Transcript Ch. 1
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 2 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 3 Defining Life 4 A View of 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 Levels of Biological Organization 6 Living Things: Acquire & Process Food A View of Life 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 7 Acquiring Nutrients 8 Living Things: Respond to Stimuli A View of Life 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 9 Living Things: Reproduce and Develop A View of Life 10 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 11 Living Things: Adapt to Change A View of Life 12 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 A View of Life 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 Terrestrial Ecosystems: A Grassland 14 Marine Ecosystems: A Coral Reef 15 A View of Life 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 A View of Life 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 17 A View of Life 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 A View of Life 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 H. sapiens Z. mays Species A View of Life Domains Bacteria Microscopic unicellular prokaryotes Archaea Bacteria-like unicellular prokaryotes Extreme aquatic environments Eukarya Eukaryotes – Familiar organisms 20 Domains: The Archaea 21 Domains: The Bacteria 22 A View of Life Kingdoms Archaea – Kingdoms still being worked out Bacteria - Kingdoms still being worked out Eukarya Kingdom Protista Kingdom Fungi Kingdom Plantae Kingdom Animalia 23 Domains: The Eukaryote Kingdoms 24 A View of Life 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 25 A View of Life 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 The Scientific Method: A Flow Diagram 27 The Scientific Method: Experimentation A View of Life 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 28 The Scientific Method: Results A View of Life 29 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 A View of Life 30 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 A View of Life 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 31 Controlled Experiments: The Variables A View of Life 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 32 Controlled Experiments: Observation & Hypotheses A View of Life 33 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 34 Controlled Experiments: Experimental Design A View of Life 35 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 36 Controlled Experiments: Results A View of Life 37 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 A View of Life 38 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 A View of Life 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 A Field Study 40 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 41 Ending Slide Chapter 01 A View of Life