Transcript The Science of Biology

Chapter 1
Lecture
Slides
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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
Figure 1.1 The six kingdoms of life
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 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 relatively stable internal
environments to optimize conditions for metabolism
and other processes
1.2 Properties of Life
• 4. Growth and reproduction
 all organisms have the capacity for growth
and reproduction
• 5. Heredity
 all organisms pass genetic information to
future 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
Figure 1.4 Levels of organization:
cellular level
Figure 1.4 Levels of organization:
organismal level
Figure 1.4 Levels of organization:
populational 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
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 relatively
stable
 organisms act to control their internal environments
so that the complex processes of metabolism function
efficiently
1.5 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
1.5 Stages of a Scientific Investigation
•
The scientific process can be said to have
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
1.5 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
1.5 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.1.5 The scientific process
1.6 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
1.6 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 judgment and
intuition
1.6 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
1.7 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 1.10 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
• All living organisms are related to one another in
a common tree of descent
 the six kingdoms of life can be grouped into three
domains
• Charles Darwin’s theory of evolution explains the
unity and diversity of life as “descent with
modification”
 scientists have been able to identify changes in
individual genes that are responsible for differences
among individuals
Fig. 1.12 The three domains of life
Figure 1.13 The theory of evolution
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?
Is the Size of the Ozone Hole
Increasing?