Outline
Defining Life - Emergent Properties
Materials and Energy
Reproduction and Development
Adaptations and Natural Selection
Biosphere Organization
Human Population
Biodiversity
Classification
The Scientific Method
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
Defining Life
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
Living Things:
Acquire & Process Food
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
Acquiring Nutrients
Living Things:
Respond to Stimuli
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
Living Things:
Reproduce and Develop
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
Living Things:
Adapt to Change
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
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
Marine Ecosystems:
A Coral Reef
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
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
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
Levels of Classification
Domains
Bacteria
Microscopic unicellular prokaryotes
Archaea
Bacteria-like unicellular prokaryotes
Extreme aquatic environments
Eukarya
Eukaryotes – Familiar organisms
Domains:
The Archaea
Domains:
The Bacteria
Kingdoms
Archaea – Kingdoms still being worked out
Bacteria - Kingdoms still being worked out
Eukarya
Kingdom Protista
Kingdom Fungi
Kingdom Plantae
Kingdom Animalia
Domains:
The Eukaryote Kindoms
Scientific Names
Binomial nomenclature (two-word namess)
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
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
The Scientific Method:
Experimentation
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
The Scientific Method:
Results
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
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
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
Controlled Experiments:
The Variables
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
Controlled Experiments:
Observation & Hypotheses
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
Controlled Experiments:
Experimental Design
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
Controlled Experiments:
Results
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
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
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
Review
Defining Life - Emergent Properties
Materials and Energy
Reproduction and Development
Adaptations and Natural Selection
Biosphere Organization
Human Population
Biodiversity
Classification
The Scientific Method