A View of Life 1 Defining Life (1) How do you know if something is alive? What are properties of living things that non- livings things do no possess? What is the smallest living thing you can think of?

A View of Life So what is required of life? Living “things” are: 2

A View of Life 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 Levels of Biological Organization

A View of Life 6 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

7 Acquiring Nutrients

A View of Life 8 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

A View of Life 9 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

10 Rockhopper Penguins & Offspring

A View of Life 11 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

A View of Life So what is required of life? Living “things” eat give off wastes reproducebreathedie respond to their environment adapt contain heritable material 12

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

14 Terrestrial Ecosystems: A Grassland

15 Marine Ecosystems: A Coral Reef

16Classification What kinds of music do you listen to? What kinds of music are there?

A View of Life 17ClassificationTaxonomy:  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 18 Levels of Classification Z. mays H. sapiens Species ZeaHomoGenus PoacaeHominidaeFamily CommelinalesPrimatesOrder LiliopsidaMammaliaClass AnthophytaChordataPhylum PlantaeAnimaliaKingdom EukaryaEukaryaDomain CornHumanTaxon

A View of Life 19DomainsBacteria  Microscopic unicellular prokaryotes Archaea  Bacteria-like unicellular prokaryotes  Extreme aquatic environments Eukarya  Eukaryotes – Familiar organisms

20 Domains: The Archaea

21 Domains: The Bacteria

A View of Life 22Kingdoms 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 Kindoms

A View of Life 24 Scientific Names Binomial nomenclature (two-word names) UniversalLatin-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