Download Chapter 1 The Science of Life

Ch 1 – The Science of Life
1
The World of Biology
• Biology: The study of life
• Characteristics of life
• Organization and Cells
• Response to Stimuli
• Homeostasis
• Metabolism
• Growth and Development
• Reproduction
• Change Through Time
Organization and Cells
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•
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•
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All living things are composed of
one or more cells
Cells are the smallest units that
can perform all life’s processes
In multicellular organisms, many
are specialized to perform
specific functions
Cells are always very small
The size of multi-celled
organisms depends on the
number of cells NOT their size
Organization and Cells, cont.
•
•
•
Organized at both the
molecular and cellular
levels
Take in substances from
the environment and
organize them in complex
ways
Specific cell structures
(organelles) carry out
particular functions
•
In multicellular organisms, cells and groups of cells are
organized by their function (hierarchy of life)
• Atom  Biological Molecule  Organelle  Cell 
Tissue  Organ  Organ System  Organism
Response to Stimuli
•
Organisms can respond to a stimulus, or a
physical or chemical change in the
internal or external environment
Homeostasis
• The maintenance of a stable level of internal
conditions even though environmental conditions are
constantly changing, (like: body temperature, water
content, glucose levels)
Metabolism
• The sum of all the chemical reactions that take in and
transform energy and materials from the environment
PHOTOSYNTHESIS
Growth and Development
• All living things grow and increase in size from the
division and enlargement of cells
• Development is the process by which an organism
becomes a mature adult; involves cell division and cell
differentiation, or specialization
Reproduction
• Production of new organisms is essential for the
continuation of a species
• Hereditary information is transferred to offspring
during two kinds of reproduction
• Sexual reproduction – hereditary information
recombines from two organisms of the same
species
• Asexual reproduction – hereditary information
from different organisms is not combined ~
original and new organisms are genetically the
same
Evolution or Change Through Time
• Populations of living organisms evolve or change
through time to better adapt to changing conditions
• Charles Darwin’s SURVIVAL OF THE FITTEST
through the process of natural selection
THEMES IN BIOLOGY
• Diversity and Unity
• Unity in the Diversity of Life
• Three Domains of Life
• Interdependence of Organisms
• Evolution of Life
• Natural Selection
Unity in the Diversity of Life
• Genetic code: rules that govern how cells use the
hereditary information in DNA (deoxyribonucleic acid
– makes up our genes or instructions for life)
• Presence of organelles: carry out all cellular
activities
• “Tree of Life” – suggests all living things have
descended with modification from a single common
ancestor; thus, all of life is connected
Three Domains of Life
• Bacteria
• Kingdom
• Archaea
• Kingdom
• Eukarya
• Kingdom
• Kingdom
• Kingdom
• Kingdom
Bacteria (Eubacteria)
Archaea (Archaebacteria)
Animalia
Plantae
Fungi
Protists
Interdependence of Organisms
• Ecology: branch of biology that studies organisms
interacting with each other and with the environment
• Ecosystems: communities of living species and their
physical environments; e.g., minerals, nutrients, water,
gases, heat, etc.
Evolution of Life
• Descent with modification: process in which the
inherited characteristics within populations change
over generations, such that genetically distinct
populations and new species can develop
• Natural Selection: organisms that have certain
favorable traits are better able to survive and
reproduce successfully than organisms that lack
these traits
• Adaptations: traits that improve an individual’s
ability to survive and reproduce
Scientific Method
Scientific Processes and Methods
• 1. Observations/Questioning
• 2. Measuring, Organizing Data, and Classifying
• 3. Hypothesizing -- a testable explanation based
on experience, reading, and/or previous
experiments. (NOT A GUESS)
• Inductive Reasoning
• 4. Predicting -- stating in advance the result that
will be obtained from testing
• Deductive Reasoning (If…then…statement)
Scientific Method, cont.
• 5. Experimenting -- A controlled procedure for
testing a hypothesis
• Control Group -- all conditions remain constant
• Experimental Group -- same as control, except
for ONE factor
• Variable
• Independent Variable - condition that
changes
• Dependent Variable - response to changed
condition
• Data
• Qualitative ~ descriptive (think quality)
• Quantitative ~ numbers (think quantity)
Scientific Method, cont.
Scientific Method, cont.
• 6. Organizing and Analyzing Data
Scientific Method, cont.
• 7. Inferring Conclusions (concluding from
evidence collected during experimentation
using facts and previous knowledge rather
than direct observations)
• 8. Modeling and Communicating
• 9. Test and Re-test ~ law or theory
formed
Scientific Method, cont.
• LAW -- general statement that describes a wide
variety of phenomena
• If a hypothesis describes HOW things happen
and continues to be supported by evidence, it
becomes a law.
• THEORY -- most probable explanation for a set of
data based on best available evidence
• If a hypothesis describes WHY things happen
and continues to be supported by evidence, it
becomes a theory.
Scientific Method -- Example
• Observations:
• Fish populations in Twin Lakes are declining.
• The pH (acidity) of the water in the lakes is
dropping to 4.2.
• One hundred miles west of Twin Lakes is a power
plant that is burning tons of coal every year,
releasing sulfur dioxide into the air.
Problem
• Twin Lakes -- Acid Rain Problem
100
miles
Power
Plant
West
Branch
East
Branch
Questioning/Hypothesizing
(Inductive Reasoning)
• Question: Is there a link between the power
plant, the pH of the lake, and the fish
decline?
• Hypothesis: If acid rain falling on Twin Lakes
is related to fish reproduction, then increasing
acid rain amounts will cause the fish to have
poor reproduction.
Experiment
• Experiment
• Twin Lakes is a lake in the mountains that can be
divided by a barrier.
• A complete inventory will gather baseline data.
• One arm of the lake, on the east side of the barrier,
will be treated with sulfuric acid to reduce the pH to
4.0.
• The west arm of the lake will be left alone, other
than monitoring.
Experiment
• Twin Lakes -- Acid Rain Problem
100
miles
East
Branch
West
Branch
Barrier
Power
Plant
No Acid Added
Acid Rain Added
Results
• East Branch:
• Fish stop reproducing.
• West Branch:
• No change in fish reproduction.
Conclusion
• The power plant emits sulfur dioxide into
the air which combines with rain to
produce acid rain. The addition of this
acidic rain to the lakes lowers the pH and
causes the fish to stop reproducing. This
results in declining fish populations and
jeopardizes the survival of the fish.