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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:

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Outline

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  1. A View of Life

  2. Outline • Defining Life - Emergent Properties • Materials and Energy • Reproduction and Development • Adaptations and Natural Selection • Biosphere Organization • Human Population • Biodiversity • Classification • The Scientific Method

  3. 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

  4. Defining Life

  5. 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

  6. Levels of Biological Organization

  7. 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

  8. Acquiring Nutrients

  9. 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

  10. 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

  11. Rockhopper Penguins & Offspring

  12. 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

  13. 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

  14. Terrestrial Ecosystems:A Grassland

  15. Marine Ecosystems:A Coral Reef

  16. 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

  17. 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

  18. 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

  19. 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 • Species • H. sapiens • Z. mays

  20. Domains • Bacteria • Microscopic unicellular prokaryotes • Archaea • Bacteria-like unicellular prokaryotes • Extreme aquatic environments • Eukarya • Eukaryotes – Familiar organisms

  21. Domains:The Archaea

  22. Domains:The Bacteria

  23. Kingdoms • Archaea – Kingdoms still being worked out • Bacteria - Kingdoms still being worked out • Eukarya • Kingdom Protista • Kingdom Fungi • Kingdom Plantae • Kingdom Animalia

  24. Domains:The Eukaryote Kindoms

  25. 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

  26. 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

  27. The Scientific Method:A Flow Diagram

  28. 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

  29. 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

  30. 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

  31. 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

  32. 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

  33. 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

  34. Root Nodules

  35. 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

  36. Crop Rotation Study

  37. 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

  38. 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

  39. 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

  40. A Field Study

  41. Review • Defining Life - Emergent Properties • Materials and Energy • Reproduction and Development • Adaptations and Natural Selection • Biosphere Organization • Human Population • Biodiversity • Classification • The Scientific Method

  42. A View of Life

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