•
1. Observation

•
science begins with careful observation of natural
phenomena
2. Hypothesis


scientists make an educated guess that might be true
often scientists formulate multiple ideas about a
phenomenon; these are called alternative hypotheses
1.7 Stages of a Scientific Investigation
• 3. Predictions
 if a hypothesis is correct, then specific
consequences can be expected
• 4. Testing
 scientists conduct experiments to attempt to
verify predictions made by hypotheses
1.7 Stages of a Scientific Investigation
• 5. Controls
 experiments usually employ a parallel design
• scientists use a control to assess the influence of
potential factors, called variables
• conditions stay the same in the control in
comparison to the variable condition
• 6. Conclusion
 a hypothesis that has been tested and not
rejected is tentatively accepted
Fig.1.7 The scientific process
1.7 Stages of a Scientific
Investigation
• Scientific research involves analyzing data
before reaching any conclusion
• Scientists must present their results
carefully so that others can interpret them
1.8 Theory and Certainty
• The term “theory” means different things
to different audiences
 to scientists,
• a theory represents certainty and is a unifying
explanation for a broad range of observations
 to the general public,
• a theory implies a lack of knowledge or guess
1.8 Theory and Certainty
• Scientists’ acceptance of theory is
provisional
 the possibility always remains that future
evidence will cause a theory to be revised
• The process of science is not just trialand-error but involves judgement and
intuition
1.8 Theory and Certainty
• science has limitations
 it is limited to organisms and processes
that can be observed and measured
• supernatural and religious phenomena are
beyond the scope of science
 there are also practical limits
• science cannot be relied upon to solve all
problems
1.9 Four Theories Unify Biology as
a Science
• 1. The Cell Theory
• 2. The Gene Theory
• 3. The Theory of Heredity
• 4. The Theory of Evolution
The Cell Theory
• all organisms are composed of at least one cell
• the cell is the most basic unit of life
• all cells come from pre-existing cells
The Gene Theory
• genetic information is encoded in molecules of
deoxyribonucleic acid (DNA)
• genes encode specific proteins or RNA or act to
regulate other genes
• the proteins and RNA encoded by an organism’s
genes determine what it will be like in terms of
form and function
Figure 1.12 The gene theory
The Theory of Heredity
• genes are passed down generations as discrete
units
 Mendel’s theory of heredity gave rise to the
field of genetics
 chromosomal theory of inheritance located
Mendelian genes on chromosomes
The Theory of Evolution
• Charles Darwin’s theory of evolution explains the
unity and diversity of life as “descent with
modification”
• All living organisms are related to one another in
a common tree of descent
Fig. 1.15 The tree of life
Classifying Life’s Diversity
• Scientists group organisms, based on
similarities, into six kingdoms
• Each of the six kingdoms are assigned, on the
basis of cell structure into one of three domains
Figure 1.16 The three domains of life
Inquiry & Analysis
• What is the dependent
variable?
• Is the size of the ozone
hole increasing?
• Why are the rates of
increase different
between 1980 - 1990 and
1995 - 2005?