Transcript A View of Life

Chapter 01
A View of Life
A View of Life
Outline
Defining Life - Emergent Properties
Materials and Energy
Reproduction and Development
Adaptations and Natural Selection
Biosphere Organization
Human Population
Biodiversity
Classification
The Scientific Method
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A View of Life
Defining Life (1)
Living things vs. nonliving objects:
Comprised of the same chemical elements
Obey the same physical and chemical laws
The cell is the smallest, most basic unit of all
life
Familiar organisms are multicellular
Some cells independent – single-celled
organisms
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Defining Life
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Defining Life (2)
Emergent Properties – Biological organization
Levels range from extreme micro to global
Each level up:
- More complex than preceding level
- Properties:
A
superset of preceding level’s properties
 Emerge
from interactions between components
Levels of Biological Organization
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Living Things:
Acquire & Process Food
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Energy - the capacity to do work
The sun:
- Ultimate source of energy for nearly all life on
Earth
- Drives photosynthesis
Metabolism - all the chemical reactions in a
cell
- Homeostasis - Maintenance of internal
conditions within certain boundaries
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Acquiring Nutrients
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Living Things:
Respond to Stimuli
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Living things detect changes in environment
Response often involves movement
Vulture can detect and find carrion a mile
away
Monarch butterfly senses fall and migrates
south
Microroganisms follow light or chemicals
Even leaves of plants follow sun
Responses collectively constitute behavior
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Living Things:
Reproduce and Develop
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Organisms live and die
Must reproduce to maintain population
Multicellular organisms:
Begins with union of sperm and egg
Developmental instructions encoded in genes
- Composed of DNA
- Long spiral molecule in chromosomes
Rockhopper Penguins & Offspring
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Living Things:
Adapt to Change
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Adaptation
Any modification that makes an organism
more suited to its way of life
Organisms, become modified over time
However, organisms very similar at basic level
- Suggests living things descended from same
ancestor
- Descent with modification - Evolution
- Caused by natural selection
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Organization of the Biosphere
Population - Members of a species within an
area
Community - A local collection of interacting
populations
Ecosystem - The communities in an area
considered with their physical environment
- How chemicals are cycled and re-used by
organisms
- How energy flows, from photosynthetic plants
to top predators
Terrestrial Ecosystems:
A Grassland
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Marine Ecosystems:
A Coral Reef
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Human Populations
Ecosystems negatively impacted by human
populations
Destroyed for agriculture, housing, industry, etc.
Degraded and destabilized by pollution
However, humans depend upon healthy ecosystems
for
Food
Medicines
Raw materials
Other ecosystem processes
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Biodiversity
Biodiversity:
The total number of species (est. 15 million)
The variability of their genes, and
The ecosystems in which they live
Extinction:
The death of the last member of a species
Estimates of 400 species/day lost worldwide
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Classification
Taxonomy:
The rules for identifying and classifying
organisms
Hierarchical levels (taxa) based on
hypothesized evolutionary relationships
Levels are, from least inclusive to most
inclusive:
- Species, genus, family, order, class, phylum,
kingdom, and domain
- A level usually includes more species than the
level below it, and fewer species than the one
above it
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Levels of Classification
Taxon
Human
Corn
Domain
Eukarya
Eukarya
Kingdom
Animalia
Plantae
Phylum
Chordata
Anthophyta
Class
Mammalia
Liliopsida
Order
Primates
Commelinales
Family
Hominidae
Poacae
Genus
Homo
Zea
H. sapiens
Z. mays
Species
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Domains
Bacteria
Microscopic unicellular prokaryotes
Archaea
Bacteria-like unicellular prokaryotes
Extreme aquatic environments
Eukarya
Eukaryotes – Familiar organisms
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Domains:
The Archaea
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Domains:
The Bacteria
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Kingdoms
Archaea – Kingdoms still being worked out
Bacteria - Kingdoms still being worked out
Eukarya
Kingdom Protista
Kingdom Fungi
Kingdom Plantae
Kingdom Animalia
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Domains:
The Eukaryote Kindoms
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Scientific Names
Binomial nomenclature (two-word names)
Universal
Latin-based
First word represents genus of organism
Second word is specific epithet of a species
within the genus
Always Italicized asa Genus species (Homo
sapiens)
Genus may occur alone (Homo), but not
specific epithet
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The Scientific Method:
Observation and Hypothesis
Begins with observation
 Scientists use their five senses
 Instruments can extend the range of senses
Hypothesis
 A tentative explanation for what was
observed
 Developed through inductively reasoning
from specific to general
The Scientific Method:
A Flow Diagram
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The Scientific Method:
Experimentation
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Experimentation
 Purpose is to challenge the hypothesis
 Designed through deductively reasoning
from general to specific
 Often divides subjects into a control group
and an experimental group
 Predicts how groups should differ if
hypothesis is valid
- If prediction happens, hypothesis is
unchallenged
- If not, hypothesis is unsupportable
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The Scientific Method:
Results
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Results
Observable, objective results from an
experiment
Strength of the data expressed in probabilities
The probability that random variation could
have caused the results
- Low probability (less than 5%) is good
- Higher probabilities make it difficult to dismiss
random chance as the sole cause of the results
The Scientific Method:
Conclusion and Review
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The results are analyzed and interpreted
Conclusions are what the scientist thinks
caused the results
Findings must be reported in scientific
journals
Peers review the findings and the conclusions
Other scientists then attempt to duplicate or
dismiss the published findings
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Scientific Theory
Scientific Theory:
Joins together two or more related
hypotheses
Supported by broad range of observations,
experiments, and data
Scientific Principle / Law:
Widely accepted set of theories
No serious challenges to validity
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Controlled Experiments:
The Variables
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Experimental (Independent) variable
Applied one way to experimental group
Applied a different way to control group
Response (dependent) variable
Variable that is measured to generate data
Expected to yield different results in control
versus experimental groups
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Controlled Experiments:
Observation & Hypotheses
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Observations:
Nitrate fertilizers boost grain crops, but may
damage soils
When grain crops are rotated with pigeon pea
it adds natural nitrogen
Hypothesis:
Pigeon pea rotation will boost crop
production as much as nitrates
Pigeon pea rotation will NOT damage soils
Root Nodules
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Controlled Experiments:
Experimental Design
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Experimental Design
Control Group
- Winter wheat planted in pots without fertilizer
Experimental Groups
- 1-Winter wheat planted in pots with 45 kg/ha
nitrate
- 2-Winter wheat planted in pots with 90 kg/ha
nitrate
- 3-Winter wheat planted in pots that had grown a
crop of pigeon peas
All groups treated identically except for above
Crop Rotation Study
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Controlled Experiments:
Results
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Experimental Prediction:
Wheat production following pigeon pea
rotation will be equal or better than following
nitrate fertilizer
Results
45 kg/ha produced slightly better than
controls
90 kg/ha produced nearly twice as much as
controls
Pigeon pea rotation did not produce as much
as the controls
Controlled Experiments:
Conclusion & Revision
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Conclusion
Research hypothesis was not supported by
results
However, research hypothesis was not proven
false by negative results
Revised experiment
Grow wheat in same pots for several
generations
Look for soil damage in nitrate pots and
improved production in pigeon pea pots
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Controlled Experiments:
Revised Results & Conclusion
Results
After second year:
- Production following nitrates declined
- Production following pigeon pea rotation was
greatest of all
After third year
- Pigeon pea rotation produced 4X as much as
controls
Revised conclusions
Research hypothesis supported
Pigeon pea rotation should be recommended
over nitrates
A Field Study
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A View of Life
Review
Defining Life - Emergent Properties
Materials and Energy
Reproduction and Development
Adaptations and Natural Selection
Biosphere Organization
Human Population
Biodiversity
Classification
The Scientific Method
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Ending Slide Chapter 01
A View of Life