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Lecture 1 Notes – Biology: Exploring Life What are the general characteristics shared by living organisms? What is the relationship between evolutionary change and the study of biology? How do scientists use the scientific method to study living organisms? 1.1 Defining and Organizing Life Biology – scientific study of life Unicellular organisms-­‐ each cell performs all life functions Multicellular organisms – specialization of cell function Levels of Organization – horizontal levels – give examples! • Biosphere – all environments on Earth that support life (most land, water, lower atmos.) • Ecosystem – all living and non living in an area • Community – all living in an area • Population – interacting individuals of same species • Organism – one individual living thing • Organ system – organs working together for vital body function • Organ – more specific function • Tissue – cooperative group of similar cells with specific function • Cell – unit of living matter separated from environment by boundary (membrane) -­‐ structural and functional units of life – lowest level of structure performing all activities of life • Organelle – a structure with a specific function within the cell • Molecule – cluster of atoms held by chemical bonds • Atom – smallest particle of matter Emergent Properties – whole larger than sum of parts – give example Characteristics of life • Regulates internal environment (homeostasis) – feedback and control mechanisms in organism • Takes in and uses energy o Energy – the capacity to do work o Metabolism – sum of chemical reactions – anabolism + catabolism o Photosynthesis – solar energy to stored chemical energy -­‐ ultimate source of energy for life on Earth is Sun • Response to environment – stimulus/response • Adaptations – modifications to function in particular environment • Growth and development • Reproduces – pass on genes – produce more of their kind • DNA – genetic material of life – double helix – 4 kinds of chemical blocks – order of blocks = instructions for making proteins (enzymes, pigments, hair, horns, venom, etc) • Order – complex organization • Evolution – change over time (generations) 1.2 Evolution and Taxonomy Three Domains of life – vertical organization of life • Species – 1.8 million named so far – binomial nomenclature for each – Genus species • Taxonomy – branch of biology that names and classifies species • Systematics – study of evolutionary relationships between organisms • Taxa – domain, kingdom, phylum, class, order, family, genus, species • Binomial nomenclature – genus + specific epithet – in Latin • Prokaryotic cells vs. Eukaryotic cells – all have membrane and DNA – explain differences • Domains o Bacteria – unicellular and microscopic – prokaryotic  Obtain nutrients by absorption, photosynthesis, or chemosynthesis o Archaea – extreme environments – unicellular – prokaryotic  Obtain nutrients by absorption or chemosynthesis  Unique chemical characteristics o Eukarya  Protists – aquatic/moist habitats – no diversification of tissue – mostly unicellular – algae (multicellular) – food by multiple methods (catch-­‐all kingdom)  Plants – multicellular – produce own food photosynthesis – cellulose cell walls – diversification of tissue  Fungi – multi-­‐ and uni-­‐ cellular – often decomposers – digest food outside the body and absorb nutrients – molds, yeasts, mushrooms – chitin cell walls  Animals – multicellular – ingest food – no cell walls – motile – diversification of tissue Evolution • Darwin – descent with modification – 1859 Origin of Species • Natural selection o Individual variation o Overproduction and competition o Unequal reproductive success • Evolutionary adaptation – accumulation of favorable variations in population over time • Example o Beetle population varying in color light gray to charcoal o Recent fire = blackened soil o Predatory birds eat beetles they see most easily = the light colored ones = darker beetles have greater survival and reproductive success o Surviving beetles reproduce = population changes (evolution by natural selection) 1.3 Interconnecting webs – ecosystem interactions between living and nonliving • Producers – produce food for ecosystem – traps sunlight, CO2, H2O, minerals from soil – makes sugar, oxygen • Consumers – eat plants and other animals – takes in O2, sugars – makes CO2, H2O, puts waste into soil • Decomposers – recycle dead matter into nutrients • Cycle of gases, nutrients, energy o Gases and nutrients cycle through ecosystem o Energy flows through ecosystem •
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Biodiversity – total number and relative abundance of species, variability of genes, and different ecosystems in which they live Extinction – human impact 1.4 -­‐The Process of Science Discovery Science • Inductive reasoning (V)– little observations to big principle o If it is true in all these little incidence, we can infer that it is generally true. o Every time I let go of something, it falls to the ground; therefore all things fall to the ground. -­‐ Induction • Deductive reasoning (^)– general principle to specific (if all organisms are made of cells and humans are organisms then humans are made of cells) o If… then … Hypothesis-­‐Based Science – a tentative answer to some question that can be tested Experimental Studies – setting up experiment with controlled and tested variables -­‐ scientific method • Hypothesis – an informed statement that can be tested by scientific process • Prediction – expected outcome • Experimental design – ensures examination of a specific variable, the experimental variable – contains a test group and a control group • Data – results – observable and objective • Standard deviation – statistical analysis of how much the data varies • Case study of dead flashlight (observation, question, hypothesis 1: dead batteries, prediction: replace batteries will solve problem, test prediction, test falsifies hypothesis or does not falsify) Scientific Theories – concepts that join together well-­‐supported and related hypotheses Examples: • Cell Theory – all organisms are composed of cells, and new cells come only from preexisting cells • Homeostasis Theory – internal environment of an organisms stays relatively constant –
within a range that is protective of life • Gene Theory – Organisms contain coded information that dictates form, function, and behavior • Ecosystem Theory – Organisms are members of populations, which interact with each other and the physical environment within a particular locale • Evolution Theory – all living things have a common ancestor, but each is adapted to a particular way of life Statistical Studies – gathering numerical information from various sources and analyzing it to form a conclusion • Example – to determine whether there is association with birth spacing and a healthy baby, correcting for maternal health and socioeconomic status • The more data, the more reliable • It is a correlation study and it does not imply causation • Another example: Obese mothers have 67% greater risk of having autistic child Field Study – based on observations • Mating habits of gorillas • Migratory patterns of butterflies